Glossary

Medical technology glossary

594 terms used by biomedical and clinical engineers, each defined in plain language. The same glossary is part of Essentia's library and of the Medical City learning layer.

5 gauss line: The boundary around an MRI scanner where the field reaches 0.5 mT. Inside it, pacemakers and some implants may be affected; public access is controlled. Also: 0.5 mT line.
5 Whys: A questioning technique that asks why repeatedly to dig beneath a symptom. Useful for thinking, but not proof; each answer needs evidence. Also: five whys.
Acceptance testing: Checks on a new device before first use: correct items delivered, no damage, electrical safety and performance tests passed, records created. Also: acceptance test, incoming inspection.
Accreditation: Formal recognition by an independent body that a service meets a defined standard, checked by assessment and regular audits. Also: service accreditation.
Accuracy: How close a measurement is to the true value.
Adjacency: How close departments or rooms are to each other. Good adjacency puts linked services, like ED and CT, near each other to save critical minutes. Also: clinical adjacency.
Administration set: The disposable tubing that carries fluid from the bag to the patient through an infusion pump. Only sets approved for that pump model give accurate flow. Also: giving set, infusion set.
ADT feed: HL7 messages that tell other systems when a patient is admitted, moved or discharged, keeping patient details and locations in step. Also: admission discharge transfer, ADT messages.
Adverse incident: An event caused by or involving a device that led to, or could have led to, harm or death. In the UK it should be reported via the Yellow Card scheme. Also: device incident.
AED: A defibrillator for use by anyone: it analyses the rhythm itself and tells the user when to shock. Pads and battery expiry checks keep it ready. Also: automated external defibrillator.
Air changes per hour: How many times the volume of air in a room is replaced each hour. Conventional theatres need about 25. Also: ACH, air change rate.
Air-in-line detector: An ultrasonic sensor that detects air bubbles in tubing and stops the pump, protecting the patient from air embolism. Also: air detector.
Airborne infection isolation room: A room kept at lower pressure than its surroundings so infectious air does not escape, with an anteroom and high air change rate. Also: AIIR, negative pressure room.
ALARP: The principle of keeping radiation dose, or any risk, as low as reasonably practicable using time, distance and shielding. Also: as low as reasonably practicable, ALARA.
Aliasing: A false low-frequency signal created when a signal is sampled too slowly, at less than twice its highest frequency.
ALS: Resuscitation by trained staff that adds rhythm analysis, defibrillation, airway devices, IV access and drugs to basic CPR, following a set algorithm. Also: advanced life support.
Alternative method: An IEC 62353 leakage method where mains parts are shorted together and a test voltage is applied. Safe and repeatable, but the device is not powered normally.
Anaesthesia machine: A workstation that mixes oxygen, air and anaesthetic vapour, delivers it through a breathing system, ventilates and monitors gases. Safety features stop a hypoxic mix. Also: anaesthetic workstation, anesthesia machine.
Anaesthetic agent: A drug that produces anaesthesia. Volatile agents are liquids vaporised into the breathing gas; each needs its own calibrated vaporiser. Also: volatile agent, inhalational agent.
Anaesthetic gas scavenging system: A system that collects waste anaesthetic gases from the breathing system and removes them from the theatre to protect staff. Flow must be in range. Also: AGSS, scavenging.
Anaesthetic vaporiser: A device on the anaesthesia machine that adds a controlled concentration of volatile agent such as sevoflurane to the fresh gas. Output depends on temperature compensation. Also: vaporiser, vaporizer.
Analogue-to-digital converter: A circuit that turns a continuous signal into numbers. Its resolution and sampling rate limit the detail a device can capture. Also: ADC (electronics).
Anti-free-flow clamp: A clamp on an administration set that closes automatically when the set is removed from the pump, preventing uncontrolled flow to the patient. Also: free-flow protection.
APL valve: A spring-loaded valve on the anaesthetic breathing system that lets the anaesthetist set the pressure at which excess gas escapes. Also: adjustable pressure limiting valve.
Apnoea: A pause in breathing, commonly defined as 20 seconds or more in newborns. Apnoea monitors and ventilators alarm when breathing stops. Also: apnea, breathing pause.
Applied part: The part of a medical device that must touch the patient for it to work, such as ECG electrodes, a probe or a cuff. It is typed B, BF or CF by how well it is isolated.
Applied part leakage current: Leakage that flows from the applied parts when mains voltage is applied to them in the test. IEC 62353 limits: type BF 5000 µA, type CF 50 µA. Also: patient leakage (applied part).
Approved body: An organisation designated in Great Britain to assess devices against UK regulations before the UKCA mark can be applied. Also: UK approved body.
APTT: A blood test of how long plasma takes to clot. Used to monitor heparin; a ratio above the target range means a higher bleeding risk. Also: activated partial thromboplastin time, APTT ratio.
Area valve service unit: A lockable valve box that isolates the gas supply to one area for emergencies or maintenance, without shutting off the rest of the hospital. Also: AVSU, zone valve.
Arterial blood gas: A test of arterial blood measuring pH, PaO2, PaCO2, bicarbonate and often lactate and electrolytes, showing breathing and acid-base status. Also: ABG, blood gas.
As-built drawings: Drawings showing exactly how something was actually installed, including any changes from the design. Essential for later maintenance and fault finding. Also: record drawings, as-installed drawings.
Asset register: The list of every managed device with its ID, model, serial number, location, owner and status. The base for maintenance, recalls and capital planning. Also: equipment inventory, inventory.
Asystole: No electrical activity in the heart. Not shockable; treated with CPR and adrenaline. Always check leads and gain before accepting a flat trace as asystole. Also: flatline.
Atrial fibrillation: An irregular rhythm where the atria quiver instead of contracting. Common in older adults; raises stroke risk because clots can form in the atria. Also: AF, a-fib.
Audit log: A system's record of who did what and when, such as logins, setting changes and alarms. Important evidence in investigations. Also: audit trail, event log.
Authentication: Checking that a user or device is who it claims to be, for example by password, card or a second factor, before giving access. Also: login, multi-factor authentication, MFA.
Authorised person (MGPS): The person appointed in writing to manage medical gas systems and issue permits to work on them. Also: AP(MGPS), AP.
Autoclave: A pressure vessel that sterilises instruments with saturated steam, typically at 134 °C for at least 3 minutes. Each cycle's time, temperature and pressure are monitored. Also: steam steriliser, sterilizer.
Automated dispensing cabinet: A computer-controlled medicines cabinet on a ward that releases drugs to authorised staff and records each transaction. Some count items by weight. Also: ADC, dispensing cabinet.
Availability: The share of time a device is ready for use. Often estimated as MTBF divided by MTBF plus MTTR, shown as a percentage. Also: operational availability, uptime.
Battery: The rechargeable power source in portable and backup-powered devices. Capacity falls with age and heat, so run-time tests are part of PM. Also: internal battery.
Bellows: A concertina chamber in some anaesthesia ventilators that is squeezed by drive gas to push breathing gas to the patient. Also: ventilator bellows.
Benchmarking: Comparing your service's measures, such as cost per device or uptime, against other services or best practice to find where to improve. Also: peer comparison.
Bidder challenge: A formal complaint by a supplier that a procurement was run unfairly or unlawfully. Good records of scoring decisions are the main defence. Also: procurement challenge, legal challenge.
Bilirubin: A yellow substance made when red blood cells break down. Blue-green light in phototherapy changes it into forms the baby can pass out more easily. Also: serum bilirubin, SBR.
Biphasic waveform: A defibrillation shock in which current flows one way and then reverses. It works at lower energy than older monophasic shocks.
Bipolar electrosurgery: Electrosurgery where current flows only between two tips of the instrument, so no return electrode is needed. Also: bipolar.
BIS: A processed EEG number from 0 to 100 showing depth of anaesthesia. About 40 to 60 is the usual target for general anaesthesia. Also: bispectral index, depth of anaesthesia monitoring.
Blood gas analyser: A point-of-care or lab analyser that measures pH, pO2, pCO2 and often electrolytes and lactate in blood. Needs regular calibration and quality control. Also: BGA, blood gas analyzer.
Blood glucose: The level of sugar in the blood, normally about 4 to 7 mmol/L. Measured at the bedside with point-of-care meters that need quality control checks. Also: glucose, blood sugar, BM.
Blood leak detector: An optical sensor in the dialysate outflow that detects red cells, showing that the dialyser membrane has torn.
Blood pressure monitor: A device that measures blood pressure non-invasively, usually by the oscillometric method with an inflatable cuff. Cuff size affects accuracy. Also: NIBP monitor, sphygmomanometer.
Bolus: A set dose given quickly over a short time, either by hand or by the pump, in addition to or instead of a continuous infusion. Also: bolus dose, loading dose.
Borderline result: A test result so close to the limit that measurement uncertainty means it could be a pass or a fail. Repeat, investigate and record it.
Bradycardia: A heart rate below about 60 beats per minute in adults. In newborns, falls below about 100 are significant and often linked to apnoea. Also: slow heart rate.
Breathing system: The tubing, valves and reservoir that carry gas between the ventilator or anaesthesia machine and the patient. Leaks and disconnections are common faults. Also: breathing circuit, patient circuit.
Bribery Act 2010: UK law that makes offering or accepting bribes a crime. It applies to gifts and hospitality from suppliers in procurement.
BS 7671: The UK wiring regulations. Section 710 adopts IEC 60364-7-710 for medical locations. Also: IET Wiring Regulations.
Building management system: The computer system that monitors and controls building services such as ventilation, heating and alarms. Also: BMS.
Business case: A document that sets out why money should be spent: the need, options, costs, benefits and risks, and the recommended choice. Also: outline business case, full business case.
Business continuity plan: A plan for keeping essential services running during disruption such as power loss, cyber attack or equipment failure, and recovering afterwards. Also: BCP, continuity plan.
C-arm: A mobile X-ray unit with the tube and detector on a C-shaped arm, giving live fluoroscopy images in theatre. Staff dose must be controlled. Also: mobile fluoroscopy, image intensifier.
Calibration: Comparing a device's readings against a traceable reference and, if needed, adjusting it. The result must state the measured error and uncertainty.
CAPA: A quality process to fix the cause of a problem that happened (corrective) and stop possible problems from happening (preventive), then check it worked. Also: corrective and preventive action.
Capital plan: The organisation's plan for spending on large assets over the coming years, ranking equipment replacements by risk and need. Also: capital programme, equipment replacement programme.
Capnography: Continuous measurement and display of exhaled CO2 as a waveform. Loss of the waveform after intubation suggests the tube is not in the airway or ventilation has stopped. Also: capnogram, CO2 waveform.
Cardiac arrest: Sudden stop of effective heart pumping, so the patient is unresponsive with no normal breathing or pulse. Needs immediate CPR and a check of rhythm. Also: arrest, crash call.
Cardiac monitor: A bedside device that displays and alarms on vital signs such as ECG, SpO2, blood pressure and respiration, often linked to a central station. Also: patient monitor, bedside monitor.
Cardiac pacemaker: An implanted device that senses the heart's rhythm and sends small electrical pulses through leads when the heart beats too slowly or pauses. Also: pacemaker, implantable pacemaker.
Cardiopulmonary bypass machine: A machine that takes over the work of the heart and lungs during heart surgery. Pumps move blood through an oxygenator and heat exchanger and back to the patient. Also: heart-lung machine, CPB, HLM.
Cardioversion: A shock timed to the R wave to reset an organised fast rhythm such as AF or VT with a pulse. Syncing avoids shocking during the T wave, which could cause VF. Also: synchronised cardioversion, DC cardioversion.
Cath lab: A room with fluoroscopy X-ray equipment where catheters are passed into the heart or vessels for tests, stents and other treatments. Also: catheter laboratory, cardiac catheter lab.
CCU: A unit for patients with serious heart conditions such as heart attacks and dangerous rhythms, with continuous ECG monitoring. Also: coronary care unit, cardiac care unit.
CE mark: The marking showing a device meets EU regulations and can be sold in the EU. Also currently accepted in Great Britain for a transition period. Also: CE marking.
Ceiling pendant: A ceiling-mounted arm that carries power, gas and data outlets and equipment shelves, keeping cables and hoses off the theatre floor. Also: boom, boom arm.
Central monitoring station: A system that shows the monitors from many beds in one place and relays their alarms, often to staff phones or pagers. Also: central station.
Centrifugal pump: A pump that moves blood with a spinning impeller. Used in ECMO and bypass because it is gentler on blood and cannot over-pressurise if the line blocks.
Centrifuge: A machine that spins samples at high speed to separate blood or other fluids into layers. Lid locks and balance are key safety features. Also: laboratory centrifuge.
Chain of custody: A record of everyone who held a device or piece of evidence, when and why, showing it was not changed. Essential if it goes to a court or coroner. Also: evidence chain.
Change control: A formal process to review, approve, record and check changes to devices, software, systems or procedures before they are made. Also: change management.
Changeover time: The time taken for a safety power supply to restore power after mains failure: up to 0.5 s for critical theatre lights, about 15 s for other safety services.
Charge time: The time a defibrillator takes to charge to maximum energy. A rising charge time often shows a weakening battery.
Clarification question: A question asked during a tender to clear up a point. Answers are usually shared with all bidders so nobody gets an unfair advantage. Also: clarification, CQ.
Class I equipment: Equipment protected against shock by basic insulation plus a protective earth connection. A broken earth wire removes a layer of protection. Also: class I.
Class II equipment: Equipment protected by double or reinforced insulation, with no protective earth. Often marked with a square inside a square. Also: class II, double insulated.
Clean and dirty flow: Arranging rooms so used items and waste move in one direction away from clean areas and never cross clean supplies. Also: one-way flow.
Clean room classification: The system for grading clean rooms by the number of airborne particles of given sizes per cubic metre. Also: ISO 14644-1.
Clearance zone: The free space needed around a bed, table or device for staff to work and for emergency access.
Clinical investigation: A planned study in people to assess the safety or performance of a device, needing ethics and regulatory approval before it starts. Also: clinical trial of a device.
Clinical triage: Sorting patients by how urgently they need care, using a standard system, so the sickest are seen first. Not the same as first come, first served. Also: triage, Manchester Triage.
Clock synchronisation: Keeping all device and system clocks set to the same reference time, usually via NTP. Without it, timelines and record times disagree. Also: NTP, time sync, network time protocol.
Cloud service: Software or storage run on a provider's servers over the internet rather than on hospital servers. Raises questions on data location, uptime and security. Also: cloud, cloud hosting.
CMMS: Software that holds the asset register, schedules planned maintenance and records work orders, giving the history of every device. Also: computerised maintenance management system, equipment management database.
CO2 absorber: A canister of soda lime in a circle breathing system that removes carbon dioxide so exhaled gas can be safely rebreathed. Also: soda lime canister.
Cochlear implant: An implanted hearing device that turns sound into electrical pulses delivered by an electrode array in the cochlea, stimulating the auditory nerve directly. Also: CI.
Collimator: A set of lead shutters or channels that shapes the X-ray beam or, in gamma cameras, lets only photons from one direction reach the detector.
Colonoscope: A long flexible endoscope used to examine the large bowel and remove polyps. It is reprocessed in an endoscope washer-disinfector after every patient.
Colony forming unit: A count of live bacteria or fungi that grow on a culture plate. Air quality in UCV theatres is measured in CFU per m3. Also: CFU.
Commissioning: Setting up, testing and proving that new equipment or a system works as designed in its real location, before it is used on patients. Also: system commissioning.
Common-mode rejection: An amplifier's ability to reject signals that appear equally on both inputs, such as mains hum picked up by the body. Also: CMRR.
Competency assessment: Checking that a person can do a task safely and correctly to the required standard, by observation, questions or test, and recording the result. Also: competence check, sign-off.
Competent person (MGPS): A trained person who carries out installation, maintenance or testing work on medical gas pipelines under a permit. Also: CP(MGPS).
Condition monitoring: Planning maintenance from measured signs of wear, such as battery impedance or tube hours, instead of fixed calendar intervals. Also: predictive maintenance.
Conductivity sensor: A sensor that measures how well dialysate conducts electricity, which shows its salt concentration. A drifting cell can give a wrong, unsafe dialysate. Also: conductivity cell.
Conflict of interest: A situation where personal interests, such as gifts or links to a supplier, could affect or appear to affect professional judgement. Must be declared. Also: COI, declaration of interest.
Contamination monitor: A hand-held or fixed detector used in nuclear medicine to check hands, surfaces and equipment for radioactive contamination.
Contingency: Money or time set aside in a project for things that may go wrong. It should be linked to identified risks, not used as spare money. Also: risk allowance, contingency budget.
Controlled area: An area under IRR17 where special procedures are needed to restrict radiation exposure. Entry follows local rules.
Coroner: An independent judicial officer who investigates deaths that are sudden, unexplained or unnatural, and may hold an inquest. Also: HM Coroner.
Corrective maintenance: Repair carried out after a fault has been found or reported. Also: breakdown repair.
CPR: Chest compressions, with or without rescue breaths, to keep blood moving to the brain and heart during cardiac arrest. Adult rate 100 to 120 per minute. Also: cardiopulmonary resuscitation, chest compressions.
CQC: The independent regulator of health and adult social care in England. It inspects services, including whether equipment is safe and well maintained. Also: Care Quality Commission.
Cranial drill: A powered surgical drill used to make holes in the skull. Perforators have a clutch that stops the drill once it passes through bone to protect the brain. Also: perforator, craniotome.
Critical examination: The check, required by IRR17, that the safety features and warning devices of a new or modified X-ray installation work before clinical use.
Critical path: The longest chain of dependent tasks in a project. Any delay to a task on it delays the whole project end date. Also: critical path method, CPM.
Cross-connection test: A commissioning test that proves each outlet delivers the right gas and no pipes are connected to the wrong supply.
Cryogen: A very cold liquefied gas used to cool superconducting magnets. Helium level and the cold head that re-condenses it must be monitored. Also: liquid helium.
Cryotherapy system: A system that destroys tissue by freezing it with probes cooled by argon gas or liquid nitrogen. Ice ball size is monitored with imaging. Also: cryoablation, cryosurgery.
CSF shunt: An implanted tube and valve that drains excess cerebrospinal fluid from the brain to the abdomen to treat hydrocephalus. Magnet-adjustable valves can be reset by MRI. Also: ventriculoperitoneal shunt, VP shunt.
CT scanner: An X-ray system where a tube and detector rotate around the patient to build cross-sectional images. Fast and detailed, but gives a higher radiation dose than a plain X-ray. Also: computed tomography, CT.
CTG: Recording of fetal heart rate and uterine contractions during pregnancy or labour, used to judge fetal wellbeing. Read as a pair of traces against time. Also: cardiotocography, fetal monitoring trace.
Cybersecurity incident response: A planned set of steps to detect, contain, remove and recover from a cyber attack, including isolating affected devices and preserving logs. Also: cyber incident response, incident response plan.
Cylinder manifold: A bank of gas cylinders connected to the pipeline as a supply or reserve, switching automatically from the running bank to the standby bank. Also: manifold.
Data backup: Keeping copies of data and settings so they can be restored after failure or attack. Backups must be tested by actually restoring them. Also: backup, restore.
Day surgery: Planned surgery where the patient goes home the same day. Relies on fast turnaround of theatres and equipment. Also: day case, ambulatory surgery.
Declaration of conformity: A document signed by the manufacturer stating that the device meets the relevant regulations. It is the manufacturer's legal statement of compliance. Also: DoC, EU declaration of conformity.
Decommissioning: Safely taking a device out of service for good: removing data, decontaminating, updating the asset register and disposing of it under the rules. Also: disposal, withdrawal from service.
Decontamination: The combination of cleaning, disinfection and sterilisation that makes a reusable device safe for handling and use.
Decontamination certificate: A signed form confirming a device has been cleaned and decontaminated before it is handled by engineers or sent away for repair. Also: decontamination declaration, decon form.
Defects liability period: A period after handover, often 12 months, when the contractor must fix any defects that appear at their own cost. Also: DLP, rectification period.
Defibrillation: An unsynchronised electric shock across the heart to stop VF or pulseless VT so the heart's own pacemaker can restart a normal rhythm. Also: shock, unsynchronised shock.
Defibrillation pads: Self-adhesive electrodes that deliver the shock and pick up the ECG. Expired or dried pads raise impedance and can make a shock fail. Also: electrode pads, pads.
Defibrillation-proof applied part: An applied part designed to survive a defibrillator shock to the patient without damage and without passing dangerous energy to the operator. Also: defib-proof.
Defibrillator: A device that delivers a controlled electric shock through the chest to stop a shockable rhythm such as VF, letting the heart's normal rhythm return. Energy is set in joules. Also: defib, manual defibrillator, AED.
Defibrillator analyser: Test equipment with a 50 ohm load that measures delivered shock energy and checks charge time and synchronised cardioversion.
Defibrillator capacitor: The component that stores electrical energy before a shock and releases it through the pads in milliseconds.
Delivered energy: The energy a defibrillator actually puts into a 50 ohm load, compared with the energy selected. Typical tolerance is ±15 percent or ±3 J.
Depreciation: Spreading an asset's cost over its useful life in the accounts. A fully depreciated device is not necessarily unsafe or due for replacement. Also: asset depreciation.
Dermatoscope: A magnifier with polarised or non-polarised light used to examine skin lesions such as moles in detail. Also: dermoscope.
Desflurane: A volatile anaesthetic agent with fast onset and offset. It boils near room temperature, so it needs a heated, pressurised vaporiser. A strong greenhouse gas. Also: des.
Device integration gateway: A system that collects data from bedside devices, links it to the right patient and sends it to the patient record. Also: device gateway, connectivity gateway.
DEXA scanner: An X-ray system that uses two energy levels to measure bone mineral density, mainly to diagnose osteoporosis. Very low dose. Also: DXA, bone densitometer.
Dialysate: The prepared fluid on the other side of the dialyser membrane. Waste and excess salts move from the blood into it; its make-up and temperature are tightly controlled. Also: dialysis fluid.
Dialysate conductivity: How well the dialysate conducts electricity, used as a quick check of its salt concentration. Typically about 13.5 to 14.5 mS/cm; out-of-range values stop dialysis. Also: conductivity, mS/cm.
Dialyser: The filter in haemodialysis: hollow fibres with blood on one side and dialysate on the other, so waste and water cross the membrane. Also: artificial kidney.
DICOM: The international standard for storing and sending medical images and related data, so scanners, PACS and workstations from different makers work together. Also: Digital Imaging and Communications in Medicine.
DICOM storage commitment: A DICOM service where the archive confirms it has safely stored images, so the scanner knows it can delete its local copies. Also: storage commitment.
Differential amplifier: An amplifier that boosts the difference between two inputs and rejects signals common to both, essential for ECG and EEG. Also: instrumentation amplifier.
Differential method: An IEC 62353 leakage method that measures the imbalance between live and neutral current, so it captures leakage by any path. Less sensitive at very low levels.
Direct method: An IEC 62353 leakage method that measures current in the earth path with the device running normally. Simple, but the device must be isolated from other earth paths.
Discounting: Reducing future money to today's value because money now is worth more than later. The UK Green Book uses a standard public sector rate of 3.5 percent. Also: discount rate.
Disinfection: Reducing live microorganisms to a safe level, but not necessarily killing bacterial spores. Used for heat-sensitive scopes. Also: high-level disinfection.
Document control: Managing procedures and forms so only the current approved version is in use, changes are reviewed and old versions are withdrawn. Also: controlled documents.
Door sensor: A switch or sensor in an infusion pump that confirms the door is fully closed and the set correctly loaded before the pump will run.
Dose error reduction software: Pump software that checks programmed doses against the drug library and warns (soft limit) or blocks (hard limit) doses outside safe ranges. Also: DERS, dose limits.
Downtime: Time a device or system is not available for clinical use, from fault or maintenance. Planned downtime should be agreed with the clinical area. Also: out-of-service time.
Downtime procedure: The agreed way of working when a system is down, such as paper forms, so patient care continues safely until the system returns. Also: paper fallback, manual downtime process.
Drift: A slow change in a sensor's reading over time or with temperature, even though the real value has not changed. Also: sensor drift.
Drug library: A list of drugs with safe dose limits loaded into smart infusion pumps, so the pump warns or stops when a programmed dose is outside the limits. Also: dose error reduction software, DERS.
Duty of candour: A legal duty on UK health providers to be open and honest with patients when a notifiable safety incident happens, including an apology in writing. Also: statutory duty of candour.
Earth bond test: Measures the resistance from the mains plug earth pin to exposed metal of Class I equipment. IEC 62353 limit is 0.3 ohm including a mains cable up to 3 m. Also: protective earth resistance test, earth continuity test.
ECG machine: A device that records the heart's electrical activity from electrodes on the skin, usually as a 12-lead recording for diagnosis. Also: electrocardiograph, 12-lead ECG.
ECMO: Long-term life support that pumps blood through an external oxygenator for days or weeks. VV ECMO supports the lungs; VA ECMO supports the heart and lungs. Also: extracorporeal membrane oxygenation.
Ectopic beat: An extra heartbeat that starts outside the normal pacemaker. Occasional ectopics are common; frequent runs may trigger arrhythmia alarms. Also: ectopic, PVC, extrasystole.
ED: The hospital department that receives unplanned and emergency patients, triages them and starts urgent treatment, open 24 hours a day. Also: emergency department, A&E, accident and emergency.
EEG system: A system that records the brain's electrical activity from scalp electrodes. Signals are only microvolts, so electrode contact and interference control are vital. Also: electroencephalograph, EEG.
Electrical safety analyser: Test equipment that performs earth bond, insulation and leakage tests on medical devices to IEC 62353 or IEC 60601-1 and records the results. Also: ESA, safety tester.
Electrode: A conductive pad or needle that makes electrical contact with the body to record signals or deliver stimulation. Gel quality affects the signal. Also: ECG electrode.
Electronic patient record: The hospital's digital record of a patient's care. Device data such as vital signs and anaesthesia records can flow into it through integration. Also: EPR, EHR.
Electrophysiology mapping system: A cath lab system that records electrical signals inside the heart through catheters and builds a 3D map to find and guide ablation of the source of an arrhythmia. Also: EP mapping, 3D mapping system.
Electrosurgical analyser: Test equipment that measures electrosurgical output power into set loads and checks return electrode monitoring. Also: ESU analyser.
Electrosurgical unit: A generator that cuts and coagulates tissue with high-frequency current. In monopolar mode current returns through a patient return electrode, which must be well applied. Also: ESU, diathermy, surgical diathermy.
EMG system: A system that records electrical activity of muscles and nerves, using surface or needle electrodes, to diagnose nerve and muscle disease. Also: electromyograph, EMG.
EN 13060: European standard for small steam sterilisers, such as benchtop units in clinics.
EN 285: European standard for large steam sterilisers used in hospitals.
Encryption: Scrambling data with a key so only authorised people or systems can read it, both when stored and when sent over a network. Also: data encryption.
End of support: The date after which the manufacturer will no longer provide parts, repairs or software updates for a device. A key trigger for replacement planning. Also: EOS, end of service life, end of life notice.
End-of-life operating system: An operating system no longer receiving security updates, such as an old Windows version, which leaves devices running it exposed to attack. Also: unsupported OS, legacy operating system.
Endoscope: A flexible tube with a camera and channels for air, water, suction and instruments, used to look inside the body. Complex channels make cleaning and disinfection critical. Also: flexible endoscope, scope.
Endoscope traceability: Recording which endoscope was used on which patient and which reprocessing cycle it went through, so a failure can be traced to patients. Also: scope tracking.
Endoscope washer-disinfector: A machine that cleans and disinfects flexible endoscopes, flushing every channel with detergent and disinfectant, then rinsing with controlled-quality water. Also: EWD, AER.
EPR integration: Linking devices and systems to the electronic patient record so data, such as observations, flow in automatically to the right patient. Also: EHR integration, electronic patient record integration.
Equipment leakage current: In IEC 62353, the total leakage from mains parts through earth and enclosure. Limits are 500 µA for Class I and 100 µA for Class II. Also: earth leakage.
Equipment library: A managed central service that stores, cleans, checks and issues shared devices to clinical areas, often with tracking and out-of-hours access. Also: medical equipment library, MEL.
Equipment tag: A label on the device with its unique asset number and often the date of last test or next service due, linking the device to its CMMS record. Also: asset label, asset tag, test label.
Escalation: Passing an issue up to someone with more authority or expertise when it is beyond your role, risk is high, or a deadline will be missed. Also: escalate.
Essential performance: The clinical function a device must keep delivering, or else risk becomes unacceptable, such as a ventilator delivering breaths or an alarm sounding.
Essential supply: Circuits backed by generators and often UPS so that critical lighting, equipment and services keep running during mains failure. Also: essential circuits.
EtCO2: The carbon dioxide level at the end of a breath out, close to arterial CO2 in healthy lungs. Normal is about 4.5 to 6.0 kPa. Used to confirm tube placement and ventilation. Also: end-tidal CO2, end-tidal carbon dioxide.
Event log: A record kept inside a device of alarms, settings, errors and power events with timestamps. It is key evidence in faults and incidents. Also: alarm log, device log.
Evoked potentials: Small electrical responses of the nervous system to a stimulus, recorded with averaging. Used to monitor spinal cord and nerve function during surgery. Also: EP, SSEP, MEP.
Expert witness: A specialist who gives an independent opinion to a court on technical matters. Their duty is to the court, not to whoever pays them. Also: independent expert.
Expiratory filter: A filter on the ventilator's exhaled gas path that protects the machine and room from infection. When it becomes wet or blocked, resistance and volume readings change.
Extubation: Removing the breathing tube once the patient can breathe and protect their airway. Planned extubation follows breathing trials on the ventilator. Also: tube removal.
Factorial test design: An experiment that changes several factors, such as temperature and RF field, in all combinations, to show how they act alone and together.
Fault reproduction: Recreating the conditions of an incident in a controlled test to show whether and how the fault happens. Also: bench reproduction.
Fennigkoh-Smith method: A 1989 scoring method that adds points for equipment function, physical risk and maintenance requirements to decide inclusion and PM frequency. Also: Fennigkoh and Smith.
Ferromagnetic detector: A detector at the MRI room entrance that alerts to iron-containing objects that could be pulled into the magnet as projectiles. Also: ferromagnetic screening.
Fetal heart rate: The heart rate of the unborn baby, normally about 110 to 160 beats per minute. Can be confused with the mother's pulse, so the two should be checked against each other. Also: FHR, baby's heart rate.
Fetal monitor: A device that records the baby's heart rate and the mother's contractions during pregnancy and labour, using ultrasound and pressure transducers. Also: CTG machine, cardiotocograph.
FEV1: The volume of air a person can blow out in the first second of a forced breath out after a full breath in. Measured by spirometry. Also: forced expiratory volume in one second.
FGI Guidelines: US guidelines for the design and construction of hospitals and outpatient facilities, used by many states as code. Also: Facility Guidelines Institute.
FHIR: A modern HL7 standard that shares health data as small resources, such as Patient or Observation, using web technologies like REST and JSON. Also: Fast Healthcare Interoperability Resources.
Field safety corrective action: Action taken by a manufacturer to reduce the risk of a device already on the market, such as modification, software update, advice or recall. Also: FSCA.
Field safety notice: A notice from a manufacturer telling users about a safety action for a device, such as a fix, extra checks or a recall. Must be acted on and recorded. Also: FSN.
Final rinse water: The water used for the last rinse in an endoscope washer-disinfector. It is tested for bacteria because it touches the disinfected scope.
FiO2: The fraction of oxygen in the gas a patient breathes in, from 0.21 (room air) to 1.0 (pure oxygen). Often written as a percentage. Also: fraction of inspired oxygen.
Firewall: A device or software that allows or blocks network traffic based on rules, used to protect device networks from unwanted connections. Also: network firewall.
Firmware: Software built into a device's hardware that controls how it works. Updates must be checked, recorded and applied in a controlled way.
Fishbone diagram: A chart that groups possible causes of a problem into branches such as people, equipment, methods and environment, to make sure none are missed. Also: Ishikawa diagram, cause and effect diagram.
Flat-panel detector: A digital X-ray detector that converts X-rays to an electrical signal, giving images in seconds without film or cassettes. Also: DR detector.
Floor loading: The weight a floor can carry per area. Heavy items such as MRI magnets and CT scanners need structural checks.
Flow sensor: A sensor that measures gas flow, often by hot-wire or pressure difference, so the ventilator can calculate delivered and exhaled volumes.
Flowmeter: A device that shows gas flow rate, either as a bobbin in a tapered glass tube or electronically. Also: rotameter.
Framework agreement: A pre-agreed arrangement with approved suppliers and terms, so buyers can place contracts quickly without running a full tender each time. Also: framework, national framework.
Functional test: A check that the device works as intended after safety testing, such as alarms sounding and controls responding. Part of IEC 62353 recurrent tests.
FVC: The total volume of air blown out in a forced breath after a full breath in. The FEV1/FVC ratio helps tell obstructive from restrictive lung disease. Also: forced vital capacity.
Gain error: An error that grows with the size of the reading, so the device is right at zero but wrong at the top of its range. Also: span error.
Gantry: The ring-shaped housing of a CT, PET or SPECT scanner that holds the rotating tube and detectors.
Gas flow analyser: Test equipment that measures flow, volume, pressure and oxygen concentration to verify ventilators and anaesthesia machines. Also: ventilator tester.
Gas identity test: Analysis of the gas at each outlet to confirm it is the right gas at the right purity before the pipeline is used. Also: purity test.
Glucometer: A hand-held meter that measures blood glucose from a drop of blood on a test strip, used at the bedside. Some strip chemistries are affected by other sugars. Also: blood glucose meter, glucose meter.
Go-live: The moment a new system or device starts being used for real patient care. Needs a rollback plan and extra support on hand. Also: cutover, go live.
Gradient coils: Coils in an MRI scanner that change the magnetic field quickly to locate the signal. They cause the loud knocking noise.
Group 0 location: A medical location where no applied parts are used, such as a consulting room.
Group 1 location: A medical location where applied parts touch the body or are invasive but not to the heart, and loss of supply does not endanger life, such as a general ward.
Group 2 location: A medical location for intracardiac procedures or vital treatment where loss of power could endanger life, such as theatres and ICU.
Haemodialysis machine: A machine that pumps blood through a dialyser so waste and water pass into dialysate. It controls conductivity, temperature and fluid removal and detects air and blood leaks. Also: dialysis machine, hemodialysis.
Haemorrhage: Loss of blood from a damaged vessel, inside or outside the body. Major haemorrhage needs rapid transfusion and control of the bleeding source. Also: bleed, major haemorrhage.
Handover: Formal transfer of a finished installation from the supplier or project team to the people who will own, use and maintain it, with documents. Also: practical completion, project handover.
HBN 04-01: NHS guidance on adult in-patient facilities, including single bedroom sizes.
HBN 26: NHS guidance on facilities for surgical procedures, including operating theatres.
HDU: A unit between a ward and ICU for patients needing close monitoring or support of one organ, but usually not invasive ventilation. Also: high dependency unit, level 2 care.
Hearing aid: A small wearable device that picks up sound, processes and amplifies it to suit a person's hearing loss, and plays it into the ear. Also: auditory amplifier.
Heat and moisture exchanger: A passive filter at the airway that keeps heat and moisture from exhaled breath to warm and humidify the next breath. Also: HME.
Heater-cooler unit: A unit that controls blood temperature through a heat exchanger during bypass or ECMO. Its water tanks need strict disinfection to prevent infection.
HEPA filter: A filter that removes at least 99.95 percent of fine particles, used in UCV theatres, isolation rooms and clean rooms. Also: high efficiency particulate air filter.
Heparin: A drug that stops blood clotting, used in dialysis, bypass and infusions. Too much risks bleeding, so doses are checked with blood tests such as APTT. Also: anticoagulant.
Hierarchy of controls: Ranking safety measures from most to least effective: remove the hazard, substitute, engineering controls, admin controls, then PPE. Also: control hierarchy.
HL7: A widely used messaging standard for sending clinical data, such as admissions, orders and results, between hospital systems as structured text messages. Also: HL7 v2, Health Level Seven.
Holter monitor: A small wearable recorder that records the ECG for 24 hours to several days while the patient goes about normal life, to catch intermittent rhythm problems. Also: ambulatory ECG.
Horizon scanning: Watching for new technologies, regulations, safety alerts and end-of-support dates early, so the organisation can plan rather than react. Also: technology horizon scanning.
HTM 01-01: NHS guidance on decontamination of surgical instruments, including washer-disinfectors and sterilisers.
HTM 08-02: NHS guidance on lifts in healthcare buildings, including bed and evacuation lifts.
Humidifier: A device that warms and adds water vapour to ventilator gas so the airways do not dry out. Temperature probes control it. Also: heated humidifier.
Hydrocephalus: Build-up of cerebrospinal fluid in the brain's ventricles, raising pressure. Often treated with a shunt that drains fluid to another part of the body. Also: water on the brain.
Hyperkalaemia: A high level of potassium in the blood. It can cause peaked T waves, wide QRS and dangerous rhythms, and is a key risk in kidney failure. Also: high potassium, raised K+.
Hyperthermia system: A system that heats tumour tissue to about 40 to 44 °C with RF, microwave or ultrasound energy to make cancer cells more sensitive to radiotherapy or chemotherapy. Also: therapeutic hyperthermia.
Hypothermia: Core body temperature below 35 °C. Newborns and patients under anaesthesia lose heat quickly, which is why warmers and incubators are used. Also: low body temperature.
Hypoxaemia: Abnormally low oxygen in the arterial blood, shown by a low PaO2 or SpO2. It is one cause of hypoxia. Also: low blood oxygen.
Hypoxia: Too little oxygen reaching the body tissues. It can be caused by low blood oxygen, poor blood flow, anaemia or cells unable to use oxygen. Also: tissue hypoxia.
Hypoxic guard: A link on the anaesthesia machine that stops the operator setting a gas mixture with less than about 25 percent oxygen. Also: oxygen ratio controller.
IBP: Blood pressure measured continuously through a fluid-filled catheter in an artery, connected to a pressure transducer that must be zeroed and levelled to the heart. Also: invasive blood pressure, arterial line pressure, art line.
ICU: A unit for the sickest patients needing organ support such as ventilation, with high nurse ratios and dense equipment per bed. Also: intensive care unit, ITU, critical care.
IEC 60529: Standard for IP codes that rate how well an enclosure resists dust and water, such as IPX4 for splashing water. Also: IP rating.
IEC 60601-1-11: Collateral standard for medical electrical equipment used in the home healthcare environment.
IEC 60601-2-19: Particular safety standard for infant incubators, including temperature control and over-temperature protection.
IEC 60601-2-2: Particular safety standard for high-frequency surgical (electrosurgical) equipment and accessories.
IEC 60601-2-25: Particular safety standard for electrocardiographs (diagnostic ECG machines).
IEC 60601-2-27: Particular safety standard for ECG monitoring equipment, such as bedside monitors.
IEC 60601-2-33: Particular safety standard for MRI equipment, including field limits and emergency stops.
IEC 60601-2-37: Particular safety standard for ultrasonic diagnostic and monitoring equipment, including thermal and mechanical indices.
IEC 60601-2-4: Particular safety standard for cardiac defibrillators, including energy accuracy and charge time.
IEC 60601-2-43: Particular safety standard for X-ray equipment for interventional procedures, such as cath labs.
IEC 60601-2-50: Particular safety standard for infant phototherapy equipment, including irradiance.
IEC 60825-1: Standard for laser product safety, including classification from Class 1 to Class 4.
IEC 81001-5-1: Standard for security activities across the life cycle of health software.
IHE: An initiative that writes profiles showing exactly how to use standards like HL7 and DICOM together for common tasks, so products connect reliably. Also: Integrating the Healthcare Enterprise, IHE profile.
In-house manufacture: Making or modifying a device within a health organisation for its own patients. Allowed under strict conditions with its own quality and safety duties. Also: health institution exemption, in-house device.
Incident report: A record of a safety event made through the organisation's local reporting system, which starts review and learning. Also: Datix, incident reporting system.
Incident timeline: An ordered record of events before, during and after an incident, built from logs and statements. Device clocks may differ, so times need aligning. Also: timeline, chronology.
Infant incubator: An enclosed, heated cot that keeps a premature or sick baby warm and humid. Air or skin temperature control and over-temperature alarms are safety critical. Also: incubator, neonatal incubator.
Infusion device analyser: Test equipment that measures the flow rate, volume and occlusion pressure of infusion pumps and syringe drivers. Also: IDA, flow analyser.
Infusion pump: A pump that delivers fluids and drugs into a vein at a set rate, usually with a peristaltic mechanism acting on an administration set. Has occlusion and air-in-line alarms. Also: volumetric infusion pump, VIP.
Inquest: A public court hearing led by a coroner to find who died and how, when and where. Device records and engineers may be called as evidence. Also: coroner's inquest.
Insulation monitoring device: A device on a medical IT system that continuously measures insulation resistance to earth and alarms when a first fault appears. Also: IMD, line isolation monitor.
Insulation resistance test: Applies about 500 V DC between mains parts and earth or applied parts to check the insulation has not broken down. Low readings point to damp or damage. Also: insulation test.
Insulin: A hormone that lowers blood glucose. Often given by infusion pump in hospital; it is a high-risk drug where dosing errors cause serious harm. Also: insulin infusion, sliding scale.
Insulin pump: A small wearable pump that delivers insulin under the skin continuously and as boluses at meals. Some link to a glucose sensor to adjust delivery automatically. Also: CSII pump.
Intended use: What the manufacturer says the device is for, who it is for and how it should be used. It decides the device's class and the evidence needed. Also: intended purpose, indications for use.
Interference filter: A filter that removes unwanted frequencies, such as 50 Hz mains hum, from a biological signal. Overuse can distort the signal. Also: notch filter, mains filter.
Interim control: A short-term action that reduces risk now, such as extra checks or quarantine, while the permanent fix is developed. Also: temporary measure, containment action.
Interlock: A switch or logic that stops a hazard when conditions are unsafe, such as a laser door interlock or centrifuge lid lock. Also: safety interlock.
Internal audit: A planned check by the organisation of its own processes against its procedures and standards, to find gaps before external auditors do. Also: self audit, first-party audit.
Internally powered equipment: Equipment that can run from its own internal battery. When connected to mains to charge, it must also meet Class I or Class II rules.
Interoperability: The ability of different systems and devices to exchange data and use it correctly without manual re-entry. Also: system interoperability.
Intra-aortic balloon pump: A device that inflates a balloon in the aorta as the heart relaxes and deflates it just before it pumps. Timed from the ECG or arterial pressure, it helps a failing heart. Also: IABP, balloon pump.
Intubation: Passing a tube through the mouth or nose into the windpipe to protect the airway and allow ventilation. Correct placement is confirmed by capnography. Also: endotracheal intubation, tube placement.
Investigational device: A device being studied in a clinical investigation that is not yet approved for general sale. It must be labelled and tracked separately. Also: device under investigation.
IONM: Monitoring of nerve and spinal cord function during surgery using evoked potentials and EMG, so the surgeon is warned before permanent nerve damage occurs. Also: intraoperative neurophysiological monitoring.
Irradiance: Light power per unit area, measured with a radiometer to check phototherapy units deliver an effective dose to the baby's skin.
ISO 14155: Standard for good clinical practice in clinical investigations of medical devices on human subjects.
ISO 15189: Standard for quality and competence in medical laboratories.
ISO 15197: Standard for accuracy of blood glucose monitoring systems for self-testing.
ISO 15883: Standard series for washer-disinfectors: Part 1 general, Part 4 for endoscope washer-disinfectors.
ISO 17665: Standard for developing, validating and routinely controlling moist heat (steam) sterilisation.
ISO 22870: Standard for point-of-care testing quality, used with ISO 15189.
ISO 23500: Standard series for preparing and checking water and dialysis fluid quality for haemodialysis.
ISO 80369: Standard series for small-bore connectors that cannot be mixed up between uses, such as enteral (ENFit) and neuraxial (NRFit). Also: small-bore connectors.
ISO 80601-2-13: Particular standard for anaesthetic workstations.
ISO 80601-2-55: Particular standard for respiratory gas monitors, such as capnographs and anaesthetic agent monitors.
ISO 81060-2: Standard for clinical validation of automated non-invasive blood pressure monitors.
ISO 9001: General quality management system standard used by many service organisations, including clinical engineering departments.
ISO/IEC 17025: Standard for the competence of testing and calibration laboratories, the basis of UKAS accreditation. Also: IEC 17025.
Isolation transformer: A transformer that separates a medical IT supply from earth so a single fault does not trip the circuit, used in Group 2 locations. Also: medical IT transformer.
IVUS: A tiny ultrasound transducer on a catheter that images the inside of a blood vessel wall, used in the cath lab to size stents and see plaque. Also: intravascular ultrasound.
Just culture: An approach that separates honest error and system failures from reckless behaviour, so people report problems without fear of unfair blame. Also: fair culture.
Ketones: Acids made when the body burns fat because it cannot use glucose. High ketones with high glucose suggest diabetic ketoacidosis. Also: blood ketones, beta-hydroxybutyrate.
KPI: A measure tracked over time to show how well a service is doing, such as PPM completion or repair turnaround. Good KPIs drive the right behaviour. Also: key performance indicator.
KVO: A low infusion rate, often 1 to 5 mL per hour, that a pump runs after the main infusion ends to keep the cannula from clotting. Also: keep vein open, KVO rate.
Lactate: A blood marker that rises when tissues lack oxygen or are under stress. A raised lactate is used in sepsis screening. Also: lactic acid, serum lactate.
Laryngoscope: A handle and blade with a light, or a camera, used to see the vocal cords and place a breathing tube. Must be checked ready for use in every emergency area. Also: video laryngoscope.
Laser classification: The grouping of lasers from Class 1 (safe) to Class 4 (can burn skin and eyes and start fires) under IEC 60825-1. Class 3B and 4 need controlled areas. Also: laser class.
Laser skin resurfacing system: A laser that removes or heats thin layers of skin to treat scars and damage. Laser safety controls such as eye protection and controlled areas apply. Also: CO2 laser, fractional laser.
Latency: The delay for data to travel across a network. High latency can delay alarms sent to central stations or pagers. Also: network delay, lag.
Lead equivalence: The thickness of lead that would give the same shielding as a wall, door or apron, such as 2 mm lead equivalent. Also: lead shielding.
Lead wires: The cables between electrodes and the monitor. Broken conductors or shields cause noise, lead-off alarms and lost traces. Also: ECG leads, patient cable.
Leakage current: Unwanted current that flows from a device through earth, the enclosure or the patient. Small amounts are normal; too much can cause shock or heart fibrillation.
LED: A semiconductor light source. Pulse oximeters use red and infrared LEDs; phototherapy units use blue LEDs. Also: light-emitting diode.
Legal hold: An instruction to keep all relevant records, data and devices unchanged because of expected legal action, overriding normal deletion or disposal. Also: litigation hold, preservation notice.
Linear accelerator: A radiotherapy machine that accelerates electrons to make high-energy X-rays aimed at a tumour. Commissioning and QA are led by medical physics. Also: linac.
Liquidated damages: A sum agreed in the contract that the supplier pays if they miss a deadline. It must be a genuine estimate of loss, not a penalty. Also: LDs, delay damages.
Lithotripter: A machine that focuses shock waves from outside the body onto a kidney stone to break it into pieces small enough to pass. X-ray or ultrasound is used to target. Also: ESWL, extracorporeal shock wave lithotripsy.
Loan pool: A shared stock of common devices such as pumps, held centrally and lent to wards as needed, so devices are cleaned, checked and tracked between uses. Also: equipment pool, central pool.
Local rules: Written instructions for working safely in a radiation area, naming the radiation protection supervisor and the controls in place.
LOLER: UK regulations requiring lifting equipment, such as patient hoists, to be safe, suitable and thoroughly examined by a competent person. Also: Lifting Operations and Lifting Equipment Regulations 1998.
Look-back exercise: A review of past patients who may have been affected by a faulty device or process, to find who needs follow-up or to be told. Also: lookback, patient recall review.
MAC: The alveolar concentration of an anaesthetic agent at which 50 percent of patients do not move in response to a surgical stimulus. A way to compare agent strength. Also: minimum alveolar concentration.
Macroshock: Shock from current passing through the body from skin contact. Around 100 mA across the chest at mains frequency can cause ventricular fibrillation.
Mains hum: Interference at the mains frequency (50 Hz in the UK and Europe, 60 Hz in the US) picked up by leads and seen as a thick or wavy trace. Also: 50 Hz interference.
Major incident: An event whose impact cannot be handled by normal resources, such as mass casualties or loss of a key system, triggering special response plans. Also: major incident declaration.
Malware: Any software designed to harm, steal from or take control of a computer or device, including viruses, worms and ransomware. Also: malicious software, virus.
Mandatory requirement: A requirement a bid must meet to be considered at all. Bids that fail it are excluded before scoring, so mandatory items must be essential and testable. Also: pass/fail criterion, must-have.
MAP: The average pressure in the arteries over one heartbeat, roughly diastolic plus one third of pulse pressure. Above about 65 mmHg is a common target for organ perfusion. Also: mean arterial pressure.
Mass casualty incident: An event with more casualties than local services can normally treat, needing triage, extra equipment and help from other organisations. Also: mass casualty, MCI.
MCCE: A swallowed camera capsule that is steered through the stomach by an external magnet, sending images wirelessly. It avoids a flexible scope for some examinations. Also: magnetically controlled capsule endoscopy, capsule endoscope.
MDS2: A standard form where manufacturers describe a device's security features, such as encryption and patching, to help buyers assess cyber risk. Also: Manufacturer Disclosure Statement for Medical Device Security.
Means of operator protection: A layer of protection for the operator rather than the patient. Requirements are less strict than MOPP, following general IT equipment rules. Also: MOOP.
Means of patient protection: A layer of insulation, spacing or protective earthing that protects the patient. IEC 60601-1 requires two MOPP between mains and an applied part. Also: MOPP.
Measurement uncertainty: The range around a measured value within which the true value is expected to lie. Results close to a limit must take it into account. Also: uncertainty.
MEAT: The basis for awarding a public contract on the best mix of quality and price, not price alone, using published criteria and weightings. Also: most economically advantageous tender.
Mechanical index: An on-screen estimate of the risk of mechanical effects such as cavitation from ultrasound pressure pulses. Also: MI (ultrasound).
Mechanical ventilator: A machine that moves gas into and out of the lungs for a patient who cannot breathe well enough. It controls pressure or volume, rate, oxygen and PEEP, with life-critical alarms. Also: ventilator, critical care ventilator.
Medical air: Clean, dry compressed air for patient breathing, produced by compressor plant or cylinders. Dew point and contaminants are tested.
Medical device safety officer: A named person in an NHS organisation who supports safe device use, improves incident reporting and links with the MHRA on device safety. Also: MDSO.
Medical devices committee: A group of clinical, technical and management staff that oversees device policy, purchasing, training and safety issues across the organisation. Also: MDC, equipment management group.
Medical gas pipeline system: The fixed system of supply plant, pipes, valves, alarms and outlets that delivers oxygen, air, nitrous oxide and vacuum to clinical areas. Also: MGPS.
Medical IT network: A network that connects medical devices. Its risks to safety, effectiveness and security should be managed jointly by clinical engineering and IT. Also: medical IT-network, clinical network.
Medical IT system: An earth-isolated supply used in Group 2 locations so a first insulation fault only raises an alarm and does not cut power to life-support equipment. Also: IT system (electrical), isolated power.
Medical location: A room or area for diagnosis, treatment or monitoring of patients, classed as Group 0, 1 or 2 for electrical installation rules.
Medical physics expert: A specialist physicist who advises on patient dose, equipment quality assurance and optimisation under IR(ME)R. Also: MPE.
Medical vacuum: The pipeline vacuum used for clinical suction. Loss of vacuum can stop airway suction in an emergency. Also: suction.
Mentoring: A more experienced person guiding a less experienced one over time, sharing knowledge, giving feedback and supporting their growth. Also: mentorship.
Method statement: A document describing step by step how a task will be done safely, including equipment, people and controls. Often paired with a risk assessment. Also: safe system of work, RAMS.
Microshock: Shock from a small current applied directly to the heart, for example through a catheter. As little as 10 µA to 100 µA can cause fibrillation.
Middleware: Software that sits between systems to route, translate and filter messages, such as converting device data into HL7 for the patient record. Also: integration engine, interface engine.
Mini-competition: A short competition among suppliers already on a framework, against the buyer's specific requirement, to choose who gets the call-off contract. Also: further competition.
Minute volume: The total volume of gas breathed in one minute: tidal volume multiplied by respiratory rate. A low minute volume alarm warns of under-ventilation. Also: minute ventilation, MV, VE.
Modality worklist: A DICOM service that sends scheduled patient and exam details to the scanner, avoiding typing errors and mismatched patient records. Also: DMWL, worklist.
Monopolar electrosurgery: Electrosurgery in which current flows from the active electrode through the patient to a return electrode. Also: monopolar.
MR Safe: Labels for items near MRI: MR Safe poses no known hazard, MR Conditional is safe only under stated conditions, MR Unsafe must never enter the magnet room. Also: MR Conditional, MR Unsafe.
MRI scanner: An imaging system that uses a strong magnetic field, radio waves and gradient coils to make detailed images of soft tissue without ionising radiation. The magnet is always on. Also: magnetic resonance imaging, MRI, MR scanner.
MRI zones: Four areas of increasing magnetic risk around an MRI scanner, from public Zone I to the magnet room Zone IV, with screening before entry to Zones III and IV. Also: MR zones, zone I to IV.
MTBF: The average working time between failures of a repairable device. Higher is better; it is an average, not a guarantee for one unit. Also: mean time between failures.
MTTR: The average time taken to restore a device to working order after a failure, including waiting for parts. Lower is better. Also: mean time to repair, mean time to restore.
Multimeter: A hand-held meter that measures voltage, current and resistance. Its CAT rating must suit the circuit being measured. Also: DMM.
Mutual aid: An agreement where organisations lend each other staff, equipment or services during an emergency. Also: mutual aid agreement.
Myocardial infarction: Death of heart muscle because its blood supply is blocked, usually by a clot in a coronary artery. Confirmed by symptoms, ECG changes and a rise in troponin. Also: MI, heart attack.
Near miss: An event that could have caused harm but did not, by luck or quick action. Reporting near misses finds risks before someone is hurt. Also: close call, no harm incident.
Nebuliser: A device that turns liquid medicine into a fine mist for inhalation, by compressed gas, ultrasound or a vibrating mesh. Also: nebulizer.
Neonatal jaundice: Yellowing of a newborn's skin and eyes caused by raised bilirubin. Often harmless, but high levels are treated with phototherapy to protect the brain. Also: newborn jaundice, hyperbilirubinaemia.
Net present value: Today's value of future costs and savings, found by discounting each year's cash flow. Lets options with different cost timings be compared fairly. Also: NPV.
Network segmentation: Splitting a network into separate zones with controlled links, so an attack or fault in one zone cannot spread easily to medical devices. Also: segmentation, zoning.
Never event: A serious, largely preventable patient safety incident that should not happen if national safety measures are in place, such as a wrong-site surgery. Also: never events.
NEWS2: A UK score built from routine observations such as breathing rate, SpO2, blood pressure, pulse, alertness and temperature. Higher scores trigger escalation. Also: National Early Warning Score 2, early warning score.
NIBP: Blood pressure measured with an inflatable cuff, usually by the oscillometric method, which detects pressure pulses in the cuff as it deflates. Also: non-invasive blood pressure, cuff pressure.
NIBP cuff: The inflatable cuff used for non-invasive blood pressure. A cuff too small reads high and a cuff too big reads low. Also: blood pressure cuff.
NIBP simulator: Test equipment that simulates cuff pressure oscillations and checks the accuracy and leak rate of non-invasive blood pressure monitors.
NICU: Intensive care for newborn babies, especially premature or very sick babies, using incubators, neonatal ventilators and specialist monitors. Also: neonatal intensive care unit.
NIST connector: A gas-specific threaded connector used on hoses between pipeline outlets and devices, so gases cannot be cross-connected. Also: non-interchangeable screw thread.
Nitrous oxide: A gas used for pain relief and as part of anaesthesia. A potent greenhouse gas; leaks from pipelines and manifolds waste large amounts. Also: N2O, laughing gas, Entonox (with oxygen).
Non-conformance: A failure to meet a requirement, such as a procedure not followed or a product out of specification. It must be recorded and dealt with. Also: nonconformity, NC.
Normal condition: The state where all means of protection are intact. Leakage limits for normal condition are the strictest. Also: NC.
Notified body: An independent organisation designated in the EU to assess whether higher-risk medical devices meet the regulations before CE marking. Also: NB.
O&M manual: Documents from the supplier explaining how to operate, maintain and service the equipment or system. Should be handed over before acceptance. Also: operation and maintenance manual.
Observations: Routine checks of breathing rate, oxygen saturation, blood pressure, pulse, temperature and alertness, recorded at set intervals and used for NEWS2. Also: obs, vital signs.
Obsolescence: When a device can no longer be properly supported because parts, software, skills or clinical need have moved on, even if it still works. Also: equipment obsolescence.
Occlusion pressure test: A test that blocks the infusion line and measures the pressure and time at which the pump alarms.
Occlusion sensor: A sensor in an infusion pump that detects rising pressure when the line is blocked and raises an occlusion alarm. Also: pressure sensor.
Oesophageal manometry: A test using a thin catheter with many pressure sensors to measure how the oesophagus muscles squeeze during swallowing. Also: esophageal manometry, high-resolution manometry.
Off-label use: Using a device in a way not covered by its intended use. The user organisation then takes on more of the responsibility and risk. Also: use outside intended purpose.
Offset: A constant error where the device reads high or low by the same amount across its range. Also: zero error.
Open disclosure: Honestly telling patients and families when something has gone wrong with their care, saying sorry and explaining what happens next. Also: being open.
Ophthalmoscope: A hand-held light and lens system used to look at the back of the eye, including the retina and optic nerve.
Orthopaedic implant: A device such as a hip, knee, plate or screw that replaces or supports bone or a joint. Materials must be biocompatible and strong for many years of loading. Also: joint replacement, orthopedic implant.
Oscillometric method: The usual NIBP method: the cuff pressure oscillations are measured while it deflates, and the device estimates systolic, diastolic and mean pressure.
Oscilloscope: An instrument that displays a voltage against time as a waveform, used to see noise, timing faults and signal shapes. Also: scope (electronics).
Otoscope: A hand-held light and magnifier with a speculum used to examine the ear canal and eardrum.
Oxygen concentrator: A device that takes room air and removes nitrogen with a molecular sieve to deliver oxygen-enriched gas, often used at home.
Oxygen failure alarm: An alarm that warns when oxygen supply pressure falls, and on anaesthesia machines also cuts off nitrous oxide so a hypoxic mix cannot be delivered.
Oxygen saturation: The share of haemoglobin in the blood that is carrying oxygen. SaO2 is measured from an arterial blood sample; SpO2 is the pulse oximeter estimate of it. Also: SaO2, sats.
Oxygenator: The artificial lung in bypass and ECMO circuits: blood flows past a membrane where oxygen enters and carbon dioxide leaves. Also: membrane oxygenator.
Pacemaker programmer: A computer with a wand or wireless link used to read and change the settings of implanted pacemakers and ICDs. Software changes on it must be controlled. Also: device programmer.
Packet loss: Data packets that fail to reach their destination over a network. It can cause gaps in waveforms or missed alarm messages. Also: dropped packets.
PACS: The system that stores, retrieves and displays medical images across the hospital, replacing film. Also: picture archiving and communication system.
PACU: The area where patients wake up after anaesthesia, with close monitoring of airway, breathing and pain until they are safe to go to a ward. Also: post-anaesthesia care unit, recovery, recovery room.
Paediatric: Relating to children. Paediatric patients need different alarm limits, drug doses and device settings from adults, which drug libraries must reflect. Also: pediatric, child.
Partial pressure: The pressure one gas in a mixture would exert on its own. In blood gases, PaO2 and PaCO2 show how much oxygen and carbon dioxide are dissolved in arterial blood. Also: PaO2, PaCO2, tension.
Patching: Applying updates that fix security holes or bugs. For medical devices, patches should be approved by the manufacturer and tested before use. Also: security patch, patch management.
Patient hoist: Lifting equipment used to move patients safely. It is lifting equipment under LOLER and needs thorough examination every 6 months. Also: ceiling hoist, hoist.
Patient identifier: A unique number used to match data to the right patient. Wrong or missing identifiers cause data to land on the wrong patient record. Also: NHS number, MRN, hospital number.
Patient leakage current: Current that flows from an applied part through the patient to earth during normal use. For type CF it is limited to 10 µA in normal condition.
Patient simulator: Test equipment that generates ECG, blood pressure, temperature and other signals so a monitor can be tested without a patient. Also: vital signs simulator, ECG simulator.
PCA: A pump that lets the patient press a button for a small dose of pain relief, with a lockout time and hourly limit to prevent overdose. Also: patient-controlled analgesia.
PCNL system: Equipment for removing large kidney stones through a small tunnel in the back, using a nephroscope with ultrasonic, pneumatic or laser stone breaking and irrigation. Also: percutaneous nephrolithotomy.
Peak inspiratory pressure: The highest airway pressure during a ventilator breath. A sudden rise can mean a blocked tube, coughing or stiff lungs; the high pressure alarm watches it. Also: PIP, Ppeak, airway pressure.
PEEP: Pressure kept in the lungs at the end of expiration by the ventilator. It stops small airways and alveoli collapsing and improves oxygenation. Set in cmH2O. Also: positive end-expiratory pressure.
PEM scanner: A small, high-resolution PET system designed for breast imaging. Detector plates sit close to the breast to find small tumours that take up a radioactive tracer. Also: positron emission mammography, PEM.
Penetration test: An authorised simulated attack on a system to find weaknesses before real attackers do. Must be planned carefully around live medical devices. Also: pen test, ethical hacking.
Performance verification: Tests that prove a device meets its specification, such as delivered flow, energy or pressure, using calibrated test equipment. Also: PV, performance check.
Perfusion: The flow of blood through tissues, delivering oxygen and removing waste. Poor perfusion can also make pulse oximeter readings unreliable. Also: tissue perfusion.
Peristaltic mechanism: A pump design where rollers or fingers squeeze a tube in sequence to push fluid forward. Used in infusion pumps, dialysis blood pumps and bypass machines. Also: pumping fingers.
Peritoneal dialysis cycler: A machine that fills and drains dialysis fluid in and out of the abdomen several times overnight, using the peritoneum as the filter membrane. Also: PD cycler, APD machine.
Permit to work: A written system that controls high-risk work by confirming hazards are isolated and safe before work starts, and signing it off when finished. Also: PTW.
Personal dosimeter: A badge worn by staff to measure radiation dose received over time. Also: dosimetry badge, TLD.
PET scanner: A nuclear medicine scanner that detects pairs of gamma rays from a positron-emitting tracer such as F-18 FDG, showing where the body is using the tracer. Usually combined with CT. Also: positron emission tomography, PET, PET/CT.
Phishing: Tricking people, usually by email, into clicking links, opening files or giving passwords. A common first step in cyber attacks on hospitals. Also: phishing email, spear phishing.
Photodetector: A component that converts light into an electrical current, used in oximeters and many optical sensors. Also: photodiode.
Photomultiplier tube: A detector that turns tiny flashes of light from a scintillation crystal into an electrical signal, used in gamma cameras and older PET systems. Also: PMT.
Phototherapy unit: A light source, usually blue LEDs, that treats neonatal jaundice by converting bilirubin in the skin into forms the baby can excrete. Irradiance must be checked. Also: bili light.
PICU: Intensive care for infants and children beyond the newborn period, with child-sized equipment and specialist staff. Also: paediatric intensive care unit.
Piezoelectric crystal: A material that changes shape when a voltage is applied and makes a voltage when pressed, used to generate and detect ultrasound. Also: piezoelectric element.
Planned preventive maintenance: Scheduled inspection, testing and servicing done before failure to keep a device safe and accurate. Also: PPM, preventive maintenance, PM.
PM yield: The share of planned maintenance jobs that find a fault needing action. It helps show whether a maintenance interval is too short or too long.
Portable appliance testing: Routine electrical safety testing of general electrical equipment. Medical devices need IEC 62353 testing instead, which covers applied parts. Also: PAT.
Post-market surveillance: The manufacturer's ongoing collection and review of data about a device in real use, to spot problems and keep it safe after it is sold. Also: PMS.
PPE: Equipment worn to protect the user, such as gloves, gowns, masks and eye protection. The last line of defence in the hierarchy of controls. Also: personal protective equipment.
PPM: Maintenance done on a set schedule to keep a device safe and working, such as inspection, parts replacement and performance checks, not waiting for a fault. Also: planned preventive maintenance, scheduled maintenance, PM.
Precision: How close repeated measurements are to each other. A device can be precise but not accurate if it has a constant offset. Also: repeatability.
Pressure cascade: Setting rooms at different air pressures so air flows from clean to less clean areas, or in isolation rooms from corridor into the room. Also: pressure regime.
Pressure transducer: A sensor that converts pressure into an electrical signal, used for invasive blood pressure, ventilator airway pressure and pump occlusion. Also: transducer.
Prosthetic limb: An artificial limb that replaces a missing arm or leg. Modern ones may use microprocessor knees or myoelectric hands controlled by muscle signals. Also: prosthesis.
Protective earth: The green and yellow conductor that connects exposed metal of Class I equipment to earth, so a fault current trips the supply instead of passing through a person. Also: PE, earth conductor.
Protective isolation room: A room at higher pressure than its surroundings, with filtered air, to protect patients with weak immunity from infection. Also: positive pressure room.
PSIRF: The NHS England framework for responding to patient safety incidents, focusing on learning, compassionate engagement and proportionate responses. Also: Patient Safety Incident Response Framework.
Pulse oximeter: A device that shines red and infrared light through tissue and uses the pulsing absorption to estimate oxygen saturation (SpO2) and pulse rate. Also: SpO2 monitor, oximeter.
QRS complex: The part of the ECG showing electrical activation of the ventricles. Normally lasts less than 120 ms; a wide QRS suggests slow or abnormal conduction. Also: QRS.
Quality control: Routine checks with known samples or test objects to show an analyser or imaging system is producing correct results each day. Also: QC.
Quarantine: Taking a device out of use and clearly labelling it so nobody uses it until it is checked, repaired or released. Also keeps evidence intact. Also: out of service, do not use.
Quench: The sudden loss of superconductivity in an MRI magnet. The helium boils off fast and must be vented outside through the quench pipe. Also: magnet quench.
Quench pipe: The duct that carries helium gas safely out of the building during an MRI quench. A blocked pipe could fill the room with helium and cause asphyxia. Also: vent pipe.
RACI: A chart showing who is Responsible, Accountable, Consulted and Informed for each task, to avoid gaps and confusion about roles. Also: RACI matrix, responsibility matrix.
Radiation protection adviser: A certified expert who advises an employer on complying with IRR17, including shielding design and critical examinations. Also: RPA.
Ransomware: Malicious software that encrypts files and demands payment to unlock them. It can shut down imaging, records and connected devices. Also: crypto-ransomware.
Recall: Return, removal or correction of a device already supplied, because of a safety or performance problem. The asset register finds affected units. Also: device recall, product recall.
Reference measurement: A measurement by a separate, trusted method used to check a device's reading, such as a lab analysis to check a dialysis conductivity cell. Also: independent reference.
Remote access: Connecting to a device or system from elsewhere, such as by a manufacturer for support. Must be controlled, logged and switched on only when needed. Also: remote support, remote service.
Replacement priority: A ranked list of devices due for replacement, scored on age, condition, support status, risk and clinical need, used to bid for capital. Also: replacement scoring, replacement ranking.
Residual current device: A safety device that cuts the supply when current leaking to earth exceeds a set level, typically 30 mA. Not used on critical medical IT circuits. Also: RCD, RCCB.
Respiratory rate: The number of breaths per minute, normally about 12 to 20 in adults. A rising rate is one of the earliest signs a patient is getting worse. Also: RR, breathing rate.
Retention: A small part of the contract price held back until defects are fixed, giving the supplier a reason to finish all remaining work. Also: retention money, retention sum.
Retinal laser photocoagulator: A laser that makes small burns on the retina to seal leaking vessels or treat diabetic eye disease. Laser safety rules and eye protection apply. Also: retinal laser, photocoagulation laser.
Return electrode: The large pad that collects current in monopolar electrosurgery. Poor contact concentrates current and can burn the patient under the pad. Also: patient plate, neutral electrode, dispersive electrode.
Return electrode monitoring: A system that measures contact quality of a split return electrode and stops the electrosurgical unit if the pad starts to lift. Also: REM, CQM, contact quality monitoring.
Reverse osmosis plant: A water treatment system that forces water through a membrane to remove salts, bacteria and chemicals so it is safe for making dialysate. Also: RO plant, water treatment plant.
RF coil: An antenna in MRI that sends radio pulses and receives the signal from the body. Faulty coils and cables can cause image artefacts or burns. Also: MRI coil.
RF shield: A conductive enclosure around an MRI room that keeps outside radio signals out and scanner signals in. Its attenuation is tested at installation. Also: Faraday cage, RF cage.
RIS: The system that manages radiology bookings, worklists, reports and billing, linked to PACS and the patient record. Also: radiology information system.
Risk assessment: A careful look at what could cause harm in a task or situation, who might be harmed, how likely and severe it is, and what controls are needed. Also: RA.
Risk register: A list of identified risks with their scores, owners, controls and actions, reviewed regularly and escalated when scores are high. Also: risk log.
Risk score: A number that ranks a device by function, physical risk and maintenance needs, used to decide whether and how often it is maintained. Also: equipment management number.
RMS value: The effective value of an alternating signal, equal to the DC value that would deliver the same power. Mains in the UK is about 230 V RMS. Also: root mean square.
Room data sheet: A document listing everything a room needs: size, finishes, power, gas, data, ventilation and equipment. Also: RDS.
Root cause analysis: A structured investigation to find the underlying reasons an incident happened, so fixes address causes and not just symptoms. Also: RCA.
ROSC: The point during resuscitation when the heart starts pumping on its own again, shown by a pulse, a rise in blood pressure or a sudden rise in EtCO2. Also: return of spontaneous circulation.
Sampling rate: How many times per second a signal is measured when it is digitised. Too low a rate misses fast changes and can cause aliasing.
SBOM: A list of all the software components in a device, including third-party libraries, so known vulnerabilities in them can be found quickly. Also: software bill of materials.
SCBU: A neonatal unit for babies who need extra care, such as feeding support, warmth or phototherapy, but not intensive care. Also: special care baby unit.
Scintillation crystal: A crystal that gives off a flash of light when hit by a gamma photon. The flash is measured to detect radiation. Also: scintillator.
Secondary alarm notification: Sending device alarms to staff phones, pagers or central stations. It supports, but must not replace, the alarm at the bedside device. Also: alarm relay, distributed alarm system, alarm forwarding.
Sedation: Drugs that reduce anxiety and awareness while the patient keeps breathing. Requires monitoring, often including capnography, because it can slide into deeper levels. Also: conscious sedation, procedural sedation.
Self-test: An automatic check a device runs when it starts or on a schedule. Passing a self-test does not prove every function is safe under clinical conditions. Also: power-on self-test, POST.
Sepsis: A life-threatening reaction to infection where the body's response damages its own organs. Needs fast recognition, antibiotics and fluids. Also: septicaemia, septic shock.
Serious incident: An event in healthcare causing, or with potential to cause, serious harm, death or major disruption, needing a formal response and learning. Also: SI, patient safety incident.
Service bulletin: A notice from the manufacturer to service engineers about updates, known issues or new procedures. Not always a safety action, but should be reviewed. Also: technical bulletin, service note.
Sevoflurane: A volatile anaesthetic agent with a pleasant smell, commonly used for gas induction in children. Delivered by a sevoflurane-specific vaporiser. Also: sevo.
Signal-to-noise ratio: How strong the wanted signal is compared with unwanted noise. Poor electrode contact or interference lowers it. Also: SNR.
Silent MI: A heart attack with few or no typical symptoms, more common in people with diabetes and older adults. Often found later on an ECG or scan. Also: silent myocardial infarction, unrecognised MI.
Single fault condition: A condition where one means of protection has failed, such as an open earth. Devices must stay safe in single fault, so higher limits apply in type tests. Also: SFC.
Single point of failure: One part of a system whose failure stops the whole service, such as one scanner or one server with no backup. Also: SPOF.
Site readiness: Confirming the room is ready for installation: power, gases, data, floor loading, shielding, ventilation and access are all in place and tested. Also: site preparation, room readiness.
SLA: A contract part that sets measurable service standards, such as response time, repair time and uptime, and what happens if they are missed. Also: service level agreement.
Smart pump: An infusion pump with dose error reduction software and a drug library, often networked so libraries can be updated and usage data collected. Also: smart infusion pump.
SMART recommendation: An action from an investigation that is Specific, Measurable, Achievable, Relevant and Time-bound, with a named owner, so it can be checked. Also: SMART action.
Snagging: Listing and fixing minor defects or unfinished items near the end of an installation, before final acceptance and handover. Also: snag list, punch list.
Software update: A new version of device or system software. Needs change control, testing and a record of the version installed on each unit. Also: software upgrade, software version.
Spare parts strategy: Deciding which parts to keep in stock based on failure rates, lead times and clinical impact, balancing cost against downtime. Also: critical spares, spares holding.
SPECT scanner: A nuclear medicine camera that rotates around the patient to detect single gamma photons from a tracer such as technetium-99m and build 3D images of organ function. Also: single photon emission computed tomography, SPECT, gamma camera, SPECT-CT.
Spirometer: A device that measures how much air a person can breathe out and how fast, giving values such as FEV1 and FVC. Needs daily calibration with a syringe. Also: lung function tester.
SpO2: The percentage of haemoglobin carrying oxygen, estimated by a pulse oximeter from red and infrared light. Normal is about 94 to 98 percent in healthy adults. Also: oxygen saturation by pulse oximetry, pulse ox reading.
SpO2 probe: The sensor clip or wrap with red and infrared LEDs and a photodetector. A dirty, wrong or damaged probe is a common cause of false readings. Also: oximeter sensor, finger probe.
SpO2 simulator: A device that mimics a finger's light absorption to check an oximeter and probe chain. It does not prove true clinical accuracy. Also: oximeter simulator.
ST elevation: A raised ST segment on the ECG. STEMI is a heart attack with ST elevation, usually caused by a fully blocked coronary artery, needing urgent reperfusion. Also: STEMI, ST-elevation myocardial infarction.
ST segment: The flat part of the ECG between the end of the QRS and the start of the T wave. Rise or fall from the baseline can indicate heart muscle injury or ischaemia. Also: ST.
Stakeholder: Anyone affected by or able to affect a decision or project, such as clinicians, patients, estates, IT, finance and suppliers. Also: stakeholders.
Standby generator: A diesel or gas generator that starts automatically when mains fails and supplies essential circuits, usually within 15 seconds. Also: generator.
Standstill period: A pause of at least 8 working days after telling bidders the award decision, before signing the contract, so losing bidders can challenge it. Also: Alcatel period, standstill.
Sterile services department: The department that cleans, disinfects, inspects, packs and sterilises reusable surgical instruments. Also: CSSD, SSD.
Sterilisation: A validated process, such as steam at 134 °C, that kills all microorganisms including spores.
Stethoscope: A device for listening to heart, lung and bowel sounds. Electronic versions amplify and filter sound and can record it. Also: electronic stethoscope.
Strain gauge: A sensor whose resistance changes when it is stretched, often arranged in a Wheatstone bridge inside pressure and load sensors.
Stroke: Sudden loss of brain function from a blocked artery (ischaemic) or a bleed (haemorrhagic). Fast imaging decides treatment, because time lost is brain lost. Also: CVA, brain attack.
Succession planning: Preparing people to take over key roles, so skills are not lost when someone leaves or retires. Also: succession plan.
Superconducting magnet: The main MRI magnet: coils cooled by liquid helium to about -269 °C carry current with no resistance, so the field stays on all the time. Also: MRI magnet.
Supervised area: An area under IRR17 where exposure must be kept under review but which does not need the stricter rules of a controlled area.
Supplementary equipotential bonding: Conductors that connect metal parts and earth terminals in a room so they all sit at the same voltage, reducing shock risk to patients. Also: equipotential bonding.
Surgical air: Compressed air at higher pressure, about 7 bar, used to drive surgical tools. It must not be connected to patient breathing devices.
Surgical robot: A system where the surgeon controls robotic arms holding instruments and a 3D camera from a console. The robot scales and filters hand movements but does not act on its own. Also: robotic surgical system, robot-assisted surgery system.
Surgical stapler: A hand-held or powered device that places rows of staples to join or close tissue, often cutting between them, in bowel, lung and vessel surgery. Also: stapler.
Synchronised cardioversion: A shock timed to the R wave of the ECG to avoid the vulnerable part of the heart cycle, used for some fast rhythms that still have a pulse. Also: sync mode, cardioversion.
Syringe driver: A pump that pushes a syringe plunger at a controlled rate to deliver small volumes accurately, used for strong drugs and in neonates. Also: syringe pump.
Syringe size detection: A syringe pump feature that measures the barrel diameter to identify the syringe, because the wrong syringe setting gives a large dose error.
Tachycardia: A heart rate above about 100 beats per minute in adults. It can be normal on exertion or a sign of pain, fever, bleeding, sepsis or arrhythmia. Also: fast heart rate.
TCO: All costs of owning a device over its life: purchase, installation, training, consumables, service, energy, downtime and disposal, not just the price. Also: total cost of ownership.
TEE probe: An ultrasound probe on a flexible tube passed into the oesophagus to image the heart from behind. It needs leakage testing and careful decontamination between patients. Also: transoesophageal echocardiography probe, TOE probe, TEE.
Temperature-controlled test: A test run with the device or sensor held at a set temperature, such as body temperature, to reveal faults that only appear when warm.
Tender: A formal process where suppliers submit offers against a published specification and criteria, so the buyer can compare them fairly and openly. Also: invitation to tender, ITT, bid.
TENS unit: A small battery device that sends mild electrical pulses through skin electrodes to reduce pain. Also: transcutaneous electrical nerve stimulator, TENS.
Terminal unit: The wall or pendant outlet where devices connect to the gas pipeline. Each gas has a unique shape so the wrong probe cannot fit. Also: gas outlet, Schrader outlet.
Test conditions: The environment and settings under which a test is done. If they do not match clinical use, a device can pass the test and still fail on the patient.
Test lung: A bag or bellows with set compliance and resistance that stands in for a patient's lungs when testing a ventilator.
Theatre list: The planned order of operations in a theatre for a session. Equipment faults can cancel or delay cases on the list. Also: operating list, surgical list.
Theatre table: A powered table that positions the patient for surgery. Load ratings, battery backup and radiolucent tops matter when choosing one. Also: operating table.
Thermal index: An on-screen estimate of how much ultrasound could warm tissue. Users keep it as low as reasonably achievable, especially in fetal and eye scans. Also: TI.
Thermal stabilisation: Letting a device or sensor reach a steady temperature before testing. A test done too early or at the wrong temperature can miss a fault. Also: warm-up.
Thermistor: A resistor whose resistance changes strongly with temperature, used for patient and device temperature measurement. It can drift with age and heat.
Thermocouple: A temperature sensor made of two different metals that produces a small voltage depending on temperature. Used in autoclaves and test equipment.
Thermometer: A device that measures body temperature, for example by infrared at the ear or forehead or by a probe. Technique and probe covers affect accuracy. Also: clinical thermometer, tympanic thermometer.
Thermoneutral environment: The temperature range where a baby uses the least energy and oxygen to keep its body temperature normal. Incubators aim to hold the baby in this range. Also: thermoneutral zone, neutral thermal environment.
Thorough examination: The legal inspection of lifting equipment under LOLER by a competent person, every 6 months for equipment that lifts people. Also: LOLER examination.
Thrombectomy: Removal of a clot from a blocked artery using a catheter device, guided by X-ray imaging. Used for large-vessel ischaemic stroke within set time windows. Also: mechanical thrombectomy, clot retrieval.
Thrombolysis: Giving a drug that dissolves blood clots, for example in ischaemic stroke. Must be ruled out for bleeding first, which is why urgent CT is needed. Also: clot-busting drug, alteplase.
Tidal volume: The volume of gas moved into or out of the lungs in one normal breath, roughly 6 to 8 mL per kg of ideal body weight on a ventilator. Also: Vt, VT (ventilation).
Timestamp: The date and time recorded with an event or data point. Only trustworthy if the clock was correct and the time zone is known. Also: time stamp, event time.
TIVA: General anaesthesia given entirely by intravenous drugs such as propofol and remifentanil, often with target-controlled infusion pumps, without vapour agents. Also: total intravenous anaesthesia, TCI.
TN-S system: An earthing arrangement where the neutral and protective earth are separate conductors all the way from the source. Recommended in hospitals to reduce EMI.
Tolerance: The allowed difference between the measured value and the set value, such as ±5 percent flow. A result outside tolerance is a fail. Also: acceptance limit.
Touch current: Leakage that would flow through a person touching the device enclosure. It is measured in IEC 60601-1 type tests. Also: enclosure leakage.
Traceability: An unbroken chain of calibrations linking a measurement back to national or international standards, such as through a UKAS accredited lab. Also: metrological traceability.
Transcranial Doppler: An ultrasound device that measures blood flow speed in the brain's arteries through the skull, used to detect vasospasm and emboli after stroke or bleeding. Also: TCD.
Transducer (ultrasound): The hand-held part of an ultrasound system with piezoelectric crystals that send and receive sound. Cracked lenses or dead elements spoil images. Also: ultrasound probe.
Troponin: A protein released into the blood when heart muscle is damaged. A rising level on repeat tests supports a diagnosis of myocardial infarction. Also: cardiac troponin, hs-troponin.
Trumpet curve: A graph from IEC 60601-2-24 showing how much an infusion pump's flow varies over different time windows. Short windows show bigger swings.
Type B applied part: An applied part that is not isolated from earth. Suitable only for parts that do not connect to the patient electrically, such as a patient couch. Also: type B.
Type BF applied part: A floating (isolated) applied part for body contact, such as an NIBP cuff or ECG for surface use. Leakage limits are tighter than type B. Also: type BF.
Type CF applied part: A floating applied part suitable for direct contact with the heart, such as invasive pressure lines. It has the tightest leakage limits of all. Also: type CF.
UAT: Testing by the real users, such as clinical staff, to confirm a system does what they need in everyday work before it goes live. Also: user acceptance testing.
UDI: A unique code on a device and its packaging identifying the model and the batch or serial number, so devices can be traced in recalls. Also: unique device identification, UDI-DI, UDI-PI.
UKAS: The UK body that accredits calibration and testing laboratories, giving confidence in traceable measurements. Also: United Kingdom Accreditation Service.
UKCA mark: The marking showing a device meets the UK medical device regulations for the Great Britain market. Also: UK Conformity Assessed.
Ultra-clean ventilation: Theatre ventilation that blows very clean, HEPA-filtered air down over the operating site to keep bacteria counts extremely low for implant surgery. Also: UCV, laminar flow.
Ultrafiltration: Removal of excess water from the blood across the dialyser membrane by a pressure difference. The UF goal and rate are set for each session. Also: UF, fluid removal.
Ultrasound scanner: An imaging system that sends high-frequency sound into the body and builds images from the echoes. No ionising radiation, but output is limited by thermal and mechanical indices. Also: ultrasound, sonography.
Uninterruptible power supply: A battery-backed unit that keeps power flowing with no break when mains fails, until generators take over. Batteries need regular testing and replacement. Also: UPS.
Uptime guarantee: A contract promise that a system will be working for a set share of time, such as 97 percent, often with service credits or term extensions if missed. Also: availability guarantee.
Urodynamics system: A system that measures bladder and abdominal pressures and urine flow while the bladder fills and empties, to diagnose bladder problems. Also: urodynamic system.
User training record: A record showing which staff have been trained and judged competent on which devices, so managers can check before staff use them. Also: training log, competence record.
Uterine contractions: Tightening of the womb muscle during labour. Shown on the lower CTG trace; their timing against fetal heart rate changes helps judge fetal wellbeing. Also: contractions, toco.
Vacuum insulated evaporator: A large insulated tank that stores liquid oxygen and evaporates it to supply the hospital pipeline. Also: VIE, oxygen tank.
Vasospasm: Sudden narrowing of an artery by its muscle wall, reducing blood flow. A known risk after bleeding around the brain and during catheter procedures. Also: arterial spasm, cerebral vasospasm.
Venous air detector: An ultrasonic detector on the dialysis venous line that clamps the line and stops the blood pump if air is detected. Also: air trap detector.
Ventricular fibrillation: A chaotic ventricular rhythm with no effective pumping, so there is no pulse. A shockable cardiac arrest rhythm treated with CPR and defibrillation. Also: VF, v-fib.
Ventricular tachycardia: A fast rhythm starting in the ventricles with wide QRS complexes. It may have a pulse or be pulseless; pulseless VT is shocked like VF. Also: VT, v-tach.
Vigilance: The system for reporting and assessing serious incidents and safety actions involving devices on the market, so lessons spread quickly. Also: vigilance system, adverse incident reporting.
Visual inspection: The first step of every safety test: look for damaged plugs, cables, cases, labels and missing parts. Many failures are found here before any meter is used.
Vitrectomy system: An eye surgery system that cuts and removes the vitreous gel with a high-speed probe while controlling infusion pressure inside the eye. Also: vitrectomy machine.
VLAN: A logical network created on shared switches so groups of devices, such as medical devices, are kept separate from other traffic. Also: virtual LAN, virtual local area network.
VNS: An implanted pulse generator with a lead around the left vagus nerve in the neck, used to reduce seizures in epilepsy and for some cases of depression. Also: vagus nerve stimulator.
VTBI: The total volume an infusion pump is set to deliver before it stops or switches to KVO and alarms. Set alongside rate and time. Also: volume to be infused.
Vulnerability: A weakness in software or hardware that an attacker could use. Public ones get a CVE number and a severity score. Also: security vulnerability, CVE.
Ward round: A regular visit by the medical team to review each patient, make decisions and update the plan. A useful time to catch staff with equipment questions. Also: rounds.
Warranty: The supplier's promise to repair or replace faults for a set period after delivery. Its start date and what it excludes matter as much as its length. Also: guarantee period.
Washer-disinfector: A machine that cleans and thermally or chemically disinfects instruments and equipment. Tested and validated to ISO 15883. Also: WD.
Weighted scoring: Scoring bids against criteria that each carry a set weight, such as 60 percent quality and 40 percent price, then combining them for a total. Also: weighted evaluation, scoring matrix.
Wheatstone bridge: A circuit of four resistances used to measure very small changes in resistance, such as those from strain gauges in pressure transducers.
Whistleblowing: Raising concerns about wrongdoing or danger at work. UK law protects workers who make such disclosures in the public interest. Also: speaking up, freedom to speak up.
Whole-life cost: The total cost of an asset from purchase to disposal. Similar to TCO; used to compare options fairly when cheap purchase means costly running. Also: life cycle cost, WLC.
Wi-Fi roaming: A wireless device moving its connection from one access point to another as it moves. Slow roaming can drop data from moving monitors or pumps. Also: roaming, access point handover.
Wireless coverage: How well the wireless signal reaches every place where devices are used. Gaps, such as in lifts or shielded rooms, cause lost data and alarms. Also: Wi-Fi coverage, signal coverage.
Witness statement: A signed, dated, factual account of what a person saw or did, written soon after events. Should stick to facts and avoid guessing. Also: statement.
Work order: A record in the CMMS for one piece of work on a device: fault, planned maintenance or install. Holds what was done, parts, time and who did it. Also: job, job ticket, WO.
X-ray system: A system with an X-ray tube and a detector that makes a projection image of the body. Controlled by kV, mA and time, under IRR17 and IR(ME)R. Also: conventional X-ray, radiography system, DR room.
X-ray tube: The vacuum tube where electrons hit a target to make X-rays. The anode heats up, so tube heat capacity limits how fast scans can be repeated.

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