Cheat sheet
CBET Memorization Sheet
Print this and keep it beside you. The CBET exam rewards recall of normal values, safety limits, device settings, units, standards, and formulas across every kind of equipment in a hospital. Every number on this sheet is fair game.
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01The exam itself
| Fact | Value |
|---|---|
| Certifying body | AAMI Credentials Institute (ACI) |
| Questions | 165 multiple choice; 150 scored, 15 unscored pretest items mixed in |
| Time and rules | 3 hours, closed book, simple calculator allowed, no phones |
| Passing | Criterion-referenced cut score (modified Angoff), about 116 of 165 correct, roughly 70% |
| Healthcare Technology and Function | 30% |
| Healthcare Technology Problem Solving | 30% |
| Healthcare Information Technology | 17% |
| Public Safety in the Healthcare Facility | 10% |
| Anatomy and Physiology | 7% |
| Fundamentals of Electricity and Electronics | 6% |
Function and problem solving are 60% of the exam. For every device: what it measures or delivers, its settings and normal values, its alarms, its common faults, and the first check.
02Anatomy and physiology
| Vital sign (adult, resting) | Normal range | Measured by |
|---|---|---|
| Heart rate | 60 to 100 bpm (below 60 bradycardia, above 100 tachycardia) | ECG, pulse oximeter, NIBP |
| Respiratory rate | 12 to 20 breaths per minute | Impedance pneumography, capnography |
| Blood pressure | About 120/80 mmHg; MAP = diastolic + (systolic minus diastolic) / 3, about 70 to 100 | NIBP, arterial line |
| Oxygen saturation (SpO2) | 95 to 100% | Pulse oximeter |
| End-tidal CO2 (EtCO2) | 35 to 45 mmHg | Capnograph |
| Body temperature | 37 C (98.6 F); fever above about 38 C | Thermistor, thermocouple, infrared |
| Fetal heart rate | 110 to 160 bpm | Doppler ultrasound |
| Tidal volume | About 500 mL at rest (6 to 8 mL/kg ideal body weight on a ventilator) | Ventilator, spirometer |
| Cardiac output | About 5 L/min = heart rate x stroke volume (about 70 mL) | Derived |
| System | Key parts | What the technician's devices do with it |
|---|---|---|
| Circulatory | Heart (right atrium, right ventricle, left atrium, left ventricle), tricuspid, pulmonary, mitral, aortic valves, arteries, veins, capillaries | ECG records electrical activity; NIBP and arterial lines measure pressure; defibrillators and pacemakers control rhythm; balloon pumps assist |
| Blood flow | Body, vena cava, RA, tricuspid, RV, pulmonary valve, pulmonary artery, lungs, pulmonary veins, LA, mitral, LV, aortic valve, aorta, body | Right side pumps to lungs, left side to body |
| Conduction path | SA node, AV node, bundle of His, bundle branches, Purkinje fibers | P wave atrial depolarization, QRS ventricular depolarization, T wave ventricular repolarization |
| Respiratory | Trachea, bronchi, bronchioles, alveoli, diaphragm | Ventilators move gas; oximeters measure oxygen carried; capnographs measure CO2 exhaled; spirometers measure volumes |
| Nervous | Brain (cerebrum, cerebellum, brainstem), spinal cord, peripheral and autonomic nerves | EEG records brain activity; EMG records muscle; stimulators test conduction; sympathetic raises heart rate, parasympathetic lowers it |
| Musculoskeletal | 206 bones, joints, skeletal (voluntary), smooth (involuntary), and cardiac muscle | Physical therapy stimulators, traction, continuous passive motion |
| Gastrointestinal | Esophagus, stomach, small intestine (absorption), large intestine, liver, pancreas, gallbladder | Feeding pumps deliver enteral nutrition; suction removes; endoscopes view |
| Endocrine | Pancreas (insulin, glucagon), thyroid, adrenals (epinephrine), pituitary | Glucose meters, insulin pumps |
| Renal | Kidneys (nephrons filter blood), ureters, bladder | Dialysis replaces filtration |
| Skin | Epidermis, dermis, subcutaneous layer; barrier, temperature control, sensation | Electrode contact and skin impedance, burns, pressure injuries |
| Blood | Plasma, red cells (hemoglobin carries oxygen), white cells (immunity), platelets (clotting) | Analyzers count and measure; oximetry depends on hemoglobin |
Directional terms and word parts
- Anterior front, posterior back; superior above, inferior below; medial toward the midline, lateral away; proximal near the trunk, distal far; supine face up, prone face down; planes: sagittal (left and right), coronal (front and back), transverse (top and bottom)
- Systole contraction, diastole relaxation. Hypertension high pressure, hypotension low. Hypoxia low oxygen, hypercapnia high CO2, apnea no breathing
- Prefixes: brady- slow, tachy- fast, hyper- high, hypo- low, a-/an- without, dys- difficult, peri- around, endo- inside
- Roots: cardio heart, pulmo/pneumo lung, nephro/reno kidney, hepat liver, neuro nerve, gastro stomach, derm skin, osteo bone, hemo/hemat blood, myo muscle, encephal brain
- Suffixes: -itis inflammation, -ectomy removal, -ostomy opening, -oscopy viewing, -graphy recording, -gram the record, -algia pain, -emia blood condition
ECG timing (normal adult)
- PR interval 0.12 to 0.20 s; QRS under 0.12 s; QT under about 0.44 s
- Paper speed 25 mm/s; 1 mV = 10 mm; small box 0.04 s (1 mm), large box 0.20 s (5 mm)
- Heart rate = 1500 / small boxes between R waves, or 300 / large boxes
- Ventricular fibrillation: chaotic, no QRS, shockable. Asystole: flat line, not shockable. Atrial fibrillation: irregular, no P waves
| Anatomy detail | Facts |
|---|---|
| Skin layers | Epidermis (stratum basale at its base) over dermis over hypodermis (deepest); sebaceous glands oil, sweat glands cool, vitamin D made in skin |
| Muscle types | Skeletal striated voluntary; cardiac striated involuntary; smooth non-striated involuntary (organs, vessels, uterus, bladder) |
| Skeleton | 206 bones: 80 axial (skull, 33 vertebrae, ribs, sternum with manubrium and xiphoid, ossicles, hyoid) and 126 appendicular (scapula, clavicle, pelvis, humerus, radius, ulna, femur, patella, tibia, fibula) |
| Brain | Forebrain: cerebrum (frontal plans, parietal senses, occipital sees, temporal hears), thalamus relays, hypothalamus drives the pituitary. Midbrain relays vision and hearing. Hindbrain: cerebellum coordinates, pons relays, medulla runs breathing and heart rate. Brain stem = midbrain + pons + medulla |
| Nerves | Somatic voluntary; autonomic involuntary (sympathetic fight or flight, parasympathetic rest and digest); neurons signal by action potentials across synapses |
| Digestion in order | Mouth (amylase, lipase), esophagus (epiglottis, lower esophageal sphincter), stomach (pH 1.5 to 3.5, pyloric sphincter releases chyme), duodenum, jejunum, ileum, large intestine (reabsorbs water); liver makes bile, glycogen, urea; gallbladder stores bile; pancreas enzymes and insulin |
| Lymph and immunity | Lymph filtered in nodes (neck, armpits, groin); tonsils, thymus (T cells), spleen (cleans blood), Peyer's patches; the immune system avoids, detects, and eliminates infection |
| Endocrine | Hypothalamus and pituitary control; thyroid metabolism; parathyroid (posterior thyroid lobes) raises calcium; adrenal cortex cortisol, medulla epinephrine; islets insulin and glucagon; pineal rhythms; negative feedback stabilizes, positive amplifies; the pons secretes nothing |
| Kidney | Cortex, medulla, pelvis; nephron: glomerulus in Bowman's capsule (blood pressure drives filtration), tubules reabsorb and secrete; ureter, bladder, urethra |
| Reproduction | Testes, epididymis, vas deferens, prostate; FSH sperm, LH testosterone. Ovaries (estrogen, progesterone), fallopian tube (fertilization), uterus (implantation) |
| Blood terms | Hemoglobin carries oxygen; hematocrit is the red-cell fraction (about 45%); about 5 liters total; lymphocytes, neutrophils, monocytes, eosinophils, basophils |
03Electricity and electronics
| Formula | Statement |
|---|---|
| Ohm's law | V = I x R; I = V / R; R = V / I |
| Power | P = V x I = I squared x R = V squared / R (watts) |
| Series resistance | R total = R1 + R2 + ... ; same current through each; voltages add |
| Parallel resistance | 1 / R total = 1/R1 + 1/R2 + ... ; two resistors: (R1 x R2) / (R1 + R2); same voltage across each; currents add |
| Kirchhoff | Currents into a node equal currents out; voltages around a loop sum to zero |
| AC values | RMS = 0.707 x peak; peak = 1.414 x RMS; peak-to-peak = 2 x peak; US mains 120 V RMS at 60 Hz (many countries 230 V at 50 Hz) |
| Transformer | V secondary / V primary = N secondary / N primary; step-down lowers voltage and raises current; isolation transformer 1:1 |
| Capacitive reactance | Xc = 1 / (2 x pi x f x C); capacitors pass AC, block DC |
| Inductive reactance | XL = 2 x pi x f x L; inductors pass DC, oppose changes in current |
| RC time constant | tau = R x C; capacitor reaches 63% of full charge in one tau, about 99% in five |
| Frequency and period | f = 1 / T; 60 Hz has a period of 16.7 ms |
| Stored energy | E = one half x C x V squared (joules); how a defibrillator capacitor stores its charge |
| Energy | E = P x t; 60 W for 8 h = 0.48 kWh; kWh is energy, kW is power |
| Voltage divider | V across R1 = V source x R1 / R total (series); 120 V across 60 and 100 ohms puts 45 V on the 60 |
| Current divider | I through a branch = I total x (1/R branch) / (sum of 1/R); the smallest resistance takes the most current |
| Kirchhoff's laws | KCL: current into a node equals current out (nodal analysis). KVL: voltages around a loop sum to zero (mesh analysis) |
| Internal resistance | (open-circuit voltage minus loaded voltage) / load current; 1.58 V to 1.46 V into 80 ohms = 6.58 ohms; rises with age |
| Wheatstone bridge | Balanced (no meter current) when R1 / R2 = R3 / R4; strain gauges and thermistors sit in bridges |
| Complex impedance | Z = R + jX; 40 mH at 60 Hz is about 15 ohms of reactance; an ideal 30 mH inductor at 60 Hz is 11.3j ohms |
| AC power | S squared = P squared + Q squared; P true (W), Q reactive (VAR), S apparent (VA); 180 W and 240 VAR give 300 VA; power factor = P / S |
| Op-amp gain | Inverting gain = R feedback / R input (gain 9 with 5 k in needs 45 k feedback); non-inverting = 1 + Rf / Rin |
| Transformer ratio | V primary / V secondary = N primary / N secondary; 240 V to 6,000 V is a 0.04 ratio |
| C-rate | Charge or discharge current relative to capacity; 60 kWh at 0.5 C = 30 kW |
- Resistor color code digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9; tolerance gold 5%, silver 10%
- US cord colors: black (or red) hot, white neutral, green or bare ground. IEC cords: brown live, blue neutral, green-yellow ground
- Schematic symbols: zigzag resistor, parallel lines capacitor, coil inductor, triangle-with-bar diode, ground, fuse, switch, battery; signals flow left to right; compare measured voltages to the values printed at test points
- Passive devices (resistors, capacitors, inductors, transformers) cannot add energy; active devices (diodes, transistors, ICs, op-amps) control or amplify
- Diode conducts one way, forward drop about 0.7 V silicon; zener regulates; LED lights; rectifiers: half-wave, full-wave, bridge; capacitor filters ripple; regulator holds output steady
- Linear power supply: heavy transformer, low noise, inefficient. Switching supply: light, efficient, more noise, needs a load
- Transistor: NPN or PNP, base controls collector-emitter; used as a switch or amplifier. SCR and triac switch AC power
- Op-amp rules: huge gain, inputs draw no current, feedback makes the inputs equal; instrumentation amplifier rejects common-mode noise (high CMRR) for ECG front ends; isolation amplifiers and optocouplers keep patient circuits floating
- Filters: low-pass keeps slow signals, high-pass removes baseline drift, band-pass keeps a range, notch removes 60 Hz
- DMM measures volts, amps (in series), ohms (power off); oscilloscope shows voltage against time, 10x probe divides by ten; function generator provides test signals
- Passive: resistor, capacitor, inductor, memristor, thermistor (no gain). Active: transistor, op-amp, IC, SCR. Transducer converts energy: sensor to electrical, actuator from electrical; piezoelectric crystals do both
- US distribution: step-up to transmit, step-down to use; split-phase 120/240 V at 60 Hz with a grounded center neutral; NEC is NFPA 70 (building wiring), NESC is IEEE (utility lines)
- Battery specifications: voltage per cell, capacity (Ah), energy density (sets weight), internal resistance (rises with age, sag under load), shelf life, discharge curve, cycle life, C-rate
- Regulators: linear drops excess as heat (quiet, inefficient); switching chops at a duty cycle (efficient, noisy); shorted switching element passes full input voltage, open element gives zero; test regulator input and output pins to ground
- Filters by what they pass: low-pass, high-pass, band-pass, band-stop (notch is a narrow band-stop)
| Power storage and conditioning | Facts |
|---|---|
| Cell voltages | Lead-acid 2.0 V, nickel-cadmium 1.2 V, nickel-metal hydride 1.2 V, lithium-ion 3.6 to 3.7 V, alkaline 1.5 V |
| Battery behavior | NiCd memory effect (condition with full cycles); Li-ion no memory but thermal runaway risk and must not over-discharge; sealed lead-acid sulfates if left discharged; capacity in amp-hours falls with age |
| UPS types | Standby (switches on loss), line-interactive (regulates voltage), online double-conversion (always on inverter, best protection) |
| Power problems | Sag or brownout (low voltage), surge (high), transient spike, noise, blackout; conditioners regulate and filter |
| Hospital essential electrical system (NFPA 99 and NFPA 70) | Generator restores power within 10 seconds; branches: life safety, critical (patient care, red outlets), equipment; UPS bridges the gap for critical devices |
| Isolated power and LIM | Ungrounded secondary of an isolation transformer; line isolation monitor alarms at 5 mA total hazard current; used in wet procedure locations |
| GFCI | Trips at 4 to 6 mA of imbalance between hot and neutral in about 25 ms; wet locations |
04Electrical safety
| Current through the body (60 Hz, hand to hand) | Effect |
|---|---|
| 1 mA | Threshold of perception (tingle) |
| 5 mA | Accepted maximum harmless current |
| 10 to 20 mA | Let-go threshold: muscles contract and the person cannot release |
| 50 mA | Pain, possible fainting, respiratory arrest |
| 100 to 300 mA | Ventricular fibrillation likely |
| 6 A and above | Sustained heart contraction, burns, respiratory paralysis |
| Microshock | As little as 10 microamps delivered directly to the heart (through a catheter or pacing wire) can cause fibrillation |
| IEC 60601-1 limit | Normal condition | Single fault condition |
|---|---|---|
| Earth (ground) leakage | 5 mA | 10 mA |
| Touch (enclosure, chassis) current | 100 microamps | 500 microamps |
| Patient leakage, type B and BF, AC | 100 microamps | 500 microamps |
| Patient leakage, type CF, AC | 10 microamps | 50 microamps |
| Patient leakage, DC (all types) | 10 microamps | 50 microamps |
| Mains voltage on the applied part | BF: 5 mA; CF: 50 microamps | (single fault test) |
| NFPA 99 and facility facts | Value |
|---|---|
| Ground (chassis to plug ground pin) resistance | 0.5 ohm maximum for patient-care equipment |
| Chassis (touch) leakage, cord-connected patient-care equipment | 500 microamps in current editions (older editions used 300 or 100 microamps; know the limit your facility cites) |
| Patient care vicinity | About 6 feet (1.8 m) beyond the bed or chair and 7.5 feet (2.3 m) above the floor |
| Line isolation monitor alarm | 5 mA total hazard current |
| GFCI trip | 4 to 6 mA (nominal 5 mA) |
| Hospital-grade receptacle | Green dot; test retention force, polarity, ground continuity |
| Relocatable power taps | Only where allowed, rated, and secured; never daisy-chained; no extension cords for patient care equipment |
| Relocatable power tap load | No more than 75% of the tap's rating (an AWG 10 tap rated 35 A carries at most 26 A); never daisy-chained |
| Prohibited | Three-to-two prong (cheater) adapters; tinned stranded wire ends under screw terminals; cords without strain relief; isolated-ground receptacles in the patient care vicinity |
| Patient room receptacles | At least 8 per general bed (more in critical care), non-locking, tamper-resistant; no minimum in bathrooms; OR receptacles single, duplex, or quadruplex with insulated grounds, locking or not |
| Household electronics | Allowed only outside the patient care vicinity unless double insulated; inspected before patient use; worn units removed |
| Gas cylinder storage | Unwrapped, secured upright, minus 7 to 52 C; oxidizers 20 ft from flammables (5 ft with sprinklers, none in a compliant cabinet); no smoking within 20 ft; not in tight enclosures; door warning for other positive-pressure gases |
| Medical gas systems | DOT/TC/ASME cylinders; gas-specific outlets, no adapters; redundant supply; alarms; labeled zone shutoff valves; inventory and inspection |
| Telecommunications rooms | No data outlet more than 90 m from its room; at least one per floor; each serves at most 20,000 sq ft; interior rooms in disaster areas |
| Nurse call | Carries device alarms, staff emergencies, code calls, patient requests; audible and visual annunciation; may forward to pagers |
| Touch current and clean agents | Touch current: chassis leakage reachable by a person via a path other than ground. Clean agents: nonconductive, residue-free extinguishants (nitrogen, CO2, noble gases, halocarbons) |
Classes, types, symbols, and testing
- Class I: protective earth (three-prong ground). Class II: double insulation, no ground (square-in-square symbol). Internally powered: battery only
- Applied part type B: body, not for direct cardiac use (stick figure). BF: body floating, isolated (figure in a box). CF: cardiac floating, safe for direct heart connection (heart in a box)
- Defibrillation-proof applied part: the symbol with paddles; withstands a defibrillator discharge
- Macroshock: current through the skin; needs milliamps. Microshock: current bypassing the skin to the heart; microamps
- Safety analyzer sequence: visual inspection and cord check, ground resistance, chassis leakage (normal, reversed polarity, open ground, open neutral), patient lead leakage, lead-to-lead, mains on applied part
- Leakage rises with open ground and reversed polarity; a rising leakage trend on PM predicts insulation failure; test at incoming inspection, after repair, and per PM schedule
05Infection control, hazards, fire, gas, radiation, MRI, and standards
Infection control
- Standard (universal) precautions: treat all blood and body fluids as infectious; hand hygiene before and after every patient contact and before touching equipment
- Transmission-based precautions: contact (gown, gloves), droplet (surgical mask), airborne (N95 respirator, negative-pressure room)
- PPE donning: gown, mask, eye protection, gloves. Doffing: gloves, eye protection, gown, mask (clean hands between)
- Cleaning removes soil; disinfection kills most microbes; sterilization kills all including spores
- Spaulding: critical items (enter sterile tissue) sterilize; semi-critical (touch mucous membranes) high-level disinfect; non-critical (intact skin) low-level disinfect
- Steam autoclave: 121 C (250 F) at 15 psi for 15 to 30 minutes, or 132 to 135 C flash cycles; biological indicators verify; ethylene oxide and hydrogen peroxide plasma for heat-sensitive items
- Clean and disinfect equipment before servicing it; sharps in puncture-resistant containers; OSHA bloodborne pathogens standard covers exposure control; report needlesticks immediately
- Universal precautions (1980s): blood and blood-contaminated fluids only, not sweat, tears, nasal secretions, or urine; bleach cleanup; bagged waste. Standard precautions (CDC 1996): all body fluids plus body substance isolation; transmission-based precautions supplement them
- Regulated waste: liquid or free-flowing blood, sealed for a licensed medical waste service; dried blood on dressings sealed in a plastic bag with regular trash; broken glass with tools, never hands
- Lab practice: annual biological risk assessment sets the biosafety level; no mouth pipetting; no food, drink, or contact lenses; retractable needles; decontaminate before disposal; eyewash station; hands-free sinks; clean utility room separate from dirty utility; lab coats are not gowns
Hazard communication and signage
- Safety data sheet (SDS): 16 sections including identification, hazards, first aid, fire fighting, handling and storage, exposure controls and PPE; must be accessible to staff
- GHS pictograms: flame (flammable), flame over circle (oxidizer), skull (acute toxicity), corrosion, exclamation mark (irritant), health hazard (silhouette), gas cylinder, environment
- NFPA 704 diamond: blue health, red flammability, yellow reactivity, white special (W with a line means water reactive, OX oxidizer); scale 0 to 4
- Laser signs state the class and wavelength; classes 1 (safe) through 4 (fire and eye hazard); wavelength-specific eyewear
- Ionizing radiation: trefoil symbol; time, distance, shielding; ALARA; inverse square law; lead aprons about 0.5 mm; dosimeters
- MRI: zones I (public) through IV (magnet room); the magnet is always on; ferromagnetic objects become projectiles; quench vents helium; MR Safe, MR Conditional, MR Unsafe labels
- Patient precaution signs at the door: contact, droplet, airborne, fall risk, latex allergy, no blood pressure on a limb
- HazCom (OSHA 29 CFR 1910.1200) requires labels, SDS access, training, and records; it adopted the UN Globally Harmonized System (GHS) for classification, pictograms, signal words, and the 16-section SDS
- SDS order: identification, hazards, composition, first aid, fire fighting, accidental release, handling and storage, exposure controls and PPE, physical and chemical properties, stability and reactivity, toxicology, ecology, disposal, transport, regulatory, other
- Toxicity and limits: LD50 lethal dose for 50%, LC50 lethal concentration; PEL legal limit (OSHA); TLV recommended (ACGIH); REL recommended (NIOSH); STEL 15-minute ceiling; carcinogen lists from NTP, IARC, OSHA
- GHS label: identity, manufacturer contact, pictograms, signal word (Danger or Warning only), hazard and precautionary statements; secondary containers need the same; pyrophoric ignites in air within 5 minutes; oxidizer pictogram exists, reducer does not
Fire and medical gas
- Fire triangle: heat, fuel, oxygen. RACE: rescue, alarm, confine, extinguish. PASS: pull, aim, squeeze, sweep
- Extinguisher classes: A ordinary combustibles, B flammable liquids, C electrical, D metals, K cooking oils
- Oxygen-enriched atmospheres burn faster; no oil or grease on oxygen fittings; cylinders secured upright, capped, stored below 125 F, full separated from empty
- US medical gas cylinder colors: oxygen green, nitrous oxide blue, carbon dioxide gray, nitrogen black, medical air yellow, helium brown; pin index and DISS fittings prevent wrong connections
- Full E cylinder of oxygen: about 2,000 to 2,200 psi, about 660 liters; wall outlets about 50 psi; zone valves shut off gas to an area
| Standards, regulators, and accreditation | What to know |
|---|---|
| CMS | Centers for Medicare and Medicaid Services; sets Conditions of Participation hospitals must meet to be paid; can survey directly |
| Deemed status | Accrediting organizations survey on CMS's behalf: The Joint Commission, DNV Healthcare, ACHC (formerly HFAP), CIHQ |
| The Joint Commission | Environment of Care and Emergency Management standards cover equipment inventory, maintenance strategies, testing, and documentation |
| FDA | Regulates devices; medical device reporting: user facilities report a device-related death to FDA and the manufacturer within 10 work days, a serious injury to the manufacturer within 10 work days; recalls Class I (serious harm), II (temporary harm), III (unlikely harm) |
| OSHA | Worker safety: hazard communication, bloodborne pathogens, PPE, electrical safety in the workplace |
| ANSI/AAMI EQ56 | Recommended practice for a medical equipment management program |
| ANSI/AAMI EQ89 | Guidance for scheduled maintenance and performance verification |
| ANSI/AAMI EQ93 | Medical equipment management vocabulary and terminology |
| ANSI/AAMI EQ103 | Alternative equipment maintenance (AEM) programs: how to justify and document maintenance strategies that differ from the manufacturer's |
| AEM rules (CMS) | Allowed with documented risk assessment by qualified staff; not for imaging or radiologic equipment, lasers, or where the manufacturer or law requires otherwise; new equipment follows the manufacturer until history supports a change |
| CMMS | Computerized maintenance management system: inventory and asset tags, work orders, PM schedules, equipment history, parts, reports (PM completion rate, mean time between failures, cost); every activity documented there |
| After an incident | Remove the device with all accessories and disposables attached, do not clear logs or settings, tag and sequester, document, report; root cause analysis asks why repeatedly |
| Joint Commission programs | Accredits and certifies by peer survey; publishes National Patient Safety Goals yearly; links quality and risk management; does not set financial benefits |
| DNV | Accredits hospitals under NIAHO, integrating CMS Conditions of Participation with ISO 9001; annual surveys |
| ISO 9000 / 9001 | Quality management standards; plan-do-check-act; risk-based thinking; customer focus, leadership, process approach |
| CMS programs | Medicare, Medicaid, CHIP; regulates human laboratory testing; publishes yearly core measure sets (clinical quality measures); fights fraud; does not accredit |
| CAP | College of American Pathologists: nonprofit accreditor of clinical laboratories under CMS authority; inspections every two years plus unannounced |
| SMDA | Safe Medical Devices Act (1990, amended 1992): user facilities report device-related deaths to FDA and manufacturer, serious injuries to the manufacturer; annual summaries |
06Physiological monitoring
| ECG fact | Value |
|---|---|
| Einthoven's triangle | Lead I = LA minus RA; Lead II = LL minus RA; Lead III = LL minus LA; Einthoven's law: Lead II = Lead I + Lead III |
| Augmented and chest leads | aVR, aVL, aVF from the limb electrodes; V1 to V6 across the chest; 12 leads from 10 electrodes |
| Electrode colors (US, AHA) | RA white, LA black, RL green (ground), LL red, V brown ("white on right, smoke over fire") |
| Bandwidth | Monitoring mode 0.5 to 40 Hz; diagnostic mode 0.05 to 150 Hz |
| Interference | 60 Hz: bad electrode contact, unshielded leads, nearby equipment; wandering baseline: respiration or motion; spikes: muscle tremor or loose lead |
| Lead-off | High impedance detected on an electrode; check gel, skin prep, cable |
| Simulator test | Patient simulator provides rate, amplitude, and arrhythmias to verify the monitor |
| Rhythms on the strip | Sinus tachycardia fast regular; atrial (supraventricular) tachycardia rapid consistent narrow complexes; atrial fibrillation irregular with quivering waves, no P; ventricular tachycardia rapid WIDE QRS; ventricular fibrillation chaotic; asystole flat (check leads) |
| Lead views and counts | aVF's positive pole is the left leg; 12 leads from 10 electrodes (4 limb, 6 chest); IEC colors RA red, LA yellow, LL green, RL black differ from AHA; thermal print head tested by printing letters or diagonals; paper speeds 10, 12.5, 25, 50 mm/s test the drive |
| Blood pressure fact | Value |
|---|---|
| Korotkoff sounds | Auscultatory method: cuff above systolic, deflate; first sound (phase 1) is systolic, sounds muffle then disappear (phase 5) at diastolic; automated devices use oscillometry instead |
| NIBP method | Oscillometric: cuff inflates above systolic, deflates in steps, MAP is the point of maximum oscillation, systolic and diastolic derived |
| Cuff sizing | Bladder width about 40% of arm circumference, length about 80%; too small reads high, too large reads low |
| Invasive line | Transducer zeroed to atmosphere and leveled at the phlebostatic axis (fourth intercostal space, midaxillary line) |
| Dicrotic notch | The small dip on the downslope of the arterial waveform marking aortic valve closure; its absence suggests overdamping |
| Height error | 13.6 cm of water equals 10 mmHg; every 13.6 cm the transducer is off level changes the reading about 10 mmHg |
| Damping | Fast-flush (square wave) test: overdamped rounds the wave and reads low systolic; underdamped overshoots and reads high |
| Transducer sensitivity | 5 microvolts per volt per mmHg (industry standard) |
| Sphygmomanometer | Cuff, bulb, valve, manometer (mercury, aneroid, electronic), stethoscope; gauge not at zero: zeroing screw; unstable: movement or placement; reads high: cuff below the heart; reads low: cuff above the heart or an air leak (most common); invasive lines read continuously even when hypotensive |
| Oximetry and capnography | Value |
|---|---|
| Pulse oximeter wavelengths | Red about 650 to 660 nm, infrared about 805 to 940 nm; oxyhemoglobin absorbs more infrared; ratio of pulsatile absorbances gives SpO2; high perfusion helps, low perfusion hurts |
| Errors | Carboxyhemoglobin reads falsely high; methemoglobin trends toward 85%; motion, low perfusion, nail polish, ambient light, dyes |
| Testing | SpO2 simulator or optical tester; check probe LED and detector, cable, and site |
| Capnography | Infrared absorption by CO2 (about 4.26 micrometers); mainstream sensor at the airway, sidestream samples through tubing (delay, water trap) |
| Capnogram | Baseline near zero, rapid rise, alveolar plateau, EtCO2 at end of plateau, drop on inspiration; loss of waveform means disconnect, apnea, or esophageal intubation |
Other monitoring
- Temperature: thermistor (resistance falls as temperature rises, NTC), thermocouple (voltage from two metals), infrared tympanic; YSI 400 and 700 series probe curves are not interchangeable
- Respiration on a monitor: impedance pneumography through the ECG electrodes; capnography is more reliable
- Alarm priorities (IEC 60601-1-8): high red flashing, medium yellow flashing, low cyan or yellow steady; alarm fatigue is a patient safety problem; alarm management programs set limits per unit
- Telemetry: WMTS bands 608 to 614 MHz, 1395 to 1400 MHz, 1427 to 1432 MHz; dropouts from antenna coverage, low battery, interference; central station shows all beds
- Fetal monitor: ultrasound Doppler for fetal heart rate (110 to 160 bpm), tocodynamometer (TOCO) for contractions by pressure on the abdomen; internal scalp electrode and intrauterine pressure catheter are the direct methods
- Respiration methods: chest impedance through ECG electrodes (most common), respiratory belts, airflow sampling (thermistor or capnograph), magnetometry; a fingertip oximeter that shuts off mid-use has a low battery
- EEG 10-20 landmarks: nasion (bridge of the nose) to inion (back of the skull); beta above 13 Hz awake and active; differential amplifier removes common signals
- EEG bands: delta under 4 Hz, theta 4 to 8, alpha 8 to 13, beta above 13; electrodes placed by the 10-20 system; EMG measures muscle electrical activity; evoked potentials time the response to a stimulus
07Test equipment and units of measure
| Test equipment | Verifies |
|---|---|
| Electrical safety analyzer | Ground resistance, chassis and patient lead leakage under normal and fault conditions |
| Patient (physiological) simulator | ECG rate, amplitude, arrhythmias, respiration, invasive pressure, temperature |
| SpO2 simulator | Saturation and pulse readings through the probe |
| NIBP simulator | Cuff pressures and oscillometric readings; leak test |
| Defibrillator analyzer | Delivered energy into 50 ohms, charge time, synchronization, pacing output |
| ESU analyzer | Output power into a load, leakage, return electrode monitoring |
| Gas flow and ventilator analyzer | Volume, flow, pressure, oxygen concentration |
| Infusion pump analyzer | Flow rate accuracy, occlusion pressure |
| DVM or DMM and meters | Voltage, current, resistance; oxygen analyzer, pressure meter, tachometer, light meter, sound level meter |
| Cable tracer or toner | Finds the far end of a network cable |
| What each analyzer does not do | Ventilator analyzer: flow, pressure, volume, O2, breath detection, no CO2 concentration. ESU analyzer: RMS power, crest factor, peak-to-peak voltage, RF leakage, REM thresholds, no handpiece continuity or chassis leakage (multimeter and safety analyzer). Defibrillator analyzer: energy, charge time, sync, not internal impedance. Simulator: no current. DVM: voltage only, draws a little current; DMM continuity = low resistance, unpowered |
| Unit | Conversion or meaning |
|---|---|
| mmHg | Blood and gas pressure; 760 mmHg = 1 atmosphere; 1 mmHg = 1.36 cm H2O |
| cm H2O | Ventilator and airway pressures; 1 cm H2O = 0.74 mmHg |
| psi | Gas cylinders and pipelines; 14.7 psi = 1 atmosphere; 1 psi = 51.7 mmHg; 1 psi = 6.9 kPa |
| bar | 1 bar = 100 kPa = 14.5 psi = 750 mmHg, about 1 atmosphere |
| kPa | 1 kPa = 7.5 mmHg; 101.3 kPa = 1 atmosphere |
| Fahrenheit and Celsius | F = C x 1.8 + 32; C = (F minus 32) / 1.8; 37 C = 98.6 F; 0 C = 32 F; 100 C = 212 F |
| Joules | Energy: 1 J = 1 watt-second; defibrillator output |
| Lumens and lux | Lumens: total light output of a lamp; lux: lumens per square meter at the surface (surgical lights are rated in lux at 1 m) |
| Decibels | Sound level and audiometer hearing threshold (dB HL); 10 dB is a tenfold power ratio |
| Weight and length | 1 kg = 2.2 lb; 1 inch = 2.54 cm; 1 L = 1000 mL; 1 mL = 1 cc |
| Prefixes | kilo 10 to the 3, milli 10 to the minus 3, micro 10 to the minus 6, nano 10 to the minus 9 |
08Diagnostic, infusion, therapeutic, and laboratory equipment
| Diagnostic device | Facts |
|---|---|
| Otoscope, ophthalmoscope | Battery or wall-powered light and optics for ear and eye; check lamp, battery, charging contacts, specula |
| Audiometer | Hearing thresholds in dB HL at 250 to 8000 Hz; calibrate with a sound level meter and coupler; quiet room or booth |
| Spirometer | FVC, FEV1, FEV1/FVC ratio (normal about 0.7 to 0.8); calibrate with a 3 L syringe; filters and mouthpieces |
| Stress test system | Treadmill or bike with 12-lead ECG and NIBP; emergency stop; treadmill speed and grade calibration; defibrillator nearby |
| Scales | Calibrate with certified test weights; zero with the bed or chair empty; load cells |
| Ultrasound | Piezoelectric transducer sends and receives; 2 to 15 MHz; higher frequency, better resolution, less penetration; Doppler measures flow; gel removes air; transducer crystals crack if dropped |
| Otoscope parts | Handle, head, lamp with collar, magnifying lens, specula, insufflation port; no microphone; loose head cuts light off, worn fibers dim it |
| Ophthalmoscope | Views the fundus; lens disc, filters, mirror, condensing lens; clean with lens wipes, alcohol discolors |
| Audiogram | Threshold in dB versus frequency; air conduction (headphones) versus bone conduction (mastoid vibrator) separates sensorineural from conductive loss; creates tones, does not measure frequencies |
| Uroflow meter | Flow rate and volume of voiding (bladder emptying); funnel, beaker, transducer; wireless within about 3 m |
| Tympanic thermometer | Infrared from the eardrum onto a thermopile; probe covers; 30 minutes to settle; ambient 10 to 40 C; torn cover reads high, cracked lens or obstruction reads low |
| Endoscope | Fiber-optic or camera, cool light source, insufflation, irrigation, suction; leak test before immersion; no wireless in flexible scopes |
| Imaging | X-ray: electrons from a tungsten filament strike a tungsten anode; radiopaque bone is white. Fluoroscopy: live X-ray through an image intensifier. CT: rotating tube and detectors, computed slices. MRI: magnet aligns hydrogen, RF, realignment signal, no ionizing radiation, pacemakers contraindicated. PET: FDG tracer, positron annihilation, two gamma photons. Ultrasound Doppler: toward the probe = higher pitch |
| Infusion device | Facts |
|---|---|
| Large-volume pump | Peristaltic; accuracy typically within 5%; rate in mL/hr; free-flow protection; occlusion and air-in-line alarms; drug library |
| Syringe pump | Precise small volumes; syringe size must be recognized; start-up delay and siphoning risks |
| PCA pump | Patient button, bolus dose, lockout interval, hourly limit; locked to prevent tampering |
| Feeding (enteral) pump | Enteral-only connectors on purpose; lower accuracy acceptable |
| Contrast injector | Programmed volume and flow for imaging; pressure limit; air detection; heated syringe |
| Rate math | mL/hr = total mL / hours; drops per minute = (mL/hr x drop factor) / 60; percent error = (delivered minus set) / set x 100 |
| Enteral versus parenteral | TPN by vein through a standard pump; enteral by rotary peristaltic head on wide tubing; low flow = empty bag, occlusion, drip chamber seated wrong or coated; no set = seating, wrong set, or bright light on the detector |
| Syringe pump settings | Must know the syringe diameter and brand; small volume, fine control; runs past empty = sensor, size setting, or multi-phase program, not low voltage |
| PCA settings | Bolus, lockout interval, maximum dose per hour or 4 hours, optional background; logged; locked; ignores requests = check settings first |
| Infusion modes | Continuous; intermittent (high-rate periods separated by low-rate intervals); bolus; secondary or piggyback; pressure infusers squeeze a bag and are not pumps |
| Therapeutic device | Facts |
|---|---|
| Infant incubator and warmer | Air and skin temperature servo control, humidity, oxygen; radiant warmer with skin probe; over-temperature alarms; phototherapy blue light about 425 to 475 nm |
| Patient temperature management | Hypo- and hyperthermia units circulate water through blankets or pads; water temperature limits about 4 to 42 C; check flow, leaks, temperature sensor |
| Aspiration (suction) | Regulators in mmHg, continuous or intermittent; adult range about 80 to 120 mmHg; check filter, collection canister, tubing, vacuum source |
| Sequential compression device | Inflates leg sleeves in sequence to prevent clots; check pressures and cycle timing, hoses, sleeves |
| Physical therapy equipment | TENS and muscle stimulators, therapeutic ultrasound (1 to 3 MHz), diathermy, traction, continuous passive motion; output and timer verification |
| Radiant warmer versus incubator | Radiant: open bed, overhead heater, skin sensor servo, easy access, drafts and dehydration. Incubator: enclosed, air, humidity, oxygen control. Fluctuating temperature = sensor attachment |
| Ultrasound therapy | 1 to 3 MHz deep heat for pain and blood flow; needs gel and motion; head too cold is not detected; overheating shutdown = too little gel; slow warming = low drive voltage |
| Hypo/hyperthermia flow | Heating needs flow of about 1 L/min or more, correct limits, and a good element; poor heating and cooling with no leaks = insufficient flow |
| Aspirator parts | Vacuum pump, gauge or regulator, tubing, collection container with overflow float, hydrophobic bacterial filter; pulmonary, gastric, surgical; fading suction = leak or filter; sudden stop = fuse or overheated pump |
| SCD and bilirubin | SCD inflates distal (ankle) to proximal (thigh), holds seconds, rests about a minute; high pressure = sleeve too tight. Bilirubin light 360 to 520 nm, blue-green most effective, brighter, closer, more skin; bulb, ballast, fan filter |
| Laboratory device | Facts |
|---|---|
| Centrifuge | Speed in RPM, force in RCF (g); balance opposite loads; lid interlock; verify speed with a tachometer and timer |
| Incubator | Temperature (often 37 C) and sometimes CO2 and humidity; verify with a reference thermometer; door seals |
| Rocker and shaker | Speed and tilt; motor and belt |
| Refrigerator and freezer | Blood and vaccine storage 2 to 8 C; freezers minus 20 or minus 80 C; continuous temperature logging and alarms; door gaskets and defrost |
| Microscope | Light source, objectives, focus; cleaning optics |
| Water bath | Gentle heating under 100 C with stirring; temperature control and uniformity via thermostat and heater; incubates microbial samples; not heating = setpoint or limit below ambient, or low water |
| Analyzers | Reagents, calibration, quality control samples, fluidics and clogs, temperature |
| Cryostat and microtome | Cryostat cuts frozen sections in a cold chamber (about minus 20 C); microtome cuts thin sections; blade safety, temperature, advance mechanism |
| Blood gas analyzer | Clark electrode pO2 (platinum cathode, silver anode, O2 membrane, current); glass electrode pH (voltage); Severinghaus electrode pCO2 (pH electrode behind a CO2 membrane in bicarbonate); too cold = thermistor; barcode = window |
| Spectrophotometer | Absorbance at selected wavelengths; tungsten lamp for visible, deuterium for UV; read a blank first; quartz cuvettes for UV; intermittent at all wavelengths = power cable |
| Hematocrit centrifuge | Packs red cells in capillary tubes at about 10,000 to 15,000 g; RCF rises with speed squared and radius |
| Microtome detail | Paraffin-embedded blocks; thickness depends on blade clamping, sharpness, clearance angle, cool block, slow steady stroke, no wax; cryostat frost = drafts or breath, splinter = too cold |
09Perioperative and life-support devices
| Electrosurgery fact | Value |
|---|---|
| Frequency | About 300 kHz to 3 MHz, above the frequency that stimulates nerves and muscle |
| Modes | Cut: continuous sine wave, vaporizes. Coag: interrupted or damped bursts, dries and seals. Blend mixes them |
| Monopolar | Current flows from the active electrode through the patient to a large return (dispersive) electrode; return electrode contact quality monitoring prevents burns |
| Bipolar | Current flows between the two tips of the forceps; no return pad needed |
| Burns | Poor return pad contact, pad on bony or hairy site, alternate paths through ECG electrodes or metal; capacitive coupling in laparoscopy |
| Video integration | Cameras, light sources, monitors, recording and routing systems; check cable, connector, light cable fibers, white balance |
| Waveform and faults | Cut = continuous sine, 100% duty cycle, monopolar; coag = pulsed or damped, low duty cycle, higher peak; on but no output = blown high-voltage fuse; will not turn on = cord, fuse, low-voltage supply, switch; footswitch dead = footswitch board then control board |
Other perioperative equipment
- Pneumatic tourniquet: cuff pressure above systolic (commonly 250 mmHg arm, 300 mmHg leg or adjusted to the patient), time limit alarms (about 2 hours), leak test, calibrated gauge
- Fluid and blood warmer: keeps fluids near body temperature; over-temperature cutoff around 41 to 42 C; check heater, sensor, alarms
- Sterilizer: steam 121 C at 15 psi or 132 C flash; verify temperature, pressure, time, gasket, chamber; biological indicator; ethylene oxide and hydrogen peroxide for heat-sensitive items
- OR table: hydraulics or motors, controls, brakes, weight rating; surgical lights: lux at 1 m, color temperature, handles, bulbs or LEDs; surgical microscope: optics, illumination, balance, focus motors
- Sterilization methods: steam (fastest; dry heat for items that cannot be wet), ethylene oxide gas (heat- and moisture-sensitive, about 10 h plus aeration), liquid chemical (small hard-to-reach lumens, rinse), ionizing gamma or beta (disposables in sealed packages); no steam = water pump, low fluid pressure, breaker, heater
- Surgical lasers: CO2 far infrared absorbed by water for skin and soft tissue; Nd:YAG near infrared penetrates (hair, tattoo, coagulation); argon blue-green for pigment and eye; excimer UV for corneas; aiming beam and articulated arm; aiming only = footswitch
- Blood warmer: countercurrent warm water around the blood line; pressurized-flow units add a compressor (loud = unseated tubing or failing compressor; hot = blocked vents); prevents transfusion hypothermia, not for lab samples or infants
- Heart-lung machine: venous reservoir, roller or centrifugal pump (gentle on cells), membrane oxygenator (older bubble), heat exchanger for hypothermia, filters, arterial return; heparin thins blood; cardioplegia stops the heart; backup pumps
- Hemodialysis order: access, arterial monitor, blood pump, heparin pump, dialyzer (countercurrent dialysate across a semipermeable membrane), venous monitor, air trap and detector (last), return
| Defibrillation and pacing | Value |
|---|---|
| Adult energy | Monophasic 360 J; biphasic 120 to 200 J (device specific); pediatric energies lower and weight based |
| Synchronized cardioversion | Shock timed to the R wave for an organized rhythm the clinician chooses to cardiovert; unsynchronized for VF and pulseless VT |
| Testing | Defibrillator analyzer with a 50 ohm load; check delivered energy, charge time, synchronization, pacing output; daily user checks |
| AED | Analyzes rhythm, advises shock only for VF and pulseless VT |
| External pacing | Demand mode paces only when intrinsic rate falls below the set rate; fixed mode paces regardless; output in mA; capture confirmed by QRS after each spike |
| Intra-aortic balloon pump | Balloon in the descending aorta inflates in diastole (raises coronary perfusion) and deflates just before systole (lowers afterload); timed to the ECG or arterial waveform; helium gas; alarms for timing, leak, and gas loss |
| Pacing routes | Transcutaneous: chest pads with gel, tens of mA, painful, fastest. Transvenous: lead through a vein (subclavian) into the right ventricle, low output. Epicardial: wires on the heart surface at surgery, no subclavian leads. External generators run on AC or battery |
| Ventilator and anesthesia | Value |
|---|---|
| Tidal volume and minute volume | 6 to 8 mL/kg ideal body weight; minute volume = tidal volume x rate |
| Typical settings | Rate 12 to 20; I:E ratio 1:2; PEEP 5 cm H2O; FiO2 0.21 to 1.0 |
| Modes | Volume control delivers a set volume; pressure control a set pressure; assist-control, SIMV, pressure support, CPAP; BiPAP has separate inspiratory and expiratory pressures |
| Alarms | High pressure: obstruction, kink, coughing, secretions. Low pressure or low volume: disconnect or leak. Apnea: no breath detected |
| Oxygen analyzer calibration | Room air 21% and 100% oxygen; galvanic cells wear out; concentrators deliver about 90 to 95% |
| Anesthesia machine | Pipeline (50 psi) and cylinder supply, flowmeters, agent-specific vaporizers (sevoflurane yellow, isoflurane purple, desflurane blue), hypoxic guard keeps oxygen at least 21 to 25%, oxygen flush, CO2 absorber, scavenging removes waste gas, pin index and DISS prevent misconnection; leak test before use |
| Anesthesia gas path | Supply (pipeline 50 psi, cylinders), regulators, flow controls and flowmeters, vaporizer (first section after the agent's flow control), common gas outlet, breathing circuit with CO2 absorber, ventilator, patient; scavenging removes waste |
10Problem solving and troubleshooting
The method, in order
- 1. Confirm the complaint: talk to the user, reproduce the problem, rule out use error (wrong settings, wrong accessory, wrong technique), and check the right disposables.
- 2. Check the simple things: power, plug, battery, fuse, cables, connectors, settings, sensors.
- 3. Isolate: which subsystem (power, sensor, signal path, processor, display, mechanical); half-split the path with a simulator and test equipment; localized device or system-wide?
- 4. Form and test one hypothesis at a time; swap known-good parts; use the schematic.
- 5. Repair or replace; follow the service manual.
- 6. Verify: full performance test and electrical safety test after any repair, before return to service.
- 7. Document in the CMMS: symptom, cause, action, parts, test results, time. Educate the user if it was a use error.
| Symptom | First suspects |
|---|---|
| Device dead, no power | Outlet, cord, plug, fuse, power switch, battery, power supply output |
| Runs on AC but not battery | Battery aged or not charging; charger circuit; battery connector |
| Intermittent reboot or errors | Failing power supply capacitors, loose connector, overheating |
| ECG shows 60 Hz noise | Electrode contact, gel, skin prep, lead cable shield, nearby equipment, ground |
| Wandering baseline | Patient movement or respiration, loose electrode, high-pass filter setting |
| Intermittent signal | Cable flex failure near connectors, loose connector, cracked solder |
| NIBP reads high | Cuff too small, cuff too low, patient movement, hose leak causing slow deflation |
| Arterial line reads low and rounded | Overdamped: air bubble, clot, kinked tubing, loose connection |
| SpO2 no reading | Probe placement, perfusion, ambient light, probe LED failure, cable |
| Ventilator high-pressure alarm | Kinked circuit, secretions, patient coughing, water in tubing |
| Ventilator low-pressure or volume alarm | Disconnect, leak, cuff leak, circuit crack |
| Infusion pump occlusion alarm | Kinked tubing, closed clamp, clotted line, set loaded wrong |
| Infusion pump air-in-line alarm | Air in set, sensor dirty, set not seated |
| Defibrillator low delivered energy | Capacitor aging, relay, paddles or pads, battery |
| ESU patient burn | Return electrode contact, alternate path, damaged cable |
| Telemetry dropouts on one patient | Transmitter battery, leads, distance; many patients: antenna system or receiver, a system-wide problem |
| Monitor not sending to the central station or EMR | One bed: cable, port, network config on that monitor. Every bed: switch, server, middleware, network outage |
| Centrifuge vibration | Unbalanced load, worn rotor or bearing |
| Refrigerator temperature alarm | Door seal, defrost cycle, compressor, probe, overloading |
| EtCO2 no value or occlusion | Cannula and tubing, filter present, moisture trap (occlusion test), internal leak (occlude upstream of filter and trap); occlusion: kink, clogged filter, full trap |
| Respiration rate missing, ECG fine | Input printed circuit board; flat or short trace: raise sensitivity, then electrodes, leads, cable |
| Blood gas analyzer will not run | Cable and outlet first; 'too cold' after warming = thermistor; no battery run = charger; barcode dead = window |
| Centrifuge rotor will not spin | Lid not closed firmly (interlock), then connections, board, motor |
| Microtome sections wrong thickness | Blade clamp, dull edge, clearance angle; compressed = dull, warm block, too fast, wax |
| Tympanic thermometer reads low | Obstruction or cracked lens (high = torn cover); rest 30 minutes; ambient 10 to 40 C |
| Enteral pump low flow versus no set | Low flow: empty bag, occlusion, drip chamber. No set: seating, wrong set, bright light |
| PCA ignores requests | Settings (lockout, maximum) before pendant or motor; 'check settings' = door locked before setup |
| Aspirator suction fades | Leak (tubing, container, vacuum line) or clogging filter; sudden stop = fuse or overheated pump; none = disconnected, blocked filter, full container |
| ESU on but no output | High-voltage supply fuse |
| Tourniquet pump runs constantly | Leak in tubing, cuff, or valves, or a bad pressure transducer; will not inflate = pump disconnected |
| Autoclave no steam | Water pump, low fluid pressure, breaker or overload, burned-out heater, low water; over-pressure = pressure switch |
| Bilirubin light dark or dim | Too hot to relight; bulb then ballast; dirty lens; overheating = fan filter, fans, thermistor |
| Device went to battery while plugged in | Outlet and power cable continuity first, then the internal power circuit; regulator: measure input and output pins to ground |
Priorities, communication, maintenance
- Priority order: life support and high-risk devices first, then patient risk, then urgency and downtime and clinical impact; loaners for critical downtime
- Device error versus use error: a device that performs to specification but was used wrongly needs education and possibly a design or labeling report, not a repair
- In-service and cross-training: teach proper use, care, cleaning, and alarm response; document attendance; communicate clearly with clinicians, staff, and manufacturers in writing and verbally
- Preventive maintenance: scheduled or risk-based; AEM programs allowed with documented justification (not imaging, lasers, or where the manufacturer requires); PM after repair; performance verification against tolerances
- Calibration traceable to national standards; test equipment has its own calibration schedule
- Incoming inspection before first use: physical, functional, safety test, inventory entry, manuals on file; lifecycle ends with data wiped, decontamination, and disposition
- Criticality = importance to the mission + likelihood of failure or PM demand + potential harm; repair time is not a factor; redundancy lowers priority but does not prevent all downtime; checklists guide user inspections
- Root cause analysis: what happened, why, how to prevent; keep asking why (five whys); ultrasound blurry = crystal then gel; oximeter erratic = ambient light; one sphygmomanometer = technique then cracked tubing (a leak reads low)
- Local versus network: one room missing = that room; several = shared configuration or network; false alarms on many monitors = alarm limits; check physical links first; search repair records for fleet patterns; ping, cable tester, multimeter help, a safety analyzer does not
- Switching supply shorted element = full input voltage out, open = zero; UPS short runtime = battery, no backup = inverter, switched over while plugged in = outlet or cable; desktop PSUs die of fan failure and heat
11Healthcare information technology
| Networking fact | Value |
|---|---|
| IPv4 address | Four numbers 0 to 255; subnet mask separates network and host; default gateway is the exit router; same subnet required to talk without a router |
| MAC address | 48-bit hardware address in 12 hex digits, burned into the network card; switches forward by MAC |
| Private ranges | 10.0.0.0/8; 172.16.0.0 to 172.31.255.255; 192.168.0.0/16 |
| DHCP and static | DHCP assigns addresses automatically; medical devices often use static addresses or DHCP reservations so they are always reachable |
| DNS | Names to addresses; ping by address works but by name fails means DNS |
| APIPA | 169.254.x.x means DHCP failed |
| Ports | HTTP 80, HTTPS 443, SSH 22, DICOM commonly 104 or 11112, HL7 commonly 2575 (site specific) |
| Devices | Switch connects devices in a LAN by MAC; router connects networks by IP; access point connects Wi-Fi clients; access point controller manages many APs; KVM switch shares one keyboard, video, and mouse among servers; virtual servers run many operating systems on one host; LAN is local, WAN spans sites, cloud is provider-hosted |
| Cabling | Cat 5e 1 Gbps, Cat 6A 10 Gbps, 100 m limit; fiber for longer runs; link light off means Layer 1; cable tracer finds the far end |
| Wi-Fi | 2.4 GHz longer range, channels 1, 6, 11; 5 GHz more channels, less interference; WPA2 or WPA3; enterprise mode uses 802.1X with RADIUS |
| Telemetry and RTLS | WMTS bands for patient telemetry; real-time location systems track equipment with RF, infrared, or ultrasound tags |
| OSI layers | 1 physical (media, hubs), 2 data link (frames, MAC, switches), 3 network (IP, routers), 4 transport (TCP/UDP, ports), 5 session, 6 presentation (format conversion, encryption), 7 application (APIs); no conversion layer |
| Topologies | Bus and ring fail on any break; star (central switch) survives one bad cable; hybrid; mesh partial or full; point-to-multipoint (central node also processes); physical versus logical |
| Binary masks | 255.255.255.240 = ...11110000 (/28, 16 addresses); 248 = 11111000; 252 = 11111100; ones must be contiguous; subnetting separates departments and limits broadcasts |
| Hub versus switch, PPP | Hub repeats to every port at layer 1, half duplex, collisions; switch keeps a source address table and forwards at layer 2, full duplex; PPP links two routers over serial or dial with authentication |
| Command or tool | Use |
|---|---|
| ping | Is the address reachable, and how fast; ping the gateway first |
| ipconfig (Windows), ifconfig or ip (Linux) | Show the device's address, mask, gateway; release and renew DHCP |
| tracert or traceroute | Every hop to a destination; where the path breaks |
| nslookup | Test name resolution |
| arp -a | IP to MAC table; duplicates |
| netstat | Open connections and listening ports |
| Cable tracer and tester | Find the far end; check pinout and continuity |
| TDR | Time-domain reflectometer: pulse reflection shows whether a cable is open and how far to the break |
| ping (ICMP) | Echo request and reply, IPv4 and IPv6; reports round-trip ms, packet loss, min, max, average, deviation; not a cable resistance test; power cycling is not a test |
| Fiber inspection microscope | Checks connector ends for dirt and damage; clean with isopropyl alcohol and lint-free wipes or cut and repolish; light source and power meter measure loss |
| Interoperability | Meaning |
|---|---|
| HL7 version 2 | Text messages between systems: ADT (admit, discharge, transfer), ORM (orders), ORU (results, including device data) |
| HL7 FHIR | Modern web-based standard using resources and APIs |
| DICOM | Standard for medical images and their transfer; modality worklist pulls patient data to the device; PACS stores and serves images |
| EMR and EHR | Electronic medical record (within one organization) and electronic health record (across); devices feed vitals in directly or through middleware |
| Middleware | Translates and routes between devices and the EMR; device gateways; where most integration faults are diagnosed |
| Time synchronization | NTP keeps device clocks aligned so records and alarms line up |
| PACS, RIS, LIS, LIMS | PACS stores and transports images with patient data (redundant servers); RIS schedules, tracks, and reports radiology; LIS tracks specimens and analyzer results; LIMS is the research and high-volume version |
| DICOM and HL7 detail | DICOM is a 22-part standard for image format and transfer referencing IEC definitions; HL7 standards: version 2 messaging, version 3 XML, Clinical Document Architecture; HL7 does not set leakage limits or breach rules |
Protected data and cybersecurity
- HIPAA: privacy rule (who may see PHI), security rule (administrative, physical, technical safeguards), breach notification; PHI is any identifiable health information; minimum necessary
- NIST Cybersecurity Framework functions: govern, identify, protect, detect, respond, recover
- HITRUST: a certifiable framework combining many requirements; HHS cybersecurity performance goals: essential and enhanced practices for hospitals (MFA, patching, backups, segmentation, training)
- MDS2: manufacturer disclosure statement for medical device security; SBOM: software bill of materials
- Controls: unique accounts and MFA, least privilege, encryption at rest and in transit, patching on the vendor's validated schedule, network segmentation for devices that cannot be patched, antivirus where the vendor allows, physical security of workstations, screen locks
- Backups: 3 copies, 2 media, 1 offsite; test restores; ransomware response: isolate, report, restore
- Incident: disconnect the device from the network, do not power off if forensics are needed, report to IT security and the vendor, document
- HITECH (2009): EHR incentives and penalties, meaningful use, breach notification to individuals and HHS, business associates bound, no sale of PHI, patient access; sets no spending guidelines
- HIPAA titles: I insurance portability; II administrative simplification with the privacy and security rules, fraud control, and fines; III medical savings accounts; IV enforcement by the Office for Civil Rights; V revenue offsets
- DMCA (1998): bans circumvention tools, raises penalties, limits provider liability; exemptions for security testing and personal implant data; does not ban copying devices as such
- FDA MDDS: systems that store, transfer, reformat, or display device data without controlling devices; reclassified Class III to Class I in 2011; a vital signs monitor yes, a lobby TV no
- IEC 80001-1 (2010, IEC and ISO): risk management for IT networks with medical devices; excludes drugs; applies to any organization's network; defines no acceptable risk level; not from the FDA
- MDS2 contents: automatic logoff, audit controls, authorization, configurable security, security updates, de-identification, backup and recovery, emergency (break-glass) access, data integrity, malware protection, node and user authentication, physical locks, third-party component plans, remote servicing; not structural integrity
Computer hardware and software troubleshooting
- Hardware: power supply (no power, random reboots), hard drive (slow, errors, clicking; SMART warnings; replace and restore image), memory (crashes), peripherals (drivers, cables, ports), connectors and cables (reseat, swap)
- Software: Windows, Office, Linux, and Unix updates and patches only on the vendor's validated schedule for medical devices; drivers after updates; event logs; restore from image; user accounts and permissions
- Order of checks: power and cables, link lights, address and gateway, ping the gateway, ping the server, name resolution, application or service, then escalate to IT or the vendor
12Acronyms
Every acronym used in this course, 288 in all.
| Acronym | Stands for | Meaning |
|---|---|---|
| 802.11 | IEEE 802.11 | The family of Wi-Fi standards. |
| 802.1X | IEEE 802.1X | Port-based network access control: a device must authenticate before the switch port or Wi-Fi passes traffic. |
| AA | AA cell | A common single-cell battery size, about 1.5 V. |
| AAMI | Association for the Advancement of Medical Instrumentation | The standards body for medical equipment and the sponsor of the CBET credential. |
| ABC | Class A, B, and C fire extinguisher | A multipurpose extinguisher for ordinary combustibles, flammable liquids, and electrical fires. |
| AC | Alternating current | Mains power that reverses direction, 60 Hz in the US and 50 Hz elsewhere. |
| ACGIH | American Conference of Governmental Industrial Hygienists | The organization that publishes threshold limit values. |
| ACHC | Accreditation Commission for Health Care | An accrediting body that absorbed the HFAP hospital program. |
| ACI | AAMI Credentials Institute | The body within AAMI that administers the CBET and related certifications. |
| ACK | Acknowledgment (HL7 message) | The reply an HL7 interface sends to confirm it received a message, carrying an accept or error code. |
| ADC | Analog-to-digital converter | Turns a continuous voltage into digital samples. |
| ADT | Admit, discharge, transfer | The HL7 messages that tell every system who is in which bed. |
| AE | Application entity | A DICOM node, identified by its AE title, IP address, and port. |
| AED | Automated external defibrillator | A defibrillator that analyzes the rhythm and advises a shock only for VF or pulseless VT. |
| AEM | Alternative equipment maintenance | A CMS-allowed program that adjusts maintenance from manufacturer recommendations based on risk and history. |
| AF | Atrial fibrillation | An irregular rhythm with no P waves. |
| AHA | American Heart Association | The organization behind CPR guidelines and the US ECG electrode color code. |
| ALARA | As low as reasonably achievable | The radiation safety principle: minimize dose with time, distance, and shielding. |
| ANSI | American National Standards Institute | The US body that accredits standards developers such as AAMI. |
| AP | Access point | The Wi-Fi radio that bridges wireless clients onto the wired network. |
| API | Application programming interface | The defined way one program talks to another, such as the web endpoints a cloud service exposes. |
| APIPA | Automatic Private IP Addressing | The 169.254.x.x address a host gives itself when it cannot reach a DHCP server. |
| ASME | American Society of Mechanical Engineers | The standards body for pressure vessels and boilers. |
| AV | Atrioventricular node | The relay between atria and ventricles that delays the impulse so the ventricles fill. |
| AWG | American Wire Gauge | The wire size scale; smaller numbers are thicker wire with higher ampacity. |
| BAA | Business associate agreement | The HIPAA contract a vendor signs before handling protected health information. |
| BF | Body floating (applied part) | An applied part that touches the patient but not the heart, isolated from ground; stick-figure-in-a-box symbol. |
| BIOS | Basic Input/Output System | The original PC firmware: 16-bit, text setup, MBR disks up to 2 TB. |
| BiPAP | Bilevel positive airway pressure | Two pressure levels, higher on inhalation and lower on exhalation, for non-invasive ventilation. |
| BP | Blood pressure | The pressure in the arteries, systolic over diastolic, in mmHg. |
| C-ECHO | DICOM echo service | The DICOM ping that verifies two application entities can communicate. |
| CAP | College of American Pathologists | The organization that accredits clinical laboratories. |
| CBET | Certified Biomedical Equipment Technician | The AAMI credential for biomedical equipment technicians. |
| CDA | Clinical Document Architecture | HL7's XML standard for clinical documents such as discharge summaries. |
| CDC | Centers for Disease Control and Prevention | The US public health agency that sets infection control guidance such as standard precautions. |
| CF | Cardiac floating (applied part) | An applied part that may connect directly to the heart, with the strictest leakage limits; heart-in-a-box symbol. |
| CFR | Code of Federal Regulations | The codified US federal rules; 29 CFR 1910 holds OSHA standards, 21 CFR the FDA's. |
| CHIP | Children's Health Insurance Program | Federal and state health coverage for children, run by CMS. |
| CIA | Confidentiality, integrity, and availability | The three goals of security: keep data secret, keep it correct, keep it reachable. |
| CIHQ | Center for Improvement in Healthcare Quality | A newer CMS-approved hospital accreditor. |
| CMMS | Computerized maintenance management system | The database that tracks equipment inventory, work orders, and preventive maintenance. |
| CMOS | Complementary metal-oxide semiconductor | The small battery-backed memory that keeps firmware settings and the clock. |
| CMRR | Common-mode rejection ratio | How well an amplifier cancels signals present on both inputs, such as 60 Hz interference. |
| CMS | Centers for Medicare and Medicaid Services | The federal agency whose Conditions of Participation hospitals must meet to be paid. |
| CO | Carbon monoxide | A toxic gas that binds hemoglobin and makes pulse oximeters read falsely high. |
| CO2 | Carbon dioxide | The gas exhaled as the waste product of metabolism; measured by capnography, and the lasing medium of CO2 surgical lasers. |
| COPD | Chronic obstructive pulmonary disease | Long-term airway obstruction, usually from smoking, with a low FEV1/FVC ratio. |
| CPAP | Continuous positive airway pressure | A constant pressure applied to the airway of a spontaneously breathing patient. |
| CPR | Cardiopulmonary resuscitation | Chest compressions and breaths to keep blood moving during cardiac arrest. |
| CPU | Central processing unit | The processor that executes instructions. |
| CT | Computed tomography | Cross-sectional X-ray imaging from a rotating tube and detector array. |
| DAC | Digital-to-analog converter | Turns digital values back into a voltage to drive displays, speakers, or outputs. |
| dB | Decibel | A logarithmic ratio unit for signal levels, gain, and sound. |
| DBP | Diastolic blood pressure | The arterial pressure between beats, while the heart fills. |
| DC | Direct current | Current in one direction: batteries and power supply outputs. |
| DHCP | Dynamic Host Configuration Protocol | Hands out IP addresses, masks, gateways, and DNS servers automatically (UDP 67 and 68). |
| DICOM | Digital Imaging and Communications in Medicine | The standard for medical image files and their network exchange, by convention on port 104. |
| DISS | Diameter Index Safety System | Gas-specific threaded fittings that make it impossible to connect the wrong gas hose. |
| dL | Deciliter | One tenth of a liter; lab values such as glucose in mg per dL. |
| DMCA | Digital Millennium Copyright Act | The 1998 copyright law that bans circumventing digital protections. |
| DMM | Digital multimeter | The handheld meter for voltage, current, resistance, and continuity. |
| DNA | Deoxyribonucleic acid | The genetic material; sterilization kills microbes by destroying it. |
| DNS | Domain Name System | Translates names such as www.example.com into IP addresses (UDP 53, TCP 53 for zone transfers). |
| DNV | DNV Healthcare | An accrediting organization that surveys hospitals annually under its NIAHO program. |
| DOT | Department of Transportation | The US agency whose rules govern compressed gas cylinders. |
| DVM | Digital voltmeter | A meter for voltage; in practice the same instrument as a DMM. |
| ECG | Electrocardiogram | The recording of the heart's electrical activity: P wave, QRS complex, T wave. |
| ECRI | ECRI Institute | The independent organization that tests devices and publishes hazard alerts and the annual top-ten hazards list. |
| EDI | Electronic data interchange | Standardized electronic exchange of business documents such as claims and payments. |
| EEG | Electroencephalogram | The recording of the brain's electrical activity from scalp electrodes, in microvolts. |
| EHR | Electronic health record | The patient's longitudinal digital record, shared across providers. |
| EM | Electromagnetic | Electric and magnetic fields; EM interference disrupts monitors and telemetry. |
| EMG | Electromyogram | The recording of muscle electrical activity. |
| EMI | Electromagnetic interference | Noise from motors, power lines, fluorescent lights, and radios that corrupts signals on copper cable. |
| EMR | Electronic medical record | The hospital's clinical record system: orders, notes, results, medications. |
| EQ | AAMI EQ series | AAMI's equipment management standards: EQ56, EQ89, EQ93, EQ103. |
| EQ103 | ANSI/AAMI EQ103 | Guidance for alternative equipment maintenance programs. |
| EQ56 | ANSI/AAMI EQ56 | The recommended practice for a medical equipment management program. |
| EQ89 | ANSI/AAMI EQ89 | Guidance for scheduled maintenance and performance verification. |
| EQ93 | ANSI/AAMI EQ93 | The vocabulary of medical equipment management. |
| ESD | Electrostatic discharge | Static electricity that can destroy chips; prevented with a wrist strap, mat, and antistatic bags. |
| ESU | Electrosurgical unit | The generator that cuts and coagulates tissue with high-frequency current above about 100 kHz. |
| EtCO2 | End-tidal carbon dioxide | The CO2 concentration at the end of exhalation, normally 35 to 45 mmHg, measured by capnography. |
| ETO | Ethylene oxide | A toxic gas used to sterilize heat-sensitive devices. |
| FDA | Food and Drug Administration | The US regulator of medical devices; classes I to III, recalls, and medical device reporting. |
| FDG | Fluorodeoxyglucose | The glucose-like radioactive tracer used in PET scans. |
| FEV1 | Forced expiratory volume in one second | The volume exhaled in the first second of a forced breath out. |
| FHIR | Fast Healthcare Interoperability Resources | HL7's web-style standard using REST APIs and JSON resources. |
| FHR | Fetal heart rate | The baby's heart rate, measured by ultrasound Doppler on a fetal monitor. |
| FiO2 | Fraction of inspired oxygen | The oxygen concentration being delivered, from 0.21 (room air) to 1.0. |
| FSH | Follicle-stimulating hormone | The pituitary hormone that drives sperm production and egg development. |
| FVC | Forced vital capacity | The total volume a patient can exhale forcefully after a full breath in. |
| Gbps | Gigabits per second | Billions of bits per second; gigabit Ethernet is 1 Gbps. |
| GFCI | Ground-fault circuit interrupter | A receptacle or breaker that trips when current leaking to ground exceeds about 5 mA. |
| GHS | Globally Harmonized System | The international standard for chemical hazard labels and safety data sheets. |
| GHz | Gigahertz | Billions of cycles per second; CPU clock speed and Wi-Fi band frequency. |
| GI | Gastrointestinal | The digestive tract. |
| H2O | Water | The pressure unit centimeters of water (cmH2O) for airway and ventilator pressures. |
| HDD | Hard disk drive | Spinning magnetic storage: cheap per terabyte, slower, and fragile. |
| HFAP | Healthcare Facilities Accreditation Program | The former osteopathic hospital accreditation program, now part of ACHC. |
| HHS | Department of Health and Human Services | The US department that enforces HIPAA through its Office for Civil Rights. |
| HIPAA | Health Insurance Portability and Accountability Act | The US law protecting health information; Title II holds the privacy and security rules. |
| HITECH | Health Information Technology for Economic and Clinical Health Act | The 2009 law that funded EHR adoption and strengthened HIPAA enforcement and breach notification. |
| HITRUST | Health Information Trust Alliance | A certifiable security framework that combines HIPAA, NIST, and other requirements for healthcare. |
| HIV | Human immunodeficiency virus | A bloodborne virus; one of the pathogens the OSHA bloodborne pathogen standard addresses. |
| HL | Hearing level | The decibel scale audiometers use, referenced to normal hearing thresholds. |
| HL7 | Health Level Seven | The messaging standard that connects clinical systems: version 2 pipes, version 3 XML, FHIR web APIs. |
| HR | Heart rate | Beats per minute, derived from the ECG or pulse. |
| HTTP | Hypertext Transfer Protocol | Web traffic in the clear on TCP 80. |
| HTTPS | Hypertext Transfer Protocol Secure | HTTP inside TLS on TCP 443. |
| HV | High voltage | The kilovolt sections of X-ray generators, defibrillators, and ESUs. |
| HVAC | Heating, ventilation, and air conditioning | The building's climate systems, which keep server rooms cool and are themselves networked controls. |
| Hz | Hertz | Cycles per second; display refresh rate, AC mains frequency, and signal frequency. |
| IaaS | Infrastructure as a service | The provider supplies virtual machines, storage, and networks; you manage the operating system and up. |
| IABP | Intra-aortic balloon pump | A balloon in the aorta that inflates in diastole and deflates in systole to support the heart. |
| IARC | International Agency for Research on Cancer | The WHO body that classifies carcinogens. |
| IBP | Invasive blood pressure | Pressure measured directly through an arterial line and a transducer. |
| IC | Integrated circuit | A chip: many transistors on one piece of silicon. |
| ICMP | Internet Control Message Protocol | The protocol behind ping and traceroute. |
| ICU | Intensive care unit | The critical care area with the highest density of monitors, ventilators, and pumps. |
| ID | Identification | A patient identifier or a device identifier. |
| IEC | International Electrotechnical Commission | The international standards body; IEC 60601-1 is the medical electrical equipment safety standard. |
| IEEE | Institute of Electrical and Electronics Engineers | The engineering body behind Ethernet (802.3), Wi-Fi (802.11), and many device standards. |
| IP | Internet Protocol | The Layer 3 protocol that addresses and routes packets between networks. |
| IPv4 | Internet Protocol version 4 | 32-bit addresses written as four decimal octets, such as 192.168.1.10. |
| IPv6 | Internet Protocol version 6 | 128-bit addresses in eight hex groups; no broadcast, built-in autoconfiguration. |
| ISO | International Organization for Standardization; also an ISO disc image | The standards body, and the .iso file format that holds a complete disc image. |
| IT | Information technology | Computers, networks, and the people who run them. |
| IUPC | Intrauterine pressure catheter | A catheter that measures contraction pressure directly. |
| IV | Intravenous | Into a vein; IV lines, pumps, and fluids. |
| KCL | Kirchhoff's current law | Current into a node equals current out. |
| kHz | Kilohertz | One thousand cycles per second. |
| kV | Kilovolt | One thousand volts; X-ray tube voltage and defibrillator charge levels. |
| KVL | Kirchhoff's voltage law | The voltages around any closed loop sum to zero. |
| KVM | Keyboard, video, mouse (switch) | One keyboard, monitor, and mouse shared among several computers. |
| KVO | Keep vein open | A very low infusion rate that keeps an IV line from clotting. |
| kW | Kilowatt | One thousand watts of power. |
| kWh | Kilowatt-hour | The energy unit on the electric bill: one kilowatt for one hour. |
| LA | Left arm electrode (also left atrium) | The black ECG electrode on the left arm; in heart anatomy, the left atrium. |
| LAN | Local area network | One site's network: a building, floor, or campus that one organization owns and runs. |
| LC50 | Lethal concentration 50 percent | The airborne concentration lethal to half of test subjects. |
| LCD | Liquid crystal display | The flat panel that shapes light from a backlight into an image; TN, IPS, and VA are the panel types. |
| LD50 | Lethal dose 50 percent | The dose that kills half of test subjects. |
| LED | Light-emitting diode | A small light source: the status lights on a port, the lamp in cheap fiber transmitters, and modern display backlights. |
| LH | Luteinizing hormone | The pituitary hormone that drives testosterone and triggers ovulation. |
| LIM | Line isolation monitor | Continuously measures how much current a fault could drive from an isolated power system to ground and alarms at 5 mA. |
| LIMS | Laboratory information management system | Sample and workflow tracking software for laboratories. |
| LIS | Laboratory information system | The software that manages lab orders, analyzer results, and reporting. |
| LL | Left leg electrode | The red ECG electrode on the left leg. |
| LV | Left ventricle | The chamber that pumps blood to the body at systemic pressure. |
| LVP | Large-volume pump | An infusion pump for bags of fluid, usually peristaltic, accurate to about 5 percent. |
| mA | Milliampere | One thousandth of an ampere; the unit for shock thresholds and leakage currents. |
| MAC | Media access control (address) | The 48-bit hardware address burned into a network interface, used at Layer 2. |
| MAP | Mean arterial pressure | The average arterial pressure: diastolic plus one third of the pulse pressure. |
| MDDS | Medical device data system | Software or hardware that transfers, stores, or displays device data without changing it. |
| MDS2 | Manufacturer Disclosure Statement for Medical Device Security | The standard form describing a device's security capabilities. |
| MFA | Multi-factor authentication | Two or more different kinds of proof of identity. |
| MHz | Megahertz | Millions of cycles per second; memory speed, radio channels, and older CPU clocks. |
| mL | Milliliter | One thousandth of a liter; tidal volumes, drug doses, and infusion rates in mL per hour. |
| mmHg | Millimeters of mercury | The pressure unit for blood pressure, gas pressures, and vacuum. |
| MR | Magnetic resonance | The MRI environment; equipment is labeled MR Safe, MR Conditional, or MR Unsafe. |
| MRI | Magnetic resonance imaging | Imaging with a strong magnet and radio pulses; no ionizing radiation, but the magnet is always on. |
| MRN | Medical record number | The hospital's unique identifier for a patient. |
| ms | Millisecond | One thousandth of a second; latency, pulse widths, and ECG timing. |
| MSH | Message header segment | The first segment of every HL7 version 2 message. |
| mV | Millivolt | One thousandth of a volt; ECG signals are about 1 mV. |
| NAT | Network address translation | Rewrites private inside addresses to a public address at the router so many hosts can share it. |
| NEC | National Electrical Code | The US wiring code, NFPA 70. |
| NESC | National Electrical Safety Code | The utility-side safety code for power lines and substations. |
| NFPA | National Fire Protection Association | The standards body for fire and electrical safety: NFPA 70 (NEC), NFPA 99 (health care facilities), NFPA 101 (life safety). |
| NIAHO | National Integrated Accreditation for Healthcare Organizations | DNV's hospital accreditation program. |
| NIBP | Non-invasive blood pressure | Automatic cuff measurement by the oscillometric method. |
| NIOSH | National Institute for Occupational Safety and Health | The CDC's research arm for workplace safety, which publishes RELs. |
| NIST | National Institute of Standards and Technology | The US standards body whose cybersecurity framework hospitals use. |
| NPN | Negative-positive-negative transistor | A bipolar transistor that conducts when its base is pulled positive. |
| NPSG | National Patient Safety Goals | The Joint Commission's annual list of safety priorities, including alarm management. |
| NTC | Negative temperature coefficient (thermistor) | A thermistor whose resistance falls as temperature rises; the sensor in patient temperature probes. |
| NTP | National Toxicology Program | The US program that publishes the Report on Carcinogens, one of the carcinogen listings cited on a safety data sheet. |
| NTP | Network Time Protocol | The protocol (UDP 123) that keeps device clocks synchronized so logs, alarms, and records line up. |
| OBR | Observation request segment | The HL7 segment describing the order a result answers. |
| OBX | Observation segment | The HL7 segment holding one observation and its value. |
| OCR | Office for Civil Rights | The HHS office that enforces HIPAA privacy and security rules. |
| OR | Operating room | The surgical suite, with isolated power, ESUs, anesthesia machines, and lasers. |
| ORM | Order message | The HL7 version 2 message that carries an order. |
| ORU | Observation result | The HL7 message that carries results, including vital signs from monitors. |
| OSHA | Occupational Safety and Health Administration | The US agency that sets workplace safety rules. |
| OSI | Open Systems Interconnection model | The seven-layer model for describing where a network function happens. |
| OX | Oxidizer (NFPA 704 symbol) | The special hazard code in the white diamond for oxidizing materials. |
| PaaS | Platform as a service | The provider runs the platform (OS, runtime, database); you deploy code. |
| PACS | Picture archiving and communication system | The server that stores and distributes medical images using DICOM. |
| PASS | Pull, aim, squeeze, sweep | How to use a fire extinguisher. |
| PC | Personal computer | A desktop or laptop for one user. |
| PCA | Patient-controlled analgesia | An infusion pump that lets the patient self-dose pain medication within programmed limits. |
| PCB | Printed circuit board | The board that holds and connects a device's components. |
| PDCA | Plan, do, check, act | The continuous improvement cycle. |
| PEEP | Positive end-expiratory pressure | Pressure the ventilator keeps in the lungs at the end of exhalation so alveoli stay open. |
| PEL | Permissible exposure limit | OSHA's legal maximum exposure to a substance, averaged over a shift. |
| PET | Positron emission tomography | Nuclear imaging of metabolic activity using a positron-emitting tracer such as FDG. |
| pH | Potential of hydrogen | The acidity scale; blood is normally 7.35 to 7.45. |
| PHI | Protected health information | Any health information tied to an identifiable person. |
| PID | Patient identification segment | The HL7 segment carrying patient name, ID, and demographics. |
| PM | Preventive maintenance | Scheduled inspection and testing of equipment before it fails. |
| PNP | Positive-negative-positive transistor | A bipolar transistor that conducts when its base is pulled negative. |
| PoE | Power over Ethernet | Delivers DC power to devices over the data cable: 802.3af 15.4 W, 802.3at 30 W, 802.3bt 60 to 90 W. |
| PP | Pulse pressure | Systolic minus diastolic pressure. |
| PPE | Personal protective equipment | Gloves, gowns, masks, eye protection, and lead aprons. |
| PPP | Point-to-Point Protocol | The Layer 2 protocol for serial and dial-up links that carries IP with authentication. |
| PR | PR interval | The ECG interval from the start of the P wave to the start of the QRS, 0.12 to 0.20 seconds; the AV node delay. |
| psi | Pounds per square inch | The pressure unit for cylinders, sterilizers, and pneumatic systems. |
| PSU | Power supply unit | Converts wall AC to the DC voltages a computer needs: 12 V, 5 V, 3.3 V. |
| PSV | Pressure support ventilation | The ventilator boosts each spontaneous breath with a set pressure. |
| PT | Physical therapy | The rehabilitation department, whose equipment includes TENS units, stimulators, and therapeutic ultrasound. |
| QC | Quality control | Running known samples to verify an analyzer is reading correctly. |
| QRS | QRS complex | The sharp ECG spike of ventricular depolarization; normally under 0.12 seconds wide. |
| QT | QT interval | The ECG interval from the start of the QRS to the end of the T wave, under about 0.44 seconds. |
| RA | Right arm electrode (also right atrium) | The white ECG electrode on the right arm; in heart anatomy, the right atrium. |
| RACE | Rescue, alarm, confine, extinguish or evacuate | The order of actions when a fire is discovered. |
| RADIUS | Remote Authentication Dial-In User Service | The AAA server behind Wi-Fi Enterprise, VPNs, and 802.1X; UDP 1812 and 1813. |
| RAID | Redundant array of independent disks | Combining disks for speed, capacity, or fault tolerance: 0 stripe, 1 mirror, 5 stripe with parity, 6 double parity, 10 mirrored stripes. |
| RAM | Random-access memory | The working memory that holds running programs and data; lost at power off. |
| RC | Resistor-capacitor (circuit) | A resistor and capacitor together, whose time constant is R times C. |
| RCA | Root cause analysis | A structured investigation of what happened, why, and how to prevent it. |
| RCF | Relative centrifugal force | The g-force a centrifuge applies, which depends on speed and rotor radius. |
| REL | Recommended exposure limit | NIOSH's recommended exposure limit. |
| REM | Roentgen equivalent man | A unit of radiation dose equivalent, 100 rem equals 1 sievert. |
| RF | Radio frequency | Radio signals; the medium of Wi-Fi, cellular, and Bluetooth, and a source of interference and, in medicine, surgical energy. |
| RIS | Radiology information system | Scheduling, tracking, and reporting for imaging departments. |
| RJ45 | Registered jack 45 | The eight-pin plug on Ethernet twisted-pair cables (properly an 8P8C connector). |
| RL | Right leg electrode | The green ECG electrode on the right leg, the reference or driven ground. |
| RMS | Root mean square | The effective value of an AC voltage or current, the DC equivalent for heating; 120 V mains is RMS. |
| RPM | Revolutions per minute | Rotation speed: hard drive platters at 5400 or 7200, fans, and laboratory centrifuges. |
| RS-232 | Recommended Standard 232 serial | The classic serial port: slow, simple, and still used for console access and legacy devices. |
| RTLS | Real-time location system | Tags and receivers that track equipment location inside the hospital. |
| RV | Right ventricle | The chamber that pumps blood to the lungs. |
| SA | Sinoatrial node | The heart's natural pacemaker in the right atrium. |
| SaaS | Software as a service | Complete applications delivered over the web, such as email and office suites. |
| SAT | Source address table | The switch's table of which MAC address lives on which port. |
| SBOM | Software bill of materials | A list of the software components inside a device. |
| SBP | Systolic blood pressure | The peak arterial pressure during ventricular contraction. |
| SCD | Sequential compression device | Inflatable leg sleeves that inflate in sequence to prevent blood clots. |
| SCR | Silicon-controlled rectifier | A thyristor that switches large currents on when triggered and stays on until current stops. |
| SDS | Safety data sheet | The document describing a chemical's hazards, handling, and first aid. |
| SIMV | Synchronized intermittent mandatory ventilation | A ventilator mode that gives a set number of breaths synchronized with the patient's own efforts. |
| SMART | Self-Monitoring, Analysis, and Reporting Technology | Hard drive self-diagnostics that warn before failure. |
| SMB | Server Message Block | Windows file and printer sharing on TCP 445. |
| SMDA | Safe Medical Devices Act | The 1990 law requiring hospitals to report device-related deaths and serious injuries to the FDA and manufacturer. |
| SMPS | Switch-mode power supply | A power supply that switches at high frequency to regulate voltage efficiently. |
| SpO2 | Peripheral oxygen saturation | The percentage of hemoglobin carrying oxygen, measured by a pulse oximeter. |
| SSD | Solid-state drive | Flash storage with no moving parts: fast, silent, and shock resistant. |
| SSH | Secure Shell | Encrypted remote command-line access and file transfer on TCP 22; replaces Telnet and FTP. |
| ST | ST segment | The ECG segment between the QRS and the T wave, where injury and ischemia show as elevation or depression. |
| STEL | Short-term exposure limit | The maximum average exposure over a 15-minute period. |
| SVT | Supraventricular tachycardia | A fast, regular rhythm originating above the ventricles, with narrow QRS. |
| TC | Transport Canada | The Canadian counterpart of the DOT for cylinder rules. |
| TCP | Transmission Control Protocol | Reliable, ordered, connection-based transport: three-way handshake, acknowledgments, retransmission. |
| TDR | Time-domain reflectometer | A cable tester that finds the distance to a break from signal reflections. |
| TENS | Transcutaneous electrical nerve stimulation | Low-level electrical pulses through skin electrodes for pain relief. |
| TLS | Transport Layer Security | The encryption layer under HTTPS and most secure protocols; use 1.2 or 1.3. |
| TLV | Threshold limit value | The ACGIH recommended exposure limit. |
| TOCO | Tocodynamometer | The pressure sensor on a fetal monitor that records uterine contractions. |
| TPN | Total parenteral nutrition | Complete nutrition delivered into a vein through an infusion pump. |
| TR | Telecommunications room | The wiring closet on each floor that serves nearby devices within the 90 m horizontal cable limit. |
| TV | Television | A display or broadcast receiver; smart TVs are IoT devices. |
| UDP | User Datagram Protocol | Connectionless, fast transport with no delivery guarantee; used for voice, video, DNS, DHCP. |
| UEFI | Unified Extensible Firmware Interface | Modern firmware that replaces BIOS: GPT disks, Secure Boot, mouse-driven setup. |
| UN | United Nations | The body whose Globally Harmonized System is the format hazard communication now uses. |
| UPS | Uninterruptible power supply | A battery unit that keeps equipment running through a power cut and conditions the power. |
| US | United States | The country; used for US standards, the 60 Hz mains frequency, and the AHA electrode color code. |
| USB | Universal Serial Bus | The standard port for peripherals, storage, and charging. |
| uV | Microvolt | One millionth of a volt; EEG signals are in microvolts. |
| UV | Ultraviolet | Light beyond violet, used for disinfection and in spectrophotometers, and absorbed by glass and plastic. |
| VA | Volt-ampere | The unit of apparent power, which a supply must deliver regardless of power factor. |
| VAR | Volt-ampere reactive | The unit of reactive power, which shuttles between source and load without doing work. |
| VF | Ventricular fibrillation | Chaotic ventricular activity with no output; the rhythm defibrillators treat. |
| VLAN | Virtual local area network | A logical LAN on a switch: ports in different VLANs are separate broadcast domains. |
| VM | Virtual machine | A complete computer running as software on a hypervisor. |
| VPN | Virtual private network | An encrypted tunnel across an untrusted network such as the internet. |
| VT | Ventricular tachycardia | A fast rhythm from the ventricles with wide QRS complexes; pulseless VT is shockable. |
| VT | Tidal volume | The volume of one breath, set on a ventilator at about 6 to 8 mL per kilogram of ideal body weight. |
| WAN | Wide area network | Connects LANs across cities or countries, usually over links leased from a provider. |
| WEP | Wired Equivalent Privacy | The original Wi-Fi encryption, broken in minutes; never use it. |
| Wi-Fi | Wireless fidelity | The trade name for IEEE 802.11 wireless networking. |
| WIPO | World Intellectual Property Organization | The UN agency for international copyright and patent treaties. |
| WLAN | Wireless local area network | A LAN delivered over Wi-Fi instead of cables. |
| WMTS | Wireless Medical Telemetry Service | The FCC-protected bands for patient telemetry: 608 to 614, 1395 to 1400, and 1427 to 1432 MHz. |
| WPA2 | Wi-Fi Protected Access 2 | Wi-Fi security using AES with CCMP; still common and acceptable. |
| WPA3 | Wi-Fi Protected Access 3 | The current Wi-Fi security standard: SAE in Personal mode, stronger encryption, protected management frames. |
| XML | Extensible Markup Language | A text format for structured data; HL7 version 3 and CDA use it. |
| YAG | Yttrium aluminum garnet (laser) | The crystal in Nd:YAG lasers, which emit near-infrared light that penetrates tissue. |
| YSI | Yellow Springs Instruments (temperature probe standard) | The company whose YSI 400 and YSI 700 thermistor curves became the standards for temperature probes. |