LC Engineering cheat sheet

Clinical engineering applies engineering principles to healthcare technology: device selection, acceptance testing, maintenance, safety, and lifecycle management.

The medical device lifecycle: needs assessment, capital planning, procurement, incoming inspection, acceptance testing, clinical use, preventive maintenance, repair, and decommissioning.

Acceptance testing verifies a new device meets manufacturer specifications and local safety standards before clinical use; it includes electrical safety, performance, and documentation.

Preventive maintenance (PM) intervals are set by manufacturer recommendations, risk level, and regulatory requirements; PM includes inspection, cleaning, calibration, and performance verification.

Risk-based PM prioritizes devices by function, physical risk, incident history, and maintenance requirements; higher-risk devices receive more frequent attention.

The Joint Commission requires hospitals to have a medical equipment management plan covering inventory, maintenance strategies, and incident reporting.

Mean time between failures (MTBF) = total operating time / number of failures; used to assess reliability and plan replacement.

Equipment replacement planning considers age, failure rate, parts availability, clinical need, and total cost of ownership (purchase + maintenance + downtime).

Human factors engineering in device design reduces use errors by considering user interface, workflow, and environmental conditions.

FDA classifies medical devices into Class I (low risk, general controls), Class II (moderate risk, general + special controls, often 510(k)), and Class III (high risk, premarket approval).

510(k) premarket notification requires demonstrating substantial equivalence to a legally marketed predicate device; PMA requires clinical evidence of safety and effectiveness.

Medical Device Reporting (MDR) requires manufacturers and importers to report deaths, serious injuries, and malfunctions to FDA; user facilities report deaths to FDA and serious injuries to FDA or manufacturer.

The Safe Medical Devices Act (SMDA) of 1990 mandates user facility reporting of device-related deaths and serious injuries.

Unique Device Identification (UDI) system requires devices to carry a unique identifier for traceability; labelers submit data to the GUDID database.

Recall classifications: Class I (reasonable probability of serious adverse health consequences or death), Class II (temporary or reversible health consequences), Class III (unlikely to cause harm).

The EU Medical Device Regulation (MDR 2017/745) requires CE marking, clinical evaluation, and post-market surveillance; classification follows risk-based rules.

Post-market surveillance includes complaint handling, adverse event reporting, and trending to detect safety signals.

Voluntary standards such as IEC 60601-1 (electrical safety) and ISO 14971 (risk management) are often used to demonstrate compliance.

Electrical safety testing includes ground continuity (resistance typically <0.5 Ω), insulation resistance (>2 MΩ at 500 V DC), and leakage current measurements.

Leakage current limits for patient-connected equipment (IEC 60601-1): earth leakage ≤500 µA (normal), patient leakage ≤100 µA (Type B/BF) or ≤10 µA (Type CF) under normal conditions.

Defibrillator testing verifies energy output (within ±15% of selected energy), charge time, and synchronized cardioversion timing.

Infusion pump testing checks flow rate accuracy (±5–10%), occlusion alarm pressure, and air-in-line detection.

Patient monitors require verification of ECG, SpO2, NIBP, and temperature channels using simulators and calibration equipment.

Ventilator testing includes tidal volume accuracy, pressure limits, alarm function, and oxygen concentration.

Calibration traceability requires an unbroken chain to national or international standards (NIST or equivalent).

Test equipment must be calibrated at defined intervals; records must include date, result, and personnel.

Documentation of maintenance and testing is required for regulatory compliance and liability protection; records retained per facility policy.

Computerized maintenance management systems (CMMS) track inventory, work orders, PM schedules, parts, and costs.

Key performance indicators include PM completion rate, mean time to repair (MTTR), uptime, and maintenance cost per device.

Inventory management includes unique equipment identifiers, location tracking, and status (in service, out of service, retired).

Capital equipment planning aligns technology acquisition with clinical strategic goals and budget cycles.

Technology assessment evaluates clinical efficacy, safety, cost-effectiveness, and integration with existing systems.

Service contracts vs. in-house service: decision based on device complexity, vendor support, staff competency, and cost.

Staffing models for clinical engineering consider device count, acuity, and regulatory requirements.

Incident investigation and root cause analysis improve safety and prevent recurrence.

Disaster preparedness includes backup power, equipment redundancy, and emergency response plans.

Medical device cybersecurity requires risk assessment, access controls, network segmentation, and timely patching.

HIPAA Security Rule requires administrative, physical, and technical safeguards for electronic protected health information (ePHI).

Network segmentation isolates medical devices from enterprise IT to limit attack surface and contain breaches.

Device inventory and vulnerability management are essential; FDA premarket and postmarket cybersecurity guidance applies.

Interoperability standards include HL7 (clinical data exchange) and DICOM (medical imaging).

Wireless medical telemetry and Wi-Fi devices require secure configurations (WPA2/WPA3, unique credentials).

Incident response plans should address medical device breaches, including containment, notification, and recovery.

Vendor remote access must be controlled and monitored; default passwords must be changed.

Data backup and disaster recovery protect clinical systems and patient data.

Ohm's law: V = I × R; power: P = V × I = I²R = V²/R.

Impedance (Z) extends resistance to AC circuits, combining resistance and reactance; Z = √(R² + X²).

Capacitive reactance Xc = 1/(2πfC); inductive reactance XL = 2πfL.

Filters: low-pass passes low frequencies, high-pass passes high frequencies; cutoff frequency fc = 1/(2πRC).

Decibel: dB = 20 log10(Vout/Vin) for voltage; 3 dB corresponds to half power.

Common-mode rejection ratio (CMRR) measures a differential amplifier's ability to reject common-mode signals; higher is better.

Biopotential amplifiers require high input impedance, high CMRR, and patient isolation.

Batteries: capacity in ampere-hours (Ah); series increases voltage, parallel increases capacity.

Electrical safety: macroshock (external current) vs. microshock (current directly to heart); microshock threshold ~100 µA.

The heart's conduction system: SA node (pacemaker), AV node (delay), bundle of His, bundle branches, Purkinje fibers.

ECG waveforms: P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization).

Cardiac output = heart rate × stroke volume; normal ~5 L/min.

Blood pressure = cardiac output × systemic vascular resistance.

Respiratory system: tidal volume, vital capacity, functional residual capacity; normal resting tidal volume ~500 mL.

SpO2 measures arterial oxygen saturation via pulse oximetry; normal 95–100%.

Kidney function: glomerular filtration rate (GFR) ~125 mL/min; dialysis removes waste products.

Nervous system: action potentials, synaptic transmission; EEG measures brain electrical activity.

Medical imaging modalities: X-ray (attenuation), CT (cross-sectional), MRI (magnetic resonance), ultrasound (echolocation).

Environment of care standards address safety, security, hazardous materials, fire safety, medical equipment, and utilities.

Electrical systems in patient care areas require isolated power or ground fault circuit interrupters (GFCIs) per code.

Emergency power must support life safety, critical care, and essential systems; tested monthly and annually.

Medical gas systems (oxygen, vacuum, medical air) require verification, labeling, and alarm systems.

HVAC controls temperature, humidity, and air quality; operating rooms require positive pressure and HEPA filtration.

Radiation safety: shielding, dosimetry, and restricted access for X-ray and nuclear medicine areas.

Infection control: hand hygiene, isolation rooms, and surface disinfection.

Fire safety: fire alarm systems, sprinklers, extinguishers, and evacuation plans.

Facility design considers patient flow, accessibility (ADA), and workflow efficiency.

Clinical engineering codes of ethics emphasize patient safety, competence, confidentiality, and integrity.

Conflicts of interest must be disclosed and managed; vendor gifts should not influence equipment decisions.

Informed consent and patient privacy are fundamental; access to patient data is limited to need-to-know.

Continuing education and certification (e.g., CCE, CHTM) maintain professional competence.

Whistleblowing protections encourage reporting of unsafe conditions or violations.

Professional liability: maintain accurate records and follow standards of care.

Collaboration with clinicians, IT, and administration is essential for safe technology management.

Research ethics: institutional review board (IRB) approval for human subjects research.

Sustainability: proper disposal and recycling of electronic waste and medical devices.