Mixed Deck — All CBET Topics Flashcards

During a procedure using a monopolar electrosurgical unit (ESU), the surgeon complains of poor cutting effect even at a high power setting. The BMET has already used an ESU analyzer to confirm the generator is delivering the correct output power. What is the MOST likely cause of this problem?

Answer: The patient return electrode has poor, limited contact with the patient's skin.

In a monopolar circuit, current must flow from the active electrode, through the patient, to the patient return electrode (dispersive pad), and back to the generator. If the return electrode has poor or partial contact, the electrical impedance of the total circuit increases significantly. This high impedance restricts current flow, leading to a poor cutting effect at the active electrode, regardless of the generator's power setting.

What does a 'risk-based PM program' use to prioritize maintenance frequency?

Answer: Device criticality, failure consequences, and maintenance history

Risk-based programs assign higher PM priority to life-sustaining or high-risk devices and extend intervals for low-risk equipment with good histories.

A hospital laboratory centrifuge vibrates excessively during operation. The MOST likely cause is:

Answer: An unbalanced load due to improperly paired or misplaced samples

Centrifuges must have balanced loads; unequal or improperly positioned samples create centrifugal force imbalance causing severe vibration.

What is the primary difference between a Class I and Class II medical device under FDA classification?

Answer: Class I requires general controls only; Class II requires special controls such as performance standards

FDA Class I devices are subject to general controls only, while Class II devices require special controls (e.g., performance standards, post-market surveillance) to ensure safety and effectiveness.

A CT scanner's X-ray tube requires replacement. Which parameter most directly indicates tube wear?

Answer: Total accumulated milliampere-seconds (mAs) / heat units

Accumulated heat units or mAs track the thermal stress on the anode; manufacturers define tube replacement thresholds based on this metric.

Which regulatory body classifies medical gas systems components as medical devices subject to 510(k) or PMA review?

Answer: FDA

The FDA classifies medical gas equipment (regulators, flowmeters, outlets) as medical devices and requires 510(k) clearance or PMA approval before marketing.

What is the function of a network firewall between the medical device network and the hospital's general network?

Answer: To control and filter network traffic based on security rules

A firewall controls and filters network traffic between segments based on security rules, protecting medical devices from unauthorized access.

A flash sterilization cycle (immediate-use steam sterilization) at 132°C in a pre-vacuum sterilizer requires a minimum exposure time of:

Answer: 4 minutes

AAMI ST79 specifies a minimum of 4 minutes at 132°C for immediate-use steam sterilization (flash sterilization) in a pre-vacuum sterilizer with lumened devices.

Which type of current flows in only one direction through a circuit?

Answer: Direct current (DC)

Direct current (DC) flows in a single, constant direction, unlike AC which reverses direction periodically.

A patient reports receiving a mild tingling sensation when touching the bed rail while connected to a patient monitor. No alarm has triggered. What is the appropriate immediate action?

Answer: Immediately disconnect the patient from the monitor, remove the device from service, and perform electrical safety testing

A tingling sensation indicates stray electrical current flowing through the patient, which is a potentially dangerous leakage current situation.

During vaporized hydrogen peroxide (VHP) sterilization, which condition causes cycle failure?

Answer: Residual moisture in the chamber or on devices

Residual moisture reacts with and depletes hydrogen peroxide vapor, reducing sterilant concentration below effective levels.

A biomedical technician needs to verify that a medical device can communicate with a remote server. Which command-line tool tests basic IP reachability?

Answer: ping

The ping command sends ICMP echo requests to test basic IP-level connectivity between a device and a target host.

What does a pulmonary artery catheter (Swan-Ganz) measure when the balloon is inflated and wedged?

Answer: Pulmonary artery occlusion pressure (PAOP), reflecting left heart filling pressure

When wedged, the inflated balloon occludes forward flow, allowing the distal port to sense pressure that reflects left atrial and left ventricular end-diastolic pressure.

A syringe pump generates an 'occlusion downstream' alarm. The patient's IV site appears patent. What is the MOST likely next step for a BMET troubleshooting this pump?

Answer: Inspect the IV line for kinks, closed clamps, or infiltration at the catheter site

A downstream occlusion alarm means the pump's pressure sensor detected resistance distal to the syringe. The most common causes are a clamped or kinked IV line, a closed stopcock, or a failed/infiltrated IV catheter. Adjusting the threshold would mask a real clinical problem, and replacing the drive mechanism is unwarranted before ruling out external causes.

According to NFPA 99, which category of electrical system must power life-safety equipment within 10 seconds of a power outage?

Answer: Category 1 (Essential Electrical System - Life Safety Branch)

NFPA 99 requires the Life Safety Branch of the Essential Electrical System to restore power within 10 seconds via emergency generators.

A BMET is performing a PM on an infusion pump. Which test is most critical for patient safety?

Answer: Flow rate accuracy test

Flow rate accuracy directly affects drug dosing; an out-of-tolerance pump can deliver under- or over-doses with life-threatening consequences.

Which MRI safety zone requires strict ferromagnetic screening of all personnel and equipment?

Answer: Zone IV

Zone IV is the MRI scanner room itself, where the static magnetic field is always present, requiring the strictest screening.

During routine PM on a medical gas manifold, a technician finds a pressure gauge reading 10% lower than the adjacent calibrated reference gauge. What is the appropriate action?

Answer: Recalibrate or replace the gauge and document the finding

A gauge reading 10% low should be recalibrated or replaced per NFPA 99 maintenance requirements, and the discrepancy documented for corrective action tracking.

Which organization publishes ANSI/AAMI standards relevant to biomedical equipment maintenance in the US?

Answer: Association for the Advancement of Medical Instrumentation (AAMI)

AAMI publishes consensus standards and technical information reports widely used by biomedical engineers for equipment maintenance and safety.

A BMET is troubleshooting a ventilator patient monitor that shows erratic tidal volume readings. The flow sensor passes bench testing. What is the NEXT most logical step?

Answer: Inspect the flow sensor for moisture condensation or secretion buildup in-line

Moisture and secretion buildup inside inline flow sensors is a common cause of erratic volume readings in ventilated patients.