CABT Biomedical Equipment Technology & Function 5 — Questions and Answers
Question 1: When testing ground wire integrity on patient care equipment, the AAMI ES1 standard specifies a maximum resistance of:
- 0.5 ohm
- 0.1 ohm (Correct answer)
- 1.0 ohm
- 0.01 ohm
Correct answer: 0.1 ohm
AAMI ES1 requires that the resistance from the grounding pin to any exposed conductive patient-contact surface not exceed 0.1 ohm to ensure effective fault current dissipation.
Question 2: A neonatal incubator's airflow system is designed to maintain what primary environmental parameter for the infant?
- Oxygen concentration above 30%
- Neutral thermal environment by controlling air temperature (Correct answer)
- Humidity above 80% at all times
- Carbon dioxide below 1000 ppm
Correct answer: Neutral thermal environment by controlling air temperature
The incubator's primary function is to maintain a neutral thermal environment (NTE) that minimizes the infant's metabolic oxygen consumption and heat loss.
Question 3: In a hemodialysis machine, the conductivity monitor of the dialysate circuit is critical because it detects:
- Blood leak into the dialysate
- Incorrect electrolyte concentration that could cause patient harm (Correct answer)
- Air bubbles in the blood circuit
- Transmembrane pressure exceeding safe limits
Correct answer: Incorrect electrolyte concentration that could cause patient harm
Conductivity correlates directly with dissolved electrolyte (sodium) concentration; a conductivity alarm stops dialysate delivery to prevent hypo- or hypernatremia.
Question 4: The purpose of a thermal compensation resistor (or thermistor) in a pressure transducer is to:
- Amplify low-amplitude pressure signals
- Correct for sensitivity drift caused by temperature changes (Correct answer)
- Provide electrical isolation from the patient
- Balance the Wheatstone bridge at initial calibration only
Correct answer: Correct for sensitivity drift caused by temperature changes
Strain-gauge pressure transducers are temperature-sensitive; a thermistor or compensation resistor adjusts the bridge output to maintain accuracy across a range of operating temperatures.
Question 5: Which FDA device classification requires the most rigorous pre-market approval (PMA) process, typically applied to life-sustaining or life-supporting devices?
- Class I
- Class III (Correct answer)
- Class II
- Class IIb
Correct answer: Class III
FDA Class III devices (e.g., implantable pacemakers, ventricular assist devices) pose the greatest risk and require PMA with clinical evidence of safety and effectiveness.
Question 6: A hospital's medical gas alarm panel shows a 'low pressure' warning for the piped oxygen system. The FIRST action a BMET should take is:
- Switch patients to portable oxygen cylinders immediately
- Verify the alarm by checking the zone valve pressure gauge and contacting the facility engineer (Correct answer)
- Shut down all equipment connected to the oxygen wall outlets
- Increase the regulator setpoint on the bulk oxygen supply
Correct answer: Verify the alarm by checking the zone valve pressure gauge and contacting the facility engineer
Confirming the alarm with a gauge reading and notifying facilities engineering ensures the response is appropriate and that clinical staff take corrective action if a true emergency exists.
Question 7: Electromagnetic interference (EMI) from a nearby electrosurgical unit most commonly affects which monitoring device by inducing artifact that mimics the signal of interest?
- Pulse oximeter plethysmographic waveform
- ECG rhythm display (Correct answer)
- End-tidal CO2 waveform
- Non-invasive blood pressure reading
Correct answer: ECG rhythm display
ESU RF energy couples into ECG lead wires, which act as antennas, producing artifact that obscures the cardiac signal during electrosurgical activation.
CABT Biomedical Equipment Technology & Function 5
When testing ground wire integrity on patient care equipment, the AAMI ES1 standard specifies a maximum resistance of: