CABT Biomedical Equipment Technology & Function 2 — Questions and Answers
Question 1: Which type of defibrillator waveform is now preferred over monophasic due to its lower energy requirements and higher first-shock efficacy?
- Monophasic truncated exponential
- Biphasic truncated exponential (Correct answer)
- Monophasic damped sine
- Triphasic sequential
Correct answer: Biphasic truncated exponential
Biphasic waveforms deliver current in two phases, reducing myocardial damage and improving defibrillation success at lower energy levels.
Question 2: An infusion pump alarming 'occlusion downstream' most likely indicates:
- Air in the IV line
- A kinked or clamped IV tubing distal to the pump (Correct answer)
- Low battery voltage
- Incorrect drip rate setting
Correct answer: A kinked or clamped IV tubing distal to the pump
A downstream occlusion alarm triggers when back-pressure exceeds the set threshold, typically caused by a clamp, kink, or infiltration at the IV site.
Question 3: In a pulse oximeter, which two wavelengths of light are used to differentiate oxyhemoglobin from deoxyhemoglobin?
- 450 nm and 580 nm
- 660 nm and 940 nm (Correct answer)
- 780 nm and 1000 nm
- 550 nm and 850 nm
Correct answer: 660 nm and 940 nm
Pulse oximeters use red light (~660 nm) and infrared light (~940 nm) because oxyhemoglobin and deoxyhemoglobin absorb these wavelengths at different ratios.
Question 4: A ventilator's tidal volume is set to 500 mL but the measured exhaled volume is consistently 450 mL. The FIRST step a BMET should check is:
- Replace the flow sensor
- Inspect the breathing circuit for leaks (Correct answer)
- Recalibrate the FiO2 sensor
- Adjust the PEEP valve
Correct answer: Inspect the breathing circuit for leaks
A consistent volume discrepancy between set and measured tidal volumes most commonly results from a circuit leak, which should be ruled out before replacing components.
Question 5: Which component in an electrosurgical unit (ESU) converts standard AC line power into the high-frequency RF current used for cutting and coagulation?
- Isolation transformer
- Resonant tank circuit (Correct answer)
- Ground fault interrupter
- Bipolar footswitch relay
Correct answer: Resonant tank circuit
The resonant tank circuit (oscillator) in an ESU generates high-frequency RF output (typically 300 kHz–5 MHz) from the rectified DC supply.
Question 6: Patient return electrode (dispersive pad) placement for monopolar ESU should avoid areas with:
- Large muscle mass
- Bony prominences, scar tissue, or metal implants (Correct answer)
- Intact, well-perfused skin
- Areas close to the surgical site
Correct answer: Bony prominences, scar tissue, or metal implants
Bony prominences cause uneven contact and current concentration; scar tissue has poor conductivity; metal implants can create localized heating, all risking burns.
Question 7: The primary safety function of a line isolation monitor (LIM) in an isolated power system is to:
- Prevent voltage surges from damaging equipment
- Detect and alarm when hazard current to ground exceeds a safe threshold (Correct answer)
- Automatically shut off power during equipment failure
- Regulate voltage to critical care outlets
Correct answer: Detect and alarm when hazard current to ground exceeds a safe threshold
A LIM continuously measures impedance to ground and alarms when leakage current exceeds ~2 mA, warning of a fault before a second fault can cause patient electrocution.
CABT Biomedical Equipment Technology & Function 2
Which type of defibrillator waveform is now preferred over monophasic due to its lower energy requirements and higher first-shock efficacy?