CABT Medical Equipment Operations 3 — Questions and Answers
Question 1: What is the primary purpose of the 'patient return electrode' (dispersive pad) in monopolar electrosurgery?
- To provide a grounding path that minimizes current density at the skin contact site (Correct answer)
- To deliver the cutting current directly to tissue
- To monitor the patient's heart rhythm during surgery
- To prevent radiofrequency interference with monitoring equipment
Correct answer: To provide a grounding path that minimizes current density at the skin contact site
The dispersive pad spreads return current over a large surface area, reducing current density and preventing burns at the electrode site.
Question 2: In a hospital isolation transformer system, what does an increase in line isolation monitor (LIM) alarm indicate?
- A ground fault has occurred in the isolated power system (Correct answer)
- The transformer has overheated
- The circuit breaker has tripped
- The UPS battery is depleted
Correct answer: A ground fault has occurred in the isolated power system
A LIM alarm indicates that hazard current from a fault has reached a threshold (typically 2 mA), warning staff that the isolation of the power system has been compromised.
Question 3: Which ventilator mode delivers a set tidal volume regardless of airway resistance or compliance changes?
- Pressure Support Ventilation (PSV)
- Volume Control Ventilation (VCV) (Correct answer)
- Continuous Positive Airway Pressure (CPAP)
- Airway Pressure Release Ventilation (APRV)
Correct answer: Volume Control Ventilation (VCV)
Volume Control Ventilation delivers a fixed tidal volume with each breath, with airway pressure varying based on lung mechanics.
Question 4: A syringe pump is programmed for 5 mL/hr but delivers only 2 mL/hr. Which mechanical issue is most likely responsible?
- Incorrect syringe size selected in the pump settings (Correct answer)
- Low battery condition
- Upstream occlusion alarm muted
- Incorrect drug concentration label
Correct answer: Incorrect syringe size selected in the pump settings
If the wrong syringe size is selected, the pump miscalculates the plunger travel distance needed, resulting in significant delivery errors.
Question 5: What is 'microshock' in the context of biomedical equipment safety?
- A brief high-voltage discharge used in cardioversion
- A small current (as low as 10 µA) applied directly to cardiac tissue causing ventricular fibrillation (Correct answer)
- Static electricity buildup on equipment surfaces
- A macroshock that occurs in pediatric patients
Correct answer: A small current (as low as 10 µA) applied directly to cardiac tissue causing ventricular fibrillation
Microshock occurs when a very small current bypasses normal skin resistance via intracardiac catheters, which can induce ventricular fibrillation at currents as low as 10 µA.
Question 6: Which gas is used as the primary drive gas for most pneumatically powered ventilators in hospitals?
- Medical air at 50 psi (Correct answer)
- Nitrous oxide at 50 psi
- Carbon dioxide at 15 psi
- Helium at 50 psi
Correct answer: Medical air at 50 psi
Medical air at 50 psi is the standard drive gas for pneumatically powered ventilators because it is abundant, safe, and meets the required pressure for reliable operation.
Question 7: An ECG monitor displays a 60 Hz artifact waveform pattern. What is the most likely source?
- Patient movement artifact
- Improper lead placement
- Electrical interference from AC power sources (Correct answer)
- Low battery in the monitor
Correct answer: Electrical interference from AC power sources
60 Hz artifact is classic electrical interference from alternating current power lines or nearby electrical equipment coupling into the ECG signal.
CABT Medical Equipment Operations 3
What is the primary purpose of the 'patient return electrode' (dispersive pad) in monopolar electrosurgery?