CABT Clinical Procedures & Techniques 5 — Questions and Answers
Question 1: A ventilator's flow sensor reads consistently lower than the rotameter reference during a performance verification. The MOST likely cause is:
- High ambient temperature affecting electronic calibration
- Moisture condensation or contamination in the flow sensor (Correct answer)
- Incorrect FiO2 setting on the blender
- Excessive PEEP level altering flow dynamics
Correct answer: Moisture condensation or contamination in the flow sensor
Moisture or secretion buildup inside the flow sensor is the most common cause of artificially low flow readings in mechanical ventilators.
Question 2: The 'dead volume' in a syringe pump infusion system is clinically significant because it:
- Causes the pump motor to draw excess current
- Delays actual drug delivery when a new syringe is loaded or rate is changed (Correct answer)
- Prevents accurate weight-based dosing calculations
- Increases the risk of air embolism in the IV line
Correct answer: Delays actual drug delivery when a new syringe is loaded or rate is changed
Dead volume in the syringe plunger and tubing means the pump must compress or expand that volume before drug flow reaches the patient, creating a clinically important delivery lag.
Question 3: Which parameter should a biomedical technician verify when performing a functional check on an automated external defibrillator (AED) self-test override?
- Shock delivery into a 50-ohm load (Correct answer)
- Voice prompt clarity at defined decibel level
- ECG analysis algorithm accuracy with stored test vectors
- Battery manufacturer date code
Correct answer: Shock delivery into a 50-ohm load
Functional AED testing requires delivering a shock into a 50-ohm test load (simulating adult thoracic impedance) and verifying the delivered energy is within specification.
Question 4: During a point-of-care (POC) i-STAT analyzer quality control failure, the FIRST action by the biomedical technician should be to:
- Remove the analyzer from service immediately
- Repeat the QC using a fresh cartridge from a different lot
- Check control expiration dates, storage conditions, and cartridge lot (Correct answer)
- Recalibrate using distilled water
Correct answer: Check control expiration dates, storage conditions, and cartridge lot
Troubleshooting QC failure starts with verifying pre-analytical variables: control solution expiration, proper storage temperature, and matching cartridge lot numbers to control insert values.
Question 5: In transcutaneous electrical nerve stimulation (TENS) therapy setup, 'conventional TENS' mode is characterized by:
- Low frequency (2–4 Hz), high intensity pulses causing muscle contraction
- High frequency (80–150 Hz), low intensity pulses below motor threshold (Correct answer)
- Burst mode at 2 Hz carrier with 100 Hz internal frequency
- Continuous DC current for iontophoresis
Correct answer: High frequency (80–150 Hz), low intensity pulses below motor threshold
Conventional TENS uses high-frequency, low-intensity stimulation that activates large-diameter A-beta sensory fibers for gate control pain relief without eliciting muscle contractions.
Question 6: When a hospital purchases a refurbished ventilator, which document provides the MOST critical assurance that the device meets original manufacturer performance specifications?
- The original operator manual
- Certificate of conformance from an ISO 13485-certified refurbisher (Correct answer)
- Biomedical technician's incoming inspection checklist
- The facility's preventive maintenance schedule
Correct answer: Certificate of conformance from an ISO 13485-certified refurbisher
A certificate of conformance from an ISO 13485-certified refurbisher provides documented evidence that the device was restored to original specifications using a validated quality management system.
Question 7: A patient undergoing cardiac monitoring develops an irregular artifact resembling ECG waveforms at 60 Hz. The MOST likely source is:
- Patient movement during deep breathing
- 60 Hz AC power line interference (electromagnetic interference) (Correct answer)
- Pacemaker spike artifact
- Lead transposition at the RA and LA positions
Correct answer: 60 Hz AC power line interference (electromagnetic interference)
60 Hz interference (powerline noise) produces a regular, high-frequency baseline artifact that is distinct from biological signals and is caused by inadequate shielding or poor electrode contact.
CABT Clinical Procedures & Techniques 5
A ventilator's flow sensor reads consistently lower than the rotameter reference during a performance verification.
The MOST likely cause is: