CBET Patient Monitoring Systems 4 — Questions and Answers
Question 1: A capnograph displays an abnormally low ETCO2 reading with a shark-fin waveform shape. What condition does this most likely indicate?
- Hyperventilation
- Bronchospasm or partial airway obstruction (Correct answer)
- Esophageal intubation
- Pulmonary embolism
Correct answer: Bronchospasm or partial airway obstruction
A shark-fin capnogram waveform indicates obstructed exhalation, classically seen in bronchospasm or COPD exacerbation.
Question 2: During routine calibration of a bedside monitor's SpO2 sensor, a BMET notices the oximeter reads 98% on a patient confirmed by ABG to have SaO2 of 84%. What is the most likely cause?
- Faulty photodetector
- Elevated carboxyhemoglobin levels (Correct answer)
- Low ambient light interference
- Incorrect wavelength LED aging
Correct answer: Elevated carboxyhemoglobin levels
Pulse oximetry cannot differentiate oxyhemoglobin from carboxyhemoglobin, causing falsely elevated SpO2 readings in CO poisoning.
Question 3: A nurse reports that a patient's invasive arterial line is showing an overdamped waveform. Which of the following is the BEST corrective action?
- Increase the flush bag pressure above 300 mmHg
- Check for air bubbles, clots, or kinked tubing in the system (Correct answer)
- Replace the transducer with a higher compliance model
- Reposition the transducer above the phlebostatic axis
Correct answer: Check for air bubbles, clots, or kinked tubing in the system
Overdamping is most commonly caused by air bubbles, clots, or mechanical occlusion that attenuates pressure wave transmission.
Question 4: What is the primary purpose of the fast flush test (square wave test) performed on an invasive hemodynamic monitoring system?
- To verify accurate zero reference at the phlebostatic axis
- To assess the dynamic frequency response and damping coefficient of the system (Correct answer)
- To detect electrical interference from nearby equipment
- To confirm catheter patency before blood draw
Correct answer: To assess the dynamic frequency response and damping coefficient of the system
The square wave test evaluates dynamic response by analyzing the oscillations after a fast flush to determine if the system is adequately damped.
Question 5: A neonatal ICU monitor alarm activates for a SpO2 reading of 80%. The BMET verifies equipment function is normal. What physiological artifact is LEAST likely responsible?
- Motion artifact from infant movement
- Peripheral vasoconstriction reducing perfusion
- Elevated fetal hemoglobin concentration (Correct answer)
- Probe placed on an edematous extremity
Correct answer: Elevated fetal hemoglobin concentration
Fetal hemoglobin (HbF) has similar optical absorption properties to adult hemoglobin at standard oximetry wavelengths and does not significantly cause inaccurate SpO2 readings.
Question 6: A telemetry technician reports frequent ST-segment false alarms on a cardiac monitor. Which monitor setting change would BEST reduce these false alarms while maintaining clinical sensitivity?
- Increase the ST alarm threshold by 2 mV
- Switch to a monitoring lead that provides a more stable baseline for that patient (Correct answer)
- Disable the ST analysis algorithm
- Reduce the ECG gain setting to 5 mm/mV
Correct answer: Switch to a monitoring lead that provides a more stable baseline for that patient
Selecting an optimal lead with a cleaner isoelectric baseline reduces motion-induced ST baseline wander without compromising detection sensitivity.
Question 7: Which parameter does a Bispectral Index (BIS) monitor measure to assess depth of anesthesia?
- End-tidal anesthetic agent concentration
- Processed electroencephalographic (EEG) activity (Correct answer)
- Cerebral oximetry via near-infrared spectroscopy
- Neuromuscular blockade train-of-four ratio
Correct answer: Processed electroencephalographic (EEG) activity
BIS monitors analyze and process raw EEG signals to produce a dimensionless index (0–100) correlating with level of consciousness.
CBET Patient Monitoring Systems 4
A capnograph displays an abnormally low ETCO2 reading with a shark-fin waveform shape.
What condition does this most likely indicate?