BCA Monitoring Equipment & Technology 3 — Questions and Answers
Question 1: The Severinghaus electrode is used to measure which blood gas parameter?
- PaO2
- pH
- PaCO2 (Correct answer)
- HCO3-
Correct answer: PaCO2
The Severinghaus electrode is a modified pH electrode designed to measure PaCO2 by detecting CO2 diffused across a membrane.
Question 2: Which transducer level is correct when zeroing an arterial line for blood pressure measurement in a supine patient?
- Level of the heart (phlebostatic axis) (Correct answer)
- Level of the wrist
- Level of the aortic root
- Level of the brain
Correct answer: Level of the heart (phlebostatic axis)
The transducer is zeroed at the phlebostatic axis (4th intercostal space, mid-axillary line) which approximates the level of the right atrium.
Question 3: What is the primary purpose of the pop-off valve (APL valve) in the anesthesia breathing circuit?
- Regulate fresh gas flow
- Prevent rebreathing of CO2
- Limit maximum circuit pressure and allow gas scavenging (Correct answer)
- Deliver precise tidal volumes
Correct answer: Limit maximum circuit pressure and allow gas scavenging
The APL (adjustable pressure-limiting) valve limits maximum breathing circuit pressure and directs excess gas to the scavenging system.
Question 4: Bispectral Index (BIS) values between 40 and 60 correspond to which anesthetic state?
- Awake and alert
- Light sedation
- General anesthesia with low recall risk (Correct answer)
- Deep burst suppression
Correct answer: General anesthesia with low recall risk
BIS values of 40-60 indicate a general anesthetic depth appropriate for surgery with a low probability of awareness.
Question 5: Which parameter does near-infrared spectroscopy (NIRS) measure in the context of cerebral monitoring?
- Intracranial pressure
- Cerebral blood flow velocity
- Regional cerebral oxygen saturation (rSO2) (Correct answer)
- EEG waveform activity
Correct answer: Regional cerebral oxygen saturation (rSO2)
NIRS uses near-infrared light to estimate regional cerebral oxygen saturation (rSO2) by measuring oxygenated and deoxygenated hemoglobin in underlying tissue.
Question 6: On a precordial stethoscope placed over the left precordium during anesthesia, which finding would raise immediate concern for air embolism?
- Distant heart sounds
- Mill-wheel murmur (Correct answer)
- S3 gallop
- Systolic ejection murmur
Correct answer: Mill-wheel murmur
A mill-wheel murmur is a characteristic churning sound heard when a large volume of air enters the right heart, indicating significant venous air embolism.
Question 7: Which device is used to measure neuromuscular blockade by delivering a supramaximal stimulus to a peripheral nerve?
- Nerve conduction velocity meter
- Train-of-four stimulator (peripheral nerve stimulator) (Correct answer)
- Electromyograph
- Evoked potential monitor
Correct answer: Train-of-four stimulator (peripheral nerve stimulator)
A peripheral nerve stimulator delivers supramaximal stimuli (e.g., train-of-four) to assess the degree of neuromuscular blockade.
BCA Monitoring Equipment & Technology 3
The Severinghaus electrode is used to measure which blood gas parameter?