EDAIC Clinical Measurement and Physics 3

Question 1

Which principle underlies the function of a vaporizer using the 'plenum' design (e.g., TEC series)?

Accepted Answer

Temperature-compensated splitting of gas flow between a bypass and a vaporizing chamber

Answer

Variable-bypass vaporizers split fresh gas flow; a thermostat-controlled valve adjusts the fraction passing through the vaporizing chamber to maintain accurate output across temperatures.

Question 2

When using a Wright respirometer to measure tidal volume, which error is most likely?

Accepted Answer

Underreading at high flow rates due to over-spinning of the vane

Answer

The Wright respirometer underestimates at high flows because the lightweight vane cannot keep pace, and it overestimates at very low flows due to vane inertia.

Question 3

Paramagnetic oxygen analyzers exploit which property of oxygen?

Accepted Answer

O₂ is paramagnetic due to unpaired electrons and is attracted to a magnetic field

Answer

Oxygen has two unpaired electrons making it paramagnetic; it is drawn into a magnetic field, allowing concentration measurement by displacement of a nitrogen-filled dumbbell.

Question 4

A damped arterial line waveform (overdamped system) will produce which measurement error?

Accepted Answer

Falsely low systolic and falsely high diastolic pressure, with accurate mean

Answer

Overdamping attenuates the waveform peaks, causing underestimation of systolic and overestimation of diastolic pressure, while mean arterial pressure remains relatively accurate.

Question 5

Which gas law explains why a patient's tidal volume may decrease when measured at body temperature compared to the ventilator setting calibrated at room temperature?

Accepted Answer

Charles's law — volume increases proportionally with absolute temperature

Answer

Charles's law (V∝T at constant P) means that gas warmed from ~20°C to 37°C expands, so the delivered volume at body temperature is larger than at room temperature, not smaller — measuring at body temp vs. BTPS vs. ATPS must be reconciled.

EDAIC - European Diploma in Anesthesiology and Intensive Care Practice Test

EDAIC - European Diploma in Anesthesiology and Intensive Care Practice Test

EDAIC Clinical Measurement and Physics 3