A comparison of functional residual capacity measured by body plethysmography with that measured by nitrogen washout reveals that the measurement obtained during the nitrogen washout test is less than that during body plethysmography.This discrepancy is most likely caused by which of the following?
A) Poor technique
B) Severe air-trapping
C) Restrictive lung disease
D) Directional valve malfunction

Question

Quizplus · Accepted Answer

Severe air-trapping will produce lower functional residual capacity results than body plethysmography because the nitrogen washout test measures gas volumes only in communicating airways.

A Comparison of Functional Residual Capacity Measured by Body Plethysmography