The Accuracy of Spirographic Recording at High Respiratory Rates

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Abstract
The usual use of a spirometer for determination of BMR or vital capacity is without essential error in recording amplitudes of a rate less than 55 breaths/min. A rate above this is capable of causing considerable error in the recording. At least 2 factors are responsible: (1) inertia of the moving parts of the spirometer, and (2) the resonance of the water column in the water jacket. There appears to be no simple way of calibrating the spirometer in an effort to correct the sources of error but some improvement results if the moving parts are made as light as possible, as by the use of the lightweight celluloid bell.
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