An Improved Method of Compensating Whole Body Plethysmographs

摘要

The frequency response of a volume plethysmograph may be improved by pressure compensation. The optimal level of compensation is a variable, however, depending upon spirometer characteristics and subject size. The Fast Fourier Transform allows the rapid determination of a transfer function describing the plethysmograph response in terms of amplitude and phase changes over a range of frequencies. The transfer function presents in an easily interpretable format the information necessary to adjust compensation gains and describe the effect of the plethysmograph system on input signals. (Author)