Calibration of the Direct Ballistocardiogram

Abstract

A simple method of calibrating the amplitude of the direct ballistocardiogram, utilizing a standard external force to the body, is described. Such a method tends to neutralize many of the variables in apparatus alignment and sensitivity, and provides a basis for comparison of amplitudes in the same and different subjects. Normals of different age groups were studied and the contrast with abnormals with known cardiovascular disease is shown.