A simple biofeedback digital data collection instrument to control ventilation during autonomic investigations

Autonomic evaluation using the heart rate spectrum is sensitive to changes in breathing parameters, but few studies using this technique have controll ed both the rate and depth of breathing. Fewer still have also measured or controlled inspiration and expiration times, or end-tidal carbon dioxide. T his study describes the development of a digital instrument that can be use d to alter tidal volume, ventilation rate and the time of inspiration and e xpiration with paced breathing visual templates displayed on a computer mon itor. The digital instrument runs during data acquisition and displays the ventilatory signal from the subject superimposed on the paced breathing tem plates. Thus, adjustment of ventilatory parameters is achieved by matching the actual breathing signal to the target template. By regulating the venti lation rate and the tidal volume, end-tidal carbon dioxide could be increas ed or decreased in small increments. This instrument provided ventilatory c ontrol to investigate the effects on the heart rate spectrum of breathing d epth, ventilation rate, end-tidal carbon dioxide and the time of expiration . Published by Elsevier Science B.V.