AN IMPEDANCE RESPIROMETER
Final rept., Aug 1961-Aug 1962
AIR FORCE AEROSPACE MEDICAL RESEARCH LAB WRIGHT-PATTERSON AFB OH
Pagination or Media Count:
When a low-intensity, HF 20-60 kc carrier signal is applied to a human subject between biaxillary electrodes, a change in impedance can be measured between the electrodes. This change in impedance closely parallels the simultaneous changes in the volume of respired air. The design and circuitry of an impedance respirometer are presented. Simultaneous tracings from this respirometer and a wedge spirometer were recorded from ten subjects during quiet sitting, standing, walking, and running in place through the physiological range of respiratory rate 8-40 breathsmin and volume 12-4 liters. The output of the impedance respirometer correlated well with the output of the wedge spirometer in the quiet, seated subject. The problems of electrode configuration, body type, and electrode artifact are discussed. This system is a reliable and unencumbering method of monitor-respiratory rate and, potentially, respiratory volume. However, its use is severely limited by base line shifts and motion artifact due to changes in electrode impedance.
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