Journal of Applied Physiology, Vol 49, Issue 3 355-362, Copyright © 1980 by American Physiological Society
Comparison of two- and four-magnetometer methods of measuring ventilation
C. H. Robertson Jr, M. E. Bradley and L. D. Homer
Two computerized methods of measuring ventilation from four pairs
magnetometers placed anteroposteriorly (AP) and laterally on the rib cage
and abdomen were compared with a method that employs two pairs of
magnetometers placed AP on the rib cage and abdomen. This comparison showed
that the most accurate method of measuring ventilation employed
four-magnetometer pairs and a model that assumes that the rib cage and
abdomen may be approximated by elliptical cylinders. In 10 subjects of
widely varying body habitus, this method predicted lung volume change
accurately during quiet breathing (R greater than 0.98) and during vital
capacity maneuvers (R greater than 0.97). With this technique, we have
confirmed that the rib cage contributes the majority (74%) of the volume
change in the upright position. Additionally, we have shown that this
method is sufficiently accurate to be used as a method of monitoring
ventilation under a wide variety of tidal volumes, postures, and exercise
states.
