Journal of Applied Physiology, Vol 52, Issue 1 267-273, Copyright © 1982 by American Physiological Society
Critical assessment of jacket plethysmographs for use in young children
P. Helms, B. W. Taylor, A. D. Milner and D. J. Hatch
In infants and very young children changes in thoracic gas volume (Vtg)
during tidal breathing and during intermittent positive-pressure lung
inflations have been estimated from pressure changes within double-layered
rubber jackets covering the thorax and abdomen. In vitro and in vivo
assessments demonstrated the linearity of these jackets over the range of
volume changes found in these young subjects during respiratory function
tests, and the small intrajacket background pressure (2.5 cmH2O) had
minimal effects on resting lung volume and lung mechanics. These jackets
can be used to monitor tidal volume in quiet subjects, and if an
intermittent positive-pressure inflation technique is used static
compliance can be accurately measured. The hysteresis of natural rubber and
the direct contact of the recording system with the subject renders it
unsuitable for the measurement of lung mechanics during tidal breathing and
for the estimation of Vtg during airway occlusions.
