title: Estimates of ventilation from body surface measurements in unrestrained subjects.
abstract: To make estimates of ventilation from measurements of body surface movements in unrestrained subjects, we measured changes in linear dimensions and cross-sectional areas of the rib cage (RC) and abdomen (AB) of six healthy unrestrained subjects during a variety of maneuvers. RC and AB anteroposterior diameters and abdominal length in the cephalocaudal axis (axial displacement) were measured with magnetometers, and RC and AB cross-sectional areas were measured with a respiratory inductance plethysmograph. Flow was measured at the mouth with a pneumotachograph and integrated electrically to give volume. Volume and body surface measurements were analyzed by multiple linear regression. Addition of the axial measurements to either the anteroposterior dimensions or cross-sectional areas of RC and AB improved estimates of tidal volume in all subjects (P less than 0.01). With measurements of axial displacement and cross-sectional area of the RC and AB, tidal volume could be reliably estimated to within 20% of actual ventilation. We conclude that measurement of axial displacements improves estimates of ventilation in unrestrained subjects.
mesh_terms: D000005:Abdomen; D000328:Adult; D001830:Body Surface Area; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009068:Movement; D011187:Posture; D012119:Respiration; D013909:Thorax; D013990:Tidal Volume