Design of a body plethysmograph for studying cardiopulmonary physiology

Abstract

A body plethysmograph may be used for the measurement in man of thoracic gas volume, airway resistance, instantaneous pulmonary capillary flow and abdominal gas volume; if functional residual capacity (dilution method) and pulmonary resistance (esophageal balloon technique) are measured concomitantly, calculations of ‘trapped’ gas (in the lungs or pleural cavity) and of pulmonary tissue resistance may also be made. The design of the plethysmograph, the electrical circuits and recording devices used and the direct reading attachments for the cathode ray oscillograph are presented together with details of operation and some suggestions for modifications of the original design. Submitted on July 14, 1958