A SIMPLE METHOD FOR ASSESSING THE VALIDITY OF THE ESOPHAGEAL BALLOON TECHNIQUE

Abstract

The validity of the conventional esophageal balloon technique as a measure of pleural pressure was tested in 10 [human] subjects in the sitting, supine and lateral positions by occluding the airways at end-expiration and measuring the ratio of changes in esophageal (.DELTA.Pes) and mouth pressure (.DELTA.Pm) during the ensuing spontaneous occluded inspiratory efforts. Similar measurements were also made during static Mueller maneuvers. In both tests, .DELTA.Pes/.DELTA.Pm values were close to unity in sitting and lateral positions; in the supine position, substantial deviations from unity were found in some instances. By repositioning the balloon to different levels in the esophagus, a locus could always be found where the .DELTA.Pes/.DELTA.Pm ratio was close to unity. No appreciable phase difference between .DELTA.Pes and .DELTA.Pm was found. By positioning the balloon according to the occlusion test procedure, valid measurements of pleural pressure can be obtained in all the tested body positions.