Effect of continuous pressure breathing on right ventricular volumes

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Abstract
We measured the end-diastolic volume (EDV) and stroke volume (SV) in the right ventricle of anesthetized dogs during continuous pressure breathing and compared them to measurements taken during breathing at atmospheric pressure. During intratracheal positive-pressure breathing, EDV, and SV decreased and end-diastolic pressure became more positive relative to atmospheric pressure. During intratracheal negative-pressure breathing, EDV enlarged and SV tended to increase; end-diastolic pressure became more negative. During extrathoracic negative-pressure breathing SV decreased, EDV fell, though not significantly, and end-diastolic pressure rose, but insignificantly. Changes in EDV observed during intratracheal positive-pressure breathing and intratracheal negative-pressure breathing were associated with minor shifts in transmural pressure (end-diastolic pressure minus intrapleural pressure) in the expected directions, but during extrathoracic negative-pressure breathing a large increase in transmural pressure took place with the nonsignificant reduction in EDV. We believe that intrathoracic pressure influences right ventricular filling by changing the peripheral-to-central venous pressure gradient. The cause of the alteration in diastolic ventricular distensibility demonstrated during extra-thoracic negative-pressure breathing remains unexplained. positive-pressure breathing; negative-pressure breathing; extrathoracic negative-pressure breathing Submitted on August 16, 1966