Acta physiologica Scandinavica. Supplementum
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Acta Physiol Scand Suppl · Jan 1994
Comparative Study Clinical TrialCardiovascular and pulmonary responses to breath-hold diving in humans.
Cardiovascular and pulmonary responses to breath-hold diving (breath holding, submersion, and compression) were investigated. In addition, the effects of transitions between dry conditions and head-out immersion during eupnea were studied. Surface breath holds at a large lung volume with relaxed respiratory muscles resulted in a positive esophageal (transthoracic) pressure and a reduced cardiac output. ⋯ Changes in the intrathoracic pressure and in the distribution of venous blood volume induce changes in cardiac output. All of these changes affect the temporal and spatial distributions of pulmonary perfusion and peripheral blood flow. Also, the circulatory changes affect the temporal and spatial distributions of alveolar gas exchange and of tissue gas stores of the body.