Central and pulmonary vascular engorgement is a characteristic feature of congestive heart failure. It has been suggested many times that this vascular engorgement might be responsible for certain phenomena associated with congestive failure, such as stiffening of the lungs, dyspnea, and orthopnea. However, the simultaneous occurrence of pulmonary edema and other changes has made it difficult to single out the effects of simple vascular engorgement.The present study was undertaken to investigate the pulmonary and circulatory effects of acute, reversible central and pulmonary vascular engorgement in normal man.Central and pulmonary vascular engorgement was produced by rapid application of pressure over the surface of the body. Two methods were used to accomplish this: inflation of an aviator's "G suit," and submersion in water while breathing against atmospheric pressure.The results indicate that vascular engorgement of the degree found in congestive heart failure can markedly stiffen the lungs. In addition, it was found that the production of acute central and pulmonary vascular engorgement in normal subjects by the present experimental means is quickly followed by changes which reduce the engorgement and which may represent an adaptive circulatory response. These changes could be modified by pre-treatment with drugs which alter vascular tone or by applying a painful stimulus. METHODS

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