On the Changes in the Minute Volume and the Stroke Volume of the Heart following the Respiration of Compressed Air
Tohoku journal of experimental medicine
Various changes in organisms provoked by the respiration of com pressed air have already been investigated by some experimentators. In the course of an experiment with the respiration of compressed air, Sommer brodt1) observed a decrease of blood pressure, and attributed this phenomenon to the les sening of the volume of blood in the arterial system, on account of the disturbance in cir culation from the venous system to the arterial side which was aroused by the compression of capillaries in
... of capillaries in the lungs due to the elevated gas pressure. Tiegel2) has found that dur ing exposure at an excessive pressure the blood pressure in the endothoracic veins is elevated, a stasis takes place in the peripheral veins and the blood-flow into the endothoraeic veins is disturbed, in consequence of the excessive pressure in the thoracic cavity. On observing also that the blood pressure is augmented in the puhnonal arteries, he attributed this occurrence to the extensive resistance in the blood-flow, which is induced by the compression of the lung capillaries due to the high pressure in the alveoli. Recently, Huggett3) investigated the heart output during respiratory obstruction. He used urethanised cats for the experiments. The obstruction used was threefold namely, simple inspiratory, simple expiratory and combined inspiratory and expiratory ob struction. Into the trachea a cannula of Y-shape was inserted, one limb of which was con nected by wide rubber tubing to a wash-bottle containing water so that the air which was to be breathed in passed through the bottle. The pressure was regulated by the depth of the inflow tube below the water. A similar but reversed bottle gave the expiratory resist ance. In the ca e of an inspiratory obstruction of 5cm. of water, the animal would have to lower the pressure inside the bottle to 5cm. below the atmospheric pressure by expanding the chest, in order that air might pass down the entry tube of the bottle. Similarly, in the revered (expiratory) bottle the animal would have to create positive pressure in order to drive the air out, thus giving rise to a forced expiration. Under such conditions the mi 1) Sommerhrodt, cited by Full and Friedrich.