Induced hypercapnia in experimental hemorrhagic shock.

The inhalation effect of a 90% oxygen and 10% carbon dioxide mixture was compared with pure oxygen inhalation in the treatment of rabbits, bled to a mean arterial pressure of 25 mmHg. A pronounced respiratory acidosis developed in the O-2-CO-2-treated rabbits. Both groups showed similar changes in the blood concentration of lactate and the base deficit values. In the rabbits inhaling O-2-CO-2, the PvO-2 was significantly higher than in those treated with oxygen. All the relationships were recorded independent of the time of onset of the inhalation treatment regardless of whether it was commenced before or after the bleeding. Our conclusion is that, in spite of the apparent increase in the shunting of oxygenated blood to the venous circulation, the perfusion through the capillaries is unaffected by the carbon dioxide inhaled in hemorrhagic shock.