The carbon dioxide and oxygen content of the blood after ligation of the abdominal aorta and the inferior vena cava

Abstract

Respiration experiments on normal and depancreatized anaesthetized animals after ligation of the abdominal aorta and the inferior vena cava 1 and on normal animals after exclusion of the liver by joining the portal vein to the inferior vena cava 2 show an increase in the respiratory quotient, which is interpreted by the v. Noorden school to demonstrate the combustion of sugar in the depancreatized animal and the dependence of the normal animal upon the liver for its ability to burn protein and fat. These experiments, however, were not accompanied by analyses of the blood gases. It is possible that the higher respiratory quotient after shortening of the circulating stream might be due to an interference with the oxygen absorption (passive congestion of the lungs) or to increased elimination of carbon dioxide by more rapid circulation of the blood through the lungs.

Preliminary to some respiration experiments on depancreatized dogs in which we are seeking the explanation of the altered respiratory quotient, we have made a number of experiments on normal dogs analyzing the carotid blood before and after simultaneous clamping of the abdominal aorta and the inferior vena cava. The results follow:

Chloretone anaesthesia was used. In the case of the last dog which eliminated about 80 C.C. of CO₂ per minute, it may be estimated that a reduction from 57 to 34 per cent. would remove from the body in the course of one hour, about 800 C.C. of CO₂ or enough to raise the R. Q. from 0.75 to 0.88. It cannot be assumed as Porges has done that the blood gases, under the circumstances, would reach an equilibrium within 10-15 minutes, for with the circulation diminished to one half and the heart beating at its normal rate, or higher, the blood would pour through the lungs twice as often and would continue to lose carbon dioxide until the tension in all the tissues became very much reduced.