Experimental Studies on Assisted Circulation in Acute Hypoxic State

Respiratory insufficiency arises from various causes. Treatment by mechanical ventilators is not always effective for it. When it arises, long term artificial pulmonary substitution is thought to be a reasonable approach to provide better results. However the best method for improving survival rate has not estadlished vet. Author studied hemodynamics in acute hypoxic state upon dogs weighing 9kg to 12kg. Secondary the hemodynamic effects and gas change capabilities of three methods of extracorporeal respiratory support which were venovenous, venoarterial and arteriovenous perfusion was studied in this state. In acute hypoxic state (PaO(2); 20-25mmHg), both left and right heart pressure rose and cardiac output increased at first which was called hypercirculatory state. Secondary, left heart pressure went down and cardiac output was decreased. However right heart pressure stayed high. Then the right heart peessure becawe low and the dogs died finally in average 63 minutes. Hypercirculatory state was early seen on venovenous and arteriovenous perfusion, and PaO(2) did not rise satisfactorily. On the other hand, hypercirculatory state was not seen on venoarterial perfusion, and PaO(2) rose satisfactory. Author concluded venoarterial perfusion was the best method for respiratory insufficiency cases which was not improved by mechanical ventilation.