Time factor in the shifting of blood produced by unilateral hypoxia.

Abstract

Using the radioactive particle distribution technique (1), it was recently demonstrated that unilateral hypoxia produced in man by ventilating one lung with 100 per cent nitrogen for a period of seven minutes resulted in a striking decrease in pulmonary arterial blood flow to the hypoxic lung. The results confirmed those of others who used different techniques (2-4) and added further data to support the concept of Liljestrand (5) that the partial pressure of respiratory gases in the alveoli and in the capillary blood regulated the vascular resistance in such a manner that an optimal relationship was maintained between ventilation and perfusion. The present experiments were designed to determine whether a shorter period of hypoxiatwo minutes rather than seven minutes-would be an adequate stimulus for the shifting of blood flow away from the hypoxic lung. In addition, the effect of atropine in pharmacologic dosages on the hypoxic redistribution of blood flow was studied, as Halmagyi (6) has shown that atropine administered by aerosol abolished this response in sheep.