Reduction of hypoxic pulmonary vasoconstriction in the dog during administration of nitrous oxide.

The pulmonary vasoconstrictor response to alveolar hypoxia was assessed by measuring the redistribution of blood flow in response to the unilateral administration of nitrogen or nitrous oxide. The response was diminished when nitrous oxide was administered and returned to previous levels when hypoxia was produced again by nitrogen. It is postulated that depression of the hypoxic vasoconstrictor response by nitrous oxide may contribute to the increased alveolar-arterial Po2 difference during anaesthesia.