Preservation of the Pulmonary Vasoconstrictor Response to Alveolar Hypoxia During Theadministration of Halothane to Dogs

Abstract

The action of halothane on the pulmonary vasoconstrictor response to unilateral alveolar hypoxia was studied in two groups of dogs. In the first group the redistribution of blood flow between the two lungs was studied with a radioactive isotope method, which provided intermittent measurements, whilst in the second group the distribution of blood flow was observed continuously. In both groups there was no significant alteration of the hypoxic vasoconstrictor response with inspired halothane concentrations varying from 0.5 to 1.5%.

One‐Lung Versus Two‐Lung Ventilation in the Closed‐Chest Anesthetized Dog: A Comparison of Cardiopulmonary Parameters

“…It must be noted, however, that the HPV response is attenuated by a number of factors. Inhalant anesthetic agents will variably decrease the response in a dose‐dependent manner 18–20 . Marshall et al observed partial inhibition of the response at a concentration of 0.57% halothane, 21 though one study reported no decrease at 1.5% halothane 19 .…”

Sevoflurane has no inhibitory effect on hypoxic pulmonary vasoconstriction (HPV) in dogs

“…Sykes et a1. 10 reported the pulmonary vasoconstrictor response to alveolar hypoxia was preserved during the administration of halothane to in vivo-intact dogs. Saidman et al, 11 reported isoflurane did not inhibit hypoxic pulmonary vasoconstriction in vivo-intact dogs.…”

Preservation of the Hypoxic Pulmonary Vasoconstrictor Mechanism During Methoxyflurane Anaesthesia in the Dog

“…Ventilation of all lung lobes was confirmed by measuring Pa 02 when both lungs were ventilated with 100% oxygen and by examining the ventilation of each lobe at autopsy. After the tracheal divider had been positioned correctly the non-rebreathing valves were connected to separate second-stage ventilator circuits which permitted unilateral control of the inspired gas composition (see Sykes et al, 1978, fig. 1).…”

“…Previous work utilizing both isolated perfused cat lungs and intact dog preparations has demonstrated that a number of inhalation anaesthetic agents depress the pulmonary vasoconstrictor response to alveolar hypoxia (Sykes et al, 1973(Sykes et al, , 1975(Sykes et al, , 1976(Sykes et al, , 1978Sykes, Hurtig et al, 1977a, b). On the basis of these experiments it has been postulated that depression of the hypoxic vasoconstrictor mechanism may increase blood flow to underventilated areas of the lung, thus contributing to a decrease in arterial oxygen tension during anaesthesia.…”

“…The purpose of the present experiments was to determine whether clinical concentrations of methoxyflurane would depress the hypoxic pulmonary vasoconstrictor mechanism in intact dogs. The activity of this mechanism was assessed by measuring the redistribution of pulmonary blood flow in response to two levels of unilateral alveolar hypoxia, the partition of pulmonary blood flow between the two lungs being recorded continuously throughout the experiment by measuring the radioactivity of the mixed expired gas from each lung whilst xenon-133 solution was infused continuously into the inferior vena cava (Sykes et al, 1977).…”