Site of Selective Action of Halothane on the Peripheral Chemoreflex Pathway in Humans
Open Access
- 1 August 1984
- journal article
- research article
- Published by Wolters Kluwer Health in Anesthesiology
- Vol. 61 (2) , 121-126
- https://doi.org/10.1097/00000542-198408000-00002
Abstract
Halothane in humans depresses the ventilatory response to hypoxemia in a manner that suggests a selective action on one or more components of the peripheral chemoreflex arc. To test the hypothesis that this action is at the carotid bodies themselves, the ventilatory response to subanesthetic concentrations of halothane (0.15-0.30% inspired) was studied in 6 fit volunteers maintained in a steady state of isocapnic hypoxemia (PEO2 [opercular O2 tension] 50 mm Hg). Upon exposure to halothane, hypoxemia-driven ventilation decreased promptly and progressively (from 7.5 .+-. 1.2 l/min per m2 in the control state to 5.9 .+-. 0.9 and 4.8 .+-. 0.7 l/min per m2 at 30 s and 60 s of inhalation respectively, means). The relationship of hypoxemia-driven ventilation to end-tidal halothane tensions at 30 and 60 s of halothane wash-in (PEHal 0.4 and 0.6 mm Hg, respectively) approached the relationship observed in near steady-states of halothane inhalation. Evidently, the site of selective action is at a tissue that accumulates halothane very rapidly during the 1st min of inhalation. To make possible such pharmacokinetics, that tissue would require a location having a brief circulatory transit time from the lungs, and an extremely high rate of perfusion in relation to its capacity for uptake of halothane. The only tissue of the peripheral chemoreflex pathway that can satisfy these requirements is that of the carotid bodies.This publication has 1 reference indexed in Scilit:
- Ventilatory response of decorticate and decerebrate cats to hypoxia and CO2Respiration Physiology, 1977