Carotid body chemoreceptor function is impaired by vecuronium during hypoxia

Background Neuromuscular blocking agents reduce the human ventilatory respo nse to hypoxia at partial neuromuscular block It was hypothesized that vecu ronium impairs carotid body chemoreceptor function during hypoxia, Method The effect of systemic administration of vecuronium on single chemor eceptor activity during hypoxia, as recorded from a single nerve fiber prep aration of the carotid sinus nerve, was studied in seven mechanically venti lated New Zealand White rabbits during continuous thiopental anesthesia. Du ring normoventilation, the isocapnic hypoxic chemosensitivity of the single carotid body chemoreceptor was measured at four levels of oxygenation; the se measurements were repeated at six separate occasions: control recording before injection, after intravenous administrations of 0.1 mg and 0.5 mg of vecuronium, and then at three occasions during a 90-mm recovery period. Ch emoreceptor chemosensitivity during isocapnic hypoxia was expressed as a hy perbolic function: Chemoreceptor output (Hz) = a + b x Pa-O2(-1) (mmHg). Results: Chemosensitivity was reduced after both 0.1 mg and 0.5 mg vecuroni um intravenous administration compared with control measurements; the hypox ic response curve was significantly depressed after both doses (P < 0.05), Notably, there was variation in the effect of vecuronium; some chemorecepto r preparations showed only minimal impairment, whereas some showed an almos t abolished response to hypoxia. The chemosensitivity remained significantl y depressed at 30 and 60 min but had recovered spontaneously at 90 min afte r 0.5 mg vecuronium, Discussion: It is concluded that vecuronium depresses carotid body chemorec eptor function to a varying extent during hypoxia and that the depression r ecovers spontaneously.