Carotid body chemoreceptor function is impaired by vecuronium during hypoxia.
BACKGROUND
Neuromuscular blocking agents reduce the human ventilatory response to hypoxia at partial neuromuscular block. It was hypothesized that vecuronium impairs carotid body chemoreceptor function during hypoxia.


METHODS
The effect of systemic administration of vecuronium on single chemoreceptor activity during hypoxia, as recorded from a single nerve fiber preparation of the carotid sinus nerve, was studied in seven mechanically ventilated New Zealand White rabbits during continuous thiopental anesthesia. During normoventilation, the isocapnic hypoxic chemosensitivity of the single carotid body chemoreceptor was measured at four levels of oxygenation; these 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-min recovery period. Chemoreceptor chemosensitivity during isocapnic hypoxia was expressed as a hyperbolic function: Chemoreceptor output (Hz) = a + b x PaO2(-1) (mmHg).


RESULTS
Chemosensitivity was reduced after both 0.1 mg and 0.5 mg vecuronium intravenous administration compared with control measurements; the hypoxic response curve was significantly depressed after both doses (P < 0.05). Notably, there was variation in the effect of vecuronium; some chemoreceptor preparations showed only minimal impairment, whereas some showed an almost abolished response to hypoxia. The chemosensitivity remained significantly depressed at 30 and 60 min but had recovered spontaneously at 90 min after 0.5 mg vecuronium.


CONCLUSIONS
It is concluded that vecuronium depresses carotid body chemoreceptor function to a varying extent during hypoxia and that the depression recovers spontaneously.
Wyon
N
N
Department of Anesthesiology and Intensive Care, Karolinska Hospital and Institute, Stockholm, Sweden.
Joensen
H
H
Yamamoto
Y
Y
Lindahl
S G
SG
Eriksson
L I
LI
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000758:Anesthesia; D000818:Animals; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000378:metabolism; D002344:Carotid Body / Q000187:drug effects*; D002628:Chemoreceptor Cells / Q000187:drug effects*; D000860:Hypoxia / Q000503:physiopathology*; D009412:Nerve Fibers / Q000187:drug effects; D009466:Neuromuscular Blocking Agents / Q000494:pharmacology*; D009475:Neurons, Afferent / Q000187:drug effects; D011817:Rabbits; D014673:Vecuronium Bromide / Q000494:pharmacology*
D009466:Neuromuscular Blocking Agents; D002245:Carbon Dioxide; D014673:Vecuronium Bromide