The effect of peripheral hypothermia on a vecuronium-induced neuromuscular block.
Seven healthy patients were investigated during midazolam-fentanyl nitrous oxide-oxygen anaesthesia. The mechanical twitch response of the adductor pollicis muscle was recorded simultaneously during bilateral supramaximal train-of-four (TOF) stimulation of the ulnar nerves at the wrist. Intense neuromuscular block was evaluated using the post-tetanic count (PTC) method. Core temperature and the peripheral skin temperature of one arm were kept normal and stable. Following cooling of the other arm to a peripheral hand skin temperature of 27 degrees C, vecuronium was administered in a bolus dose of 0.05 mg.kg-1 followed by maintenance doses of 0.02 mg.kg-1. In the hypothermic and the normothermic arm the onset time following the bolus dose was 180 +/- 40 (mean +/- s.d.) seconds and 140 +/- 30 s, respectively, the duration of action was 26.4 +/- 4.5 and 16.5 +/- 4.0 min and the recovery time was 265 +/- 90 and 130 +/- 60 s (P less than 0.01). The time course of action following maintenance doses showed a similar marked difference between the hypothermic and the normothermic arm. In the normothermic arm a close correlation was found between the number of post-tetanic twitches and the time to first response to TOF stimulation. In contrast, in the hypothermic arm the number of post-tetanic twitches showed great variation with a poor correlation to the duration of intense neuromuscular block. It is concluded that the time course of action of a vecuronium-induced neuromuscular block is markedly prolonged during peripheral hypothermia and intense neuromuscular block cannot reliably be assessed using the PTC method at low peripheral temperature.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Anaesthesia and Intensive Care, Faculty of Health Sciences, University Hospital, Linköping, Sweden.
L I
LI
Eriksson
J
J
Viby-Mogensen
C
C
Lennmarken
D000769:Anesthesia, Inhalation; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000601:surgery; D009469:Neuromuscular Junction / Q000187:drug effects*; D009609:Nitrous Oxide; D010100:Oxygen; D014673:Vecuronium Bromide / Q000494:pharmacology*
D014673:Vecuronium Bromide; D009609:Nitrous Oxide; D010100:Oxygen