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)
Eriksson
L I
LI
Department of Anaesthesia and Intensive Care, Faculty of Health Sciences, University Hospital, Linköping, Sweden.
Viby-Mogensen
J
J
Lennmarken
C
C
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