JAW RELAXATION AFTER A HALOTHANE SUCCINYLCHODINE SEQUENCE IN CHILDREN

Background: Lack of complete jaw relaxation after a halothane-succinyl choline sequence has been described in the literature. To date, howeve r, most existing studies are retrospective, and lack agreement on the magnitude and incidence of this phenomenon. This prospective study exa mined the incidence and degree of incomplete jaw relaxation in 500 chi ldren who were given intravenous succinylcholine during halothane anes thesia. Methods: Five hundred consecutive unmedicated children receive d a minimum dose of 2 mg/kg intravenous succinylcholine after inductio n of anesthesia with halothane. The degree of jaw relaxation was asses sed 45-60 s later by the same observer using a standardized clinical s cale. The degree of relaxation was correlated with the type of surgica l procedure, and the presence and intensity of fasciculations. Results : Complete relaxation (mouth opened easily and fully) occurred in 95.4 % of study patients. Incomplete relaxation (firm manual separation req uired to open the mouth fully) was seen in 4.4% of the patients. One c hild (0.2%) had masseter muscle rigidity (mouth could not be fully ope ned but intubation possible). There were no incidents of trismus (teet h clamped shut and intubation via direct visualization impossible). Th e incidence of incomplete relaxation and masseter muscle rigidity did not correlate with the presence or degree of fasciculations or the typ e of surgical procedure. There were no clinical signs of a hypermetabo lic state or myoglobinuria in any patient. Conclusions: Incomplete jaw relaxation after a halothane-succinylcholine sequence is not uncommon in children, and is considered a normal response.