INTRAMUSCULAR ATROPINE SULFATE IN CHILDREN - COMPARISON OF INJECTION SITES

In children undergoing inhaled induction of anesthesia with halothane who suffer bradycardia, submental glossal injection of atropine may re sult in more rapid onset of vagolysis than traditional intramuscular s ites. We compared the intervals between injection and onset of heart r ate acceleration (t(HR) up arrow) after intramuscular injection of atr opine into the deltoid, vastus lateralis, and glossa in children betwe en 1 mo and 10 yr of age scheduled for elective surgery. The t(HR) up arrow after intramuscular injection of atropine into the deltoid, vast us lateralis, and glossa in children between 1 mo and 10 yr of age sch eduled for elective surgery. The t(HR) up arrow was determined by meas uring the interval between atropine injection and the time point at wh ich the slope of the heart rate curve initially became positive. To en sure that the drug had taken effect before surgical stimulation, heart rate observation was continued until it increased at least 5% above b aseline with evidence of continuing acceleration. Anesthesia was induc ed in all subjects by mask with nitrous oxide and halothane. After tra cheal intubation, constant inspired concentrations of the anesthetics were administered for 3 min. While heart rate was monitored, atropine (0.02 mg/kg) was injected into one of the three sites. Each patient's end-tidal anesthetic concentrations were recorded, and minimum alveola r anesthetic concentrations (MAC) were subsequently calculated and adj usted for age. The t(HR) up arrow was recorded and averaged for each g roup. The study groups did not differ by age, weight, end-tidal anesth etic concentrations, age-adjusted MAC, or heart rate at the time atrop ine was administered. After submental glossal injection (n = 11), t(HR ) up arrow increase was fastest (3.0 +/- 1.1 min) and was significantl y faster than that found with deltoid injection (n = 16; 4.4 +/- 1.1 m in) or vastus lateralis injection (n = 8; 6.4 +/- 2.4 min) (P < 0.05 c ompared with both). The t(HR) up arrow also differed significantly bet ween the deltoid and the vastus lateralis (P < 0.05). We conclude that submental glossal injection of atropine results in a more rapid onset of vagolysis than injection at traditional intramuscular sites.