ADMINISTRATION OF ATROPINE AND ONSET OF NEUROMUSCULAR BLOCK PRODUCED BY ATRACURIUM IN INFANTS

In this prospective study we tested the hypothesis that atropine admin istration, which is known to increase heart rate and cardiac output in infants, will result in a faster onset of neuromuscular block with at racurium. Thirty infants scheduled for elective surgery had anaesthesi a induced with nitrous oxide and halothane. Fifteen patients were give n atropine and 15 patients acted as controls. Ail the infants were giv en atracurium 0.5mg.kg(-1), and neuromuscular block was recorded with the Datex 221 neuromuscular transmission monitor. Although atropine ca used an increase in heart rate compared to the control group (median 1 64 [range 151-182] vs 120 [98-160]min(-1) P<0.0001), there was not a s tatistically significant difference in the onset of neuromuscular bloc k between the two groups. We conclude that onset of neuromuscular bloc k after atracurium is determined mainly by noncirculatory factors and less by the circulation time to the muscle. The effect of atropine on the time course of neuromuscular block might be different with faster acting neuromuscular blockers.