TYK45

Which one of the following neuromuscular blocking agents (NMBA) can increase heart rates via vagolysis in children at normal intubation doses?

A. Rocuronium

B. Atracurium

C. Vecuronium

D. Cisatracurium

Answer

The answer is A. The vagolytic effects of NMBA are well known. This phenomenon is most well known and associated with pancuronium. However, at two times the ED95, increases in heart rate are seen with pancuronium and rocuronium in children. I seem to always see the heart rate rise when giving rocuronium. These agents seem to have less affect on the heart rate of infants. The ED95 of rocuronium is 0.31 mg/kg so a normal dose of 0.6 mg/kg is 2 times the ED95. Atracurium MAY cause an increase in heart rate, but this is via a histamine release (not vagolysis). It may also cause bronchospasm, flushing, hypotension, etc. associated with histamine release. Cisatracurium does not cause significant histamine release. Vecuronium does not cause histamine release or vagolysis. However, it is the biggest offender for IgE-mediated anaphylaxis among the NMBA. NMBA caused the largest number of reactions in a recent study for intraoperative anaphylaxis.

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