Hemodynamic changes following the administration of propofol to facilitate endotracheal intubation during sevoflurane anesthesia

Background: The common intravenous anesthetic agent, propofol, is frequently reported to have negative inotropic and chronotropic effects. In the pediatric population, propofol is commonly used after inhalation induction to facilitate endotracheal intubation without the need for a neuromuscular blocking drug agent. In this setting, we have noted that propofol administration is commonly followed by tachycardia. The current study prospective evaluates heart rate and blood pressure changes following the administration of propofol to pediatric patients anesthetized with nitrous oxide (N2O) and sevoflurane. Methods: ASA class 1 and 2 pediatric surgical patients were enrolled in the study. After premedication with midazolam and inhalation induction with N2O in oxygen and sevoflurane, a bolus dose of propofol was administered to facilitate endotracheal intubation. Heart rate (HR) was measured at baseline and at 30 second intervals following propofol administration. Blood pressure (MAP) was measured at baseline and 120 seconds post-administration. Results: The study cohort consisted of 40 patients who ranged in age from 1 to 15 years. After inhalation induction, propofol (average dose of 2.6 mg/kg) was administered. The end-tidal N2O and sevoflurane concentrations were 62.2 +/- 10.3% and 5.7 +/- 1.1% respectively. Nineteen of 40 patients had a HR increase >10 bpm. When comparing these patients to those who did not experience a HR increase >10 bpm, there were no differences in the demographic data. Those with a HR increase received a greater dose of propofol when compared to patients whose HR change was <10 bpm (3.0 +/- 0.8 versus 2.2 +/- 0.5 mg/kg; p=0.0007). There was a significantly greater decreased in the MAP at 120 seconds following propofol administration in the group that did not sustain a >10 bpm HR increase. Conclusion: Tachycardia following propofol administration occurs in approximately 50% of pediatric patients despite preceding inhalation induction and concurrent administration of N2O and sevoflurane. Future studies are needed to define the mechanism for this effect.