Comparative haemodynamic effects of sevoflurane and halothane in infants at the intubation MAC

Objective: To compare the cardiovascular changes at the end-tidal concentrations of sevoflurane versus halothane required for tracheal intubation in infants (intubation MAC). Study design: Prospective randomized study. Patients: Thirty-two infants, ASA physical status 1 or 2, scheduled for elective surgery, randomized to receive either halothane or sevoflurane for anaesthetic induction by inhalation. Methods: Cardiovascular and echocardiographic data were recorded in both groups at baseline, and at the end-tidal concentrations needed for intubation. Results: Intubation MAC was significantly less with sevoflurane than with halothane in infants. Sevoflurane did not change heart rate (HR) and cardiac index (CI) compared to values when awake. Sevoflurane significantly decreased blood pressure, systemic vascular resistance (SVR) and shortening fraction (SF). Myocardial contractility assessed by stress-velocity index (SVI) and stress-shortening index (SSI) decreased significantly at the intubation MAC, but did not fall into the abnormal range. Halothane caused a greater decrease in HR, SF, SSI, and CI than sevoflurane. Conclusions: Sevoflurane decreases cardiac output less than halothane in infants at the intubation MAC, due to a lower end-tidal concentration at intubation MAC and to less effects on haemodynamic variables. (C) 1998 Elsevier, Paris.