Similar haemodynamic, respiratory and metabolic changes with the use of sevoflurane or halothane in children breathing spontaneously via a laryngeal mask airway

Background: In preschool children, short-lasting surgical procedures are of ten performed under combined inhalational and regional anaesthesia with the child breathing spontaneously via a laryngeal mask airway (LMA). Despite w idespread use, only limited data are available on haemodynamic, respiratory and metabolic effects of sevoflurane and halothane during LMA anaesthesia. Methods: In an open-label, randomised, controlled study, 49 children (aged 3-8 years) were allocated to receive either sevoflurane or halothane in 60% nitrous oxide. After insertion of the LMA, end-tidal concentrations of sev oflurane or halothane were maintained at 1 MAC with the child ventilating s pontaneously throughout the entire procedure. Analgesia was provided by cau dal block. Haemodynamic and respiratory parameters were recorded, and capil lary blood-gas samples were obtained repeatedly. Results: Changes in heart rate (HR) and systolic blood pressure were simila r in both groups during all observed periods, apart from a significantly hi gher increase in HR during inhalational induction with sevoflurane (P <0.05 ). Regression slope analysis during anaesthesia revealed a decrease of the respiratory rate of 5 breaths h(-1) (P <0.001) and an increase of end-tidal PCO2 and capillary PCO2 of about 0.25 kPa h(-1) (P <0.001), with no signif icant difference between the two groups. Base excess, calculated in capilla ry blood gas samples, did not change over time (P >0.5) in either group. Conclusions: The use of approximately 1 MAC sevoflurane or halothane in 60% N2O in children breathing spontaneously via LMA resulted in comparable hae modynamic, respiratory and metabolic changes, and clinically relevant deter iorations did not occur during the 65-min study period.