Sevoflurane EC50 for intravenous cannulation attempt and movement in children

BACKGROUND: Intravenous cannulation at lighter planes of anaesthesia can lead to adverse respiratory and haemodynamic events. So far, there is no consensus on optimum end tidal sevoflurane concentration required for intravenous cannulation in children. We aimed to evaluate the optimum end tidal concentration at which an intravenous cannulation can be successfully attempted without movements in paediatric patients after inhalational induction of general anaesthesia. MATERIAL AND METHODS: In this clinical trial, paediatric subjects of either sex aged 1-3 years, weighing 7-15 kg having American Society of Anaesthesiologists physical status I/II of undergoing elective cataract surgery were included. After inhalational induction of general anaesthesia with 8% sevoflurane and 100% oxygen, end tidal sevoflurane concentration was maintained at 2% for 4 minutes for the first child. This was followed by intravenous cannulation attempted by an experienced anesthesiologist. The intravenous cannulation was considered to be unsuccessful if there was "movement" and successful if there was "no movement" in response to the stimuli of cannulation. End-tidal concentration was increased/decreased (step-size 0.2% for sevoflurane) using Dixon and Massey up and down method in the next patient depending upon previous patient's response. RESULTS: The sevoflurane EC50 for successful intravenous cannulation is 1.32% ± 1.0%. Pearson correlation (r) between weight of the child and response to intravenous cannulation was found to be 0.40 with P value of 0.008. CONCLUSION: Intravenous cannulation can be accomplished without movements at end tidal sevoflurane of 1.3% in children aged 1-3 years in 50% of children.