title: A simple method for evaluation of the uptake of isoflurane and its comparison with the square root of time model.
abstract: BACKGROUND
  The square root of time (SqRT) model had been used to predict the uptake of volatile agents.
  
  
  METHODS
  We studied the rate of uptake of isoflurane in 10 patients using liquid isoflurane infusion through syringe pump into the closed circuit. The infusion rates were titrated to maintain a constant end tidal concentration of isoflurane of 1.5%. The predicted uptake values were also calculated from the square root principle and compared with the derived uptake.
  
  
  RESULTS
  The observed rate of uptake was higher than predicted from the Lowe and Ernst equation (P<0.001). There exists considerable inter-individual variability in uptake pharmacokinetics and it showed statistically significant correlation with ideal body weight, body weight (P<0.01), body surface area, and body weight¾ from 30 min of start of isoflurane infusion (P<0.05).
  
  
  CONCLUSIONS
  SqRT model is inaccurate in predicting isoflurane uptake and underestimates it during closed circuit anaesthesia.
authors: Department of Anaesthesiology and Pain Medicine, Fellow Liver Transplant Anaesthesia, Asan Medical Centre, Seoul, Korea.
authors: Ashish
authors: A
authors: Bangaari
authors: Nidhi Bidyut
authors: NB
authors: Panda
authors: Goverdhan Dutt
authors: GD
authors: Puri
keywords: Anaesthetics; equipment; isoflurane; pharmacokinetic; volatile
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