A Novel Method for Determining the Blood/Gas Partition Coefficients of Inhalation Anesthetics to Calculate the Percentage of Loss at Different Temperatures

The loss by blood/gas (lambda) partition of inhalation anesthetics can be estimated by an equation for the percentage of loss. However, because lambdas of inhalation anesthetics at different temperatures have not been fully determined so far, the percentage of loss at varying temperature in various headspace volumes cannot be estimated. Therefore, a novel method was developed for the determination of inhalation anesthetic lambda, in this study. The method was precise, with a relative standard deviation of less than 5%. The average of lambda from seven distinct blood samples at 4 degrees C, 25 degrees C, and 37 degrees C were determined as 6.68, 2.04, and 1.32 of isoflurane; 3.47, 1.10, and 0.65 of sevoflurane; and 2.31, 0.75, and 0.46 of desflurane, respectively. In addition, increasing temperature was found to decrease lambda profoundly by a secondary order mechanism. Using the obtained value of lambda, the percentage of loss of isoflurane, sevoflurane, and desflurane were then predicted using a 5-mL vacuum tube as a collecting container for an example. In conclusion, a novel method was developed here for lambda determination, and lambdas of isoflurane, sevoflurane, and desflurane at various temperatures were given for estimating the loss resulting from liquid/gas partitioning.