Discrepancy between manual charting and measured inspired concentration of inhalational anesthetic

In this study, an attempt was made to assess the relationship between manually charted isoflurane vaporizer concentration and the measured inspired agent concentration. Using an IRB-approved protocol, computerized anesthesia records were reviewed retrospectively. Isoflurane was identified as the inhaled agent, and the vaporizer settings were entered in the computerized record manually. The inspired volatile agent concentration (VAC) was recorded automatically. The data were subdivided according to magnitude of inspired VAC and analyzed using ANOVA and multiple contrasts. The results indicate that manual recording of vaporizer settings do not accurately reflect inspired VAC of isoflurane.