Pulse perfusion values to predict eye opening after intravenous anesthesia : An explorative study

Variables measured in modern pulse oximetry apparatuses include a graphic pulse curve and a specified perfusion value (PV) that could be a sensitive marker for detecting differences in sympathetic activity. We hypothesized that there is a correlation between a reduction of PV and the time to eye opening after anesthesia with propofol-remifentanil. This study includes 29 patients, ASA physical status 1 or 2, scheduled for elective thyroid surgery. Main outcome measures were PV measured by pulse oximetry, heart rate, and noninvasive mean arterial blood pressure recorded before anesthesia, 15 minutes after induction, and at start of surgery, end of surgery, and eye opening at the end of anesthesia. Carbon dioxide (PETCO2) and oxygen inspiratory (FI-PO2) and expiratory (FE-PO2) concentrations were measured at all times except before anesthesia. Results demonstrated that PVs before anesthesia and at eye opening were lower than 15 minutes after induction and at end of surgery (P <.05). The PETCO2 and difference of FI-PETO2 increased at eye opening compared with the end of surgery (P <.05). We conclude that the pulse oximetry PV and the increased PETCO2 could be useful variables to predict timing of recovery in terms of eye opening after intravenous anesthesia