Utility of the Perfusion Index as an Indicator of Anesthetic Depth during Total Intravenous Anesthesia in...

Anesthetics influence sympathetic tone, a key determinant of anesthetic depth. This study aimed to evaluate whether the perfusion index (Pi), reflecting propofol-mediated sympathetic modulation, can serve as a continuous real-time indicator of anesthetic depth during propofol-based total intravenous anesthesia (TIVA) requiring intraoperative neuromonitoring (IOM) in neurosurgery.

This single center, prospective observational study included patients scheduled for anterior cervical decompression and fusion under propofol-based TIVA with IOM. Patients were eligible for inclusion (anterior cervical decompression and fusion) if they were aged 40-75 years and classified as American Society of Anesthesiologists physical status 1 or 2. At designated time intervals, from preinduction to extubation, the Bispectral index (BIS), a marker of anesthetic depth, alongside finger and ear perfusion indices (FPi and EPi) was assessed to examine correlations between these variables. The primary outcome was to find correlation between FPi and BIS.

Thirty participants were enrolled in this study. FPi and BIS showed significant correlation (correlation coefficient, -0.629; 95% confidence interval, -0.696 to -0.551; p<0.001), while EPi showed no significant correlation with BIS (correlation coefficient, 0.078; 95% confidence interval, -0.042 to 0.196; p=0.202).

FPi monitoring may serve as a complementary technique for evaluating anesthetic depth during propofol-based TIVA requiring IOM in neurosurgery, as indicated by its correlation with BIS.