Intraoperative analgesic requirement using surgical plethysmographic index guidance in lumbar spine surgeries: A comparative study

Context: The surgical plethysmographic index (SPI) has been introduced as a measure of the balance between nociception and anti-nociception. The SPI is proposed for the titration of intraoperative analgesic drugs during general anesthesia. Aims: This study aimed to compare the requirement of intraoperative analgesic consumption between SPI-guided analgesia and conventional analgesia practices, requirement of rescue analgesics and to study recovery time. Subjects and Methods: In this double-blind, randomized control study, 64 patients undergoing lumbar spine surgery were randomly divided into SPI-guided analgesia group (SPI) and conventional practice group (control). In the SPI group, patients received injection fentanyl bolus of 0.5 μg/kg whenever SPI value increased above 50. While in the conventional group, injection fentanyl 0.5 μg/kg was administered according to conventional clinical practice. Statistical Analysis Used: The statistical significance of difference of various categorical variables across two groups was tested using the Chi-square test. For assessing intergroup statistical significance of difference of various continuous measurements, independent sample t-test was used. Results: Intraoperative fentanyl requirement was 119.53 ± 16.48 μg in the conventional group and 142.97 ± 24.78 μg in SPI-guided group (P < 0.05). The difference was statistically significant. The mean recovery time in conventional group was 13.03 ± 1.03 min, and for SPI group, it was 13.53 ± 1.14 min (P > 0.05). Conclusions: We can conclude that SPI guidance may not always help in decreasing the dose of intraoperative opioid consumption. It should be used in combination with hemodynamic parameters. SPI guidance may not affect recovery time.