Surgical Pleth Index for Predicting Postoperative Moderate-to-Severe Pain: A Systematic Review and Meta-Analysis

BACKGROUNDConventional vital signs lack the specificity for intraoperative nociception. The Surgical Pleth Index (SPI), calculated from photoplethysmographic waveforms, provides a quantitative measure of nociceptive status ranging from 0 to 100. Elevated SPI values correspond to increased nociceptive intensity. While some evidence suggests that SPI may help predict pain, its accuracy in forecasting postoperative pain requires further validation. AIMThis study aimed to assess the capacity of the Surgical Pleth Index (SPI) to predict moderate to severe pain following surgery. METHODSWe conducted a systematic literature search across three databases to identify studies investigating SPIs predictive value for postoperative pain. A random-effects model was applied to pool summary estimates of sensitivity, specificity, and the area under the summary receiver operating characteristic curve (SROC-AUC). RESULTSAnalysis included ten studies encompassing 1,042 patients. Pooled sensitivity and specificity were 0.74 (95% CI: 0.67-0.80) and 0.65 (95% CI: 0.55-0.74), respectively. The SROC-AUC reached 0.76, suggesting a moderate level of predictive accuracy. Significant heterogeneity was observed and not explained by differences in SPI cutoff values. CONCLUSIONThe SPI demonstrates moderate accuracy in forecasting moderate-to-severe postoperative pain and may serve as a useful adjunct to conventional clinical assessment. What is known?The Surgical Pleth Index has been suggested as a reliable monitor for nociceptive states. What new information does this article contribute?The Surgical Pleth Index (SPI) demonstrated moderate accuracy in predicting moderate-to-severe postoperative pain. Current evidence supports its role as a validated supplementary instrument to guide analgesic administration during surgery. Core Tip:This meta-analysis confirms that the Surgical Pleth Index (SPI) provides moderate predictive accuracy for moderate-to-severe postoperative pain and, as such, has a complementary role in guiding intraoperative analgesia, provided its outputs are interpreted within the context of a comprehensive clinical assessment.