Intra-operative nociceptive responses and postoperative major complications after gastrointestinal surgery under general anaesthesia A prospective cohort study

BACKGROUND Surgical procedures stimulate nociception and induce physiological responses according to the balance between nociception and antinociception. The severity of surgical stimuli is associated with major postoperative complications. Although an intra-operative quantitative index representing surgical invasiveness would be useful for anaesthetic management to predict and prevent major complications, no such index is available. OBJECTIVES To identify associations between major complications after gastrointestinal surgery and intra-operative quantitative values from intra-operative nociception monitoring. DESIGN A multi-institutional observational study. SETTING Two university hospitals. PATIENTS Consecutive adult patients undergoing gastrointestinal surgery under general anaesthesia. MAIN OUTCOME MEASURES Averaged values of nociceptive response index from start to end of surgery (mean NR index) and risk scores of the Surgical Mortality Probability Model (S-MPM) were calculated. Pre and postoperative serum C-reactive protein (CRP) levels were obtained. After receiver-operating characteristic (ROC) curve analysis, all patients were divided into groups with high and low mean nociceptive response index. Associations between mean nociceptive response index and postoperative major complications, defined as Clavien-Dindo grade at least Illa, were examined using logistic regression analysis. RESULTS ROC curve analysis showed a nociceptive response index cut-off value for major complications of 0.83, and we divided patients into two groups with mean nociceptive response index less than 0.83 and at least 0.83. The incidence of major complications was significantly higher in patients with mean nociceptive response index at least 0.83 (23.1%; n = 346) than in patients with mean nociceptive response index less than 0.83 (7.7%; n = 443; P< 0.001). Multivariate analysis revealed emergency surgery, S-MPM risk score, mean nociceptive response index and postoperative CRP levels as independent risk factors for major complications. CONCLUSION Mean nociceptive response index during surgery likely correlates with major complications after gastrointestinal surgery.

Automated summary

The mean nociceptive response index during gastrointestinal surgery may correlate with major complications in the postoperative period.