Correlation between Peritoneal Carcinomatosis Index and Postoperative Pain after Cytoreductive Surgeries and Hyperthermic Intraperitoneal Chemotherapy: A Retrospective Cohort Study

Background and Aims: Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) is associated with significant postoperative pain due to both nociceptive and neuropathic mechanisms. The extent of peritoneal disease, quantified by the Peritoneal Carcinomatosis Index (PCI), may influence postoperative pain severity and analgesic requirements. This study evaluates the correlation between PCI and postoperative pain scores and assesses the effectiveness of different analgesic modalities in CRS-HIPEC patients. Methods: A retrospective analysis was conducted on 112 patients who underwent CRS-HIPEC. Pain scores at rest and during movement were recorded for 96 h postoperatively. The correlation between PCI class (0–10, 11–20, 21–30 and >30) and worst pain scores on postoperative days (PODs) 1–4 was analysed. The impact of PCI on analgesic requirements, mechanical ventilation duration and postoperative coagulopathy was also assessed. Results: A significant correlation was observed between PCI severity and worst pain scores on POD 2 ( P = 0.009), but not on POD 1, 3 or 4. The mean duration of mechanical ventilation was 1.2 days (28.8 h), during which continuous opioid infusion was administered. Epidural analgesia was used in 85.2% of patients (median duration: 4 days). In addition, 19% required intravenous patient-controlled analgesia (IV-PCA) and 6.7% received both epidural and IV-PCA due to inadequate pain relief. Despite these interventions, 39.3% reported moderate-to-severe pain at rest and 67.8% experienced severe pain during movement. Higher PCI scores were significantly associated with postoperative coagulopathy ( P < 0.001), with 4% requiring blood products for epidural catheter removal. Conclusion: PCI severity influences acute postoperative pain, particularly on POD 2. Multimodal analgesic strategies, including truncal blocks and patient-controlled analgesia, should be considered for better pain management in CRS-HIPEC patients.