Open Colorectal Surgery

The goal of this study is to identify the genes as well as their association with Nalbuphine. This will help the investigator to identify opioid vulnerability in Pakistani population in the postoperative patients and will contribute to overcoming the opioid crisis, resulting in better and safer outcomes. Research question is: Is there any association between the underlying genetic variations and the analgesic efficacy of Nalbuphine in postoperative patients? The Research Objectives are 1. To identify the underlying genes in postoperative patients having pain. 2. To find an association between identified genes and nalbuphine clinical efficacy. Procedure: After the written informed consent adult men and women will be enrolled in the study. On the day of surgery in the preoperative area, a 5 ml blood sample will be drawn before surgery and will be sent to laboratory for analysis. After routine hemodynamic monitoring in the operative room, general anesthesia will be given including nalbuphine. Standard routine anesthesia monitoring will be done and maintained while monitoring heart rate, ECG, NIBP oxygen saturation, ETCO2 and temperature. Incremental analgesia will be provided whenever needed. After extubation and shifting to recovery room the 2nd sample of blood will be taken and will be sent for analysis. Pain score, nausea vomiting, sedation, requirement of analgesia will be assessed till 24 hours postoperatively.