Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 0 0 2026 04 29 1523 1523 Kousha Farhadi Anesthesia, Critical Care, and Pain Management Research Center, Tehran University of Medical Sciences, Tehran, Iran. Mohammadreza Neishaboury Anesthesia, Critical Care, and Pain Management Research Center, Tehran University of Medical Sciences, Tehran, Iran. Farhad Etezadi Anesthesia, Critical Care, and Pain Management Research Center, Tehran University of Medical Sciences, Tehran, Iran. Hesam Varpaei College of Nursing, Michigan State University, East Lansing, MI, United States. Erta Rajabi Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Reza Khajavi Anesthesia, Critical Care, and Pain Management Research Center, Tehran University of Medical Sciences, Tehran, Iran Mahsa Arab Mohammadi Department of General Surgery, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Reza Shariat Moharari Anesthesia, Critical Care, and Pain Management Research Center, Tehran University of Medical Sciences, Tehran, Iran Atabak Najafi Anesthesia, Critical Care, and Pain Management Research Center, Tehran University of Medical Sciences, Tehran, Iran. Reza Bahman Anesthesia, Critical Care, and Pain Management Research Center, Tehran University of Medical Sciences, Tehran, Iran. Hamidreza Sharifnia Anesthesia, Critical Care, and Pain Management Research Center, Tehran University of Medical Sciences, Tehran, Iran. Pejman Pourfakhr Anesthesia, Critical Care, and Pain Management Research Center, Tehran University of Medical Sciences, Tehran, Iran. 2025 12 14 2025 12 16 Background: Non-depolarizing neuromuscular blocking agents have been shown to play a role in postoperative delirium (POD) and postoperative cognitive dysfunction (POCD). Cisatracurium is known for its higher potency, lower induction dose, anti-inflammatory activity, lower histamine release, and better hemodynamic stability compared to atracurium, all of which may benefit postoperative cognitive function. This study aims to assess the preventive effects of cisatracurium compared with atracurium on POD incidence in patients undergoing colorectal surgery. Methods: This single-center, randomized, controlled trial will be conducted at a tertiary care hospital of Sina (Tehran, Iran) from November 2025, assessing the preventive effects on POD of 0.2 mg/kg cisatracurium compared to 0.5 mg/kg atracurium induction dose with subsequent similar drug maintenance on a total of 200 patients undergoing mass resection surgery of colorectal cancers. Patients will be randomly assigned to a 1:1 allocation to each group. The primary outcome will be the prevalence of POD, assessed twice daily from the night after surgery until day 5, using the intensive care delirium screening checklist (ICDSC). The secondary aims are clinically relevant outcomes, including POCD, as measured by the Montreal Cognitive Assessment (MoCA), postoperative pain using a visual analogue scale (VAS), POD severity using the ICDSC, and duration of hospitalization. Conclusion: This paper provides the protocol for the study comparing the activity of two neuromuscular blocking agents in preventing POD in colorectal cancer surgeries based on the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guideline. https://aacc.tums.ac.ir/index.php/aacc/article/view/1523