Hepato

introductionSurgical stress results in immune dysfunction, predisposing patients to infections in the postoperative period and potentially increasing the risk of cancer recurrence. Perioperative immunonutrition with arginine-enhanced diets has been found to potentially improve short-term and cancer outcomes. This study seeks to measure the impact of perioperative immunomodulation on biomarkers of the immune response and perioperative outcomes following hepatopancreaticobiliary surgery. METHODS AND ANALYSIS: This is a 1:1:1 randomised, controlled and blinded superiority trial of 45 patients. Baseline and perioperative variables were collected to evaluate immune function, clinical outcomes and feasibility outcomes. The primary outcome is a reduction in natural killer cell killing as measured on postoperative day 1 compared with baseline between the control and experimental cohorts. ETHICS AND DISSEMINATION: This trial has been approved by the research ethics boards at participating sites and Health Canada (parent control number: 223646). Results will be distributed widely through local and international meetings, presentation, publication and ClinicalTrials.gov (identifier: NCT04549662). Any modifications to the protocol will be communicated via publications and ClinicalTrials.gov. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov identifier: NCT04549662.