Rationale and design of a pilot randomized control trial of permissive hypotension after cardiac surgery: The PHACS trial.

Background: Vasopressors are frequently used in the early postoperative period after cardiac surgery to treat hypotension and support organ perfusion. However, increasing evidence suggests that excessive vasopressor exposure may lead to adverse outcomes. In critically ill populations, permissive hypotension has been shown to reduce vasopressor use without increasing harm. This strategy has not been studied in postoperative cardiac surgery patients. Study design: The Permissive Hypotension After Cardiac Surgery (PHACS) Trial is a pilot single-center, open-label, pragmatic randomized controlled trial of adult patients undergoing non-emergent cardiac surgery. Patients who develop hypotension requiring vasopressor support within the first 24 h of intensive care unit (ICU) admission are randomized 1:1 to a permissive hypotension arm (target mean arterial pressure [MAP] 60-65 mmHg) or usual care. The primary outcome is hourly MAP during vasopressor therapy. Secondary outcomes include vasopressor and inotrope exposure, ICU and hospital length of stay, end-organ injury and support requirements, and in-hospital mortality. Conclusion: The PHACS Trial is designed to address a critical gap in postoperative cardiac surgical care by evaluating whether a permissive hypotension strategy can safely reduce vasopressor exposure. The study results will help define optimal vasopressor use and blood pressure targets in cardiac surgery patients where evidence-based targets remain undefined. Results from this pilot trial will inform the development of a larger multicenter trial. Trial registration: NCT06476613.