PRO STRESS Trial: Proactive Low-Dose Norepinephrine to Reduce Intraoperative Fluid Administration in Patients at High-Risk for Postoperative Pulmonary Complications Undergoing Laparoscopic Abdominal Surgery

Proactive Low-Dose Norepinephrine to Reduce Intraoperative Fluid Administration in Patients at High-Risk for Postoperative Pulmonary Complications Undergoing Laparoscopic Abdominal Surgery: A Randomized Controlled Trial

Intraoperative hypotension is commonly treated with fluid administration; however, excessive fluid therapy may contribute to postoperative pulmonary complications. This randomized double-blind controlled trial evaluates whether proactive administration of fixed low-dose norepinephrine reduces intraoperative crystalloid administration while maintaining hemodynamic stability in high-risk patients undergoing laparoscopic abdominal surgery. One hundred and thirty patients will be randomized to receive either norepinephrine infusion (0.03 µg/kg/min) or placebo from induction until skin closure within a protocolized hemodynamic strategy guided by mean arterial pressure and pulse pressure variation.

Inclusion Criteria:

• Adult patients aged 18 years or older.
• American Society of Anesthesiologists (ASA) physical status I-III.
• Scheduled for elective laparoscopic major abdominal surgery under general anesthesia with an expected duration greater than 2 hours.
• Patients with ARISCAT score ≥ 45 indicating high risk for postoperative pulmonary complications.

Exclusion Criteria:

• Known hypersensitivity to norepinephrine.
• Severe left ventricular dysfunction with ejection fraction < 35%.
• Significant cardiac arrhythmia.
• Uncontrolled hypertension defined as systolic blood pressure ≥ 180 mmHg or diastolic blood pressure ≥ 110 mmHg.
• End-stage renal disease.
• Requirement for vasopressor support before induction of anesthesia.
• Emergency surgery.