Cytoreductive surgery (CRS) with heated intraperitoneal chemotherapy (HIPEC) is a treatment for peritonitis carcinomatosa. These procedures often involve significant blood and fluid loss, leading to hyperdynamic circulation and vasodilation, necessitating intraoperative fluids and vasoconstrictors such as catecholamines. Excessive fluid administration to counteract vasodilation can cause intraoperative fluid overload, which is linked to increased postoperative complications. Vasopressin has emerged as a potential alternative to catecholamines, restoring vascular tone via non-adrenergic pathways and supporting perfusion pressure, potentially reducing the need for compensatory fluids solely administered to compensate for vasodilation. We hypothesise that compared with norepinephrine, vasopressin reduces cumulative intraoperative fluid administration during CRS-HIPEC within a goal-directed fluid therapy (GDFT) protocol, ultimately leading to a lowering of postoperative complications.

HiPress is a two-centre, two-arm randomised clinical trial with blinding of both patients and outcome assessors. A total of 70 adult patients undergoing CRS-HIPEC will be included. Patients will be randomised to receive either continuous low-dose argipressin or continuous low-dose norepinephrine. Both groups will receive standardised GDFT during the procedure. The primary endpoint is cumulative intraoperative fluid administration (mL). Secondary endpoints include direct fluid-related outcomes (eg, cumulative intraoperative fluid (ml/kg/hour), postoperative fluid balance until day five and ultrasound-assessed pulmonary oedema and venous congestion) and indirect fluid-associated outcomes (eg, quality of recovery, surgical and abdominal complications, acute kidney injury (AKI), pulmonary complications, length of ICU and hospital stay and 30-day mortality).

The study is enrolling patients since February 2025. The trial is approved by the Medical Research Ethics Committee (hereinafter: MREC) NedMec, The Netherlands (Ref: D-25-500202). Results of the trial will be published in an international peer-reviewed journal and announced at national and international scientific meetings.

Clinical Trials Information System (CTIS): European Union clinical trials register (EUCT) number: 2024–5 13 598-33-00