Renal medullary oxygenation during laparoscopic vs open surgery: the impact of blood pressure management-a pilot randomized controlled trial

Abstract

The impact of blood pressure targets and surgical approach (laparoscopic or open) on continuous urinary oxygenation (PuO₂), a validated surrogate of renal medullary PO₂, during general surgery, is unclear. We aimed to assess the effects of different blood pressure targets and surgical procedures on PuO₂. We randomized patients receiving either laparoscopic or open surgery into two mean arterial pressure (MAP) target groups: usual MAP or a high MAP. We measured PuO₂ in real-time and analyzed it according to the type of surgery and blood pressure target. The study was retrospectively registered on the 5th of July 2023 (ACTRN12623000726651). We included 43 participants who underwent either laparoscopic (n = 20) or open surgery (n = 23). We found that PuO₂ significantly decreased during both laparoscopic and open surgery under a usual blood pressure target (- 51% and - 49%, respectively). However, there was a sharper fall with laparoscopic surgery resulting in a higher PuO₂ with open surgery (mean difference: 11 ± 1 mmHg higher; p < 0.001). Targeting a higher MAP resulted in a higher PuO₂ over time during laparoscopic surgery (mean difference: 7 ± 1 mmHg, p < 0.001). In contrast, targeting a usual MAP resulted in a higher PuO₂ during open surgery (mean difference: 7 ± 1 mmHg, p < 0.001). Surgical approach and intraoperative blood pressure targets significantly impact urinary oxygenation. Further studies with larger sample sizes are needed to confirm these findings and understand their potential clinical implications.Registration number: ACTRN12623000726651; Date of registration: 05/07/2023 (retrospectively registered).

Keywords: Acute kidney injury; Laparoscopic surgery; Mean arterial pressure; Medullary oxygenation; Open surgery; Urinary oxygenation.