Effect of isotonic sodium bicarbonate infusion on perioperative acid-base status among patients undergoing emergency laparotomy for perforation peritonitis (ISABEL trial): a randomized controlled trial.

Purpose: Perioperative metabolic acidosis negatively affects patient outcomes. Perioperative fluid therapy has a clinically significant effect on acid-base balance. This study was conducted to evaluate the effects of isotonic sodium bicarbonate infusion (ISB) versus balanced crystalloid solution (BCS) on perioperative acid-base balance, in terms of postoperative base excess, among patients undergoing emergency laparotomy for perforation peritonitis.

Methods: This prospective, randomized, single-center, double-blinded study was conducted in a tertiary hospital from October 2021 to November 2022. A total of 90 patients undergoing emergency laparotomy for perforation peritonitis were randomly assigned to receive either isotonic sodium bicarbonate (ISB) or Ringer's Lactate as a balanced crystalloid solution (BCS) for perioperative maintenance fluid therapy. The primary outcome was to compare the base excess (BE) at the end of surgery. The secondary outcomes were to compare the postoperative clinical outcomes, including the requirement of vasopressors, duration of mechanical ventilation, HDU/ICU stay, the incidence of AKI within seven days, the incidence of re-exploration, and in-hospital mortality. Additionally, pH, PaCO2, HCO3, BE, and lactates intraoperatively and up to 24 h postoperatively were also compared.

Results: The median base excess (BE) values at the end of surgery were significantly better in the ISB group - 4.80 [- 6.80, - 4.10] as compared to the BCS group - 7.30 [- 8.50, - 6.30]. The ISB group had a lower incidence of postoperative AKI (9% ISB versus 24% BCS) and requirement of vasopressors (18% ISB versus 44% BCS). However, there was no major difference between the incidence of re-exploration, length of ICU/HDU stay, and in-hospital mortality.

Conclusion: Infusing isotonic sodium bicarbonate (ISB) for intraoperative maintenance fluid therapy in patients undergoing emergency laparotomy for perforation peritonitis significantly improves perioperative acid-base balance with better postoperative clinical outcomes compared to a balanced crystalloid solution (BCS).