Peritoneal antiseptic irrigation to prevent surgical site infection after laparotomy for hepatobiliary or gastrointestinal surgery (PAISI) – Study protocol for a double-blind randomized controlled trial

Abstract Background: Postoperative surgical site infections (SSI) remain common after laparotomy for resections of the gastrointestinal or hepatobiliary tract. Especially CDC class III SSIs (organ/space) can be life-threatening, require relaparotomy, intensive care or interventional drainage of intraabdominal abscesses. The PAISI study aims to investigate whether the use of prophylactic peritoneal irrigation with NaOCl/HOCl solution can reduce the SSI rates following laparotomy for resections of the gastrointestinal or hepatobiliary tract, compared to standard irrigation with physiological electrolyte solution (Ringer’s solution). Secondarily, to evaluate whether the use of prophylactic peritoneal irrigation with NaOCl/HOCl solution can reduce postoperative morbidity and mortality as well as the rate of re-operations and length of hospital stay.Methods: PAISI is a prospective, randomized, observer- and patient-blinded, monocentric, two-arm surgical study in an adaptive parallel groups design, comparing peritoneal and wound irrigation with NaOCl/HOCl (50/50ppm) solution to irrigation with Ringer’s solution. The primary endpoint of the study is the SSI rate within 30 days postoperatively. Since there is no data on incidence rates from randomized clinical trials, the rates for sample size calculation were estimated according to the clinical experience at our institution. Therefore, the study design includes one unblinded look at the data by a second statistician, which will be performed after half of the patients reached the primary endpoint. This interim information will be used to check the assumptions and if needed, the sample size will be adjusted. The O’Brien-Fleming spending function is used to determine the efficacy test boundary and the non-binding futility boundary. The one-sided z-test (Group sequential test of two proportions) at the 2.5% significance level with a total of two looks at the data will have overall 80% power.Discussion: The results of this study will provide high-level evidence for future research and clinical recommendations regarding the use of NaOCl/HOCl solution in abdominal surgery and provide the participating patients the opportunity of a potentially improved treatment.Trial registration: The study was registered at the German Clinical Trials Register (DRKS) on the 27.05.2022, number DRKS00028037.