Perioperative supplemental oxygen and NT-proBNP concentrations after major abdominal surgery - A prospective randomized clinical trial

Abstract

Study objective: Supplemental oxygen is a simple method to improve arterial oxygen saturation and might therefore improve myocardial oxygenation. Thus, we tested whether intraoperative supplemental oxygen reduces the risk of impaired cardiac function diagnosed with NT-proBNP and myocardial injury after noncardiac surgery (MINS) diagnosed with high-sensitivity Troponin T.

Design: Parallel-arm double-blinded single-centre superiority randomized trial.

Setting: Operating room and postoperative recovery area.

Patients: 260 patients over the age of 45 years at-risk for cardiovascular complications undergoing major abdominal surgery.

Intervention: Administration of 80% versus 30% oxygen throughout surgery and for the first two postoperative hours.

Measurements: The primary outcome was the postoperative maximum NT-proBNP concentration in both groups, which was assessed within 2 h after surgery, and on the first and third postoperative day. The secondary outcome was the incidence of MINS in both groups.

Main results: 128 patients received 80% oxygen and 130 received 30% oxygen throughout surgery and for the first two postoperative hours. There was no significant difference in the median postoperative maximum NT-proBNP concentration between the 80% and the 30% oxygen group (989 pg.mL^-1 [IQR 499; 2005] and 810 pg.mL^-1 [IQR 409; 2386], effect estimate: 159 pg.mL^-1, 95%CI -123, 431, p = 0.704). There was no difference in the incidence of MINS between both groups. (p = 0.703).

Conclusions: There was no beneficial effect of perioperative supplemental oxygen administration on postoperative NT-proBNP concentration and MINS. It seems likely that supplemental oxygen has no effect on the release of NT-proBNP in patients at-risk for cardiovascular complications undergoing major abdominal surgery.

Trial registration: ClinicalTrials.gov: NCT03366857. https://clinicaltrials.gov/ct2/results?cond=NCT+03366857&term=&cntry=&state=&city=&dist=.

Keywords: Cardiovascular risk; MINS; Major abdominal surgery; NT-proBNP; Supplemental oxygen.