Abstract
BackgroundElevated postoperative N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations are predictive for cardiac adverse events in noncardiac surgery. Studies indicate that supplemental oxygen decreases sympathetic nerve activity and might, therefore, improve cardiovascular function. Thus, we will test the effect of perioperative supplemental oxygen administration on NT-proBNP release after surgery.Methods/designWe will conduct a single-center, double-blinded, randomized trial at the Medical University of Vienna, including 260 patients with increased cardiac risk factors undergoing moderate- to high-risk noncardiac surgery. Patients will be randomly assigned to receive 80% versus 30% oxygen during surgery and for 2 h postoperatively. The primary outcome will be the difference in maximum NT-proBNP release after surgery.As secondary outcomes we will assess the effect of supplemental oxygen on postoperative maximum troponin T concentration, oxidation-reduction potential, von Willebrand factor concentration and perioperative fluid requirements. We will perform outcome measurements 2 h after surgery, on postoperative day 1 and on postoperative day 3. The NT-proBNP concentration and the oxidation-reduction potential will also be measured within 72 h before discharge.DiscussionOur trial should determine whether perioperative supplemental oxygen administration will reduce the postoperative release of NT-proBNP in patients with preoperative increased cardiovascular risk factors undergoing noncardiac surgery.Trial registrationClinicalTrials.gov, ID: NCT03366857. Registered on 8th December 2017.
Highlights
Elevated postoperative N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations are predictive for cardiac adverse events in noncardiac surgery
Our trial should determine whether perioperative supplemental oxygen administration will reduce the postoperative release of NT-proBNP in patients with preoperative increased cardiovascular risk factors undergoing noncardiac surgery
As supplemental oxygen has no effect on the incidence of surgical site infections, it is reasonable to question the effect of hyperoxia on other organ systems [3,4,5,6]
Summary
Elevated postoperative N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations are predictive for cardiac adverse events in noncardiac surgery. Studies indicate that supplemental oxygen decreases sympathetic nerve activity and might, improve cardiovascular function. We will test the effect of perioperative supplemental oxygen administration on NT-proBNP release after surgery. In patients over the age of 45 years the risk of developing postoperative complications is even higher [2]. The systemic effect of perioperative supplemental oxygen, especially on the cardiovascular system, still remains unknown. A post-hoc analysis of the PROXI trial indicated an increased long-term risk of myocardial infarction or other heart diseases in patients receiving supplemental oxygen [7]. Despite the current controversy regarding toxic effects of supplemental oxygen [8], there are studies indicating the beneficial effects of higher oxygen concentrations on the cardiovascular system. A decrease in heart rate and myocardial oxygen consumption as well as an increase in myocardial oxygen supply was shown previously [9,10,11]
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