Normoxic management of cardiopulmonary bypass reduces myocardial oxidative stress in adult patients undergoing coronary artery bypass graft surgery

Abstract

Introduction: We aimed to investigate whether normoxic cardiopulmonary bypass would limit myocardial oxidative stress in adults undergoing coronary artery bypass grafting. Methods: Patients scheduled to undergo elective isolated on-pump coronary artery bypass grafting were randomized to normoxia and hyperoxia groups. The normoxia group received 35% oxygen during anesthetic induction, 35% during hypothermic bypass, and 45% during rewarming. The hyperoxia group received 70%, 50%, and 70% oxygen, respectively. Coronary sinus blood samples were taken prior to initiation of cardiopulmonary bypass and after reperfusion for myocardial total oxidant and antioxidant status measurements. The primary endpoint was myocardial total oxidant status. Secondary endpoints were myocardial total antioxidant status and length of intensive care unit and hospital stay. Results: Forty-eight patients were included. Twenty-two received normoxic management. Mean ± standard deviation of age was 58 ± 9.07 years. Groups were balanced in terms of demographics, risk factors, and operative data. Myocardial total oxidant status was significantly lower in the normoxia group following reperfusion (p = 0.03). There was no statistically significant difference regarding myocardial total antioxidant status and length of intensive care unit and hospital stay (p = 0.08, p = 0.82, and p = 0.54, respectively). Conclusions: Normoxic cardiopulmonary bypass is associated with reduced myocardial oxidative stress compared to hyperoxic cardiopulmonary bypass in adult coronary artery bypass patients.

Intraoperative Oxygen Concentration and Neurocognition after Cardiac Surgery

“…Potential reasons hyperoxia may be harmful in patients having cardiac surgery utilizing CPB are cardiovascular dysfunction, 28,29 enhancement of ischemia-reperfusion injury, 30,31 and direct injury from reactive oxygen species. [32][33][34][35] However, we did not find evidence of such harm in our study, at least that manifested as cognitive dysfunction. In interpreting these results, it is entirely plausible that the arterial oxygen content is a minor variable in the response to ischemia-reperfusion injury, dwarfed by that from the systemic inflammatory response to CPB.…”

Reply to: The many sides of oxidative stress during coronary artery bypass surgery

“…Bastopcu and Ozhan 1 for their interest and valuable commentary on our article. 2 As they have mentioned, direct sampling of coronary sinus blood was one of the main advantages of our study. 1,2 Needless to say, there were many disadvantages too.…”

“…2 As they have mentioned, direct sampling of coronary sinus blood was one of the main advantages of our study. 1,2 Needless to say, there were many disadvantages too. Cardiac index measurement was not performed after cardiopulmonary bypass (CPB), because routine use of pulmonary artery catheters, and other forms of thermodilution techniques, in patients undergoing isolated coronary artery bypass grafting (CABG) was already abandoned in our institution at the time of writing of the article.…”

“…Reply to: The many sides of oxidative stress during coronary artery bypass surgery Ahmet Can Topcu, 1  Kamile Ozeren-Topcu 1 and Ilyas Kayacioglu 2 We thank Drs. Bastopcu and Ozhan 1 for their interest and valuable commentary on our article.…”

The many sides of oxidative stress during coronary artery bypass surgery

“…We have read with great interest the article "Normoxic management of cardiopulmonary bypass reduces myocardial oxidative stress in adult patients undergoing coronary artery bypass graft surgery" by Topcu et al 1 The authors applied a novel method to determine myocardial oxidative stress and demonstrated increased oxidants in myocardial circulation with hyperoxic management during cardiopulmonary bypass (CPB). We hope that this and other related evidence will guide the cardiac surgeons to further investigate the benefits of perioperative normoxic strategies.…”