Effects of 60 minutes of hyperoxia followed by normoxia before coronary artery bypass grafting on the inflammatory response profile and myocardial injury
1 North Estonia Medical Centre, Clinic of Anaesthesiology, Tallinn, Estonia
2 Department of Anaesthesiology and Intensive Care, University of Tartu, Puusepa 8, Tartu, Estonia
3 Department of Cardiology, University of Tartu, Tartu, Estonia
4 Tartu University Hospital, Tartu, Estonia
5 Institute of Biochemistry, Centre of Excellence for Translational Medicine, University of Tartu, Tartu, Estonia
Journal of Negative Results in BioMedicine 2012, 11:14 doi:10.1186/1477-5751-11-14Published: 14 September 2012
Ischemic preconditioning induces tolerance against ischemia-reperfusion injury prior a sustained ischemic insult. In experimental studies, exposure to hyperoxia for a limited time before ischemia induces a low-grade systemic oxidative stress and evokes an (ischemic) preconditioning-like effect of the myocardium. We hypothesised that pre-treatment by hyperoxia favours enchanced myocardial protection described by decreased release of cTn T in the 1st postoperative morning and reduces the release of inflammatory cytokines.
Forty patients with stable coronary artery disease underwent coronary artery bypass grafting with cardiopulmonary bypass. They were ventilated with 40 or >96% oxygen for 60 minutes followed by by 33 (18–59) min normoxia before cardioplegia.
In the 1st postoperative morning concentrations of cTnT did not differ between groups ((0.44 (0.26-0.55) ng/mL in control and 0.45 (0.37-0.71) ng/mL in hyperoxia group). Sixty minutes after declamping the aorta, ratios of IL-10/IL-6 (0.73 in controls and 1.47 in hyperoxia, p = 0.03) and IL-10/TNF-α (2.91 and 8.81, resp., p = 0.015) were significantly drifted towards anti-inflammatory, whereas interleukins 6, 8and TNF-α and interferon-γ showed marked postoperative rise, but no intergroup differences were found.
Pre-treatment by 60 minutes of hyperoxia did not reduce postoperative leak of cTn T in patients undergoing coronary artery bypass surgery. In the hyperoxia group higher release of anti-inflammatory IL-10 caused drifting of IL-10/IL-6 and IL-10/TNF-α towards anti-inflammatory.