Open Access Research

Effects of 60 minutes of hyperoxia followed by normoxia before coronary artery bypass grafting on the inflammatory response profile and myocardial injury

Inga Karu12*, Peeter Tähepõld34, Arno Ruusalepp34, Kersti Zilmer5, Mihkel Zilmer5 and Joel Starkopf24

Author Affiliations

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

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Journal of Negative Results in BioMedicine 2012, 11:14  doi:10.1186/1477-5751-11-14

Published: 14 September 2012

Abstract

Background

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.

Methods

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.

Results

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.

Conclusions

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.

Keywords:
Coronary artery bypass grafting; Preconditioning; Hyperoxia; Troponin T; Cytokine; Interleukin; Tumor necrosis factor alfa; Interferon gamma