| Ischemic preconditioning is an adaptational response of briefly ischemic tissues that serves to protect against subsequent prolonged ischemic insults and reperfusion injury. This phenomenon is an innate protective mechanism that significantly reduces ischemic reperfusion injury (IRI) in most human tissues. Direct mechanical preconditioning in which the target organ is exposed to brief ischemia prior to prolonged ischemia has the benefit of reducing IRI but its main disadvantage is trauma to major vessels and stress to the target organ and difficulty to manipulate. The purine nucleoside adenosine is recognized as a major local regulator of tissue function, especially when energy supply acutely fails to meet cellular energy demand. A considerable body of information has accumulated over the past years regarding the ability of this endogenous molecule to limit cellular death and dysfunction during and following ischemic insult. Adenosine preconditioning (AP) also exerts a protective role against myocyte injury caused by established ischemia. Studies in experimental and clinical settings have shown that remote ischemic preconditioning (RIPC) is a novel method whereas ischemia followed by reperfusion of one organ is believed to protect heart against following ischemic injury.The objective of the present study is to investigate the protective effect of AP and RIPC on heart and lung. There are two parts of the study.Part one Protective Effect of Adenosine Preconditioning on Infants Undergoing Open Heart SurgeryAIM To investigate the protective effect of adenosine preconditioning on infants subjected to cardiac surgery.METHODS Forty infants were randomized into two groups: adenosine preconditioning (AP) group (n=20) and control group (n=20). Blood samples were taken after the induction of anesthesia, at the end of ultrafiltration, and at 1, 3, 6, 12, and 24 hours after ICU arrival for determination of plasma cardiac troponin I (cTnI), interleukin-6 (IL-6) and tumor necrosis factor-а(TNF-а) concentrations. The pulmonary functional data including artery blood oxygen pressure (PaO2), airway resistance, oxygenation index (OI) and pulmonary compliance were recorded.RESULTS Compared with the control group, levels of plasma cTnI were markedly lower in AP group (P=0.02), and the ICU time in AP group was significantly longer(P<0.05).CONCLUSION Adenosine preconditioning appears to protect the heart against ischemic-reperfusion injury, but fails to improve the pulmonary function or the systemic inflammation in the settings of cardiac surgery of infants. Part two Protective Effect of Remote Ischemic Preconditioning on Infants Undergoing Open Heart SurgeryAIM To investigate the protective effect of remote ischemic preconditioning on infants subjected to cardiac surgery. METHODS Forty infants were randomized to two groups: remote ischemic preconditioning (RIPC) group (n=20) and control group (n=20).Blood samples were taken after the induction of anesthesia, at the end of ultrafiltration, and at 1, 3, 6, 12, and 24 hours after ICU arrival for determination of plasma cardiac troponin I (cTnI), interleukin-6 (IL-6) and tumor necrosis factor-а(TNF-а) concentrations. The pulmonary functional data including artery blood oxygen pressure (PaO2), airway resistance, oxygenation index (OI) and pulmonary compliance were recorded.RESULTS Compared with the control group, levels of plasma cTnI were lower in the RIPC group , but there was no statistic significance (P=0.07). At 3 hour after ICU arrival, levels of plasma cTnI were markedly lower in the RIPC group as compared with the control group(P<0.01). Levels of plasma TNF-аwere markedly lower in the RIPC group than in the control group at 3 and 6 hours after ICU arrival(P<0.05), and levels of IL-6 were markedly lower in RIPC group as compared with the control group at 6 and 24 hours after ICU arrival (P<0.05).CONCLUSION Remote ischemic preconditioning appears to protect the heart against ischemia-reperfusion injury and to attenuate the systemic inflammation, but can not improve the pulmonary function in the setting of cardiac surgery of infants. |
