During cardiac surgery with cardiopulmonary bypass , injury occurs to the heart muscle and the lung.The heart and lung injury is a serious complication ,which increases both mortality and morbidity of cardiac surgery .Remote ischemic preconditioning(RIPC) with transient upper limb ischemia/reperfusion is a novel, simple, cost-free,non-pharmacological and non-invasive strategy.Recent some trials suggested that RIPC could provide myocardial protection by reducing serum cardiac biomarkers,however, more recent multicenter studies[9-11] had failed to show the protective effects of RIPC with respect to the troponin release and lung injury.

Remote ischemic preconditioning (RIPC) is reported to have the early-phase and delayed-phase organ protective effects, whether the modified RIPC protocol induced repeatedly has the cardiopulmonary protective effect is still uncertain.

modified RIPC was induced at 24 h, 12 h and 1 h before surgery to reinforce the protective effects of RIPC.The single RIPC protocol was induced by three cycles of upper-limb ischemia, a standard blood-pressure cuff was placed on the ringt upper arm, then inflated the cuff to 200 mm Hg for 5 minutes, followed by 5 min of cuff deflation.

Inclusion Criteria:

1. Patients undergoing heart surgery on cardiopulmonary bypass
2. Patients aged 18 years to 80 years

Exclusion Criteria:

1. Inability to give informed consent
2. Cardiogenic shock
3. Cardiac arrest on current admission
4. Left ventricular ejection fraction less than 30%
5. Current atrial fibrillation
6. Preoperative use of inotropics or mechanical assist device
7. Patients with significant hepatic dysfunction (Prothrombin>2.0 ratio)
8. Patients with known renal failure with a GFR<30 mL/min/1.73 m2
9. Patients with significant pulmonary disease (FEV1<40% predicted)
10. Recent myocardial infarction (within 7 days)
11. Recent systemic infection or sepsis (within 7 days)
12. Severe stroke (within 2 months)
13. Significant peripheral arterial disease affecting the upper limbs
14. Previous serious psychiatric disorders (e.g. schizophrenia, dementia)
15. Surgeries: cardiac transplantation, concomitant carotid endarterectomy , previous heart surgery,off-pump surgery, emergency surgery

IPD will be available when this trial is finished and the article have been published.