Remote Ischemic Preconditioning on Pulmonary Injury in Cardic Surgery

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. Preoperative severe impairment of respiratory function (arterial oxygen tension (PaO2) <60 mmHg or FEV1<50% predicted)
3. Prior receipt of chemotherapy or radiation therapy or immunotherapy
4. left ventricular ejection fraction less than 30%
5. preoperative use of inotropics or mechanical assist device
6. Patients with significant hepatic dysfunction (Prothrombin>2.0 ratio)
7. Patients with known renal failure with a GFR<30 mL/min/1.73 m2
8. recent myocardial infarction (within 7 days)
9. Systemic or local active infections (either clinically defined or suggested by evidence such as elevated C-reactive protein levels, leukocytosis, or a body temperature>38℃)
10. Significant peripheral arterial disease affecting the upper limbs
11. surgeries: cardiac transplantation, concomitant carotid endarterectomy , previous heart surgery,, off-pump surgery, emergency surgery