To study the effects of Acute normovolemic hemodilution on central and peripheral perfusion in patients Undergoing off-pump coronary artery bypass grafting surgery

Off-pump coronary artery bypass surgery is an alternative to conventional coronary artery bypass grafting using cardiopulmonary bypass (CPB). It avoids adverse effects of CPB such as systemic inflammatory response, impaired myocardial protection, and air or plaque embolism. However, OPCAB surgery involves displacement and manipulation of the heart to expose target coronary arteries. These manipulations cause hemodynamic instability as a result of transient annulo-mitral distortion and acute mitral regurgitation, compression of the right ventricle, and impaired cardiac contractility due to epicardial stabilizers. signs of impaired perfusion such as metabolic acidosis, increased serum lactate and decreased urine output are commonly seen intraoperatively

Excessive surgical bleeding causes hypovolemia and hemodynamic instability, anemia, and reduced oxygen delivery to tissues

Acute normovolemic hemodilution (ANH) is an alternative method of management of intraoperative blood loss, in which a certain volume of blood is collected from the patient, stored at room temperature and replaced by an equal volume of colloid solution. By the end of surgery, this blood is returned to the patient, usually within eight hours of collection, with little deterioration of platelets or coagulation factors

This work aims to study the effects of Acute normovolemic hemodilution on central and peripheral perfusion in patients Undergoing off-pump coronary artery bypass grafting surgery

Inclusion Criteria:

• Patients scheduled for off- pump CABG surgery

Exclusion Criteria:

• Ejection fraction less than 40%
• Hematocrit less than 11 g/dl
• patients with severe renal impairment