Pneumatic tourniquet is usually used in orthopedic surgeries, as it helps to decrease operative bed bleeding, and thus, maintaining a clean and dry surgical field allowing easy and clear identification of the anatomical structures. Despite that advantage, after its deflation, there is a blood volume shift towards that ischemic area, which may decrease cardiac preload leading to hypotension

Hemodynamic changes after tourniquet deflation include; hypotension, tachycardia and increase in cardiac index. These changes may be insignificant for healthy individuals but, risky for patients with compromised cardiovascular system and geriatric population.

Hypovolemia is a common problem in many clinical situations. The mortality of hypovolemic shock is directly related to the severity and duration of organ hypoperfusion.

Management of hypotension include frequent monitoring of blood pressure, fluid therapy, non-pharmacological methods, and vasopressors. Fluid therapy by crystalloids or colloids has been the traditional approach to restore volume and can be given as preload or co-load .Non pharmacological methods include positioning and leg compression. Trendelenburg position can increase venous return to the heart. Leg compression by flexion of the hip, elastic bandages, or stockings. An efficient method to treat spinal hypotension is administration of vasopressors, either given by infusion or boluses. Vasopressor drugs act by reversing the circulatory effect of sympathetic blockade. They also restore vascular tone and preserve venous return and cardiac filling

Inclusion Criteria:

• Adult Patients of both gender
• American Society of Anesthesiologists (ASA) I or II
• scheduled for elective unilateral total knee arthroplasty

Exclusion Criteria

• Patient refusal.
• Major cardiopulmonary disorders
• Uncontrolled systemic hypertension.
• Hepatic or renal disorders.
• Patient with relative contraindication for tourniquet use as peripheral vascular disease, sickle cell anemia, deep venous thrombosis, diabetic neuropathy and crushed injury.
• Cases having American Society of Anesthesiologists [ASA] > II
• Coagulopathy and bleeding tendency.
• Revision knee arthroplasty and bilateral knee arthroplasty