Assessment of intravascular volume status is crucial in order to predict the efficacy of volume status in major abdominal surgery. The aim of the study is to verify the feasibility and usefulness of the internal jugular vein distensibility index as an adjunct to the pleth variebility index(PVI) to predict fluid responsiveness in major abdominal surgery.

Forty patients above age 18 and ASA status I-III who are undergoing major abdominal surgery will be enrolled in the study. patients with right heart failure, arrythmia, severe valve stenosis or regurgitation will be excluded. After induction of general anesthesia, when the patients are hemodynamically stabilised, PVI and jugular vein distensibility will be calculated and recorded. after volume load with 500 ml gel infusion(in 15 min), measurements will be repeated within 10 minutes and recorded. Patients will be allocated to 2 groups according to the change in mean arterial pressure(MAP) after volume expansion: Responders will be defined as an increase in MAP by >%10; while nonresponders will be defined as an increase in MAP <%10 or decrease in MAP.

Inclusion Criteria:

• American Society of Anesthesiologists(ASA) physical status I-III patients
• patients undergoing major abdominal surgery

Exclusion Criteria:

• arrythmia
• severe right ventricle failure

patients undergoing major abdominal surgery