the aim in this study to assess the effect of fluid management in patient undergoing orthotopic liver transplantation either by using pulse pressure variation or by central venous pressure. we will assess the impact of fluid management by either methods on oxygenation and extra vascular lung water visualized by lung ultrasound.

After induction of anesthesia lung ultrasound will be performed and arterial blood gases (ABG) will be taken.

All patients in both groups will receive maintenance fluid in the form of crystalloids (ringer acetate) 4 ml/kg/H. Then fluid boluses will be given according to each group:

Group c (cvp): will receive 250 ml albumin 5% boluses to maintain CVP around 5 cmH2o Group P (ppv): will receive 250 ml albumin 5% boluses to maintain PPV below 13% as detected from invasive blood pressure monitor.

For all patients in both groups: blood transfusion will be indicated with decreased HB% level below 7 mg/dl in arterial blood gases. Other blood product (FFP, platelets and cryoprecipitate) transfusion will be guided by lab results and clinical status of patient. Plasma will be transfused if INR > 1.5 and platelets will be transfused if count < 50, 000

Lung ultrasound will be performed to diagnose EVLW. A Philips C5 ultrasound system (frequency 5Hz; Philips Medical Systems, Suresnes, France) with an ordinary echo probe will be used. Chest ultrasound will be performed using the 12 regions method. Intercostals spaces on each side will be examined anteriorly (midclavicular line), laterally (anterior axillary line) and posteriorly (posterior axillary line) Four ultrasound aeration patterns a. Normal aeration (N): 0 score ; line sliding sign associated with respiratory movement or less than 3 B lines ; b. Moderate loss of lung aeration: score 1 ; a clear number of multiple visible B-lines with horizontal spacing between adjacent B lines ≤ 7 mm (B7 lines) c. Severe loss of lung aeration: score 2; multiple B lines fused together that were difficult to count with horizontal spacing between adjacent B lines ≤ 3 mm (B3 lines); and d. Pulmonary consolidation: score 3; hyperechoic lung tissue, accompanied by dynamic air bronchogram.

The final LUS of the patient was the sum of each regional ultrasound score (ranging from 0 to 36).

Inclusion Criteria:

1. ASA physical status II- IV
2. Child C (end stage liver disease) ESLD patient.
3. Age (18- 70) years
4. Patients undergoing orthotopic liver transplantation.

Exclusion Criteria:

1. Parents' refusal.
2. Patients with chronic pulmonary disease ( Asthma, obstructive lung disease or restrictive lung diseases)
3. Patient with impaired diastolic function more than grade I.

patient will be blinded and person who will do lung ultrasound