General anaesthesia results in developement of atelectasis in dependent areas of the lungs exposing patients to an increased risk of hypoxaemia.During pelvic robotic surgeries pneumoperitoneum and steep trendelenburg position further increases atelectasis. Lung Ultrasound imaging is a promising , noninvasive , non-radiant, portable tool to study intraoperative lung atelectasis.

Methodology -In the Operation Room 5 lead Electrocardiogram (ECG) , Pulse Oximetry (SPO2 ) , Noninvasive blood pressure (NIBP), End tidal carbon di Oxide (ETCO2 )and core temperature will be monitored , intravenous assess will be established with large bore cannula ,under Local anesthesia Radial artery cannulation will be performed , standard general anesthesia with oral cuffed Endotracheal tube and Intermittent Positive Pressure Ventilation (IPPV ) will be provided to all patients.Anaesthesia will be induced with Fentanyl 1-2 mcg/kg-1 , Morphine 0.5mg/kg-1 ,Propofol sleeping dose , Atracurium 0.5mg/kg-1,and maintained with Air/O2 Sevoflurane , Propofol infusion @100- 150 mcg/kg-1 to maintain Bispectral Index (BIS) between 40 -60 and atracurium infusion to maintain Train -of - Four (TOF Ratio) < 0.5 Baseline Lung Ultrasound Imaging will be performed to record 4 point Lung aeration score ( 0= Normal lung /No aeration loss , 1= mild aeration loss, 2=moderate aeration loss ,3=severe aeration loss ) at T1 - 5 minutes after induction of anaesthesia and before docking robotic instruments in 6 basal zones in both lungs ( 3 zones in each lung ) and labelled as Zone I (Right anterior basal ) Zone II ( Right lateral basal) and Zone III (Right posterior basal) . Zone IV ( Left anterior basal) , Zone V (Left lateral basal ) , Zone VI ( Left Posterior basal ).T2 - Lung Ultrasound Imaging will be performed to record aeration score after removal of robotic arms at the end of robotic surgery and before extubation in 6 basal zones in both lungs.Ti Arterial blood gas 5 minutes after induction of anesthesia and before docking robotic instruments.Tii -Arterial blood gas 5 minutes after the end of robotic surgery and de docking robotic instruments.All patients will receive Positive End Expiratory Pressure (PEEP) 5 cms of water (H2O) intraoperatively . Intraabdominal Pressure will be maintained at 15 cms H2O. Any decrease in Oxygen saturation < 96 % and intervention required will be noted. At the end of surgery , neuromuscular blockade will be reversed , trachea extubated and patient shifted to Postanaesthesia Care Unit.

Inclusion Criteria:

* Patients undergoing Robotic Pelvic surgeries under general anaesthesia

Exclusion Criteria:

• Lung consolidation
• Lung fibrosis
• Cardiac failure
• Previous thoracic surgery
• BMI > 32

Adult patients undergoing pelvic robotic surgery under general anaesthesia.