Role of Lung Ultrasound Imaging for Intraoperative Monitoring of Atelectasis During Laparoscopic Surgery

• Lung aeration [ Time Frame: From arrival in the operating theatre to immediately before discharge from the recovery room (Day 0) ] [ Designated as safety issue: Yes ]
  Estimate lung aeration by ultrasound imaging using a four point aeration score (0 = normal lung, 1 = moderate aeration loss, 2 = severe aeration loss, 3 = complete aeration loss and consolidation)
  
  

• Gas exchange [ Time Frame: From 5 minutes following induction of anesthesia to immediately before discharge from the recovery room (Day 0) ] [ Designated as safety issue: Yes ]
  Assess the impact of the different stages of anesthesia and surgery on gas exchange by measuring arterial blood gases.
  
  
• Diaphragmatic function [ Time Frame: On arrival in the operating theatre and immediately before discharge from the recovery room (Day 0) ] [ Designated as safety issue: Yes ]
  Assess diaphragmatic function by ultrasound imaging
  
  
• Incidence of pneumothorax [ Time Frame: From 5 minutes following induction of anesthesia to immediately before discharge from the recovery room (Day 0) ] [ Designated as safety issue: Yes ]
  Estimate the incidence of pneumothorax by ultrasound imaging
  
  
• Incidence of endobronchial intubation [ Time Frame: From 5 minutes following induction of anesthesia to immediately before discharge from the recovery room (Day 0) ] [ Designated as safety issue: Yes ]
  Estimate the incidence endobronchial intubation by ultrasound imaging
  
  

On arrival in the operating theatre, each patient will undergo a baseline lung ultrasound examination.

The anesthetic technique and monitoring will be standardized. The radial artery will be cannulated after induction of anesthesia for blood gas monitoring.

Lung ultrasound examinations will be performed 5 minutes following induction of general anesthesia and 5 minutes after insufflation of the abdomen with carbon dioxide. In the event of a desaturation needing an intervention (increase of FiO2 or PEEP), ultrasound imaging will be repeated before and after the intervention. Presence of a pneumothorax or endobronchial intubation will be assessed during each examination. Fifteen minutes after arrival and immediately before discharge from the recovery room, lung ultrasound examinations will also be performed.

FiO2 and vital signs will be recorded at each ultrasound examination. Arterial blood samples will be collected simultaneously. Pain rating using the visual analog scale and diaphragmatic function will be assessed during the preoperative ultrasound examination and before discharge from the recovery room.