During pneumoperitoneum insufflation the insufflated gas increase intra-abdominal pressure. The generated pressure can lead to a different increase in volume depending on the abdominal cavity and patients' characteristics.

The primary objective is to determine the relationship between intraabdominal pressure (IAP) and intraabdominal volume (IAV) during pneumoperitoneum insufflation. The secondary objective is to determine the rate of abdominal-thoracic transmission (ATT) assessing the correlation between IAP and respiratory driving pressure (ΔPRS).

Inclusion Criteria:

• Enrolled one of the three studies (IPPCollapse I, II or III).
• underwent an initial insufflation procedure with a stepwise change in intraabdominal pressure to record Intraabdominal volume
• data from insufflation at 5 cmH2O of PEEP

Patients undergoing pneumoperitoenum insufflation during general anesthesia and mechanical venitlation.