Effects of AbClo Fascial Approximation Device in Patients With Open Abdomen on Respiratory Mechanics

Patients who underwent an abdominal surgery and had the abdomen remain open are called to have an "open abdomen". To limit the risk of further widening of their wounds, surgeons can use AbClo, which is a non-invasive abdominal binding device, to keep the abdominal wall together (i.e., approximate the fascia). However, as the device also compresses on the abdomen and adjacent lungs, this study aims: * To assess whether the abdominal binding device causes changes in the pressure compressing the lungs, the lung volume, and the function of the lungs. * To assess whether adjusting the breathing machine can mitigate such negative changes. Participants will already be on the abdominal binding device when joining the study. Measurements on various aspects of the lung function (including its physical properties and capability to oxygenate the blood) will be done before and after adjustment of the abdominal binding device to the pressure (measured in the device itself) recommended by the manufacturer, as well as after the surgery to close the abdomen.

Inclusion Criteria: * Adult patients aged 18 years or older * Patients admitted to an ICU * Patients with postoperative abdominal surgery with open abdomen * Patients treated with AbClo device * Patients intubated and mechanically ventilated * Patients treated with intravenous sedation with a sedation-agitation scale score of 1-3 Exclusion Criteria: * Transient criteria: Patients with severe hemodynamic instability, defined systolic blood pressure less than 75 mmHg or mean arterial pressure less than 60 mmHg despite vasopressor use * Transient criteria: Patients with severe bleeding diathesis, defined as the latest platelet count less than 20 · 109/L, or the latest INR higher than 2.0 * Patients with concurrent injuries to upper gastrointestinal tract that would preclude esophageal balloon insertion * Patients with bronchopleural fistula * Patients with measured and uncontrolled increased intracranial pressure