Overview
This randomized clinical trial compares two methods of setting positive end-expiratory pressure (PEEP) during general anesthesia in adults undergoing upper abdominal digestive surgery who are at moderate or high risk of postoperative pulmonary complications.
All participants will receive lung-protective mechanical ventilation. Participants will be randomly assigned to one of two groups. In the individualized PEEP group, PEEP will be adjusted to achieve the lowest driving pressure following a lung recruitment maneuver. In the standard PEEP group, PEEP will be fixed at 5 cmH2O.
The main question is whether driving pressure-guided individualized PEEP reduces the proportion of participants who develop one or more postoperative pulmonary complications during the first 7 days after surgery compared with standard PEEP.
Description
Postoperative pulmonary complications are common after upper abdominal surgery and can increase postoperative morbidity and length of hospital stay. Although positive end-expiratory pressure may help prevent alveolar collapse during general anesthesia, a fixed PEEP level may be insufficient for some patients and excessive for others.
Driving pressure is calculated as plateau pressure minus PEEP and reflects the pressure required to deliver the tidal volume to the respiratory system. Individualizing PEEP according to the lowest driving pressure may improve respiratory-system compliance while limiting both alveolar collapse and overdistension.
In this prospective, randomized, controlled, parallel-group trial, eligible participants will be randomly allocated in a 1:1 ratio to either driving pressure-guided individualized PEEP or standard PEEP. In the individualized PEEP group, a lung recruitment maneuver will be followed by a decremental PEEP trial. The PEEP level associated with the lowest driving pressure will be selected, provided that adequate oxygenation and hemodynamic stability are maintained. In the standard PEEP group, PEEP will be maintained at 5 cmH2O. All other aspects of lung-protective ventilation and perioperative care will be standardized between the groups.
Participants and the independent postoperative outcome assessor will remain unaware of treatment allocation. Postoperative pulmonary complications will be assessed from the day of surgery through postoperative day 7.
Eligibility
Inclusion Criteria:
- Age 18 years or older.
- Scheduled for supra-mesocolic upper abdominal digestive surgery.
- American Society of Anesthesiologists (ASA) physical status I, II, or stable III.
- Moderate or high risk of postoperative pulmonary complications, defined by an Assess Respiratory Risk in Surgical Patients in Catalonia (ARISCAT) score of 26 or higher.
- Provision of written informed consent.
Exclusion Criteria:
- Refusal to participate or inability to provide written informed consent.
- Pregnancy.
- ASA physical status greater than III.
- History of acute respiratory distress syndrome.
- Pulmonary hypertension.
- Bronchopleural fistula.
- Chronic obstructive pulmonary disease with severe emphysema.
- Pre-existing cardiac arrhythmia.
- Decompensated heart failure.
- Known condition associated with increased intracranial pressure.
- Intra-abdominal hypertension.
