Reducing pulmonary risk during mechanical ventilation under general anesthesia has become a major focus of perioperative medicine because postoperative pulmonary complications remain a significant source of morbidity, postoperative hospitalization, and increased healthcare costs. General anesthesia tends to reduce lung volume, increases the risk of partial lung collapse, and interferes with the body's natural mechanisms for clearing secretions. These changes make the lungs more vulnerable to injury during surgery. Historically, patients were ventilated with relatively large breaths to improve oxygenation, but research has shown that excessive stretching of lung tissue can trigger inflammation and contribute to postoperative respiratory problems. As a result, during general anesthesia, clinicians have increasingly adopted lung-protective ventilation strategies that are designed to minimize stress on the lungs and reduce the risk of pulmonary injury (1).
Current evidence supports the use of lower tidal volumes, typically 6–8 mL per kilogram of predicted body weight, rather than the larger volumes that were once common in the operating room. This approach helps prevent overexpansion of the lungs while maintaining adequate gas exchange. A landmark randomized trial by Futier and colleagues demonstrated that patients undergoing major abdominal surgery who received a protective ventilation strategy consisting of lower tidal volumes, moderate positive end-expiratory pressure (PEEP), and periodic recruitment maneuvers experienced better postoperative lung function and fewer pulmonary complications than patients receiving conventional ventilation (1).
Positive end-expiratory pressure plays an important role in preventing the repeated collapse and reopening of alveoli, the tiny air sacs where oxygen enters the bloodstream. By helping keep alveoli open at the end of exhalation, appropriate levels of PEEP improve oxygenation and reduce strain on lung tissue. However, determining the ideal amount of PEEP remains challenging. The PROVHILO trial found that higher levels of PEEP did not significantly reduce postoperative pulmonary complications when compared with lower PEEP levels in patients already receiving low tidal volume ventilation and were associated with more episodes of low blood pressure during surgery (2).
Another important factor is driving pressure, which reflects the amount of pressure needed to deliver each breath after accounting for PEEP. Lower driving pressures generally indicate that the lungs are receiving ventilation with less mechanical stress. Research suggests that driving pressure may be more closely associated with postoperative pulmonary complications than tidal volume or PEEP alone (3). It is therefore valuable to consider overall respiratory mechanics when adjusting ventilator settings during surgery.
Additional support for lung-protective ventilation comes from a large meta-analysis that found protective ventilation strategies were associated with lower rates of pulmonary complications, including pneumonia and respiratory failure, across a variety of surgical populations (4). Experts also emphasize that ventilation is only one component of pulmonary risk reduction. Careful fluid management, appropriate pain control, and early postoperative mobilization can further decrease the likelihood of respiratory complications (5).
Reducing pulmonary risk during general anesthesia can be achieved by minimizing stress from mechanical ventilation on the lungs while maintaining adequate oxygenation. Lower tidal volumes, individualized use of PEEP, and attention to driving pressure have emerged as key elements of modern lung-protective ventilation. Evidence from clinical trials and meta-analyses suggests that these approaches can reduce postoperative pulmonary complications and improve patient outcomes.