Dissociation between airway and transpulmonary pressures during external chest wall restriction: a prospective self-controlled physiological study.

Background: External chest wall restriction can alter how airway pressure is transmitted to the lung. This may make airway pressure an unreliable surrogate for lung stress during mechanical ventilation. We aimed to determine whether short-term chest strapping dissociates airway pressure from transpulmonary pressure by increasing chest wall elastance in mechanically ventilated postoperative intensive care unit (ICU) patients. Methods: This was a single-center, prospective, self-controlled physiological study. Postoperative ICU patients receiving invasive mechanical ventilation were screened for eligibility. Ventilator settings were kept constant. A chest strap was tightened for 30 minutes as a model of acute external chest wall restriction. Airway and esophageal pressures were recorded before and during strapping, and transpulmonary pressure (P Results: During strapping, gas exchange and hemodynamics remained stable, whereas peak and plateau airway pressures, along with airway driving pressure (ΔP), increased. End-inspiratory and end-expiratory esophageal pressures rose, while the corresponding P Conclusions: In sedated, volume-controlled postoperative ICU patients undergoing short-term external chest wall restriction, chest strapping increased airway pressures mainly through chest wall loading. Higher airway pressures did not correspond to higher P