SUBGLOTTIC POSITIVE END-EXPIRATORY PRESSURE IN EXTUBATED PATIENTS RECOVERING FROM ACUTE LUNG INJURY

Objective: To examine the glottic function in extubated patients recov ering from acute lung injury by simultaneous measurement of airway ope ning and subglottic airway pressures while patients are breathing at a mbient pressure and receiving continuous positive airway pressure by a face mask. Design: Descriptive, prospective study. Setting: Intensive care unit at a university hospital. Patients: Ten patients who requir ed continuous positive airway pressure of at least 7 cm H2O in order t o restore gas exchange after mechanical ventilation for acute lung inj ury. Interventions: Spontaneous breathing at ambient airway pressure a nd with continuous positive airway pressures of 5 and 10 cm H2O via fa ce mask. Measurements and Main Results: Intratracheal pressure, airway opening pressure, and airflow at the airway opening were measured. Br eathing at ambient pressure resulted in significantly higher end-expir atory intratracheal pressure than end-expiratory airway opening pressu re (p < .01). No significant differences between end-expiratory intrat racheal pressure and end-expiratory airway opening pressure were obser ved during breathing with continuous positive airway pressures of 5 an d 10 cm H2O. A significant end-expiratory airflow at the airway openin g (p < .01), observed during ambient pressure breathing, was not detec table while the patient received mask continuous positive airway press ure. The partial pressure of oxygen in the arterial blood (PaO2) incre ased significantly while patients breathed with 10 cm H2O, but not whi le patients breathed 5 cm H2O continuous positive airway pressure comp ared with breathing at ambient pressure (p < .05). Conclusions: Our da ta imply that patients recovering from acute lung injury create an int ratracheal positive end-expiratory pressure by braking the expiratory airflow, probably by glottic narrowing. Despite compensatory glottic n arrowing, extubated patients with reduced lung function may benefit fr om higher levels of continuous positive airway pressure.