A52-07 Successful Use of Prone Positioning as Rescue Therapy for Severe Postoperative Atelectasis

Abstract Introduction Pulmonary atelectasis is a well-recognized postoperative complication, particularly following general anesthesia. It results from a combination of increased pleural pressure, low alveolar pressure, and impaired surfactant function. Atelectasis can lead to respiratory failure, occasionally severe enough to necessitate mechanical ventilation. Standard interventions include early mobilization, chest physiotherapy, and pulmonary toilet, including bronchoscopy. Positive pressure ventilation, employing high tidal volumes, elevated positive end-expiratory pressure (PEEP), and recruitment maneuvers, may also be utilized. To our knowledge, prone ventilation as a therapeutic strategy for postoperative atelectasis has not previously been described. Case Presentation A 39-year-old woman with a history of bronchial asthma underwent elective repair of a non-reducible umbilical hernia under general anesthesia. The procedure was uneventful, and she was extubated to 2 L/min supplemental oxygen via nasal cannula. Within one hour, she developed progressive hypoxemia with decreased bibasilar breath sounds. Chest radiography demonstrated shallow inspiration, and therapy for a possible asthma exacerbation was initiated, including bronchodilators, systemic corticosteroids, incentive spirometry, and ambulation. Over the next 48 hours, hypoxemia worsened, necessitating high-flow nasal cannula. Computed tomography angiography revealed bilateral lower-lobe atelectasis. She was subsequently intubated for bronchoscopy, which demonstrated only thin, white secretions. Lung-protective mechanical ventilation with a PEEP of 15 cm H2O, neuromuscular blockade, and an inspiratory-to-expiratory ratio of 1:1 failed to improve oxygenation despite 100% fraction of inspired oxygen (FiO2). Repeat imaging was unchanged, and echocardiography excluded cardiogenic or shunt-related causes. Prone ventilation was initiated, resulting in rapid and dramatic oxygenation improvement. PEEP and FiO2 were subsequently reduced to 10 cm H2O and 50%, respectively. After 24 hours, she maintained saturations of 100% in the supine position. Over the next 48 hours, ventilatory support was weaned, and she was successfully extubated with oxygen saturations maintained on 3 L/min nasal cannula. Discussion Mechanical ventilation in the prone position is recommended in the treatment of adult patients with acute respiratory distress syndrome (ARDS) due to a demonstrated improvement in oxygenation and mortality. Possible mechanisms include improved ventilation-perfusion matching, increased end-expiratory lung volume, and reduced ventilator-induced lung injury through more uniform tidal volume distribution and chest wall mechanics. Although ARDS criteria were not met, prone positioning was believed to enhance ventilation-perfusion matching and tidal volume distribution, facilitating resolution of atelectasis. Oxygenation improved markedly within hours, underscoring the efficacy of this approach. Conclusion The physiologic mechanisms underlying prone ventilation suggest potential benefit in pulmonary conditions beyond ARDS, including severe atelectasis. This abstract is funded by: None