A52-11 A High-Pressure Catastrophe: Bilateral Pneumothoraces, Pneumomediastinum, Pneumoperitoneum, and Subcutaneous Emphysema From Ventilator-Induced Barotrauma

Abstract Introduction Ventilator-induced barotrauma results from alveolar rupture and dissection of air along bronchovascular sheaths, known as the Macklin effect. While pneumothorax and pneumomediastinum are recognized complications, concurrent pneumoperitoneum and diffuse subcutaneous emphysema are exceedingly rare, with only scattered case reports in the literature. Understanding this spectrum is critical to avoid unnecessary surgical intervention and to guide lung-protective strategies. Case Presentation A 37-year-old man with tobacco and polysubstance use (street “Xanax,” fentanyl-laced) was admitted for detoxification. He initially only had mild nausea and headaches but later deteriorated clinically and developed dark brown emesis with suspected aspiration and progressive hypoxemia. Despite high-flow oxygen and non-rebreather mask, he remained tachypneic and desaturated, necessitating emergent intubation for acute hypoxemic respiratory failure. Initial mechanical ventilation required high peak inspiratory pressures to achieve adequate tidal volumes. Although it normalised quickly with increased sedation. His saturation still remained necessitating imaging revealing bilateral pneumothoraces, extensive pneumomediastinum, and pneumoperitoneum without evidence of visceral perforation. Subsequently, diffuse subcutaneous emphysema appeared over the neck and anterior chest. Chest tubes were placed, and he was managed with pressure-controlled ventilation, sedation, and broad-spectrum antibiotics (cefepime, vancomycin, later micafungin and metronidazole). Surgical evaluation favored conservative management. Bronchoscopy demonstrated thick mucoid secretions positive for Staphylococcus aureus; he completed cefazolin, was extubated, transitioned to buprenorphine for withdrawal, and discharged in stable condition. Discussion The coexistence of bilateral pneumothoraces, pneumomediastinum, pneumoperitoneum, and subcutaneous emphysema secondary to ventilator barotrauma is very uncommon. Non-surgical pneumoperitoneum from mechanical ventilation occurs in less than 1-2 % of intubated patients and typically accompanies other forms of extra-alveolar air. The Macklin effect provides a unifying mechanism whereby alveolar rupture allows air to dissect centrally to the mediastinum and inferiorly through diaphragmatic hiatuses into the peritoneal cavity. Recognition of this phenomenon prevents unnecessary exploratory laparotomy and supports conservative management. Conclusion This case illustrates an extreme manifestation of ventilator-induced barotrauma with multi-compartment air dissection. Clinicians should suspect this cascade in any ventilated patient with sudden subcutaneous emphysema and elevated peak pressures. Prompt imaging and adherence to lung-protective ventilation, limiting plateau pressures, avoiding dynamic hyperinflation, and permitting mild hypercapnia are essential for optimal outcomes. This abstract is funded by: None