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1134: MALIGNANT CLOT AN UNUSUAL WAY OF TISSUE DIAGNOSIS OF SQUAMOUS CELL CARCINOMA OF LUNGS

Learning Objectives: We present a case of unilateral pneumothorax as a complication of adaptive support ventilation (ASV) during discontinuation of mechanical ventilation in the setting of lung parenchyma heterogeneity. Methods: A seventy five-year-old woman with history of end-stage renal disease status post renal transplantation on Tacrolimus, Prednisone and Mycophenolate presented with worsening hypoxemic respiratory failure requiring volume-controlled mechanical ventilation in the setting of bilateral and peripherally located lung nodular consolidations and ground-glass opacities. While on lung protective mechanical ventilation, bronchoscopy and bronchoalveolar lavage were performed. Empiric antibiotic treatment was initiated with Vancomycin, Cefepime and Azithromycin, as well as Sulfamethoxazole-Trimethoprim with Prednisone for possible Pneumocystis Jirovecii Pneumonia (PJP). Due to lack of clinical improvement, a chest computed-tomography (CT) was performed on her third day of hospitalization which revealed a large right-sided pneumothorax not previously seen on admission chest CT or daily chest x-rays. Upon review of her mechanical ventilation strategy, the incidental pneumothorax was found a few hours after spontaneous breathing trial while on ASV and Adaptive Pressure Ventilation (APV) resulting in a difference between set (machine-intended) and exhaled tidal volumes ranging ~300–350 milliliters, however, no relevant changes on inspiratory airway pressures were found to indicate complications such as pneumothorax. All infectious workup remained negative and patient underwent a right CT-guided lung biopsy along with chest tube decompression. Unfortunately, she developed hemorrhagic shock secondary to bleeding from the biopsy site resulting in tension hemothorax requiring emergent thoracotomy. Biopsy showed metastatic adenocarcinoma with unknown primary malignancy. Patient developed multiple organ dysfunction syndrome and altered mental status which prompted comfort care measures. Results:Our case illustrates the inability of “smart modes” such as ASV and APV to track changes in regional ventilation and compliance or to account for the influence of respiratory efforts on focal lung stress (transpulmonary pressures) during discontinuation of mechanical ventilation causing a pneumothorax.