ACUTE-ONSET ADULT TRACHEOBRONCHOMALACIA. A.C. Sura 1 , M. Ghajarnia 1 , R. Granieri 1 ; 1 University of Pittsburgh, Pittsburgh, PA (Tracking ID #73859) LEARNING OBJECTIVES: 1) To recognize the clinical presentation and diagnostic workup of tracheobronchomalacia in adults. 2) To manage the patient with severe hypoxemia secondary to tracheobronchomalacia. CASE INFORMATION: A 74 year-old male with hypertension and degenerative joint disease presented for preoperative evaluation prior to hip replacement. He endorsed progressively worsening dyspnea with exertion in the past three weeks, orthopnea and lower extremity edema. His oxygen saturation was found to be 69% on room air. He denied fever, chills, chest pain, or chronic cough but endorsed occasional wheezing and cough productive of white sputum in the past two months. He had a distant history of 20 pack-years tobacco use as well as a 50 year history of work in a coal mine. On physical, blood pressure was 147/84, pulse of 69, and respiratory rate of 25; oxygen saturation improved to 91% on non-rebreather facemask. ABG revealed respiratory acidosis with metabolic compensation. The patient developed ventilatory failure with a drop in O2 saturation to 45% and PCO2 of 140. He was intubated, and chest CT revealed left lower lobe collapse. Bronchoscopy showed complete collapse of the left mainstem bronchus. The patient's subsequent hospital course consisted of intermittent respiratory failures requiring repeat intubations. Once extubated, he was maintained on supplemental oxygen and BiPAP. Repeat bronchoscopy found similar findings of flaccid airways. The patient was deemed ineligible for stent placement and high risk for distal collapse given extensive airway involvement. The patient was discharged on oxygen and BiPAP but subsequently weaned off of supplemental oxygen completely. IMPLICATIONS/DISCUSSION: Hypoxemia and hypercarbia refractory to standard treatments for obstructive pulmonary disease may result from airway collapse without any immediately identifiable causes. Well recognized in infants, tracheobronchomalacia (TBM) may also be present in 4.5±15% of all adult patients with respiratory complaints and can mimic chronic bronchitis. It is a disease of middle to late age, more common in males, and in those with a history of chronic respiratory irritation or inflammation but without a clear association to obstructive lung disease. Identified pathology has been limited to a decrease in the longitudinal elastic fibers of the trachea. Bronchoscopy under local anesthesia is the diagnostic gold standard, demonstrating airway narrowing greater than 50% during expiration. Also supportive are pulmonary function tests showing a low FEV1/EIV1 ratio and characteristic notching in the forced expiratory spirogram. Bronchodilators, antibiotics, and mucolytics may be beneficial in patients with concomitant obstructive airway disease or asthma; however, definitive treatment in TBM involves reversing the airway collapse. Avoidance of airway irritants and cough suppression are first line measures. Surgical stenting has been used with success in many cases, but in patients too frail to undergo such procedures or in those with extensive airway involvement, positive airway pressure appears to be the best means of medically managing patients with TBM. Moreover, airway inflammation may play a role in acute airway collapse, and the element of reversibility noted in our patient may point to a role for adjuvant anti-inflammatory medications.