NEGATIVE PRESSURE PULMONARY EDEMA FOLLOWING OUTPATIENT SHOULDER ARTHROSCOPY WITH AN INTERSCALENE BLOCK

Abstract

SESSION TITLE: Medical Student/Resident Critical Care Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Negative Pressure Pulmonary Edema (NPPE) complicated by acute hypoxemic respiratory failure (AHRF) following extubation in patients undergoing elective shoulder surgery is uncommon. We report a case of unilateral NPPE complicated by AHRF requiring emergent reintubation in a patient who received an interscalene block. CASE PRESENTATION: A 50-year-old obese male with history of obstructive sleep apnea (OSA) and unprovoked DVT presented for elective left shoulder arthroscopy. Patient was a difficult intubation, but surgery was otherwise uncomplicated. Following extubation, patient developed hypoxemia requiring noninvasive ventilation (NIV) with transition to bilevel NIV. On post-op evaluation, patient was tachycardic and hypoxemic with bilateral crackles on lung auscultation. A portable chest x-ray showed bilateral alveolar opacities, right greater than left, consistent with pulmonary edema. Given history of unprovoked DVT, a CT pulmonary angiogram (CTPA) was obtained, and patient was transiently placed on a non-rebreather mask for transport. After CTPA, patient developed red frothy sputum, altered sensorium, and worsening hypoxemia. Returning to the ICU, patient had an oxygen saturation of 80%. Rapid sequence intubation was successfully performed on first pass. During intubation patient had a brief episode of PEA arrest requiring CPR and one dose of epinephrine. Mechanical ventilation (MV) with high PEEP and supportive care led to clinical improvement and extubation 36 hours after reintubation. DISCUSSION: NPPE is a post-anesthesia complication occurring in 0.1% of cases. Patient had risk factors for NPPE: male gender, OSA, known difficult airway, and obesity. Patient’s pharyngeal obstruction due to OSA likely caused NPPE. NPPE can be difficult to differentiate from pneumonitis and other causes of pulmonary edema. The anesthesiologist did not observe perioperative aspiration, and patient had a net even fluid balance making cardiogenic pulmonary edema unlikely. In patients with post-op hypoxemia and concern for NPPE, a chest radiograph is the test of choice. NIV and supportive care are the main treatments for NPPE, but some cases require reintubation and MV. Patient’s chest CT showed alveolar opacities much greater on the right than left along with left hemidiaphragm elevation. Interscalene block on the left likely caused left phrenic paresis. The supine position required for CT imaging likely further exacerbated patient’s respiratory failure requiring emergent airway management. CONCLUSIONS: NPPE is a rare life-threatening post-anesthesia complication. Interscalene block can lead to phrenic nerve paresis with resultant diaphragmatic dysfunction. NPPE in the setting of unilateral phrenic nerve paresis has seldom been described. Most patients require NIV; however, some patients need reintubation and a brief period of MV with supportive care. Reference #1: Bhattacharya M, Kallet RH, Ware LB, Matthay MA. Negative-Pressure Pulmonary Edema. CHEST. 2016 Oct; 150 (4): 927-933 Reference #2: Betts A, Eggan JR. Unilateral Pulmonary Edema with Interscalene Block. Anesthesiology. 1998 Apr; 88 1113-4 Reference #3: Mulkey Z, Yarbrough S, Guerra D, Roongsritong C, Nugent K, Phy MP. Postextubation pulmonary edema: a case series and review. Respiratory Medicine. 2008;102 (11):1659 DISCLOSURES: No relevant relationships by Max Barnes, source=Web Response No relevant relationships by Matthew Koroscil, source=Web Response No relevant relationships by Paul Pikman, source=Web Response