IT’S ALL IN THE STORY: A MISLEADING CHEST CT

Abstract

SESSION TITLE: Fellows Critical Care Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: An abnormal chest CT is a common reason for pulmonary consultation. There is a wide differential and a thorough history is important in helping to hone in on a diagnosis. Here, we present a case where the floridly abnormal chest CT was misleading. CASE PRESENTATION: The pulmonary team was consulted for an abnormal chest CT with request for bronchoscopy. A 32 yo woman without major past medical history presented to the ED short of breath - she described running for the bus and suddenly not being able to breathe. Labs on arrival significant for lactic and respiratory acidosis, suggesting near respiratory arrest. She improved rapidly with nebulizers, rest, and oxygen, and quickly weaned back to room air; her labs also improved rapidly. Her CXR showed patchy opacities so a chest CT was obtained showing diffuse ground glass opacities (Figure 1). She denied a wide range of exposures. Part of the thyroid obtained on the chest CT looked enlarged; she reported having been told several months ago that her thyroid was enlarged, and on exam it was noticeably large. A CT of the neck showed enlarged thyroid causing compression of the upper airway (Figure 2). We suspected the cause of her abnormal CT to be negative pressure pulmonary edema in the setting of likely upper airway obstruction caused by her enlarged thyroid. The initial ENT consult team did not feel this was related, however a secondary consult with endocrine surgery agreed with immediate resection of the thyroid. The patient was monitored in the MICU with heliox at the bedside, and underwent the resection without complication; she was surprisingly able to be intubated easily. She recovered fully and is now doing well; repeat CXR showed improvement. DISCUSSION: Negative pressure pulmonary edema (NPPE) is most commonly reported in the post-operative period from laryngospasm causing deep inspiration against a closed upper airway.1 This intense negative pressure pulls fluid into the alveolar space. Treatment involves addressing the underlying issue, whether it be laryngospasm or upper airway obstruction, with which the edema should rapidly resolve. Other cases have reported large thyroid masses causing similar presentations.2 Heliox can be used in cases of respiratory distress from narrowed airways, as its properties provide much less turbulent flow.3 It has been used to decrease intubation rates in children with croup, patients with subglottic stenosis, and even in severe asthma exacerbations. CONCLUSIONS: NPPE can cause an extremely abnormal chest CT, though the history and rapid improvement will help rule out other causes and rapidly narrow the differential. Heliox can be used to help improve oxygenation and ventilation in the setting of a narrowed upper airway. Patients improve with treatment of underlying obstruction or laryngopasm. Reference #1: Bhattacharya, M., Kallet, R. H., Ware, L. B. & Matthay, M. A. Negative-Pressure Pulmonary Edema. Chest 150, 927–933 (2016). Reference #2: Goh, K. J., Koh, M. S. & Tay, C. K. The Aftermath of Relieving an Upper Airway Obstruction. A Case of Postobstructive Pulmonary Edema. Am. J. Respir. Crit. Care Med. 198, e106–e108 (2018). Reference #3: Hashemian, S. M. & Fallahian, F. The use of heliox in critical care. Int. J. Crit. Illn. Inj. Sci. 4, 138–142 (2014). DISCLOSURES: No relevant relationships by Catherine Gao, source=Web Response No relevant relationships by Lisa Wolfe, source=Web Response