DON’T FORGET TO BREATHE: A CASE OF HYPOXEMIA AFTER CAROTID BODY RESECTION

Abstract

SESSION TITLE: Pulmonary Physiology SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Carotid body tumors (CBTs) are paragangliomas, slow-growing neuroendocrine tumors that secrete catecholamines. Management involves surgical resection or radiation. Although chronic hypoxia has been identified after resection of these tumors, the effects of altitude on oxygenation in these patients has not been well-described. We present a case of chronic hypoxia in a patient after bilateral CBT resection. CASE PRESENTATION: A 72 year-old male with a personal and family history of bilateral CBTs presented for evaluation of hypoxia. He underwent resection of these tumors one year prior to presentation. Final tissue exam identified benign carotid body paragangliomas. He had a significant history of tobacco use but had quit 5 years prior. Given his new hypoxia, he underwent evaluation for COPD. Review of systems was notable for dyspnea with heavy exertion but he was otherwise without respiratory complaints. He lived at 1200m above sea level without significant dyspnea, but frequently traveled to 2500m above sea level where his dyspnea would worsen. On exam his baseline SpO2 was 90-91%, but increased quickly to 97-98% with frequent deep breaths. Due to concern for COPD, pulmonary function testing (PFT), plethysmography and DLCO were obtained and all normal. 6MWT was significant for desaturations that improved with 2-3L/min of supplemental O2. ABG showed minimal hypoventilation with a PaCO2 42mm Hg at rest. Overnight oximetry showed mild sustained hypoxemia. CT chest, PET and a V/Q scan were obtained and were all unremarkable. The patient was started on 2-3L/min of supplemental O2 with ambulation and sleep. At one year follow-up he reported control of his dyspnea even at high altitudes. DISCUSSION: The effects of ventilatory control in patients after bilateral carotid-body resection has been previously described. It is theorized that the carotid bodies are responsible for the hyperpnea that results from hypoxia; the aortic chemoreceptors to a much lesser extent. Brainstem respiratory centers receive afferent impulses from the carotid bodies during hypoxia and hypercapnia to control ventilation by increasing MV. In those who have undergone bilateral carotid body resection, there is minimal to no change in MV during hypoxia. At altitudes higher than 2000m the atmospheric O2 pressure decreases causing chronic hypoxia. This case demonstrates the effects of this reduced atmospheric O2 pressure in a patient that has undergone a bilateral carotid body resection. CONCLUSIONS: Providers should be aware that in patients who have undergone carotid body resection, regulatory control of ventilation is impaired, resulting in diminished increase in MV response to hypoxia. At higher altitudes, this becomes clinically significant due to the reduced atmospheric O2 pressure inspired. Patients with hypoxia after bilateral carotid body resections should be advised to use supplementary O2, especially at high altitudes. Reference #1: Erickson et al. “Benign Paragangliomas.” J Clin Endocrinol Metab. 2001 Nov; 86 (11): 5210-5216. Reference #2: Lugliani et al. “Effect of bilateral carotid-body resection on ventilatory control at rest and during exercise in man,” The New England Journal of Medicine. 1971; 285 (20):1105–1111. Reference #3: Rodríguez-Cuevas et al. "Carotid body tumors in inhabitants of altitudes higher than 2000 meters above sea level.” Head & Neck. 1998; 20:374-378. DISCLOSURES: No relevant relationships by David Dorsey, source=Web Response No relevant relationships by Brian Foster, source=Web Response