Recreational amyl nitrate use as a culprit of unexplained hypoxia in a young patient

SESSION TITLE: Pulmonary Physiology Case Report Posters 1 SESSION TYPE: Case Report Posters PRESENTED ON: 10/10/2023 09:40 am - 10:25 am INTRODUCTION: Amyl nitrate, also known as "poppers," has been used recreationally since the 1960s for its euphoric and smooth muscle-relaxing effects. The use of amyl nitrite "poppers" is gaining popularity among the homosexual male population owing to the anal smooth muscle relaxing effects and enhancing sexual pleasure. It can induce methemoglobinemia by converting the Fe2+ iron in normal hemoglobin to its Fe3+ state with resulting cyanosis. We present a rare case of a young male patient with unexplained hypoxia that was related to amyl nitrate abuse. CASE PRESENTATION: A 29-year-old homosexual non-smoker male patient with human immunodeficiency virus (HIV) infection on antiretroviral therapy was referred to our emergency department with low oxygen saturation levels at their primary physician's office on serial occasions for the last 2 weeks. He reported mild exertional dyspnea for 4 weeks but denied other respiratory symptoms or recent travel. The vital signs upon arrival revealed a pulse rate of 94 beats per minute, respiratory rate of 18 breaths per minute, and blood pressure of 153/86 mmHg. The oxygen saturation was 88% on breathing room air on the pulse oximeter. No signs of respiratory distress were noted. The physical examination was essentially unremarkable. Arterial blood gas on breathing room air demonstrated a PH of 7.35, PaCO2 of 42.4 mmHg, PaO2 of 88 mmHg, and HCO3 of 23 mEq/L. Methemoglobin level was within the normal limits (0.8%, normal levels < 3.0%). Comprehensive metabolic panel and blood counts were within normal limits. The patient was placed on 4L supplemental oxygen and was admitted to the intensive care unit for observation. CT chest angiogram ruled out pulmonary embolism. A High-resolution CT scan depicted normal parenchymal lung tissues. HIV viral loading was undetectable and the CD4 count was 803 cells/mm3. Transthoracic echocardiography with bubble studies demonstrated no evidence of intracardiac shunts and pulmonary arterial pressures were within normal ranges. Upon further review, the patient disclosed frequent use of "poppers" for 2 months to relax the anal smooth muscles. The patient's symptoms improved, and oxygen saturation returned to normal on room air. The latter substance use was presumed to be the likely culprit of the low oxygen saturation. The patient was advised to stop using poppers. The patient was discharged in good condition. DISCUSSION: Amyl nitrate use was the likely etiology of the low O2 saturation levels given the temporal association between its use and the onset of symptoms in our patient in the lack of other possible etiologies of hypoxia on serial investigations. The induction of methemoglobinemia represents the key mechanism for amyl nitrite-induced hypoxia. There is no definitive test to detect amyl nitrite in the blood, and intravenous methylene blue is considered the current treatment option for symptomatic patients. CONCLUSIONS: This case highlights the importance of considering amyl nitrite use in the differential diagnosis of unexplained hypoxia in recreational drug users. A detailed history taking is vital in patients with persistent hypoxia with negative diagnostic workup. A normal routine co-oximetry may not completely rule out the possibility of methemoglobinemia as shown in our patient. REFERENCE #1: Olazagasti C, Paralkar J, Vishnevetsky M, Chakravarti A, Sulica R, Favila K. Poppers Not Only Make You High: A Rare Case of Amyl Nitrate-Induced Hypoxia. Chest. 2016 Oct 1;150(4):1108A. REFERENCE #2: Faley B, Chase H. A case of severe amyl nitrite-induced methemoglobinemia managed with methylene blue. J clinic toxicol. 2012;2(4):127-8. REFERENCE #3: Nee R, Fitzgerald M. Two cases of methaemoglobinaemia secondary to amyl nitrate use. Ir Med J. 2014 Feb 1;107(2):48-50. DISCLOSURES: No relevant relationships by Mohammed Elamin Faris No relevant relationships by Harvey Friedman No relevant relationships by ELTAIB SAAD