INTRODUCTION: Amiodarone, a commonly used antiarrhythmic drug, has various side effects, one of which is pulmonary toxicity. Pulmonary toxicity with Amiodarone is usually subacute or chronic. Amiodarone with supplemental oxygen interaction results in rapid progression to respiratory failure in the form of adult respiratory distress syndrome (ARDS). We present a case of ARDS due to Amiodarone and supplemental oxygen interaction.CASE PRESENTATION: 88-year-old male with a medical history of coronary artery disease, paroxysmal atrial fibrillation on long-term amiodarone therapy, hypertension, hyperlipidemia, and melanoma presented to the hospital after a syncopal episode. He passed out while working in his yard, but after regaining consciousness, he was alert and oriented. He was admitted due to cardiogenic syncope resulting from bifascicular block and was planned for permanent pacemaker placement. On admission, he was saturating 94% on room air with stable vitals. Subsequently, his oxygen requirement progressively worsened to the point that he needed BiPAP with 100% FiO2. The respiratory viral panel was negative. Echocardiography showed ejection fraction >70% and moderate concentric left ventricular hypertrophy. CT chest initially showed bronchiectasis with no acute changes. Repeat CT chest showed diffuse ground-glass opacities. Amiodarone was discontinued and the patient was started on steroids, following which his respiratory status and oxygen requirement improved significantly.DISCUSSION: Pulmonary toxicity with amiodarone occurs in 5-10% of cases (1), manifesting as organizing pneumonia, chronic interstitial pneumonitis, solitary pulmonary mass, ARDS, and diffuse alveolar hemorrhage (3). Mechanism of toxicity is unclear, could be due to direct cytotoxicity or hypersensitivity reactions (2). Congestive heart failure, prolonged pump oxygenator time, superimposed pulmonary infection, exposure to high FiO2 are proposed as the factors leading to amiodarone-induced pulmonary toxicity. Amiodarone in lung tissues increases the susceptibility to the toxic effects of oxygen (1). Risk factors for Amiodarone pulmonary toxicity include high daily (>400mg/day) or cumulative (duration >2 months) doses, male gender, age >60 years, and pre-existing lung disease (3). Management includes discontinuation of the drug. However, due to prolonged half-life and accumulation of amiodarone in adipose tissue, the disease may progress initially (2).CONCLUSIONS: Patients on amiodarone should be monitored frequently with chest X-Ray and pulmonary function testing, especially those requiring supplemental oxygen. In case of pulmonary toxicity, amiodarone should be discontinued. Symptomatic patients may benefit from steroid therapy.
