1236 A Case of Systemic Amyloidosis and Sleep-Related Hypoventilation

Abstract

Abstract Introduction Amyloidoses are a group of systemic diseases characterized by misfolded protein fragment deposition within the organs, including the heart, kidney, liver, gastrointestinal tract, nervous system, pulmonary system, and soft tissues1. Obstructive and central sleep apnea are known to occur frequently in those with cardiac amyloidosis. This case discusses a patient with systemic amyloidosis and chronic hypercarbic, hypoxic respiratory failure. Report of Case A 66 year old female with a history of systemic amyloidosis, non-ischemic cardiomyopathy, hypertension, and obstructive sleep apnea was admitted for acute on chronic heart failure. Despite intravenous diuresis, she remained hypoxemic, requiring 1 liter per minute of oxygen. She was found to have bilaterally reduced diaphragmatic excursion and a restrictive ventilatory defect on spirometry. She had a preceding history of chronic carbon dioxide retention with elevated CO2 levels for greater than a year (52-74 mmHg). Sleep medicine was consulted to assist in evaluation of the patient’s obstructive sleep apnea and hypoxic, hypercarbic respiratory failure. Baseline polysomnogram revealed sleep related hypoventilation with transcutaneous CO2 (TCO2) ranging between 77-86 mmHg without clear obstructive sleep apnea. A bilevel positive airway pressure (BPAP) titration was then performed (TCO2 54-69 mmHg) and while the patient’s obstructive sleep apnea was well treated, sleep-related hypoventilation and central apneas persisted. Average volume assured pressure support (AVAPS) was initiated for management of sleep related hypoventilation. In follow up, the patient is feeling well, off oxygen, with daytime TCO2 38 mmHg. Conclusion This case demonstrates a rare complication of systemic amyloidosis in the setting of respiratory failure attributed to amyloid infiltration of the diaphragm. In the few previously reported cases of neuromuscular respiratory failure in systemic amyloidosis there is rapid progression and high mortality3, which highlights the importance of assessing for sleep disordered breathing and additional causes of respiratory failure in a patient with a complex systemic disease.