What is it about?

A 79-year-old man, who had significant cardiovascular morbidities, presented with out-of-hospital respiratory arrest. He regained breathing after brief cardiopulmonary resuscitation by his paramedic son. Further workup excluded acute cardiovascular events and metabolic causes while features of obstructive sleep apnea were elicited. The findings on in-laboratory polysomnography was compatible with severe obstructive sleep apnea, with unusually prolonged apnea duration of up to 2.7 minutes which most likely accounts for the presentation as ‘respiratory arrest’. Thyroid function test for investigation of his weight gain confirmed hypothyroidism. His symptoms improved gradually after positive airway pressure therapy with bi-level support and thyroxine replacement. On further evaluation, his hypothyroidism was believed to be a complication of long term amiodarone exposure. The case highlights the combination of obstructive sleep apnea and hypothyroidism can lead to catastrophic manifestation and the unusually long apnea could be a feature prompting further workup for possible hypothyroidism.

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Why is it important?

1. Both OSA and hypothyroidism are common medical conditions. They present similarly with tiredness and lethargy. Sinister manifestation and complications may occur when they co-exist. 2. Hypothyroidism is closely linked to OSA, and the relationship is probably bidirectional. 3. Unusually prolonged apnea events and low nadir oxygen saturation characterize the OSA in patients with hypothyroidism.

Perspectives

The case report highlights the need to revisit the role of thyroid function screening in selected OSA population. High index of suspicion should be given to those with unexplained weight gain, excessive sleepiness not correctable by CPAP therapy, presence of systemic symptoms not explainable by OSA, and prolonged respiratory events on polysomnography. Investigations on the pathophysiology underlying the OSA in hypothyroidism, for example high arousal threshold and poor anatomy, will allow more understanding of condition and planning of the best approach to management.

Mei Sze Lui
University of Hong Kong

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This page is a summary of: Respiratory arrest requiring resuscitation as a rare presentation of obstructive sleep apnoea and hypothyroidism, BMJ Case Reports, August 2019, BMJ,
DOI: 10.1136/bcr-2019-230163.
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