A case of unusually long apnoea in a young man with obstructive sleep apnoea

Sir,

Obstructive sleep apnoea (OSA) is characterized by extended episodes of complete cessation of breathing for more than 10 seconds. OSA is a major risk factor for the development of cardiovascular complications, hypertension (HTN), stroke and neuropsychological impairments due to prolonged oxygen deprivation. Prolonged apnoea exceeding 30 seconds or more has been associated with a higher risk for HTN.[1] Here, we report a case of OSA with exceptionally prolonged obstructive breathing events throughout the diagnostic sleep study. A 32-year-old man, with a body mass index (BMI) of 49 Kg/m² having type II diabetes mellitus (T2DM) and HTN presented with a 2-year history of sleep disturbance, loud snoring, witnessed apnoeas, choking and excessive daytime sleepiness {Epworth Sleepiness Score (ESS) 12 (normal ≤10)}. He also had a history of two roadside accidents while driving due to sleepiness. He also had nocturia, sleep talking, history of nightmares and symptoms of depression. He usually sleeps around 12 a.m. and awakes at 7 a.m. He did not have any history of cataplexy, sleep attacks, hypnagogic hallucinations, sleep paralysis and restless leg syndrome. Physical examination revealed macroglossia and modified Mallampati class III. The patient was on metformin twice a day for DM. In spite of taking telmisartan hydrochlorothiazide (40/12.5 mg) and cilnidipine (10 mg) for HTN, his blood pressure was high (158/90 mm of Hg). Spirometry and thyroid function tests and arterial blood gas analysis were normal. An overnight level I polysomnography showed severe OSA with an apnoea-hypopnoea index of 108/hr. One of the obstructive apnoeas lasted 188 seconds [Figure 1]. It was associated with desaturation (decreased SPO₂ from 92% to 55%). During this event, electrocardiogram (ECG) heart rate increased from 84 to 140. During manual titration of this patient, continuous positive airway pressure (CPAP) was ineffective in abolishing events, and optimal titration could be achieved only at bilevel positive airway pressure (BiPAP) (inspiratory positive airway pressure (IPAP) 29 and expiratory positive airway pressure (EPAP) 20). His symptoms of nocturia and excessive sleepiness improved (ESS 3), after using BiPAP. This patient experienced exceptionally long apnoea episodes, with the longest reaching 188 seconds. This is one of the longest apnoeic episodes reported in India and among a few reported worldwide. Previously, three reported cases of prolonged apnoea had a duration of 220 to 275 seconds.[2,3] These cases had underlying causes, such as opioids and autonomic dysfunction, which was reported to be the reason for these prolonged events. However, in our case, no such cause was evident. Longer apnoea leads to deeper oxygen desaturations and increased sympathetic activation. Patients with longer apnoea duration in OSA have more severe HTN compared to those with shorter duration of apnoea.[4]

Figure 1.

A 5-minute tracing depicting an obstructive apnoea of 188 seconds followed by an oxygen desaturation from 92 to 55% in stage N2 sleep

This case emphasizes the importance of addressing prolonged apnoeas in OSA patients. The impact of exceptionally long apnoea events on cardiovascular health and overall well-being should not be underestimated, as OSA poses a significant threat to health.

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