睡眠醫學- 中樞神經性睡眠窒息症

數年前心臟科同事轉介了一個心臟衰歇的病人(黃先生,假名)給我匯診，他之前已患上阻塞性睡眠窒息症(OSA)及使用自動連續正氣壓機(AUTO-CPAP)，但隨著他心臟衰歇變壞，他的睡眠質素也變得甚差。所以我安排了黃先生再進行睡眠測試(Polysomnography,PSG)，結果顯示他同時患上中樞神經性睡眠窒息症( Central Sleep Apnea, CSA)，這窒息症是由於腦部中樞神經受不明因素影響，未能有效地把呼吸訊號送到有關的器官和組織，令患者在睡眠期間出現呼吸暫停的情況。

這種因心臟衰歇引起的CSA十分特別，他的呼吸模式有點像波浪一般(the breathing cycle has long crescendo decrescendo arms, Cheyne-Stokes breathing)，因而有人譯它作潮式呼吸(1,2)。心臟衰歇病人患上睡眠窒息症是相當普遍的:一個包涵1250個病人的研究數據(3-7)顯示，其中52% 病人有中等至嚴重的睡眠窒息症、31% 病人有中樞神經性睡眠窒息症及21% 病人有阻塞性睡眠窒息症。

心臟科同事用盡了一切藥物治療黃先生，可惜他的心臟衰歇情況實在太差，因而他需要進行心臟再同步化治療(Cardiac Resynchronization Therapy, CRT)，只不過CRT的費用達港幣十四萬之高，所以等候官方批淮的時間甚長。我大膽使用了Adaptive Servo-Ventilation(ASV)來控制黃先生的潮式呼吸(Cheyne-Stokes breathing)(8)，幸好他的病情在使用ASV後得到大幅改善；最終，黃先生亦完成了CRT治療。

他的心臟衰歇不但受到控制，潮式呼吸亦消失了，黃先生也可以用回自己的自動連續正氣壓機。在2015年，有學者發現使用ASV可能令某些心臟衰歇病人死亡率上升(9)，那項研究震驚全醫學界，但隨後有不同權威質疑其可信及通用性，亦引發另一研究(Adaptive Servo-Ventilation for Therapy of Central and Obstructive Sleep Apnea in Heart Failure, ADVENT-HF)(10)，但可惜那研究直至筆者執筆時還未完成。

中樞神經性睡眠窒息症亦會發生在病人腦中風後(11)，而且同是潮式呼吸(Cheyne-Stokes breathing)(12)。發生在腦幹及脊髓的疾病同樣可能造成中樞神經性睡眠窒息症(13-16)。由於神經肌肉疾病(neuromuscular disorders) 可以影響呼吸肌(respiratory muscle)、膈神經(phrenic nerve)及肋間神經(intercostal nerve)的功能，因此這組疾病都有可能造成CSA(17)。若果那組病人的腦幹功能仍然正常，使用高低正氣壓機(Bilevel Positive Airway Pressure)就可以控制他們的CSA。然而若病人同時有節律發生(Rhythmogenesis)及上呼吸道阻塞(upper airway obstruction)的問題，醫生就要考慮透過氣管造口術(tracheostomy)來輔助通氣(assisted ventilation) (18-21)。

此外，OSA 和CSA 都可以同時發生在患有巨人症(acromegaly)(22)或甲狀腺功能減退(hypothyroidism) (23)的病人身上。 

整體來說，中樞神經性睡眠窒息症(CSA)遠比阻塞性睡眠窒息症(OSA)複雜得多，成因亦多樣化，因而治療方案也必須對準病因或病理，作出個別處理(individualized )，CSA 往往是醫護人員的挑戰，甚或是病人的噩夢。

 

參考文獻:

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8.    The Treatment of Central Sleep Apnea Syndromes in Adults: Practice Parameters with an Evidence-Based Literature Review and Meta-Analyses. SLEEP 2012;35(1):17-40.

9.    Increased mortality associated with adaptive servo-ventilation therapy in heart failure patients with central sleep apnea in the halted SERVE-HF trial. Can J Cardiol 2015;31:1202-3

10.  ClinicaTrials.gov, Effect of adaptive servo ventilation [ASV] on survival and hospital admissions in heart failure(ADVENT-HF). NCT01128816. Available from https://clinicaltrials.gov/ct2/show/NCT01128816

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13.  Ondine’s curse in association with diabetes insipidus following transient vertebrobasilar ischemia. Clin Neurol Neurosurg 1999;101:196–8.

14. Respiratory control and respiratory sensation in a patient with a ganglioglioma within the dorsocaudal brain stem. Am J Respir Crit Care Med 2000;161:2100–6.

15.  Central sleep apnoea and unilateral diaphragmatic paralysis associated with vertebral artery compression of the medulla oblongata. J Neurol 2003;250:503–5.

16. Chiari type 1 malformation, glossopharyngeal neuralgia and central sleep apnea in a child. J Child Neurol 1996;38:1126–30.

17. Neuromuscular disorders. In: Kryger MH, Roth T, Dement WC, editors. Principles and practices of sleep medicine. 3rd edition. Philadelphia: WB Saunders; 2000. p. 1087–92.

18.  Nocturnal positive pressure ventilation via nasal mask. Am Rev Respir Dis 1987;135:738–40.

19.  Treatmentof respiratory failure during sleep in patients with neuromuscular disease: positive-pressure ventilation through a nose mask. Am Rev Respir Dis 1987;135:148–52.

20.  The effect of non-invasive positive pressure ventilation (NIPPV) on cognitive function in amyotrophic lateral sclerosis: a prospective study. J Neurol Psychiatr 2001;71:482–7.

21. Reversal of sleep-induced hypoventilation and chronic respiratory failure by nocturnal negative pressure ventilation in patients with restrictive ventilator impairment. Am Rev Respir Dis 1987;135:1049–55.

22. Systemic complications of acromegaly: epidemiology, pathogenesis, and management. Endocr Rev 2004;25:102–52.

23. Central sleep apnea in hypothyroidism. Am Rev Respir Dis 1983;127:504–7.

 

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