睡眠醫學---邪惡軸心 (肥胖、哮喘、睡眠窒息症)

今天肥文(假名)如常回來覆診哮喘，不經不覺原來已認識他廿多年了，他也已由肥仔變成大叔。這些年來肥文不斷增磅，他的哮喘也愈來愈難於處理(1,2) 及多了因哮喘發作入院治療(3)。肥文屬於早發病(early onset asthma)及多附帶特應性疾病(Atopic diseases)的顯型(4)。他對控制發作藥 (controller)的反應也隨體重不斷增加而下降了(5,6)，幸好他對緩解發作藥（reliever）的反應仍算是正常的(7)。

但今天肥文告訴我他新增了許多疑似睡眠窒息症的病徵。看他那龐大身形，其實我一點也不感到意外，只是更擔心他的健康。肥胖、哮喘加睡眠窒息症絕對是一個危機! 肥胖是典型的睡眠窒息症危險因素(8)，但原來哮喘也是鮮為人知的打鼻鼾，日間嗜睡甚至是睡眠窒息症的危險因素(9,10,11)。哮喘病的病史長短也與患上睡眠窒息症的風險成正比(12)。另外睡眠窒息症的病人也較多患上哮喘(13,14) ，並且他們的哮喘更容易發作(15)，更難控制(16)。無論日與夜，他們的哮喘病徵也較多(17)，睡眠窒息症的嚴重程度又同肺功能的衰歇速度有關(18)，真叫人怕怕! 一個超大型的研究(包涵179,789位哮喘病人)發現睡眠窒息症會令因發作入院的哮喘病人需要住院更長，需要接受更多入侵性呼吸治療(19)。

說到這處，肥文已嚇得泠汗直冒!我立時安慰他持續正壓機(continuous positive airway pressure, CPAP) 除了可以治療睡眠窒息症外，亦同時能改善病人的哮喘病徵、減少哮喘發作次數及提昇生活質素(20-22)，上述益處尤以中或嚴重哮喘及嚴重睡眠窒息症的病人最明顯(23)。但歸根究底，認真去減肥才能一併幫助哮喘和睡眠窒息症的，肥文即擰檸頭:「講呢D!」

參孝文獻:

1.    Body mass index and asthma severity in the National Asthma Survey. Thorax. Jan; 2008 63(1):14–20. [PubMed:18156567]

2.    BMI and health status among adults with asthma. Obesity (Silver Spring, Md. Jan; 2008 16(1):146–52.

3.    The relationship between obesity and asthma severity and control in adults. J Allergy Clin Immunol. Sep; 2008 122(3):507–11. e6. [PubMed: 18774387]

4.    Obesity and asthma: an association modified by age of asthma onset. J Allergy Clin Immunol .June;2011 127(6):1486-93

5.    Body mass index and response to asthma therapy: fluticasone propionate/salmeterol versus montelukast. J Asthma. Feb; 2010 47(1):76–82. [PubMed: 20100025]

6.    Comparative effect of body mass index on response to asthma controller therapy. Allergy Asthma Proc. Jan-Feb;2010 31(1):20–5. [PubMed: 20167142]

7.    Impact of obesity on the severity and therapeutic responsiveness of acute episodes of asthma. J Asthma. Aug; 2011 48(6):546–52. [PubMed: 21604921]

8.    Obesity and obstructive sleep apnea: Pathogenic mechanisms and therapeutic approaches. Proc Am Thorac Soc 2008;5:185‑92.

9.    Longitudinal study of risk factors for habitual snoring in a general adult population: The Busselton Health Study. Chest 2006;130:1779‑83.

10.  Findings of a Berlin Questionnaire survey: Comparison between patients seen in an asthma clinic versus internal medicine clinic. Sleep Med 2008;9:494‑9

11.  The prevalence of asthma in patients with obstructive sleep apnoea. Prim Care Respir J 2009;18:328‑30

12.  Association between asthma and risk of developing obstructive sleep apnea. JAMA 2015; 313: 156–64.

13.  Increased prevalence of sleep disturbances and daytime sleepiness in subjects with bronchial asthma: a population study of young adults in three European countries. Eur. Respir. J. 1996; 9: 2132–8.

14.  Obstructive sleep apnea syndrome is common in subjects with chronic bronchitis. Report from the Obstructive Lung Disease in Northern Sweden studies. Respiration 2001; 68: 250–5.

15.  Risk factors of frequent exacerbations in difficult‑to‑treat asthma. Eur Respir J 2005;26:812‑8

16.  National Institutes of Health, National Heart, Lung and Blood Institute Severe Asthma Research Program (SARP) Investigators. Obstructive sleep apnea risk, asthma burden, and lower airway inflammation in adults in the Severe Asthma Research Program (SARP) II. J. Allergy Clin. Immunol. Pract. 2015; 3: 566–75.

17.  Obstructive sleep apnea and inflammation: relationship to cardiovascular co-morbidity. Respir. Physiol. Neurobiol. 2011; 178: 475–81.

18.  Obstructive sleep apnoea accelerates FEV1 decline in asthmatic patients. BMC Pulm. Med. 2017; 21: 55.

19.  Healthcare burden of obstructive sleep apnea and obesity among asthma hospitalizations: results from the U.S.-based Nationwide Inpatient Sample. Respir. Med. 2016; 117: 230–6.

20.  Nocturnal asthma: role of snoring and obstructive sleep apnea. Am. Rev. Respir. Dis. 1988; 137: 1502–4.

21.  Nocturnal asthma: snoring, small pharynx and nasal CPAP. Eur. Respir. J. 1988; 1:902–7.

22.  Effect of nasal continuous positive airway pressure in uncontrolled nocturnal asthmatic patients with obstructive sleep apnea syndrome. Respir. Med. 2005; 99: 529–34.

23.  Asthma outcomes improve with continuous positive airway pressure for obstructive sleep apnea. Allergy 2017; 72: 802–12.

**為保障個人私隱及達到教育效果，因此文中案例可能由真實及/或虛構病例改編而成***