An Update on Nocturnal Asthma and the Association With Sleep Disordered Breathing

Christopher J. Lettieri, MD, MAJ, MC, USA

Disclosures

July 21, 2005

In This Article

Introduction

Obstructive sleep apnea (OSA) and nocturnal asthma are 2 distinct disease processes that share similar, often overlapping and confusing symptoms. These disorders may result in fragmented sleep and frequent arousals, with subsequent excessive daytime somnolence.[1,2,3,4,5,6] Similarly, both may manifest with recurrent episodes of choking, coughing, and breathlessness during the sleep period. Both involve repetitive arousals and sleep stage changes associated with functional limitations in airflow and increasing respiratory efforts with resulting desaturation or lability in SpO2 during sleep.[4,6,7] This similarity further adds to the overlapping symptoms and pathogenesis. Common treatments for asthma, such as methylxanthines, beta-agonists, and systemic corticosteroids frequently cause sleep fragmentation leading to nonrestorative sleep, similar to the complaints noted by patients with sleep apnea.[8] Nocturnal asthma and OSA follow similar circadian patterns. Peak expiratory flow rates and the forced expiratory volume in 1 second (FEV1) nadir in the early morning hours.[6,9] Similarly, there are typically more obstructive respiratory events during rapid eye movement (REM) sleep, which predominates during this same time period. Consequently, both disorders classically show an increased number of symptomatic events at the end of the habitual sleep period. Given these similarities, nocturnal asthma is considered by some to be another form of sleep disordered breathing (SDB).

The presence of both SDB and nocturnal asthma in the same individual is not uncommon. This may be due in part to the high prevalence of each disorder in the general population. However, this may also be the result of overlapping pathogenesis. Additionally, both OSA and nocturnal asthma are commonly associated with gastroesophageal reflux disease (GERD), which itself is often worse at night (during recumbent sleep) and can result in similar symptoms independent of these disorders.[10,11,12] These 3 nocturnal entities not only share common symptoms and synergistic manifestations, they may share common etiologies, each contributing to the presence and severity of each other. GERD may result in both upper and lower airway inflammation.[11,12,13] The increased negative inspiratory pressure generated to overcome upper airway obstruction during apneic events may precipitate gastric reflux.[14,15] It has been suggested that both asthma and inhaled corticosteroids may result in pharyngeal muscle dysfunction, predisposing to upper airway obstruction. OSA commonly results in mouth breathing, which can lead to inspiration of dry air and subsequent bronchoconstriction. Sinus disease and nasal congestion are common in patients with both GERD and asthma and can manifest as snoring. In short, each disorder may cause or worsen the others.

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