Use of continuous positive airway pressure reduces airway reactivity in adults with asthma

Abstract

Asthma is characterised by airway hyperreactivity, which is primarily treated with β-adrenergic bronchodilators and anti-inflammatory agents. However, mechanical strain during breathing is an important modulator of airway responsiveness and we have previously demonstrated in animal models that continuous positive airway pressure (CPAP) resulted in lower in vivo airway reactivity. We now evaluated whether using nocturnal CPAP decreased airway reactivity in clinically-stable adults with asthma. Adults with stable asthma and normal spirometry used nocturnal CPAP (8–10 cmH2O) or sham treatment (0–2 cmH2O) for 7 days. Spirometry and bronchial challenges were obtained before and after treatment. The primary outcome was the provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (PC20). The CPAP group (n=16) had a significant decrease in airway reactivity (change in (Δ)logPC20 0.406, p<0.0017) while the sham group (n=9) had no significant change in airway reactivity (ΔlogPC20 0.003, p=0.9850). There was a significant difference in the change in airway reactivity for the CPAP versus the sham group (ΔlogPC20 0.41, p<0.043). Our findings indicate that chronic mechanical strain of the lungs produced using nocturnal CPAP for 7 days reduced airway reactivity in clinically stable asthmatics. Future studies of longer duration are required to determine whether CPAP can also decrease asthma symptoms and/or medication usage.

Asthma outcomes improve with continuous positive airway pressure for obstructive sleep apnea

“…Other studies of shorter treatment periods did not found any improvement 33. The relationship between OSAS, obesity, local airways inflammation, and bronchial hyperresponsiveness (BHR) has also been extensively studied, as well as the response after CPAP therapy 33, 34, 35, 36, 37, 38. In patients with asthma, a reduction in BHR has been reported in the majority of studies 34, 35.…”

“…The relationship between OSAS, obesity, local airways inflammation, and bronchial hyperresponsiveness (BHR) has also been extensively studied, as well as the response after CPAP therapy 33, 34, 35, 36, 37, 38. In patients with asthma, a reduction in BHR has been reported in the majority of studies 34, 35. By contrast, in nonasthmatic patients with OSAS, BHR frequently increases 33, 36, although not always 37.…”

“…Improvement of gastroesophageal reflux may also be accompanied by a reduction in nocturnal asthma symptoms 15. Additionally, reduction in bronchial hyperresponsiveness produced by CPAP 34 can be also associated with a clinical improvement of asthma.…”

“…With respect to sham‐CPAP, it is possible, moreover, that this procedure may not be a suitable placebo in patients with asthma. Busk et al 34 studied the effect of CPAP in the short term (7–10 days) on BHR in asthmatic patients with low risk of OSAS. In the control group, with pressures of 0‐2 cmH2O CPAP, the increase in the provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (PC20) was lower than in the group using CPAP therapeutic pressures.…”

“…On the other hand, in patients with OSAS, it has been observed a significant difference after using sham‐CPAP both in the degree of daytime hypersomnia and in several polysomnographic parameters: While hypersomnia improved 42, the quality of the sleep became worse (decreased sleep efficiency, increased time in stage 1 NREM sleep, and prolonged latency to REM sleep) 43. Therefore, taking into account the existing correlations between sleep quality, daytime hypersomnia, quality of life, and asthma control 44, 45, and the potential effect of sham‐CPAP in BHR 34, it cannot be excluded that subtherapeutic CPAP pressures, used as a placebo in asthmatic patients with OSAS, may have relevant effects on asthma outcomes that would distort the results of a controlled study. Finally, there are ethical issues regarding keeping patients with OSAS without active treatment, in patients with two potentially severe diseases.…”