The effect of lung stretch during sleep on airway mechanics in overweight and obese asthma

Association of the Time to First Cigarette and the Prevalence of Chronic Respiratory Diseases in Chinese Elderly Population

BACKGROUND

Increasing number of studies has suggested the time to first cigarette after waking (TTFC) have significant positive effect on respiratory diseases. However, few of them are focused on Chinese population. This study aims to estimate the impact of TTFC on the prevalence of chronic respiratory diseases (CRD) in Chinese elderly and explore the association in different sub-populations.

METHODS

Cross-sectional data of demographic characteristics, living environment, smoking-related variables, and CRD were drawn from the Chinese Longitudinal Healthy Longevity Survey in 2018. Multivariate stepwise logistic regression analyses were conducted to examine the association of the TTFC with the prevalence of CRD.

RESULTS

This study includes 13208 subjects aged 52 years and older, with a mean age of 85.3 years. Of them, 3779 participants are ex- or current smokers (44.9% had the TTFC ≤30 minutes, 55.1% >30 minutes) and 1503 have suffered from CRD. Compared with non-smokers, participants with TTFC ≤30 minutes seemed to have higher prevalence of CRD (OR 1.97; 95% CI, 1.65-2.35) than those with TTFC >30 minutes (OR 1.70; 95% CI, 1.44-2.00), although the difference was statistically insignificant (P_interaction=0.12). Compared with TTFC >30 minutes, TTFC ≤30 minutes could drive a higher prevalence of CRD among female participants, those aged 90 years and older, urban residents, and those ex-smokers (P_interaction<0.05).

CONCLUSIONS

Shorter TTFC relates to higher prevalences of CRD in Chinese older females, those aged 90 years and older, urban residents, and ex-smokers. Delaying TTFC might particially reduce its detrimental impact on respiratory disease in these specific subpopulations.

Nocturnal bilevel positive airway pressure for the treatment of asthma

Nocturnal worsening of asthma may be due to reduced lung volumes and fewer sigh breaths, which have been shown to increase airway resistance and bronchoreactivity. We hypothesized that mimicking deep inspiration using nocturnal mechanical support would improve symptoms in patients with asthma. Subjects with asthma underwent usual care and bilevel positive airway pressure (PAP) therapy for 4 weeks, separated by 4 weeks, and methacholine challenge (PC20) and subjective assessments. 13 patients with asthma alone and 8 with asthma + OSA completed the protocol. Change in bronchoreactivity (ratio of Post/Pre PC20) was not significantly different during usual care and bilevel PAP [0.86 (IQR 0.19, 1.82) vs 0.94 (IQR 0.56, 2.5), p = 0.88], nor was the change in Asthma Control Test different: 0.1 ± 2.2 vs. -0.2 ± 2.9, p = 0.79, respectively. Bilevel PAP therapy for four weeks did not improve subjective or objective measures of asthma severity in patients with asthma or those with asthma and OSA, although there was heterogeneity in response.

Effects of Coexisting Asthma and Obstructive Sleep Apnea on Sleep Architecture, Oxygen Saturation, and Systemic Inflammation in Women

STUDY OBJECTIVES

Both asthma and obstructive sleep apnea (OSA) are strongly associated with poor sleep. Asthma and OSA also have several features in common, including airway obstruction, systemic inflammation, and an association with obesity. The aim was to analyze the effect of asthma, OSA, and the combination of asthma and OSA on objectively measured sleep quality and systemic inflammation.

METHODS

Sleep and health in women is an ongoing community-based study in Uppsala, Sweden. Three hundred eighty-four women ages 20 to 70 years underwent overnight polysomnography and completed questionnaires on airway diseases and sleep complaints. C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor α were analyzed.

RESULTS

The group with both asthma and OSA had higher CRP, higher IL-6, a longer sleeping time in stage N1 sleep and stage N2 sleep, and less time in stage R sleep than the control group with no asthma or OSA. The group with both asthma and OSA had lower mean oxygen saturation (93.4% versus 94.7%, P = .04) than the group with OSA alone. The results were consistent after adjusting for age, body mass index, and smoking status. Asthma was independently associated with lower oxygen saturation, whereas OSA was not.

CONCLUSIONS

Our data indicate that coexisting asthma and OSA are associated with poorer sleep quality and more profound nocturnal hypoxemia than either of the conditions alone. The results are similar to earlier findings related to OSA and chronic obstructive pulmonary disease, but they have not previously been described for asthma.

The overlaps of asthma or COPD with OSA: A focused review

Asthma, chronic obstructive pulmonary disease (COPD) and obstructive sleep apnoea (OSA) are the most common respiratory disorders worldwide. Given demographic and environmental changes, prevalence for each is likely to increase. Although exact numbers are not known, based on chance alone, many people will be affected by both lower airways obstruction and concomitant upper airway obstruction during sleep. Some recent studies suggest that there is a reciprocal interaction, with chronic lung disease predisposing to OSA, and OSA worsening control and outcomes from chronic lung disease. Thus, the combination of wake and sleep respiratory disorders can create an overlap syndrome with unique pathophysiological, diagnostic and therapeutic concerns. Although much work needs to be done, given the above, Respirologists, Sleep Medicine and Primary Care providers must be vigilant for overlap syndromes. Accurate diagnosis of, for example, OSA as a cause of nocturnal symptoms in a patient with asthma is likely to limit further ineffective titration of medications for asthma. Moreover, prompt treatment of OSA in the overlap syndromes will not only offer symptomatic benefit of OSA, but also improve symptoms and healthcare resource utilization attributable to obstructive lung disease, and in COPD, it may reduce mortality.

Innovative exhaled breath analysis with old breathing manoeuvres-is there a problem or an advantage?

As the field of exhaled breath research is expanding, the question that arises is can the old usual method of spirometry be used in all cases? The answer is yes for some analysation methods and definitely not for others: it all depends on the result you are looking for. Exhaled breath condensate collection can be accomplished with silent tidal breathing, but not in the analysation of the amount of exhaled particles, as they become very low during tidal breathing. There are gases that are exhalation flow dependent, e.g. nitric oxide, acetone and ethanol, that require a special breathing manoeuvre with flow control. Physiological changes of the lung, i.e. inhalation to total lung capacity or forced exhalation such as during spirometry, will affect the result of exhaled biomarkers. The standardisation of exhaled breath requires further development, and there are many aspects to consider.

Variability of respiratory mechanics during sleep in overweight and obese subjects with and without asthma

Variability of respiration may provide information regarding disease states. We sought to characterize variability of ventilation and resistance in healthy and asthma, to determine how respiratory control may be altered in sleep and with bi-level positive airway pressure (BPAP). Overweight and obese subjects with and without asthma were studied during sleep at baseline and with BPAP, while measuring respiratory system resistance (Rrs) continuously. Stable periods (>20min) of wake, NREM, and REM sleep were identified and correlation metrics of respiratory parameters were calculated, including coefficient of variation (CV). Variability of Rrs was also characterized over short time scales (20 breaths) during sleep and defined as either "leading to arousal" or "not leading to arousal". Data from 10 control and 10 subjects with asthma were analyzed. CV of Rrs was decreased in asthma at baseline (p<0.001) and decreased on BPAP as compared to baseline (p<0.001). Long time scale correlations were found in respiratory parameters, but the degree of correlations was decreased from wake to sleep (p<0.05). The variance and CV of Rrs was increased preceding an arousal from sleep at baseline; however, during BPAP, the CV was decreased and was not increased preceding arousals. At baseline, resistance was greater in those with asthma, but variability was smaller. BPAP reduced both resistance and overall variability. We conclude that the BPAP-induced decrease in variability may indicate that those with asthma are more likely to remain in a low resistance state, and that low resistance variability may reduce arousals from sleep.