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

Abstract

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.

Perspectives of patients and healthcare professionals on mHealth for asthma self-management

“…Other physiological parameters that were identified as being useful included measurements of heart rate, respiratory rate and sleep quality. Given that heart rate variability may be associated with asthma control [24], that respiratory rate variability during sleep may differ between individuals with and without asthma [25], and that nocturnal wakening is a common complaint of individuals with asthma, the potential for these measurements to provide support for asthma self-management warrants further investigation. Each year 5.5 million deaths can be attributed to poor air quality [26], whilst air pollution exposure is associated with increased frequency of asthma attacks in children and adults [27].…”

Correlated Variability in the Breathing Pattern and End-Expiratory Lung Volumes in Conscious Humans

“…Even though several studies investigated the correlation properties of breathing pattern[ 2 – 5 , 7 ], only few addressed the correlation properties of EEV such as functional residual capacity (FRC) in humans, likely because of the difficulties in continuous monitoring. To our knowledge, the only study addressing this issue is by Hlastala et al [ 19 ], in which the authors used a complicated set-up based on total body plethysmography in supine position to record FRC fluctuations and other respiratory parameters in four healthy subjects for 40 min.…”

“…There are several possible reasons for the difference. For example, correlation properties of V T and T i have been shown to depend on sleep stage [ 5 ]. Additionally, the α of respiratory resistance at 8 Hz in human subjects decreased from wake to sleep [ 5 ] suggesting less active brain control of respiratory variables during sleep.…”

“…One of the key life-support control systems of the body is the respiratory system. Many physiological variables associated with breathing such as tidal volume (V T ) or respiratory rate exhibit significant breath-to-breath variabilities [ 2 – 5 ]. While some studies correlated variability and irregularity in breathing pattern with the presence of obstructive lung disease [ 6 ] or the maturation in preterm infants [ 4 , 7 ], the origin of the variabilities is not well understood even in normal subjects.…”

MyAirCoach: the use of home-monitoring and mHealth systems to predict deterioration in asthma control and the occurrence of asthma exacerbations; study protocol of an observational study

“…2 Previous research showed that variability of RR during sleep is different in asthmatics. 48 Additionally, an increased resting RR during the day might also indicate loss of asthma control. Therefore, continuous analysis of RR during the day and while sleeping might prove useful in the prediction of asthma control.…”