Breathing rate variability in obstructive sleep apnea during wakefulness

Abstract

Study objectives: Obstructive sleep apnea (OSA) is defined by pauses in breathing during sleep, but daytime breathing dysregulation may also be present. Sleep may unmask breathing instability in OSA that is usually masked by behavioral influences during wakefulness. A breath-hold (BH) challenge has been used earlier to demonstrate breathing instability. One measure of breathing stability is breathing rate variability (BRV). We aimed to assess BRV during rest and in response to BH in OSA.Methods. We studied 62 participants (31 untreated OSA: Respiratory Event Index (REI) [mean±s.d.] 20±15 events/hour, 12 females, age 51±14years, BMI 32±8kg/m 2 ; 31 control: 17 females, age 47±13; BMI 26±4). Breathing movements were collected using a chest belt for 5 minutes rest and during a BH protocol (60 s baseline, 30 s BH, 90 s recovery, 3 repeats). From the breathing movements, we calculated median breathing rate (BR) and interquartile BRV at rest. We calculated change in BRV during BH recovery from baseline. Group comparisons of OSA vs. control were conducted using analysis of covariance (ANCOVA) with age, sex and BMI as covariates.Results. We found 10% higher BRV in OSA vs. control (p<0.05) during rest. In response to BH, BRV increased 7% in OSA vs. 1% in controls (p<0.001). Resting BR was not significantly different in OSA and control, and sex and age did not have any significant interaction effects. BMI was associated with BR at rest (p<0.05) and change in BRV with BH (p<0.001), but no significant BMI-by-group interaction effect was observed. Conclusions.The findings suggest breathing instability as reflected by BRV is high in OSA during wakefulness, both at rest and in response to a stimulus. Breathing instability together with high blood pressure variability in OSA may reflect a compromised cardiorespiratory consequence in OSA during wakefulness.

Interictal respiratory variability predicts severity of hypoxemia after generalized convulsive seizures

“…39 There is evidence for increased variability in patients with obstructive sleep apnea and asthma, as well as patients on methadone maintenance therapy et cetera. 37,40,41 In contrast, low IBI variability is associated with pathological conditions [42][43][44] and is a predictor of failed extubation in mechanically ventilated patients. 45,46 Hence, both increased and decreased variability may be bad in different ways.…”

“…We studied IBI variability as the only measure of respiratory variability; however, there are other parameters that could also be assessed, such as tidal volume, V E , inspiratory time, expiratory time, and inspiratory time to total breath time (duty cycle). The latter has been reported to be altered in OSA patients compared to healthy adults 41 . These measures were not collected when the patients were enrolled in the prospective study.…”

“…The latter has been reported to be altered in OSA patients compared to healthy adults. 41 These measures were not collected when the patients were enrolled in the prospective study. Therefore, they were not available for us to be considered in this study.…”

“…It has been proposed that there is a “normal range” for respiratory variability in healthy subjects 39 . There is evidence for increased variability in patients with obstructive sleep apnea and asthma, as well as patients on methadone maintenance therapy et cetera 37,40,41 . In contrast, low IBI variability is associated with pathological conditions 42–44 and is a predictor of failed extubation in mechanically ventilated patients 45,46 .…”

Role of Nasal Surgery in Adult Obstructive Sleep Apnea: A Systematic Review

“…Breathing dysfunction is estimated to affect 9,5% of the general population. 104 It has been correlated with OSA pathophysiology, specifically with reduced ventilatory control stability, and an elevated loop gain, 105 a non-anatomical contributor trait to OSA. 106…”