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Effect of continuous positive airway pressure therapy on circadian patterns of cardiac repolarization in patients with obstructive sleep apnoea: data from a randomized trial


Schlatzer, Christian; Bratton, Daniel J; Schwarz, Esther I; Gaisl, Thomas; Pepperell, Justin C T; Stradling, John R; Kohler, Malcolm (2018). Effect of continuous positive airway pressure therapy on circadian patterns of cardiac repolarization in patients with obstructive sleep apnoea: data from a randomized trial. Journal of Thoracic Disease, 10(8):4940-4948.

Abstract

BACKGROUND: Regular airway clearance by chest physiotherapy and/or exercise is critical to lung health in cystic fibrosis (CF). Combination of cycling exercise and chest physiotherapy using the Flutter® device on sputum properties has not yet been investigated. METHODS: This prospective, randomized crossover study compared a single bout of continuous cycling exercise at moderate intensity (experiment A, control condition) vs a combination of interval cycling exercise plus Flutter® (experiment B). Sputum properties (viscoelasticity, yield stress, solids content, spinnability, and ease of sputum expectoration), pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) were assessed at rest, directly and 45 min post-exercise (recovery) at 2 consecutive visits. Primary outcome was change in sputum viscoelasticity (G', storage modulus; G", loss modulus) over a broad frequency range (0.1-100 rad.s- 1). RESULTS: 15 adults with CF (FEV1range 24-94% predicted) completed all experiments. No consistent differences between experiments were observed for G' and G" and other sputum properties, except for ease of sputum expectoration during recovery favoring experiment A. DLNO, DLCO, alveolar volume (VA) and pulmonary capillary blood volume (Vcap) increased during experiment A, while DLCO and Vcap increased during experiment B (all P < 0.05). We found no differences in absolute changes in pulmonary diffusing capacity and its components between experiments, except a higher VA immediately post-exercise favoring Background Obstructive sleep apnoea (OSA) has been proposed as an independent risk factor for sudden cardiac death (SCD). This study takes advantage of a previous randomized trial and seeks to evaluate circadian patterns of the QTc-interval, a marker of cardiac repolarization and biomarker for SCD, in patients with OSA. We hypothesized that patients with OSA would exhibit longest QTc during the night-time and that continuous positive airway pressure (CPAP) therapy would reverse this. Methods One hundred eighteen patients diagnosed with moderate-to-severe OSA were randomized to receive therapeutic or subtherapeutic CPAP for 4 weeks. Of these, 84 had full 24 h-Holter monitoring data at baseline and follow-up. Weighted means of all QTc-intervals were analysed over 24 h, during four time-periods (12 pm-6 am, 6 am-12 am, 12 am-6 pm, 6 pm-12 pm) as well as during each individual hour. A two-sided P value <0.05 was considered to be of statistical significance. Results QTc-intervals at baseline [mean (SD) over 24 h: 407.8 ms (36.6)] were highest from 6 pm-12 pm [411.7 ms (42.0)] and shortest from 6 am-12 am [405.4 ms (39.5)]. Overall 24 h CPAP treatment effect on QTc was -11.3 ms [95% confidence interval (CI), -22.1 to -0.6; P=0.039] and was estimated to be greater from 6 pm-12 pm than from 12 pm-6 am (P=0.068). The CPAP treatment effect on QTc was driven by those patients in the highest QTc decile at baseline (all >430 ms). In these patients, CPAP led to reductions in QTc, allowing reclassification into lower risk-associated values of QTc (<430 ms). Conclusions In this exploratory study, CPAP treatment led to an overall reduction in the QTc-interval compared with subtherapeutic CPAP. This reduction seems more pronounced during evening hours and in patients with a QTc above 430 ms.experiment A (P = 0.032). CONCLUSIONS: The additional use of the Flutter® to moderate intensity interval cycling exercise has no measurable effect on the viscoelastic properties of sputum compared to moderate intensity continuous cycling alone. Elevations in diffusing capacity represent an acute exercise-induced effect not sustained post-exercise.

Abstract

BACKGROUND: Regular airway clearance by chest physiotherapy and/or exercise is critical to lung health in cystic fibrosis (CF). Combination of cycling exercise and chest physiotherapy using the Flutter® device on sputum properties has not yet been investigated. METHODS: This prospective, randomized crossover study compared a single bout of continuous cycling exercise at moderate intensity (experiment A, control condition) vs a combination of interval cycling exercise plus Flutter® (experiment B). Sputum properties (viscoelasticity, yield stress, solids content, spinnability, and ease of sputum expectoration), pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) were assessed at rest, directly and 45 min post-exercise (recovery) at 2 consecutive visits. Primary outcome was change in sputum viscoelasticity (G', storage modulus; G", loss modulus) over a broad frequency range (0.1-100 rad.s- 1). RESULTS: 15 adults with CF (FEV1range 24-94% predicted) completed all experiments. No consistent differences between experiments were observed for G' and G" and other sputum properties, except for ease of sputum expectoration during recovery favoring experiment A. DLNO, DLCO, alveolar volume (VA) and pulmonary capillary blood volume (Vcap) increased during experiment A, while DLCO and Vcap increased during experiment B (all P < 0.05). We found no differences in absolute changes in pulmonary diffusing capacity and its components between experiments, except a higher VA immediately post-exercise favoring Background Obstructive sleep apnoea (OSA) has been proposed as an independent risk factor for sudden cardiac death (SCD). This study takes advantage of a previous randomized trial and seeks to evaluate circadian patterns of the QTc-interval, a marker of cardiac repolarization and biomarker for SCD, in patients with OSA. We hypothesized that patients with OSA would exhibit longest QTc during the night-time and that continuous positive airway pressure (CPAP) therapy would reverse this. Methods One hundred eighteen patients diagnosed with moderate-to-severe OSA were randomized to receive therapeutic or subtherapeutic CPAP for 4 weeks. Of these, 84 had full 24 h-Holter monitoring data at baseline and follow-up. Weighted means of all QTc-intervals were analysed over 24 h, during four time-periods (12 pm-6 am, 6 am-12 am, 12 am-6 pm, 6 pm-12 pm) as well as during each individual hour. A two-sided P value <0.05 was considered to be of statistical significance. Results QTc-intervals at baseline [mean (SD) over 24 h: 407.8 ms (36.6)] were highest from 6 pm-12 pm [411.7 ms (42.0)] and shortest from 6 am-12 am [405.4 ms (39.5)]. Overall 24 h CPAP treatment effect on QTc was -11.3 ms [95% confidence interval (CI), -22.1 to -0.6; P=0.039] and was estimated to be greater from 6 pm-12 pm than from 12 pm-6 am (P=0.068). The CPAP treatment effect on QTc was driven by those patients in the highest QTc decile at baseline (all >430 ms). In these patients, CPAP led to reductions in QTc, allowing reclassification into lower risk-associated values of QTc (<430 ms). Conclusions In this exploratory study, CPAP treatment led to an overall reduction in the QTc-interval compared with subtherapeutic CPAP. This reduction seems more pronounced during evening hours and in patients with a QTc above 430 ms.experiment A (P = 0.032). CONCLUSIONS: The additional use of the Flutter® to moderate intensity interval cycling exercise has no measurable effect on the viscoelastic properties of sputum compared to moderate intensity continuous cycling alone. Elevations in diffusing capacity represent an acute exercise-induced effect not sustained post-exercise.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Pneumology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:August 2018
Deposited On:04 Jan 2019 10:07
Last Modified:25 Sep 2019 00:00
Publisher:AME Publishing Company
ISSN:2072-1439
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.21037/jtd.2018.07.17
PubMed ID:30233868

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