Slow-Paced Breathing and Autonomic Function in People Post-stroke.

Mia Larson,Ninitha Asirvatham-Jeyaraj,Manda L Keller-Ross,Ann Van De Winckel,Daniel P Chantigian

doi:10.3389/fphys.2020.573325

Mia Larson, Ninitha Asirvatham-Jeyaraj + Show 3 more

Open Access

https://doi.org/10.3389/fphys.2020.573325

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Abstract

Purpose: To determine if acute slow breathing at 6 breaths/min would improve baroreflex sensitivity (BRS) and heart rate variability (HRV), and lower blood pressure (BP) in adults after stroke.Methods: Twelve individuals completed two randomized study visits where they performed a 15-min bout of breathing exercises at 6 breaths/min (slow) and at 12 breaths/min (control). Continuous BP and heart rate (HR) were measured throughout, and BRS, BRS response to elevations in blood pressure (BRSup), BRS response to depressions in blood pressure (BRSdown), and HRV were calculated and analyzed before (pre), during, and after (post) breathing exercises.Results: BRS increased from pre to post slow breathing by 10% (p = 0.012), whereas BRSup increased from pre to during slow breathing by 30% (p = 0.04). BRSdown increased from pre to post breathing for both breathing conditions (p < 0.05). HR (control: Δ − 4 ± 4; slow: Δ − 3 ± 4 beats/min, time, p < 0.01) and systolic BP (control: Δ − 0.5 ± 5; slow: Δ − 6.3 ± 8 mmHg, time, p < 0.01) decreased after both breathing conditions. Total power, low frequency power, and standard deviation of normal inter-beat intervals (SDNN) increased during the 6-breaths/min condition (condition × time, p < 0.001), whereas high frequency increased during both breathing conditions (time effect, p = 0.009).Conclusions: This study demonstrated that in people post-stroke, slow breathing may increase BRS, particularly BRSup, more than a typical breathing space; however, paced breathing at either a slow or typical breathing rate appears to be beneficial for acutely decreasing systolic BP and HR and increasing HRV.

Highlights

More than 7 million Americans, equating to 2.8% of the population in the United States, suffer from a stroke during their lifetime (Benjamin et al, 2018)
Reduced cardiac baroreflex sensitivity (BRS) increases the likelihood of developing arrhythmias, which occur in approximately 19% of patients post-stroke, 4% of which are fatal (Billman et al, 1982; Soros and Hachinski, 2012)
Two leading contributors to stroke, atherosclerosis and hypertension, are both diseases accompanied by autonomic dysfunction, in which they exhibit an increase in sympathetic activity and a decrease in BRS and parasympathetic function (Yperzeele et al, 2015)

Summary

Introduction

More than 7 million Americans, equating to 2.8% of the population in the United States, suffer from a stroke during their lifetime (Benjamin et al, 2018). Autonomic dysfunction is common in people with stroke demonstrated by an attenuated heart rate variability (HRV) and impaired baroreflex sensitivity leading in part to decreased vagal modulation and increased. Paced-Breathing and Autonomic Function After Stroke sympathetic modulation (Nayani et al, 2016). Autonomic dysfunction increases risk for infarct expansion, cardiovascular complications, and poorer prognosis at 1 year post-stroke (Nayani et al, 2016). Autonomic regulation of blood pressure (BP) occurs by modulation of heart rate (HR) and cardiac output, via both parasympathetic and sympathetic activity and alterations to vascular reactivity via sympathetic activity. Reduced cardiac BRS increases the likelihood of developing arrhythmias, which occur in approximately 19% of patients post-stroke, 4% of which are fatal (Billman et al, 1982; Soros and Hachinski, 2012)

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