Device-guided slow-breathing effects on end-tidal CO₂and heart-rate variability

Abstract

Previous studies have reported that regular practice of a device-guided slow breathing (DGB) exercise decreases resting blood pressure (BP) in hypertensive patients. The performance of DGB is associated with acute decreases in sympathetic vascular tone, and it has been suggested that the decreases in resting BP produced by regular practice of DGB over periods of weeks is due to chronic decreases in sympathetic nervous system activity. However, the kidneys respond to sympathetically-mediated changes in BP by readjusting blood volume levels within a few days. Thus, the mechanism by which DGB could produce long-term BP changes remains to be clarified. Previous research with laboratory animals and human subjects has shown that slow, shallow breathing that increases pCO2 potentiates blood pressure sensitivity to high sodium intake. These findings raise the possibility that deeper breathing during DGB that decreases BP might involve opposite changes in pCO2. The present study tested the hypothesis that performance of DGB acutely decreases a marker of pCO2, end tidal CO2 (PetCO2). Breathing rate, tidal volume, and PetCO2 were monitored before, during, and after a 15 min session of DGB by patients with elevated blood pressure. Blood pressure, heart rate, and heart rate variability (HRV) were also measured under these conditions. A control group was also studied before, during, and after a 15 min session of spontaneous breathing (SB). The DGB group, but not the SB group, showed progressive and substantial increases in tidal volume and low frequency HRV, and decreases in PetCO2 and systolic blood pressure. The PetCO2 effects persisted into the post-task, rest period. The findings are consistent with the hypothesis that habitual changes in breathing patterns of the kind observed during DGB could potentiate an antihypertensive adaptation via effects on pCO2 and its role in cardiovascular homeostasis.

Salbutamol Worsens the Autonomic Nervous System Dysfunction of Children With Sickle Cell Disease

“…The first issue deals with the results of stimulated conditions when compared to the baseline condition. Stimulation by paced ventilation induced an increase in the HRV (increase in Ptot) that was related to LFa that resulted in an increase in the LF/HF ratio as previously evidenced in asthmatic and control subjects using a similar breathing pattern (Anderson et al, 2009;Garcia-Araújo et al, 2015). Stimulation by salbutamol administration induced an increase in HR, a decrease in Ptot and HFa, and an increase in LF/HF ratio as previously demonstrated in asthmatic children (Jartti et al, 1997).…”

The effects of breathing at a frequency of 0.1 Hz on affective state, the cardiovascular system, and adequacy of ventilation

“…They showed that hyperventilation increases levels of affective and physiological arousal (Carter, Suchday, & Gore, 2001;Thyer, Papsdorf, & Wright, 1984;Van de Borne et al, 2000;Wilhelm, Gerlach, & Roth, 2001). Paced breathing at low frequency has been shown to lead to hyperventilation among untrained participants (Anderson, McNeely, & Windham, 2009;Lehrer et al, 1997;Vaschillo, Vaschillo, & Lehrer, 2006). However, previous studies on the affective effects of breathing at 0.1 Hz did not measure adequacy of ventilation.…”

Regular slow-breathing exercise effects on blood pressure and breathing patterns at rest

“…The DGB condition involved the use of a commercially available device (RESPeRATE, Lod, Israel) that guides breathing by auditory stimulation. 12 The device includes a microcomputer that is connected to a band worn around the torso and a set of earphones. The band senses individual breathing rhythm, and calculates an initial rate to which the subject entrains breathing cycle in accord with a series of ascending and descending tones presented over the earphones.…”

“…Previous studies of DGB have found not only that tidal volume increases as breathing rate falls, but also that end tidal CO 2 (PetCO 2 ) decreases, apparently because of improved gas transfer associated with deeper breathing. 12 To date, however, no studies have examined possible changes in resting breathing rate, tidal volume, minute ventilation or PetCO 2 in response to regular practice of DGB. If PetCO 2 chronically decreased in response to regular DGB, long-term effects on BP could involve alterations in blood gases and acid-base balance that alter total body sodium levels.…”