Previous studies reported that a device-guided slowbreathing (DGB) exercise decreases resting blood pressure (BP) in hypertensive patients. This study investigated the effects of daily practice of DGB on (a) 24-h BP and breathing patterns in the natural environment, as well as (b) BP and breathing pattern during clinic rest. Altogether, 40 participants with pre-hypertension or stage 1 hypertension were trained to decrease breathing rate through DGB or to passively attend to breathing (control, CTL) during daily 15-min sessions. The participants practiced their breathing exercise at home for 4 weeks. The DGB (but not the CTL) intervention decreased clinic resting BP, mid-day ambulatory systolic BP (in women only) and resting breathing rate, and increased resting tidal volume. However, 24-h BP level was not changed by DGB or CTL interventions, nor was overnight breathing pattern. These findings are consistent with the conclusion that a short-term, autonomic mechanism mediated the observed changes in resting BP, but provided no evidence that regular DGB affected factors involved in long-term BP regulation. Additional research will be needed to determine whether 24-h BP can be lowered by a more prolonged intervention.

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.