Device-guided slow-breathing effects on end-tidal CO(2) and heart-rate variability

Area of Science:

• Cardiovascular Physiology
• Respiratory Medicine
• Homeostasis

Background:

• Device-guided slow-breathing (DGB) is linked to reduced resting blood pressure (BP) in hypertensive individuals.
• The long-term mechanisms for DGB's BP-lowering effects, beyond acute sympathetic tone reduction, are unclear.
• Existing research suggests breathing patterns influence BP sensitivity, particularly concerning carbon dioxide (CO2) levels.

Purpose of the Study:

• To test the hypothesis that DGB acutely decreases end-tidal CO2 (PetCO2), a marker of arterial CO2.
• To investigate the relationship between DGB, PetCO2, and cardiovascular parameters like BP and heart rate variability (HRV).

Main Methods:

• Patients with elevated BP performed 15 minutes of DGB or spontaneous breathing (SB) as a control.
• Breathing rate, tidal volume, and PetCO2 were monitored before, during, and after the breathing sessions.
• BP, heart rate, and HRV were also measured throughout the study.

Main Results:

• The DGB group exhibited significant increases in tidal volume and low-frequency HRV.
• DGB also led to substantial decreases in PetCO2 and systolic BP.
• These PetCO2 reductions persisted into the post-exercise rest period.

Conclusions:

• DGB acutely decreases PetCO2 in patients with elevated BP.
• The findings support the hypothesis that DGB's antihypertensive effects may involve modulation of CO2 levels.
• Habitual DGB practice could promote long-term BP adaptation through effects on pCO2 and cardiovascular homeostasis.