Effect of controlled breathing on short-term cardiovascular variability: An investigation in chronic heart failure patients

Voluntary control of breathing (CB) has been proposed as a means to standardize short-term investigations on cardiovascular variability (CVV). In this study, we assessed the changes induced by CB on ventilatory and cardiovascular parameters in 17 chronic heart failure (CHF) patients. We recorded the instantaneous lung volume (ILV), R-R interval (RR), systolic arterial pressure (SAP) and end-tidal CO₂ (ETCO₂, 10 patients only) during 8 minutes of spontaneous breathing (SB) and 8 minutes of CB at 0.22 Hz. CB caused a 14% reduction in respiratory rate, a 57% increase in tidal volume, a 27% increase in minute ventilation and a 7% decrease in ETCO₂. A negligible change was observed in mean RR and SAP. No significant change was observed in the low-frequency (LF) power of RR and SAP and in baroreflex sensitivity, whereas the high-frequency (HF) power increased markedly. Hence, CB in CHF patients causes a mild hyperventilation but does not seem to influence autonomic cardiovascular control. Only respiratory-related oscillations of CVV signals are affected by CB