Respiratory effects on arterial pressure: A novel signal analysis approach

The authors previously determined that the transfer function between broadband respiratory activity and the heart rate (HR) response can be used to elucidate the frequency-dependent phase and magnitude characteristics of the respiratory sinus arrhythmia (RSA). To understand the complex links between respiratory activity and arterial blood pressure (ABP), the authors determined the transfer function between instantaneous lung volume (ILV) and the systolic, diastolic, and pulse pressure (SBP, DBP, and PP) in healthy human volunteers during 6-minute periods in which the respiratory rate was voluntarily controlled in predetermined but erratic fashion. A pharmacologic autonomic blockade was used to separate the direct links between respiration and ABP from the effects of RSA and ABP. Results suggest that with HR fluctuations eliminated, respiration affects ABP in proportion to the rate of change of ILV; however, when neural control of HR remains intact, the RSA plays an important role in the genesis of ABP fluctuations.