Cardiovascular and cerebrovascular information transfer might depend on the type of conditioning respiratory signal

nformation transferred from heart period (HP) to systolic arterial pressure (SAP) along baroreflex and from mean arterial pressure (MAP) to mean cerebral blood flow (MCBF) along the pressure-to-flow relationship is commonly estimated by conditioning for the respiratory activity. Results might depend on the type of selected respiratory signal. In 18 healthy individuals (age: 28 13 yrs; 5 males) we acquired the spontaneous variability of HP, SAP, MAP and MCBF and two respiratory signals, namely respiratory chest movement (RCM) and end-tidal carbon dioxide (EtCO2). Data were acquired at rest in supine position (REST) and during active standing (STAND). The effect of STAND over the information transfer from MAP to MCBF was similar using RCM or EtCO2, while it was different when information transfer from SAP to HP was evaluated. Changes of the information transfer during STAND suggests that EtCO2 is a weak conditioning signal for the evaluation of information transferred along baroreflex.