Types of instantaneous functional interference effects on the autonomic-cardiovascular response to the simultaneous performance of cold face and active orthostatic tests

摘要

In 25 healthy subjects we assessed the effects of cold face test (CFT), active orthostatic test (AOT) and their simultaneous performance (CFAOT) on: RR intervals (RR), systolic pressure (SP), and peak arterial pressure derivative (dmAP) time series, their instantaneous low- and high-frequency powers, baroreflex sensitivity (BRS) and respiratory sinus arrhythmia sensitivity (RSAS), obtained by a time-frequency distribution. The functional interference effect index (FIEI) of each variable was computed as the CFAOT to CFT+AOT ratio. In relation to CFT+AOT, CFAOT showed: greater initial sympathetic estimators overshoots, associated to greater SP and dmAP increments and RR, BRS and RSAS undershoots, all with FIEI>1; followed by vagal increase and gradual recoveries of BRS, RSAS, sympathetic and cardiovascular estimators with FIEI>1. At the end, all variables but RR presented FIEI<;1. CFAOT initially induces a potentiative sympathetic activation associated to great reductions of RR, BRS and RSAS, and potentiative SP and dmAP increases, followed by potentiative sympathetic recovery and vagal activation with potentiative RR, BRS, RSAS, SP and dmAP gradual recoveries that become suppressive at the end. FIEI of all variables fluctuates between suppressive and potentiative, showing the convergence of autonomic inputs.