Characterization of the cardiovascular control during modified head-up tilt test in healthy adult humans

It is unknown whether modified head-up tilt (MTILT) with inclination of the back rest, thigh rest and shank rest of 60, 0 and 15° respectively challenges autonomic control as assessed from beat-to-beat variability of heart period (HP) and systolic arterial pressure (SAP). In 15 healthy adult humans we found that during MTILT the SAP power in the low frequency band increased and baroreflex sensitivity assessed in the high frequency band decreased. Conversely, the HP power in the high frequency band was unmodified. MTILT can be fruitfully exploited to stress sympathetic control directed to vessels in bedridden, uncooperative patients.