The aim of this study was to differentiate whether lower body positive pressure (LBPP) induced diminution of CBR was associated with the activated IMR or the increased central venous pressure (CVP). Heart rate (HR) and mean arterial pressure (MAP) responses were assessed using a train of pulsatile neck pressure and suction (+40 to -65 torr) in 7 normal healthy male volunteers (age:25±lyr., wt.:82±4.7kg, ht.:179±2cm). The maximal gains of CBR-HR and CBR-MAP were compared during supine rest, LBPP 30 torr, and volume expansion (VE) with 6% dextran in saline by increasing 5.8+0.2% (3.6±0.2 ml/kg, VE-1) and 9.5+0.3% (6.1±0.3 ml/kg, VE-II) of total blood volume, respectively (see table). Though CVP was similarly CVP(mmHg) HR(cbp) MAP(mmHg) CBR-HR(bcm.mmHg) CBR-MAP(mmHg/mmHg) Baseline 6.6±0.8 57 ± 3 93±4 0.45S±0.078 0.313±0.037 LBPP 8.1-tO0.57±3 95±4 0.27210.055- 0.235±0.026VE-I 8.4±0.356±2 88±3 0.424±0.090 0.360±0.122 VE-11 10.2±0.5S9±4 97±3 0.343±0.0840.197±0.063indicates a significant change from the baseline. increased by LBPP and VE-1, LBPP, not VE-I, significantly decreased CBR, indicating that the LBPP induced CVP increase could not exclusively explain the diminished CBR. We concluded that an activated IMR resulted in a reduced CBR Rain.
|State||Published - 1 Dec 1996|