Table 1.
Absolute values of heart rate (HR), mean arterial pressure (MAP), stroke volume (SV), cardiac output (Q), oxyhemoglobin (OHb), deoxyhemoglobin (RHb), total hemoglobin (THb), and tissue O2 saturation (StO2) at baseline and at 100% LBNP tolerance. Δ indicates the absolute changes from the baseline values, while f_ indicates the percentage changes relative to the baseline values.
| Baseline | 100% LBNP Tolerance | p value | |
|---|---|---|---|
| Heart rate (beats/min) | 57.6±2.3 | 104±3 | <0.001 |
| Mean arterial pressure (mmHg) | 96.7±3.4 | 73±1 | 0.012 |
| Stroke volume (ml) | 139.5±14.3 | 84±2 | <0.001 |
| Cardiac output (l/min) | 7.9±0.7 | 4.5±0.5 | <0.001* |
| Lipid fraction (%) | 46.3±5.5 | 48.2±5.3 | 0.464 |
| Water fraction (%) | 49.2±5.9 | 48.3±5.1 | 0.684 |
| Oxyhemoglobin (µM) | 50.6±5.9 | 37.9±4.3 | 0.098 |
| Deoxyhemoglobin (µM) | 13.4±2.0 | 12.2±2.1 | 0.678 |
| Total hemoglobin (µM) | 64.1±7.8 | 50.1±6.0 | 0.171* |
| Tissue O2 saturation (%) | 79.7±1.2 | 76.0±1.7 | 0.095* |
| Δ Tissue O2 saturation (%) | −0.1±0.2 | −3.9±0.9 | <0.001* |
| f_oxyhemoglobin (%) | 0.5±0.3 | −24.7±2.8 | <0.001 |
| f_deoxyhemoglobin (%) | 0.8±0.9 | −9.9±7.1 | 0.150 |
| f_total hemoglobin (%) | −0.3±0.4 | −21.6±3.2 | <0.001* |
*
Q, THb, and StO2 are derived variables.