Table 1.
Haemodynamic and oscillatory responses to LBNP
| Variable | Baseline (n = 20) | LBNP 15 (n = 20) | LBNP 30 (n = 20) | LBNP 45 (n = 18) | LBNP 60 (n = 17) | LBNP 70 (n = 13) | LBNP 80 (n = 7) | Recovery (n = 20) |
|---|---|---|---|---|---|---|---|---|
| HR (bpm) | 63 ± 2 | 64 ± 2 | 69 ± 3 | 76 ± 3* | 90 ± 5* | 97 ± 5* | 102 ± 8* | 59 ± 2 |
| SAP (mmHg) | 128 ± 2 | 126 ± 3 | 122 ± 3* | 120 ± 3* | 115 ± 3* | 110 ± 5* | 114 ± 5* | 132 ± 3* |
| DAP (mmHg) | 75 ± 2 | 75 ± 2 | 75 ± 2 | 77 ± 2 | 77 ± 2 | 76 ± 3 | 81 ± 3 | 81 ± 2* |
| MAP (mmHg) | 94 ± 2 | 93 ± 2 | 91 ± 2 | 92 ± 2 | 90 ± 2* | 88 ± 3* | 92 ± 3* | 101 ± 2* |
| SV (ml) | 96 ± 3 | 91 ± 3 | 79 ± 3* | 68 ± 3* | 55 ± 3* | 45 ± 3* | 37 ± 5* | 97 ± 4 |
| RR (breaths min−1) | 15 ± 1 | 14 ± 1 | 13 ± 1 | 13 ± 1 | 13 ± 1 | 13 ± 1 | 13 ± 2 | 15 ± 1 |
| SAPHF (mmHg2) | 2.4 ± 0.3 | 2.3 ± 0.3 | 2.4 ± 0.3 | 2.6 ± 0.3 | 3.7 ± 0.6 | 4.3 ± 0.7* | 5.3 ± 1.7* | 2.0 ± 0.3 |
| DAPHF (mmHg2) | 0.78 ± 0.12 | 0.84 ± 0.16 | 0.97 ± 0.19 | 1.11 ± 0.18 | 2.00 ± 0.46* | 2.14 ± 0.44* | 2.25 ± 0.72* | 1.56 ± 0.39 |
| DAPLF (mmHg2) | 3.7 ± 0.5 | 5.6 ± 0.8 | 6.5 ± 0.9 | 7.7 ± 1.1* | 12.1 ± 1.6* | 17.1 ± 2.5* | 24.9 ± 2.6* | 4.1 ± 0.9 |
| SAP-MSNA coherence | 0.46 ± 0.03 | 0.50 ± 0.02 | 0.50 ± 0.04 | 0.59 ± 0.04 | 0.60 ± 0.05 | 0.49 ± 0.05 | 0.66 ± 0.04* | 0.42 ± 0.03 |
| DAP-MSNA coherence | 0.47 ± 0.03 | 0.52 ± 0.03 | 0.52 ± 0.04 | 0.62 ± 0.04* | 0.60 ± 0.05 | 0.52 ± 0.05 | 0.68 ± 0.04* | 0.44 ± 0.04 |
HR, heart rate; SAP, systolic arterial pressure; DAP, diastolic arterial pressure; MAP, mean arterial pressure; SV, stroke volume; RR, respiratory rate; SAPHF and DAPHF, spectral power of high frequency (0.15–0.4Hz) oscillations in systolic and diastolic arterial pressure; DAPLF, spectral power of low frequency (0.04–0.15 Hz) oscillations in diastolic arterial pressure.
*
P ≤ 0.045 compared with baseline value.