Table 1.
Various cardiovascular and respiratory variables at baseline and after 4- and 3.5-h head-down tilt
| Baseline (before −6°) | −6° | Baseline (before −12°) | −12° | Baseline (before −18°) | −18° | Baseline (before −12° +1% CO2) | −12° + 1% CO2 | |
|---|---|---|---|---|---|---|---|---|
| MAP, mmHg | 73.17 ± 10.83 | 87.92 ± 11.18‡ | 75.3 ± 13.7 | 84.72 ± 14.32† | 70.95 ± 7.16 | 82.13 ± 10.77† | 76.85 ± 12.08 | 84.02 ± 12.22 |
| SBP, mmHg | 123.29 ± 17.37 | 140.98 ± 14.67‡ | 125.33 ± 9.94 | 138.15 ± 15.88* | 124.67 ± 11.38 | 131.49 ± 20.28 | 134.38 ± 14.7 | 135.85 ± 15.98 |
| DBP, mmHg | 56.28 ± 9.07 | 68.71 ± 9.69‡ | 58.77 ± 13.44 | 66.06 ± 13.17 | 53.28 ± 6.81 | 64.99 ± 9.08‡ | 59.3 ± 11.38 | 66.5 ± 10.51 |
| HR, beats/min | 61.92 ± 9.7 | 60.8 ± 8.14 | 65.06 ± 8.85 | 63.31 ± 11.71 | 59.84 ± 8.23 | 58.01 ± 9.29 | 60.13 ± 9.61 | 60.41 ± 11.87 |
| ETCO2, % | 5.14 ± 0.74 | 4.52 ± 0.56* | 4.98 ± 0.96 | 4.76 ± 0.87 | 4.79 ± 0.97 | 4.67 ± 0.75 | 4.8 ± 0.68 | 5.23 ± 0.75 |
| Minute ventilation, l/min | 7.96 ± 3.12 | 8.17 ± 2.75 | 9.0 ± 3.02 | 9.51 ± 3.66 | 8.52 ± 3.97 | 8.8 ± 4.2 | 8.51 ± 3.98 | 8.17 ± 3.45 |
Values are means ± SD. All baseline measurements were taken in the supine position (0°).
MAP, mean arterial blood pressure; SBP, systolic arterial blood pressure; DBP, diastolic arterial blood pressure; HR, heart rate; ETCO2, end-tidal carbon dioxide.
Difference from baseline:
*
P < 0.05,
†
P < 0.01,
‡
P < 0.001.