Table 1.
Cardiovascular and respiratory variables during head-up tilt
| Degrees of tilt | Supine | 20 deg | 40 deg | 60 deg | 70 deg | 80 deg |
|---|---|---|---|---|---|---|
| Number of subjects | 9 | 9 | 9 | 9 | 7 | 6 |
| R–R intervals (s) | 1.06 ± 0.18 | 0.98 ± 0.17 | 0.88 ± 0.15 | 0.79 ± 0.12 | 0.81 ± 0.12 | 0.75 ± 0.14 |
| A | AB | BC | CD | CD | D | |
| Systolic pressure (mmHg) | 115.9 ± 13.6 | 122.7 ± 12.6 | 129.3 ± 14.8 | 137.5 ± 12.6 | 138.4 ± 13.8 | 140.6 ± 16.2 |
| A | B | B | C | C | C | |
| Diastolic pressure (mmHg) | 61.6 ± 6.9 | 68.9 ± 7.8 | 77.7 ± 7.9 | 84.6 ± 8.5 | 87.6 ± 9.8 | 89.9 ± 10.3 |
| A | B | C | D | DE | E | |
| Mean pressure (mmHg) | 79.7 ± 7.9 | 86.8 ± 8.4 | 94.9 ± 8.9 | 102.3 ± 8.7 | 104.5 ± 9.3 | 106.8 ± 10.1 |
| A | B | C | D | DE | E | |
| CO2 (%) | 5.1 ± 0.79 | 4.7 ± 0.94 | 4.6 ± 0.99 | 4.4 ± 0.99 | 4.1 ± 1.04 | 3.9 ± 1.20 |
| A | AB | B | B | C | C | |
| Breath number (breaths min−1) | 12.1 ± 0.67 | 12.2 ± 0.86 | 12.3 ± 0.76 | 12.1 ± 0.58 | 12.2 ± 0.68 | 11.8 ± 0.74 |
| A | A | A | A | A | A |
Values are means ± s.d.; means with the same letter are not significantly different across tilt angles.