Table 1.
Hemodynamic variables
| Variable | Seated | HDT | HDT+CO2 |
|---|---|---|---|
| Stroke volume, mL | 81.9 (71.3–92.6) | 101.2 (90.5–111.9)a | 102.5 (91.8–113.1)a |
| Heart rate, bpm | 58 (52–65) | 48.3 (42–55)a | 48 (41–55)a |
| Cardiac output, mL·min−1 | 4631 (4354–4910) | 4816 (4539–5095) | 4809 (4532–5088) |
| Mean arterial pressure, mmHg | 89 (82–96) | 87 (80–94) | 88 (80–95) |
| Systolic blood pressure, mmHg | 116 (108–125) | 124 (115–133) | 123 (115–132) |
| Diastolic blood pressure, mmHg | 73 (66–81) | 69 (61–76) | 72 (64–79) |
| Pulse pressure, mmHg | 43 (36–51) | 55.5 (48–63)a | 51.4 (44–59)a |
| Common carotid artery flow, mL·min−1 | 680.8 (605.5–756.0) | 630.53 (555.3–705.7)a | 669.3 (594.1–744.5) |
| Mean MCAv, cm·sec−1 | 52.2 (45.63–58.70) | 62 (55.51–68.58)a | 62 (55.55–68.62)a |
| Mean MCAv, % change from seated | – | 20.1 (12.1–28.2) | 19.7 (11.6–27.7) |
HDT, head‐down tilt; MCA, middle cerebral artery. Values are mean (95% CI).
a
P < 0.05 versus Seated. There were no significant differences between HDT and HDT + CO2.