Table 3. Estimated marginal means, F values, and CIs of heart rate, blood pressure, peripheral and regional brain saturations, end tidal CO2, calculated oxygen content, transcranial doppler, MRA-measured velocities and ultrasound and MRI-measured diameters, calculated flows, and calculated oxygen delivery.
| Normoxia | 90 minutes Hypoxia | 180 minutes Hypoxia | Sig | |
|---|---|---|---|---|
| Pulse (beats/min) (CI) | 58.00 (46.99–69.01) | 62.71 (53.39–72.04) | 64.14 (55.03–73.26) | 0.27 |
| Systolic BP (mm Hg) | 115.90 (109.32–122.40) | 113.86 (105.36–122.36) | 114.71 (97.13–132.30) | 0.67 |
| Diastolic BP (mm Hg) | 68.00 (58.95–77.05) | 62.86 (59.30–66.42) | 66.57 (55.54–77.61) | 0.167 |
| SaO2 (%) | 98.29a (96.06–100.51) | 76.00b (67.66–84.34) | 74.86b (67.55–82.16) | <0.001 |
| rSO2 (mean R&L) (%) | 71.10a (63.58–78.61) | 50.47b (45.92–55.03) | 50.33b (44.62–56.04) | <0.001 |
| End tidal CO2 (kPa) | 5.23a (4.43–6.03) | 2.64b (1.95–3.33) | 2.63b (1.97–3.30) | <0.001 |
| Oxygen content (mL per 100 mLs) | 18.78a (17.84–19.71) | 14.57b (12.51–16.63) | 14.34b (12.53–16.15) | 0.001 |
| TCD-measured MCAv (cm/s) | 65.23a (48.36–82.10) | 74.29b (55.60–92.98) | 71.60a,b (51.51–91.68) | 0.004 |
| MRA-measured MCAv (cm/s)§ | 32.80 (21.61–43.99) | — | 38.75 (27.25–50.35) | 0.006 |
| TCD-measured diameter (mm) | 5.44a (5.17–5.70) | 6.23b (5.67–6.78) | 6.28a,b (5.61–6.95) | 0.021 |
| MRA-measured diameter (mean R&L) (mm)§ | 3.04a (2.79–3.29) | — | 3.27b (3.01–3.53) | 0.006 |
| TCD calculated flow (mL/s) | 14.83a (12.34–17.31) | 22.07b (18.31–25.84) | 21.87b (15.90–27.84) | 0.002 |
| MRA calculated flow (mL/s)§ | 2.33a (16.54–29.98) | — | 3.23b (22.75–41.76) | 0.013 |
| TCD calculated O2 delivery (mLsO2/s) | 2.77 (2.38–3.15) | 3.18 (2.63–3.74) | 3.15 (2.15–4.14) | 0.184 |
| MRA Calculated O2 delivery (mLsO2/s)§ | 0.44 (0.32–0.55) | — | 0.45 (0.32–0.59) | 0.586 |
BP, blood pressure; CI, confidence interval; MCA, middle cerebral artery; MRA, magnetic resonance angiography; MRI, magnetic resonance imaging; TCD, Transcranial Doppler.
§No MRI studies done at 90 minutes of hypoxia.
Note: altitudes with the same superscript letter do not differ significantly (i.e., they belong to a homogenous subset).