Table 4.
Cerebral vasomotor reactivity
| Young (n = 12) | Middle aged (n = 14) | Elderly (n = 11) | |
|---|---|---|---|
| Baseline (breathing room air) | |||
| Mean BP (mmHg) | 92 ± 13 | 94 ± 10 | 100 ± 11 |
| Mean MCAV (cm·s−1) | 69 ± 16 | 55 ± 12b | 54 ± 14b |
| PetCO2 (mmHg) | 40 ± 4 | 40 ± 4 | 37 ± 5 |
| Hyperventilation | |||
| Mean BP (mmHg) | 93 ± 14 | 96 ± 11 | 105 ± 10a |
| Mean MCAV (cm·s−1) | 45 ± 10a | 38 ± 6a | 39 ± 8a |
| PetCO2 (mmHg) | 26 ± 3a | 26 ± 3a | 24 ± 4a |
| Inhalation of 5% CO2 | |||
| Mean BP (mmHg) | 96 ± 14a | 105 ± 13a | 114 ± 12a , b |
| Mean MCAV (cm·sec−1) | 97 ± 24a | 80 ± 14a | 83 ± 23a |
| PetCO2 (mmHg) | 50 ± 5a | 54 ± 4a | 51 ± 4a |
| Full range PetCO2 | |||
| ∆ Mean MCAV/∆ PetCO2 (%·mmHg−1) | 3.1 ± 0.7 | 2.8 ± 0.4 | 3.1 ± 0.7 |
Data are presented as mean ± SD. BP, blood pressure; HR, heart rate; CO, cardiac output; MCAV, middle cerebral artery blood flow velocity; PetCO2, end‐tidal CO2 partial pressure.
a
P < 0.05 versus baseline.
b
P < 0.05 versus young.