Table 2.
Cerebrovascular measurements during poikilocapnic and isocapnic exercise while breathing either normoxia or hyperoxia
| Stage |
||||||
|---|---|---|---|---|---|---|
| Measurement/Condition | BL1 | BL2 | 20 % | 40% | 60% | 80% |
| Poikilocapnia | ||||||
| MCAv,† cm/s | ||||||
| Normoxia | 61 ± 8.4 | 60 ± 9.2 | 65 ± 11* | 67 ± 12* | 70 ± 12* | 75 ± 16* |
| Hyperoxia | 60 ± 8.4* | 55 ± 8.5 | 61 ± 8.7* | 66 ± 14* | 69 ± 12* | 71 ± 14* |
| CVCiMCA, cm·s−1 ·mmHg−1 | ||||||
| Normoxia | 0.71 ± 0.12 | 0.70 ± 0.11 | 0.67 ± 0.10 | 0.66 ± 0.1 | 0.66 ± 0.1 | 0.69 ± 0.1 |
| Hyperoxia | 0.67 ± 0.12* | 0.58 ± 0.09 | 0.63 ± 0.08 | 0.67 ± 0.1* | 0.65 ± 0.12* | 0.64 ± 0.14* |
| QICA, ml/min | ||||||
| Normoxia | 234 ± 64 | 232 ± 66 | 249 ± 76 | 277 ± 79* | 288 ± 80* | 279 ± 97* |
| Hyperoxia | 226 ± 52 | 223 ± 53 | 257 ± 62 | 282 ± 79* | 305 ± 106* | 295 ± 81* |
| ICAdiam, cm | ||||||
| Normoxia | 0.50 ± 0.06 | 0.50 ± 0.06 | 0.50 ± 0.06 | 0.49 ± 0.06 | 0.49 ± 0.06 | 0.47 ± 0.06 |
| Hyperoxia | 0.49 ± 0.06 | 0.48 ± 0.04 | 0.48 ± 0.06 | 0.49 ± 0.06 | 0.49 ± 0.07 | 0.49 ± 0.06 |
| ICAvel, cm/s | ||||||
| Normoxia | 40 ± 9.3 | 39.8 ± 8.7 | 43.4 ± 9.2* | 49.0 ± 10* | 50.5 ± 10* | 53.2 ± 11* |
| Hyperoxia | 39.4 ± 8.1 | 40.0 ± 7.0 | 47.8 ± 7.4* | 50.2 ± 8.3* | 53.2 ± 11* | 53.8 ± 13* |
| CVCiICA, ml·min−1·mmHg−1 | ||||||
| Normoxia | 2.6 ± 0.1 | 2.6 ± 0.7 | 2.5 ± 0.7 | 2.6 ± 0.7 | 2.6 ± 0.7 | 2.4 ± 0.8 |
| Hyperoxia | 2.5 ± 0.6 | 2.5 ± 0.6 | 2.5 ± 0.5 | 2.8 ± 0.6 | 2.7 ± 0.7 | 2.6 ± 0.7 |
| PCAv,† cm/s | ||||||
| Normoxia | 43 ± 6.4 | 42 ± 6.8 | 45 ± 7.4* | 47 ± 7.4* | 48 ± 7.6* | 49 ± 6.8* |
| Hyperoxia | 42 ± 10* | 39 ± 9.7 | 43 ± 13* | 45 ± 13* | 48 ± 16* | 50 ± 17* |
| CVCiPCA,† cm·s−1·mmHg−1 | ||||||
| Normoxia | 0.52 ± 0.12 | 0.51 ± 0.12 | 0.50 ± 0.14 | 0.49 ± 0.14 | 0.48 ± 0.13 | 0.48 ± 0.13 |
| Hyperoxia | 0.48 ± 0.14*† | 0.42 ± 0.12† | 0.45 ± 0.17† | 0.47 ± 0.17* | 0.46 ± 0.18 | 0.46 ± 0.18 |
| QVA, ml/min | ||||||
| Normoxia | 86 ± 31 | 85 ± 34 | 87 ± 35 | 92 ± 38 | 96 ± 44* | 94 ± 38 |
| Hyperoxia | 80 ± 28 | 75 ± 27 | 82 ± 28 | 93 ± 33* | 102 ± 38* | 101 ± 44* |
| VAdiam, cm | ||||||
| Normoxia | 0.36 ± 0.7 | 0.36 ± 0.07 | 0.36 ± 0.07 | 0.36 ± 0.07 | 0.36 ± 0.07 | 0.35 ± 0.07 |
| Hyperoxia | 0.35 ± 0.06 | 0.34 ± 0.06 | 0.34 ± 0.06 | 0.34 ± 0.06 | 0.35 ± 0.06 | 0.34 ± 0.06 |
| VAvel,† cm/s | ||||||
| Normoxia | 29 ± 6.2 | 28 ± 5.6 | 29 ± 5.4 | 30 ± 7.0 | 31 ± 7.2* | 33 ± 8.8* |
| Hyperoxia | 27 ± 5.2 | 27 ± 5.8 | 30 ± 5.7* | 33 ± 6.9* | 35 ± 8.8* | 36 ± 11* |
| CVCiVA,† ml·min−1·mmHg−1 | ||||||
| Normoxia | 1.0 ± 0.4 | 1.0 ± 0.4 | 0.9 ± 0.4 | 0.9 ± 0.4 | 0.9 ± 0.5 | 0.9 ± 0.4 |
| Hyperoxia | 0.9 ± 0.4*† | 0.8 ± 0.3 | 0.9 ± 0.3 | 1.0 ± 0.4* | 1.0 ± 0.4* | 1.0 ± 0.5* |
| gCBF,† ml/min | ||||||
| Normoxia | 640 ± 140 | 634 ± 146 | 673 ± 179 | 738 ± 188* | 770 ± 204* | 773 ± 256* |
| Hyperoxia | 611 ± 109 | 596 ± 108 | 677 ± 132 | 751 ± 190* | 814 ± 238* | 792 ± 184* |
| Isocapnia | ||||||
| MCAv, cm/s | ||||||
| Normoxia | 59 ± 6.6 | 59 ± 7.8 | 61 ± 9.2 | 65 ± 12 | 71 ± 16* | — |
| Hyperoxia‡ | 56 ± 8.9 | 55 ± 7.9 | 57 ± 10.6 | 57 ± 9.8 | 64 ± 15* | — |
| CVCiMCA, cm·s−1·mmHg−1 | ||||||
| Normoxia | 0.67 ± 0.1 | 0.68 ± 0.1 | 0.65 ± 0.1* | 0.65 ± 0.1* | 0.65 ± 0.1* | — |
| Hyperoxia | 0.64 ± 0.1 | 0.62 ± 0.1 | 0.60 ± 0.1 | 0.57 ± 0.1* | 0.59 ± 0.1* | — |
| QICA, ml/min | ||||||
| Normoxia | 241 ± 58 | 240 ± 58 | 255 ± 57 | 269 ± 76* | 282 ± 78* | — |
| Hyperoxia‡ | 229 ± 57 | 237 ± 52 | 255 ± 64 | 262 ± 51* | 278 ± 74* | — |
| ICAdiam, ml | ||||||
| Normoxia | 0.49 ± 0.06 | 0.49 ± 0.06 | 0.49 ± 0.07 | 0.49 ± 0.07 | 0.48 ± 0.06 | — |
| Hyperoxia | 0.50 ± 0.06 | 0.49 ± 0.05 | 0.48 ± 0.06 | 0.48 ± 0.06 | 0.48 ± 0.06 | — |
| ICAvel, cm/s | ||||||
| Normoxia | 42 ± 9.9 | 42 ± 10 | 45 ± 10* | 47 ± 10* | 51 ± 9* | — |
| Hyperoxia | 40 ± 9.4 | 42 ± 6.1 | 46 ± 7.0* | 49 ± 7.8* | 50 ± 8.3* | — |
| CVCiICA | ||||||
| Normoxia | 2.7 ± 0.7 | 2.7 ± 0.7 | 2.6 ± 0.6 | 2.6 ± 0.7 | 2.5 ± 2.7 | — |
| Hyperoxia | 2.5 ± 0.6 | 2.6 ± 0.6 | 2.6 ± 0.7 | 2.5 ± 0.7 | 2.5 ± 0.7 | — |
| PCAv, cm/s | ||||||
| Normoxia‡ | 42 ± 7.0 | 41 ± 6.5 | 43 ± 6.0 | 46 ± 7.0* | 49 ± 6.8* | — |
| Hyperoxia‡ | 43 ± 11 | 43 ± 12 | 44 ± 13 | 45 ± 13* | 50 ± 18* | — |
| CVCiPCA, cm·s−1 ·mmHg−1 | ||||||
| Normoxia | 0.48 ± 0.07 | 0.46 ± 0.06 | 0.44 ± 0.07 | 0.45 ± 0.07 | 0.46 ± 0.07 | — |
| Hyperoxia | 0.48 ± 0.1 | 0.46 ± 0.1 | 0.44 ± 0.1 | 0.43 ± 0.4 | 0.44 ± 0.1 | — |
| QVA, ml/min | ||||||
| Normoxia | 81 ± 26 | 80 ± 28 | 86 ± 36 | 91 ± 40 | 95 ± 47* | — |
| Hyperoxia‡ | 76 ± 25 | 76 ± 25 | 82 ± 27 | 85 ± 34‡ | 93 ± 38*‡ | — |
| VAdiam, cm | ||||||
| Normoxia | 0.35 ± 0.06 | 0.36 ± 0.07 | 0.35 ± 0.07 | 0.35 ± 0.07 | 0.35 ± 0.07 | — |
| Hyperoxia | 0.35 ± 0.06 | 0.35 ± 0.06 | 0.35 ± 0.06 | 0.34 ± 0.07 | 0.34 ± 0.06 | — |
| VAvel, cm/s | ||||||
| Normoxia | 28 ± 5.0 | 27 ± 5.4 | 29 ± 7.1 | 31 ± 7.3* | 33 ± 7.2* | — |
| Hyperoxia | 26 ± 3.6 | 27 ± 4.1 | 29 ± 4.6 | 30 ± 5.0* | 33 ± 7.8* | — |
| CVCiVA | ||||||
| Normoxia | 0.93 ± 0.3 | 0.90 ± 0.3 | 0.89 ± 0.4 | 0.90 ± 0.4 | 0.84 ± 0.4 | — |
| Hyperoxia | 0.86 ± 0.3 | 0.84 ± 0.3 | 0.84 ± 0.3 | 0.83 ± 0.4 | 0.82 ± 0.3 | — |
| gCBF, ml/min | ||||||
| Normoxia | 644 ± 128 | 641 ± 123 | 682 ± 124 | 719 ± 181* | 755 ± 214* | — |
| Hyperoxia‡ | 609 ± 120 | 626 ± 115 | 675 ± 148 | 693 ± 132* | 741 ± 180* | — |
Values are means ± SD. MCAv and PCAv, middle and posterior cerebral arteries; CVCiMCA and PCA and CVCiICA and VA, cerebrovascular resistance in intracranial and extracranial vessels; QICA and QVA, blood flow in the internal carotid artery and vertebral artery; VAvel and VAdiam, vertebral artery velocity and diameter; ICAvel and ICAdiam, internal carotid artery velocity and diameter; gCBF, global cerebral blood flow.
*
P < 0.05, from BL2.
†
P < 0.01, interaction normoxia vs. hyperoxia.
‡
P < 0.017, interaction poikilocapnia vs. isocapnia.