Table 5.
Cerebral haemodynamic function
| GROUP: | AMS– (n= 9) | AMS+ (n= 9) | |||||
|---|---|---|---|---|---|---|---|
| CONDITION: | Normoxia | Hypoxia | Δ | Normoxia | Hypoxia | Δ | |
| Haemodynamics | |||||||
| MCAv (cm s−1) | 60.1 ± 10.6 | 51.8 ± 9.2 | −8.3 ± 6.7 | 56.6 ± 10.7 | 53.2 ± 14.1 | −3.3 ± 14.4 | Condition main effect |
| CVR (mmHg cm−1 s−1) | 1.44 ± 0.30 | 1.60 ± 0.25 | 0.16 ± 0.22 | 1.44 ± 0.31 | 1.72 ± 0.49 | 0.28 ± 0.50 | Condition main effect |
| CVC (cm s−1 mmHg−1) | 0.72 ± 0.13 | 0.64 ± 0.10 | −0.08 ± 0.09 | 0.72 ± 0.16 | 0.63 ± 0.20 | −0.09 ± 0.22 | Condition main effect |
| Autoregulation | |||||||
| LF Gain (cm s−1 mmHg−1) | 1.22 ± 0.07 | 1.17 ± 0.09 | 0.03 ± 0.07 | 1.25 ± 0.07 | 1.43 ± 0.19*† | 0.26 ± 0.15† | Group main effect/Group × Condition interaction |
| LF phase (radians) | 1.17 ± 0.04 | 1.15 ± 0.09 | −0.03 ± 0.05 | 1.14 ± 0.07 | 1.13 ± 0.06 | −0.02 ± 0.04 | — |
| LF Coherence (units) | 0.73 ± 0.06 | 0.69 ± 0.06 | −0.01 ± 0.06 | 0.72 ± 0.05 | 0.68 ± 0.06 | −0.01 ± 0.03 | — |
| RoR (s) | 0.27 ± 0.08 | 0.32 ± 0.11 | 0.05 ± 0.15 | 0.28 ± 0.08 | 0.18 ± 0.05*† | −0.10 ± 0.09† | Group and Condition main effects/Group × Condition interaction |
Values are mean ±s.d.; subjects without (AMS–) and with (AMS+) acute mountain sickness; main effect for group indicates a pooled (normoxia + hypoxia) difference (P < 0.05) between AMS–versus AMS+; main effect for condition indicates a pooled (AMS–+ AMS+) difference (P < 0.05) between normoxia versus hypoxia;
*
different within and
†
between groups (P < 0.05); MCAv, middle cerebral artery velocity; CVR, cerebrovascular resistance; CVC, cerebrovascular conductance; RoR, rate of regulation; LF, low frequency (0.07–0.20Hz); Δ, delta value (hypoxia minus normoxia).