TABLE 2.

Cerebral hemodynamics during normocapnia and hypercapnia.

Variable	TCD N = 39	4D flow MRI N = 39	p-value
MCAv (cm/s)
Normocapnia	53 ± 12	31 ± 7	< 0.001
4% CO2	60 ± 14	32 ± 6	< 0.001
6% CO2	64 ± 15	33 ± 7	< 0.001

MCAv (%Δ)
Normocapnia to 6% CO2	16 ± 10	6 ± 10	< 0.001

MCAv (%Δ) vs. MCA Flow (%Δ)
Normocapnia to 6% CO2	16 ± 10	13 ± 10	0.327

Pulsatility Index (a.u.)
Normocapnia	0.78 ± 0.13	1.07 ± 0.21	< 0.001
4% CO2	0.73 ± 0.09	1.03 ± 0.17	< 0.001
6% CO2	0.71 ± 0.09	1.00 ± 0.17	< 0.001

Pulsatility Index (%Δ)
Normocapnia to 6% CO2	−9 ± 9	−5 ± 12	0.141

Data are presented as mean ± standard deviation. MCA, middle cerebral artery; MCAv, middle cerebral artery velocity.

Statistical significance was set α priori at p < 0.05 with significant p-values indicated in bold.