Table 1:

Age-dependent hemodynamic parameters of the carotid siphon segments C1 (upper) and C5 (lower)

Factor	Mean	<39 Years (95% CI)	SD	Mean	40–59 Years (95% CI)	SD	Mean	>60 Years (95% CI)	SD	P Value
C1 PSV	69.9	65.1–74.8	23.7	69.2	64.9–73.6	19.7	71.3	66.1–76.4	23.39	.96
C1 EDV	29.0	27.0–31.1	10.0	29.8	27.6–32.1	10.2	27.8	25.5–30.1	10.4	.28
C1 MFV	42.7	39.8–45.6	14.2	43.0	40.1–45.8	13.0	42.4	39.2–45.5	14.38	.72
C1 PI	0.86	0.82–0.91	0.22	0.86	0.81–0.90	0.19	0.96	0.91–1.01	0.21	.003
C1 RI	0.52	0.50–0.54	0.10	0.54	0.52–0.55	0.08	0.58	0.56–0.61	0.10	<.001
C1/ICA	1.24	1.15–1.34	0.45	1.31	1.20–1.42	0.49	1.53	1.41–1.64	0.52	<.001
C1/CCA	0.83	0.72–0.94	0.30	1.06	0.95–1.16	0.38	1.30	1.18–1.42	0.46	<.001
C5 PSV	50.9	47.9–53.9	14.4	49.4	45.9–53.0	15.9	51.6	47.8–55.4	17.0	.81
C5 EDV	19.3	18.0–20.6	6.04	20.7	18.9–22.4	7.8	19.6	17.7–21.6	8.7	.31
C5 MFV	29.8	28.1–31.6	8.4	30.3	28.0–32.5	10.1	30.3	27.8–32.7	10.9	.81
C5 PI	0.95	0.89–1.00	0.27	0.88	0.83–0.94	0.25	0.99	0.94–1.04	0.22	.02
C5 RI	0.55	0.52–0.58	0.12	0.54	0.51–0.56	0.11	0.59	0.57–0.61	0.10	.01
C5/ICA	0.73	0.68–0.78	0.26	0.80	0.73–0.86	0.29	0.89	0.82–0.96	0.31	<.001
C5/CCA	0.70	0.59–0.80	0.28	0.78	0.69–0.88	0.33	0.96	0.88–1.03	0.30	<.001

Note:—All velocities are given in centimeters per second. C1/ICA, C1/CCA, C5/M1, and C5/CCA indicate divisions of mean velocities; C5, the ganglionic segment of the carotid siphon; C1, the distal segment of the carotid siphon; ICA, the distal (submandibular) portion of the extracranial ICA; CI, confidence interval; CCA, common carotid artery; PSV, peak systolic velocity; EDV, end diastolic velocity, MFV, mean blood flow velocity; PI, pulsatility index; RI, resistance index.