Table 2. Doppler velocities and breath-holding index according to HTN severity.

Variable – mean ± SD		Normotension (57)	HTN stage 1 (72)	HTN stage 2 (51)	p
Resting (Middle cerebral artery)	Initial velocity (m/s)	57.2 ± 10.8	52.2 ± 13.9	56.5 ± 13.7	0.76
	Final velocity (m/s)	59.3 ± 12.8	60.3 ± 15.5	57.9 ± 13.7	0.66
Apnea maneuver	Initial velocity (m/s)	57.9 ± 12.3	59.9 ± 12.3	58.4 ± 14.4	0.68
	Final velocity (m/s)	81.5 ± 20.1	79.2 ± 18.4	75.4 ± 20.9	0.29
	Breath-holding index	1.4 ± 0.6	1.1 ± 0.6	1.0 ± 0.6	0.004a
Handgrip maneuver	Initial velocity (m/s)	59.1 ± 12.3	60.3 ± 14.3	56.9 ± 15.3	0.43
	Final velocity (m/s)	63.6 ± 15.3	63.9 ± 17.3	60.7 ± 19.0	0.57

P value refers to comparisons of the means among the groups by the 1-way ANOVA step-wise test with Bonferroni post-hoc analysis. HTN, hypertension; SD, standard deviation. asignificance difference (Normotension vs. HTN stage 1 and HTN stage 2).