Ambulatory blood pressure monitoring in children suffering from orthostatic hypertension

BACKGROUND: It is particularly important to utilize appropriate blood pressure measurement methods to evaluate the changes of orthostatic hypertension (OHT) for children, and this study was designed to analyze the blood pressure type in OHT children with 24 h semiautomatic ambulatory blood pressure monitoring. METHODS: Children who were diagnosed by head-up tilt table test as OHT patients (OHT group) and treated or hospitalized in the syncope specialist outpatient unit of the Second Xiangya Hospital of Central South University mainly for syncope or pre-syncope with unknown causes during the October, 2009 to September, 2013 were recruited in the study. Healthy children that came to the hospital for physical examination at the same time period according to age and sex were matched as control group. Semiautomatic ambulatory blood pressure monitoring of every child was recorded. The differences of daytime systolic (diastolic) pressure and night systolic (diastolic) pressure were calculated, and the average systolic pressure and diastolic pressure of the entire day, daytime and night were also calculated, respectively. RESULTS: There were 23 boys and 17 girls in OHT group, aging (11.5 ± 1.9) years. There were 22 boys and 18 girls in the control group, aged (10.6 ± 2.4) years. The difference of daytime systolic pressure and night systolic pressure of the control group was higher than that of OHT group, while the average systolic pressure of the whole day, the average diastolic pressure of the whole day, the daytime average systolic pressure, the daytime average diastolic pressure, the night average systolic pressure and the night average diastolic pressure were higher than that of the control group (P > 0.05). The difference of daytime diastolic pressure and night diastolic pressure of the control group was higher than that of OHT group (P > 0.05). Most children of the OTH group had non-dipper blood pressure type (72.5%), while most children of the control group had a dipper blood pressure type (55.0%). In addition, the time domain SDNN and SDANN in the OHT group were higher than those in the control group (P < 0.01). And, the indicators including TP, ULF, VLF, and LF/HF were higher in the OHT group, when compared with control group (P < 0.01). Besides, in terms of subgroup analysis within the OHT group, the age difference between boys and girls was not statistically significant (P > 0.05). When compared with grils, the time domain SDNN increased (P = 0.003), and the frequency index TP, ULF, and VLF increased in boy group (P < 0.05). CONCLUSION: OHT Children’s autonomic nervous system showed dysfunction, and differences of systolic blood pressure between day and night were much lower than those of healthy children, and the main blood type was non-dipper blood pressure with circadian rhythm disappearing.