I. Definition
For adults, the 2017 Guidelines by the American College of Cardiology, American Heart Association, and several other organizations jointly revised the earlier definition and classification of hypertension (HTN) of 2003. The following are the new classification (Whelton et al., 2018). Table 23.1 shows different levels of blood pressure (BP) readings by the new definition of elevated BP.
- 1.
Normal BP is defined as <120 mm Hg systolic pressure (SP) and <80 mm Hg diastolic pressures (DP).
- 2.
SP between 120 and 129 mm Hg and DP <80 mm Hg are now called “elevated blood pressure,” formerly called “prehypertension.”
- 3.
Hypertension is classified as stage 1 and stage 2, depending on the level of abnormalities.
- a.
Stage 1 HTN is defined as SP 130 to 139 systolic mm Hg or DP 80 to 89 mm Hg.
- b.
Stage 2 HTN is defined as SP ≥140 mm Hg or DP ≥90 mm Hg.
In children, hypertension is defined statistically, because BP levels vary with age and gender and because outcome-based data are not available for children. Following the new definition of hypertension in adults, the American Academy of Pediatrics updated the earlier guidelines of 2004 (Flynn et al., 2017) (see Table 23.1 ). In the new guidelines, the term “prehypertension” has been replaced with “elevated blood pressure” for children as in the adults.
- a.
- 1.
Normal BP is defined as systolic and diastolic pressure <90th percentile.
- 2.
Elevated BP is defined as an average systolic and diastolic pressure between the 90th and 95th percentiles for age and gender.
- 3.
HTN is defined as systolic or diastolic pressure levels that are greater than the 95th percentile for age and gender. As in adults, adolescents with BP levels ≥120/80 mm Hg by auscultatory method are considered hypertensive even if they are <95th percentile. HTN is further classified into stage 1 and stage 2.
- a.
Stage 1 HTN is present when BP readings are between 95th percentile and 99th percentiles + 12 mm Hg.
- b.
Stage 2 HTN is present when BP readings higher than 95th percentile + 12 mm Hg.
- a.
- 4.
White coat HTN is present when BP readings in health care facilities are greater than the 95th percentile but are normotensive outside a clinical setting. This condition may not be as benign as once thought to be and regular follow-up is now recommended. This topic is discussed further later in this chapter.
| Adults a and Adolescent >13 Years b | ||||
|---|---|---|---|---|
| SP (mm Hg) | DP (mm Hg) | Children and Adolescents <13 Years b | ||
| Normal BP | <120 | and | <80 | <90th % |
| Elevated BP | 120-129 | and | <80 |
|
| Stage 1 HTN | 130-139 | or | 80–89 |
|
| Stage 2 HTN | ≥140 | or | ≥90 |
|
a Adapted from Whelton, P. K., Carey, R. M., Aronow, W. S., et al, (2018). ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guidelines for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Journal of the American College of Cardiology, 71 (10), e127-e248.
b Adapted from Flynn, J. T., Kaelber, D. C., Barker-Smith, C. M., et al. (2018). Clinical practice guideline for screening and management of high blood pressure in children and adolescents. Pediatrics, 140 (3), e20171904.
II. Normative BP Standards
- 1.
The BP tables provided by the Working Group of the National High Blood Pressure Education Program (NHBPEP) are not acceptable standards because they are obtained by a methodology currently unacceptable and are discordant from their own recommendations, statistically unsound, and impractical for practitioners (as discussed in Chapter 1 ).
- 2.
Normative BP standards from the San Antonio Children’s Blood Pressure Study (SACBPS) are the most reliable sets; they are the only large sets of BP standards obtained using the currently recommended methodology. In that study, both auscultatory and oscillometric (Dinamap 800) methods were used.
- a.
The auscultatory BP standards for children 5 to 17 years old are shown in Table B.3 , Table B.4 in Appendix B .
- b.
A different set of BP standards is needed for the oscillometric method because BP readings by Dinamap monitor model 8100, a popular oscillometric device, are significantly different from those obtained by the auscultatory method. Dinamap readings are on average 10 mm Hg higher for the SP and 5 mm Hg higher for the DP than readings using the auscultatory method.
- (1)
Normative oscillometric BP standards for children 5 to 17 years old from the SACBPS are presented in Table B.5 , Table B.6 in Appendix B .
- (2)
Oscillometric BP standards for neonates and small children up to 5 years of age are presented in Table 1.3 .
- (1)
- a.
- 3.
Kaelber et al. (2009) have recommended a simplified table of BP levels according to age and gender (without height percentiles), above which further evaluation should be carried out for possible HTN. This approach is well justified and more practical because one does not need to use the unscientific normative standards of the NHBPEP and because height is not measured at some BP screening sites (as discussed in Chapter 2 ). Table 23.2 shows the 90th percentile BP values by both methods side-by-side. Table 23.2 is replication of Table 1.4 in Chapter 1 . It is interesting to note that the auscultatory BP levels recommended by Kaelbert et al. are almost the same as the 90th percentile of BP levels by the San Antonio study (Park et al., 2005).
Table 23.2
The 90th Percentiles of Blood Pressure by Auscultatory and Oscillometric Methods from the San Antonio Study
Auscultatory a,b
Oscillometric c
Age (yr)
Male
Female
Age (YR)
Male
Female
SP
DP
SP
DP
SP
DP
SP
DP
5
103
60
102
60
5
115
68
114
68
6
105
64
103
63
6
117
68
115
68
7
107
66
104
65
7
118
69
116
69
8
108
68
106
67
8
119
70
118
70
9
109
68
108
67
9
121
70
119
70
10
111
68
110
68
10
122
71
121
71
11
113
68
112
68
11
124
71
122
71
12
116
68
113
68
12
126
71
123
71
13
118
68
115
68
13
129
71
125
71
14
120
68
116
68
14
131
72
125
72
15
120
69
117
69
15
133
72
126
72
16
120
71
117
69
16
134
72
126
72
17
120
73
118
70
17
134
72
126
72
≥18
120
73
120
70
SP , systolic pressure; DP , diastolic pressure.
a The 90th percentile of systolic pressure for males 14 years and older are higher than 120 mm Hg, but 120 mm Hg is listed in the table to be consistent with the definition of “elevated blood pressure” in adults.
b Data from Park, M. K., Menard, S. W., & Yuan, C. (2001). Comparison of blood pressure in children from three ethnic groups. American Journal of Cardiology, 87 (11), 1305-1308.
c Data from Park, M. K., Menard, S. W., & Schoolfield, J. (2005). Oscillometric blood pressure standards for children. Pediatric Cardiology, 26 (5), 601-607. These values were obtained by Dinamap model 8100 and in general fall between the 90th and 95th percentiles of blood pressure (prehypertension range).
III. Causes of Hypertension
- 1.
With the increasing prevalence of obesity in recent decades, overweight and obesity have become the most common causes of pediatric HTN.
- 2.
More than 90% of secondary HTN in nonobese children is caused by three conditions: renal parenchymal disease, renal artery disease, and COA.
- 3.
In general, children with essential HTN are older than 10 years, have mild HTN, and often are obese.
- 4.
Children with secondary HTN are generally younger than 10 years and have higher levels of BP. Children with secondary HTN rarely are obese and often are less than normal height.
- 5.
Table 23.3 lists the common causes of HTN by age group in (nonobese) children. Box 23.1 lists causes of secondary HTN.
TABLE 23.3
Common Causes of Chronic Hypertension According to Age
Adapted from Task Force on Blood Pressure Control in Children. National Heart, Lung, and Blood Institute. (1987). Report of the second task force on blood pressure control in children. Pediatrics, 79 (1), 1-25.
Age Group
Causes
Newborns
Renal artery thrombosis, renal artery stenosis, congenital renal malformation, COA, bronchopulmonary dysplasia (transient)
<6 yr
Renal parenchymal disease, COA, renal artery stenosis
6-10 yr
Renal artery stenosis, renal parenchymal disease, COA
>10 yr
Primary hypertension, renal parenchymal disease
COA , coarctation of the aorta.
