Chapter 39 Hypertension
PATHOPHYSIOLOGY
Hypertension in the pediatric client is described as blood pressure that is persistently between the 90th and 95th percentiles. Table 39-1 identifies guidelines (based on age and sex) for suspect blood pressure values. A variety of mechanisms are associated with hypertension. The renin-angiotensin-aldosterone system maintains fluid volume and vascular tone through the production of angiotensin II (a vasoconstrictor) and the stimulation of aldosterone production (for sodium retention). The sympathetic nervous system affects peripheral vascular resistance, cardiac output, and renin release, influencing the regulation of blood pressure.
Table 39-1 Approximate Guidelines for Suspect Blood Pressure
| Age (years) | Blood Pressure (mm Hg) | |
|---|---|---|
| Supine Position—Lowest of Three Readings | ||
| Boys and girls | 3–5 | 110/70 |
| 6–9 | >120/75 | |
| 10–14 | >130/80 | |
| Seated Position—Average of Second and Third Readings | ||
| Girls | 14–18 | >125/80 |
| Boys | 14 | >130/75 |
| 15 | >130/80 | |
| 16–18 | >135/85 | |
Modified from Gilles S, Kagan B: Current pediatric therapy, ed 13, Philadelphia, 1990, WB Saunders.
Hypertension is classified as primary or secondary. Primary hypertension can be ascribed to no identifiable cause, whereas secondary hypertension is attributable to a structural abnormality or to an underlying disease (renal, cardiovascular, endocrine, central nervous system, or collagenous). A variety of factors have been identified as contributing to hypertension, including diet (high in calories, saturated fats, and sodium), contraceptive use, positive family history, obesity, and minimal physical exercise. Children generally manifest no overt symptoms. If symptomatic, the disease may be quite severe. Prognosis is variable, depending on the age of onset and response to treatment.
Problems evident in adults may have originated during the first or second decade of life. The earlier the onset, the more severe the disease will be.
INCIDENCE
1. Incidence is increased among children in lower socioeconomic groups.
2. Incidence is increased among African-American adolescents.
3. Incidence rates vary from 0.6% to 20.5% (depends on methodology used).
4. Noncompliance with treatment occurs among more than 50% of affected children; compliance improves when the child is dependent on the parent.
5. Males are affected more often than females.
6. In individuals 2 to 18 years of age, 45% to 100% of cases of hypertension are attributed to primary hypertension.
7. Of children with primary hypertension, 25% have a positive family history of the disorder.
8. Overall, 1% to 2% of children and 11% to 12% of adolescents are affected.
9. Hypertension is most often associated with coarctation of the aorta or renal disease.
