Blood Pressure

Although there are special challenges to obtaining accurate blood pressure readings in young infants, this measurement, nevertheless, is important and should be part of the physical examination of every child older than 2 years of age, and of any younger child whose history or physical examination suggests that the blood pressure may be abnormal. Hypertension during childhood is more common than previously thought, and it is important to recognize, confirm, and appropriately manage it.

Children have elevated blood pressure during exercise, crying, and anxiety. Although young children may be anxious at first, when the procedure is explained and demonstrated beforehand, most children are cooperative. If the blood pressure is initially elevated, you can perform blood pressure readings again at the end of the examination; one trick is to leave the cuff on the arm (deflated) and repeat the reading later. Elevated readings must always be confirmed by subsequent measurements.

Select the blood pressure cuff as you would in adults. It should be wide enough to cover two thirds of the upper arm or leg. A narrower cuff falsely elevates the blood pressure reading, while a wider cuff lowers it and may interfere with proper placement of the stethoscope diaphragm over the artery. Thus, a proper cuffsize is essential for accurate determinations of blood pressure in children.

With children, as with adults, the point at which the Korotkoff sounds disappear constitutes the diastolic pressure. At times, especially among chubby young children, the Korotkoff sounds are not easily heard. In such instances, you can use palpation to determine the systolic blood pressure (see pp. 7677), remembering that the systolic pressure is approximately 10 mm Hg lower by palpation than by auscultation.

A relatively inaccurate means is to use "inspection." Watch for the needle to bounce about 10 mm Hg higher than it does in auscultation. While this technique is suboptimal, in squirming children sometimes it is all you can get.

The most easily used measure of the systolic blood pressure of infants and young children is obtained with the Doppler method, which detects arterial blood flow vibrations, converts them to systolic blood pressure levels, and transmits them to a digital read-out device. However, Doppler instruments are expensive, and readings tend to be higher than by auscultation.

The systolic blood pressure gradually increases throughout infancy and childhood. For example, normal systolic pressure in males is about 70 mm Hg

The most frequent "cause" of an elevated blood pressure in children is probably an improperly performed examination, often due to an incorrect cuff size.

In children, as in adults, blood pressure readings from the thigh are approximately 10 mm Hg higher than those from the upper arm. If they are the same or lower, coarctation of the aorta should be suspected.

Blood Pressure PhysicalsPhysical Pressure Pushing Aorta

at birth, 85 mm Hg at 1 month, and 90 mm Hg at 6 months. Turn to Table 17-3, pp. 740-741, for normal blood pressure levels by year of life for boys and girls, including percentiles specific to age and height.

In 1995, the National Heart, Lung, and Blood Institute's National High Blood Pressure Working Group on Hypertension Control in Children and Adolescents defined normal, high-normal, and high blood pressure as follows, with measurements on at least three separate occasions:

Although most adults with hypertension have normal blood pressure as children, essential hypertension often is detectable in adolescents.

Blood Pressure Category

Average Systolic and/or Diastolic Blood Pressure for Age, Sex, and Height

Normal

<90th percentile

High Normal

90th-95th percentile

High

>95th percentile

Children who have hypertension should be evaluated extensively to deter- It is also important not to falsely mine the cause. For infants and young children, a specific cause can usually be label a child or adolescent as found. In older children and adolescents, however, an increasing proportion having hypertension, because of has essential or primary hypertension. In all cases, it is important to repeat the stigmata of labeling, potential measurements to reduce the possibility that the elevation reflects anxiety. limitations to activities, and possi-

Sometimes repeating measurements in school is a way to obtain readings in ble side effects of treatment. a more relaxed environment.

Causes of Sustained Hypertension in Children

Newborn

Middle Childhood

Renal artery disease (stenosis, thrombosis) Congenital renal malformations Coarctation of the aorta

Renal parenchymal or arterial disease Primary hypertension Coarctation of the aorta

Infancy and Early Childhood

Adolescence

Renal parenchymal or artery disease Coarctation of the aorta

Primary hypertension Renal parenchymal disease Drug induced

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