Blood pressure is the force of blood as it moves through the arteries. Blood pressure readings include two measurements. Systolic pressure, the top number in a blood pressure value, gauges pressure in the arteries when the heart contracts. Diastolic pressure, the bottom number, measures pressure in the arteries between heartbeats.
What’s considered a normal blood pressure changes as a child grows. Children under age 5 typically have a systolic pressure of 110 and a diastolic pressure of 70, or 110/70 or less. During adolescence, blood pressure can increase to around 120/80. Blood pressure varies throughout the day. It also depends on your child’s position -whether he or she is sitting or standing – and levels of physical activity and emotional stress.
A child has prehypertension when a blood pressure reading is above the 90th percentile compared with other children of the same age, sex, and height. That means that 90 percent of comparable children have a lower blood pressure. Children with a blood pressure reading equal to or above the 95th percentile have hypertension.
Methods to recognize children with high blood pressure.
1. Physical Exam
During a physical exam, the doctor looks at your child’s medical and family history to identify risk factors for hypertension. The doctor asks you if your child is taking any medications, such as corticosteroids or over-the-counter decongestants, or eating and drinking foods and beverages that contain caffeine, all of which can increase blood pressure.
In addition, the doctor calculates a ratio of your child’s height to weight, called body mass index, to determine if weight is contributing to hypertension.
2. Blood Pressure Measurement
A blood pressure cuff, also called a sphygmomanometer, is the device used to measure blood pressure. The cuff is wrapped around your child’s upper arm and is inflated to temporarily stop blood flow in a large artery. The device measures blood pressure as air is gradually released from the cuff, which allows blood to flow through the artery again.
A nurse or other healthcare professional places a stethoscope over the artery as air is released from the cuff, while watching a gauge that measures pressure in millimeters of mercury, or mmHg. The first pulse heard as blood flows through the vessel is the systolic pressure. Diastolic pressure is measured when the pulse is no longer heard.
Blood pressure readings that are higher than the 95th percentile for children of the same age, sex, and height during several different appointments confirm a diagnosis of hypertension.
