Doppler Ultrasound & Children
April 16th, 2006 (High Blood Pressure)
Diagnosing high blood pressure is different for children. Size matters. Measuring blood pressure in the smallest infants and children with a stethoscope is difficult because the sounds are so hard to hear in their tiny arms. To overcome this problem, pediatricians use Doppler ultrasound instruments in place of a stethoscope to take blood pressure in the smallest arteries.
Doppler was an Austrian who discovered that sound changed its pitch when it comes toward you as compared to when it’s going away from you. If a sound wave is directed to an artery and a blood pressure cuff cuts off the blood flow, it bounces back with one sound wave appearance. When blood begins to flow through the artery as the cuff is deflated, the sound wave has a different appearance (this is the systolic blood pressure).
As the cuff is opened further, the flow reaches its peak and the sound wave changes again (the diastolic blood pressure). The Doppler ultrasound instrument looks like a pencil held over the artery. It sends out sound waves that are altered by blood flow. The same “pencil” is connected to a machine that amplifies the altered sound wave of the artery, so you hear a distinct difference as blood flow starts.