Blood pressure - Blood pressure readings are obtained by using a sphygmomanometer and a stethoscope to measure the force exerted by the blood on an artery in the arm. This procedure is one requiring accuracy and skill that are acquired through practice.
Blood pressure varies in the healthy person due to many factors. Emotion and physical activity have an effect on the blood pressure. During periods of physical rest and freedom from emotional excitement, the pressure will be lowered. Age in itself will be a factor in elevating blood pressure.
An injury or internal bleeding can result in a great loss of blood, which causes a lowered blood pressure. Shock is marked by a dangerous drop in blood pressure.
Blood pressure is expressed in millimeters of mercury. The systolic pressure (as the heart beats or contracts) is recorded above a line and the diastolic pressure (as the heart rests) is recorded below the line. In the blood pressure recording 120/80 the systolic pressure is 120 and the diastolic pressure is 80. These are within normal range. A slight variation from this value is insignificant.
When taking a blood pressure, the patient should lie or sit with the arm that is to be used supported. Measurement may be made in either arm. When taking a blood pressure, this procedure should be followed:
1. Explain the procedure to the patient to prevent excitement and anxiety.
2. Place the cuff around the patient's arm, above the elbow. Check to see that the valve on the bulb has been fully closed (turned clockwise).
3. Before inflating the cuff with air, find the arterial pulse on the inner side of the bend of the elbow.
4. Keep fingers on this pulse and inflate the cuff by pumping on the rubber bulb until the pulse disappears.
5. Place the earpieces of the stethoscope in your ears (with the earpieces directed up) and position the disc of the stethoscope over the space where the pulse was felt. 6. Hold the disc of the stethoscope snugly in position over the pulse with one hand, while pumping the cuff with the other.
7. Pump the cuff until the mercury on the scale of the mercury apparatus, or the needle on the gauge of the aneroid apparatus, is about 30 points above the systolic pressure that was obtained previously, by noting when the arterial pulse was felt to disappear.
8. Loosen the valve slightly and permit the pressure to drop slowly while listening carefully for the sound ofthe blood pressure. Soon a definite beat will be heard, but it will be quite faint. If this beat is missed or if there is a question as to the reading where it started, the valve should be tightened again, pumped again once more, and you should listen for the sound. The number at which the first sound is heard is the systolic pressure. Record this number.
9. Continue slowly to deflate the cuff until the last sound is heard. The reading at which the sound disappeared is the diastolic pressure.
10. Open the valve completely and allow the cuff to deflate.
If there is difficulty obtaining the blood pressure reading, it may be due to the valve being opened too much, causing the pressure to drop too rapidly; or you might have expected a louder sound through the stethoscope.
