Measuring Blood Pressure
In order to determine the estimated systolic pressure and how high the cuff will need to be inflated, baseline palpable systolic pressure will need to be performed. As you feel the radial artery of the extremity, you will be determining the patient’s blood pressure. Semi-rapidly inflate the cuff until the radial pulse disappears. This will establish an estimate of systolic pressure. When inflating the blood pressure cuff for actual measurement, you should inflate the cuff to 30 mmHg greater than the estimated systolic value. This avoids over-inflation and subsequent patient discomfort from increased pressure. It also avoids the error of an auscultatory gap. This gap is a silent interval sometimes occurring between phase I and phase V of the Korotkoff sounds. If this gap is unrecognized by a clinician, it can lead to a drastic underestimation of systolic pressure.
The cuff should be deflated at a rate of 2-3 mmHg per second. You should note when the sounds first appear with two consecutive beats; this is the systolic pressure. Continue to lower the pressure at a rate of 2-3 mmHg per second until the sounds are muffled and disappear; this is the diastolic pressure. To confirm that this is the correct value, continue to deflate the cuff for another 10-20 mmHg, and then deflate the cuff completely. Blood pressure readings should be read to the nearest 2mmHg. It is then recommended to wait 2 or more minutes and repeat this procedure. If the first two readings differ by more than 5 mmHg, take additional readings.
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