The newer hybrid sphygmomanometers have an electronic transducer in place of a mercury column; BP measurement is performed in the same fashion as with a mercury device, using a stethoscope and auscultation for the Korotkoff sounds.
Variations in technique for BP measurement can result in significantly different readings. In 2005, the AHA published recommendations for BP monitoring to increase the accuracy of in-clinic measurements.10 Recommendations for accurate BP measurement include:
Patient preparation. The patient should be seated in a chair with his or her back supported, legs uncrossed, and feet flat on the floor. The patient’s bare arm should be supported such that the midpoint of the upper arm is at heart level. An appropriately sized cuff (ie, bladder encircles 80% of the arm for an adult or 100% of the arm for a child younger than 13 years) should be secured around the bare upper arm and the bladder centered over the brachial artery, with the lower edge of the cuff about 2 cm above the antecubital fossa.10
Technique. The cuff is inflated while palpating the radial artery to the approximate systolic pressure (ie, the point at which the radial pulse is no longer palpated). The bell of the stethoscope is placed just proximal and medial to the antecubital fossa and the cuff is inflated another 20 to 30 mm Hg above the point at which the radial pulse is no longer felt. The cuff is deflated at a rate of about 2 mm Hg per second.10
BP recording.The systolic BP is recorded at the appearance of the Korotkoff sounds (phase I) for an auscultatory measurement. The diastolic BP is recorded at the disappearance of the Korotkoff sounds (phase V) in adults and at the muffling of sounds (phase IV) in children for an auscultatory measurement.10
Continue to: Oscillometric methods of BP measurement
