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Blood Pressure Measurement in the Clinic or Office[/SIZE]
Subject Preparation
A number of factors related to the subject can cause significant deviations in measured blood pressure. These include room temperature, exercise, alcohol or nicotine consumption, positioning of the arm, muscle tension, bladder distension, talking, and background noise.
28 The patient should be asked to remove all clothing that covers the location of cuff placement.
The individual should be comfortably seated, with the legs uncrossed, and the back and arm supported, such that the middle of the cuff on the upper arm is at the level of the right atrium (the mid-point of the sternum).
Measurements made while the patient is on an examining table do not fulfill these criteria and should preferably be made while the patient is seated in a chair. At the initial visit, blood pressure should be measured in both arms.
The patient should be instructed to relax as much as possible and to not talk during the measurement procedure; ideally, 5 minutes should elapse before the first reading is taken.
Effects of Body Position
Blood pressure measurement is most commonly made in either the sitting or the supine position, but the 2 positions give different measurements. It is widely accepted that diastolic pressure measured while sitting is higher than when measured supine (by
5 mm Hg), although there is less agreement about systolic pressure.
88 When the arm position is meticulously adjusted so that the cuff is at the level of the right atrium in both positions, the systolic pressure has been reported to be 8 mm Hg higher in the supine than the upright position.
89
Other considerations include the position of the back and legs. If the back is not supported (as when the patient is seated on an examination table as opposed to a chair), the diastolic pressure may be increased by 6 mm Hg.90 Crossing the legs may raise systolic pressure by 2 to 8 mm Hg.
91
In the supine position, the right atrium is approximately halfway between the bed and the level of the sternum
92; thus, if the arm is resting on the bed, it will be below heart level. For this reason, when measurements are taken in the supine position the arm should be supported with a pillow. In the sitting position, the right atrium level is the midpoint of the sternum or the fourth intercostal space.
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Important Points for Clinical Blood Pressure Measurement[/SIZE]
- The patient should be seated comfortably with the back supported and the upper arm bared without constrictive clothing. The legs should not be crossed.
- The arm should be supported at heart level, and the bladder of the cuff should encircle at least 80% of the arm circumference.
- The mercury column should be deflated at 2 to 3 mm/s, and the first and last audible sounds should be taken as systolic and diastolic pressure. The column should be read to the nearest 2 mm Hg.
- Neither the patient nor the observer should talk during the measurement.
