Taking Accurate Blood Pressure


Be well trained and observant
Blood pressure recording is a process that should be practiced and re-practiced. The reading that is taken is an important tool in diagnosing a patient. That's why it is considered one of the Vital Signs. When taking a blood pressure always be sure to concentrate on the task at hand. Good eyesight and hearing, as well as hand-eye-ear coordination is important.

Use actual numbers

Most people have a tendency to round off numbers; for example, 152 becomes 150; 166 may become 170. In blood pressure recording, a few millimeters may make the difference in a patient's diagnosis. Always record the reading to the nearest 2mm Hg.2

Don't be biased

Just because a patient (or yourself, in the case of home readings) is normally around 126/82 (for example), don't prematurely assume the next reading will fall near that range.3 Record each reading based on your observations at that time.

Position the patient properly

For regular blood pressure recordings, the patient is seated with the midpoint of the upper arm at the level of the heart.4 When the arm is below the heart level, the reading will be too high.5 In fact, it has been reported that the reading can be as much as 8mm high when the patient's arm is hanging at their side.6 However, some circumstances may require the patient to be in a different position. When lying down, position the patient's arm at the side of the body, slightly raised; when the patient is standing, raise the patient's arm and support at the heart level.7 Document the patient's position when recording their measurement on their chart.

Have a calm manner and peaceful environment

Try to keep the patient relaxed and have everything ready (equipment, charts, pen, etc.) for the reading before the patient is seated. Since blood pressure levels are affected by emotions, physical activity, and the surroundings, minimize disturbances that may affect the reading.

Check your equipment

Routinely inspect your blood pressure equipment - sphygmomanometer, cuffing system, bladders, tubes, valves, etc. - to make sure it is functioning properly. Check to see if the mercury level of your instrument is at zero. Check aneroid gauges over the entire range against a mercury sphygmomanometer.9 Repair, replace, and clean as necessary. Consider using a cuff that has an antimicrobial agent to help prevent bacterial growth and mildew on the cuff fabric. It has been reported that blood pressure cuffs can carry significant bacterial colonization, particularly in the Operating Room, P.A.C.U. and I.C.U, and can actually be a source of transmission of infection.

Select the right size inflation system

Choose the appropriate size cuff based on the circumference of the patient's bare upper arm. The bladder (inside the cuff) should encircle 80 percent of an adult's arm and, for a child less than 13 years old, 100 percent.11 A cuff/bladder that is too narrow for the arm will result in a high blood pressure reading.12 This situation may lead to the overtreatment of hypertension; conversely, using a cuff too large may lead to the undertreatment of hypertension.13 Have a full range of cuff sizes available to accommodate your patient population.

1 "Human Blood Pressure Determination by Sphygmomanometry," American Heart Association, Dallas, Texas, ©1967, 1980, 1987, 1994 American Heart Association, p. 13. 2 Ibid., p. 14. 3 Ibid., p. 14. 4 Ibid., p. 14. 5 Ibid., p. 25 6 Cooper, Karen, "Measuring Blood Pressure the Right Way," Nursing92, April 1992, p. 75. 7 "Human Blood Pressure Determination by Sphygmomanometry," p. 14-15. 8 Ibid, p. 15. 9 American Society of Hypertension, "Recommendations for Routine Blood Pressure Measurement by Indirect Cuff Sphygmomanometry," American Journal of Hypertension, April 1992, p. 207. 10 Sternlicht, Andrew L., "Significant Bacterial Colonization Occurs on the surface of Non-Disposable Sphygmomanometer Cuffs and Re-Used Disposable Cuffs," Anesthesia & Analgesia, February 1990, p. S391. 11 "Human Blood Pressure Determination by Sphygmomanometry," p. 15. 12 Ibid., p. 24 13 Manning, Dennis M., "Miscuffing: Inappropriate Blood Pressure Cuff Application," Hypertension, October 1993, p. 765.