Comments on the New AHA Recommendations for Blood Pressure Measurement

In this issue of The Journal of Clinical Hypertension, Pickering et al. ¹ summarize the American Heart Association (AHA) Recommendations from the Council of High Blood Pressure Research for blood pressure (BP) measurements in humans. This is an expanded and excellent update of the 1985 National High Blood Pressure Education Program recommendations for medical devices for measuring BP and the AHA recommendations in 1993. ² , ³ The report is a must‐read for anyone involved in screening, treatment programs, or research that involve BP measurements. There are, however, certain questions that practitioners may have about its content.

For years, concerns have been expressed about problems with the usual methods of recording casual BPs—problems that may result in misdiagnoses and occasional inappropriate treatment. The report appropriately notes that physicians (and other health care providers) traditionally round out the mm Hg numbers favoring a “5” and “0” rather than recording more exact readings. The AHA recommendations state that the number should be more carefully determined and recorded to the nearest 2 mm Hg. It is important to note, however, that while scientifically this is an important and correct recommendation, especially in research studies, this is difficult to do in the real world of practice. Determining specific numbers, i.e., 2, 4, 6, 8, etc. on the BP monitor is difficult and involves very careful attention with the current method of using a stethoscope and mercury sphygmomanometer.

The recommendations note that the bell portion of the stethoscope, rather than the diaphragm, be used in taking BP. This is to be desired since there are fewer outside noises with the bell. Again, in the real world, many physicians do not even have a bell attachment and use the diaphragm. They will probably continue to use what they are accustomed to when measuring BP. However, it may not make that much difference in most clinical settings if careful attention is paid to the procedure.

The discussion in this report of the various methods of taking BP should be helpful. Recognition of the increasing use of digital readout instruments that do not require a stethoscope is also important. Convenience is greater with these instruments. Although there is always some question about careful calibration of the electronic digital machines, in general, these are acceptable for use not only in offices or clinics but as home BP measuring devices. There may come a time when we may not be able to test them against a mercury manometer if these are eventually restricted or eliminated, but other standard pressure devices will be available for the necessary calibration. As noted, these devices do not require the use of a stethoscope and eliminate digit preference. They are easier to use for home BP follow‐up; many machines on the market have been carefully calibrated.

Despite many problems appropriately pointed out in the AHA recommendations about clinic or office casual BPs, it should be remembered that the casual pressures taken in an office or clinic have proved predictive of risk in epidemiologic studies as well as predictive of outcome in long‐term clinical trials. A lower BP in the clinic is indicative of a better prognosis; a lower BP in a long‐term clinical study indicates a better outcome (BPs are often taken only three to four times a year). White coat hypertension is real and not uncommon and the report stresses the use of the ambulatory BP monitoring to rule this out. This syndrome, however, can also be ruled out with less expense and effort with home BP recordings, which do not involve one or two office visits for attachment and removable of the automated BP machine and the cost of the procedure. Home readings will often give a better picture of BP over time than one 24‐hour or even two 24‐hour measurements of BP levels. In some situations, ambulatory BP monitoring may be useful to determine the status of BP changes during the night, but, for example, physicians may use available data on nondipping that is common in many black or diabetic patients to determine a treatment plan without doing the procedure.

It should be emphasized that clinic levels are predictive. While these may not be as accurate as an ambulatory BP monitoring in predicting some target organ involvement, such as left ventricular hypertrophy, this may not be of great importance in management. Individuals with office BPs consistently >140/90 mm Hg should be treated whether or not they have left ventricular hypertrophy. Although there is some disagreement regarding this issue, it is probably reasonable at present to use the office BP to determine treatment decisions, except in unusual situations (unexplained dizziness or headaches, etc.). In these cases, home BPs are useful.

The report notes that individuals with white coat hypertension can progress to sustained hypertension. In addition, some studies have reported that people with normal BPs at home and in the office or clinic are different physiologically from those patients with higher BPs in the clinic and normal pressures at home. Vascular resistance may be increased and there may be evidence of left ventricular diastolic dysfunction. White coat hypertension is an important entity, but these patients should not be ignored; if the white coat syndrome persists, some treatment should be instituted.

The AHA report reviews data on systolic and diastolic BP and pulse pressure differences. It concludes that, although pulse pressures are predictors of outcome, the use of systolic BP and diastolic BP readings should be used in making diagnostic and treatment decisions.

While some practicing physicians may question some of the recommendations for BP measurement of this expert panel regarding a procedure that is probably performed more often in medical care than almost any other, the report is an excellent update.