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For Seniors: What to Do About High Blood Pressure
Dr. Ali is a Fellow, Geriatrics Division, Saint Louis University School of Medicine, St. Louis, MO. Dr. Ali reports no conflict of interest.
Among seniors, more than half have high blood pressure (hypertension). What is blood pressure? How high is high? And what should you do about it?
Blood pressure is measured in units of mercury (mm Hg) and expressed as a fraction. The top number is the systolic blood pressure (SBP) and is an indicator of the force with which blood pumped from the heart hits the walls of the arteries. The bottom number is called the diastolic blood pressure (DBP) and reflects the pressure that remains in the circulatory system after the force of the ejected blood is spent. So, if you have a blood pressure of 120/80 mm Hg, the "120" is the systolic and the "80" is the diastolic.
The difference between the systolic pressure and the diastolic (for example, 120 minus 80 = 40) is also important and usually ranges between 30 and 60 in normal individuals. When the difference is larger, as we will see, a person may experience episodes of, for example, low blood pressure upon standing (orthostatic hypotension).
The special concern for the elderly is the increased incidence of systolic blood pressure (SBP), the fall of diastolic blood pressure (DBP) and the increased frequency of orthostatic hypotension because of the widened difference between the top and bottom numbers.
The fall in diastolic BP results from decreased resistance in the largest artery, the aorta, because it is stiff and no longer flexible. This so-called decreased aortic impedance, a manifestation of not only aging but also other factors that accelerate arteriosclerosis including a high SBP. Higher SBP, left untreated, may worsen aortic stiffness and perpetuate a vicious cycle.(1)
Another relevant factor is the increased frequency of low blood pressure following meals (postprandial hypotension) and frailty; both relatively preventable. Overall, the reality is that for many individuals their blood pressure is not well controlled.(2)(3)(4)
Blood Pressure Measurement: Proper TechniqueIt is important that the dimensions of the blood pressure cuff be appropriately sized for each individual. Smaller cuffs on bigger arms, for exampe, may give readings that are inaccurately higher.(5)
Before taking your blood pressure, avoid food, exercise, caffeine and smoking one hour prior to BP measurement.(6) Smoking two cigarettes (3.4 mg nicotine) will elevate BP by 10/8 mm Hg for 15 minutes. Drinking coffee (200 mg caffeine) will elevate BP by up to 10/7 mm Hg for one to two hours.(7) For an accurate blood pressure reading, sit in a warm room for at least five minutes with your arm supported at the level of the heart, for example, resting on a table. Don't let your arm dangle, for this will elevate SBP by 10 mm Hg because of hydrostatic pressure induced by gravity.(8) Make sure the medical staff checks your BP in both arms and then uses the arm with the higher reading for subsequent measurements.(10)
In some older patients, compression of the brachial artery in the arm, from arterial thickening caused by calcification, will cause overestimation of the systolic and diastolic pressures by 10 mm Hg or more.(11)
Risk Factors for Essential Hypertension.
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