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pressure ≥140 mm Hg and diastolic pressure <90 mm Hg) is recognized as an important risk factor for cardiovascularmorbidity and mortality in older adults.Etiology and PathogenesisAmong the aging processes that contribute to an increase in blood pressure are a stiffening of the large arteries,particularly the aorta; decreased baroreceptor sensitivity; increased peripheral vascular resistance; and decreased renalblood flow. Systolic blood pressure rises almost linearly between 30 and 84 years of age, whereas diastolic pressure risesuntil 50 years of age and then levels off or decreases. This rise in systolic pressure is thought to be related to increasedstiffness of the large arteries. With aging, the elastin fibers in the walls of the arteries are gradually replaced by collagenfibers that render the vessels stiffer and less compliant. Differences in the central and peripheral arteries relate to the factthat the larger vessels contain more elastin, whereas the peripheral resistance vessels have more smooth muscle and lesselastin. Because of increased wall stiffness, the aorta and large arteries are less able to buffer the increase in systolicpressure that occurs as blood is ejected from the left heart, and they are less able to store the energy needed to maintain thediastolic pressure. As a result, the systolic pressure increases, the diastolic pressure remains unchanged or actuallydecreases, and the pulse pressure or difference between the systolic pressure and diastolic pressure widens.Diagnosis and Treatment
26The recommendations for measurement of blood pressure in older adults are similar to those for the rest of thepopulation. Blood pressure variability is particularly prevalent among older adults, so it is especially important to obtainmultiple measurements on different occasions to establish a diagnosis of hypertension. The effects of food, position, andother environmental factors also are exaggerated in older adults. Although sitting has been the standard position for bloodpressure measurement, it is recommended that blood pressure also be taken in the supine and standing positions in theelderly. In some older adults with hypertension, a silent interval, called theauscultatory gap,may occur between the end ofthe first and beginning of the third phases of the Korotkoff sounds, providing the potential for underestimating the systolicpressure, sometimes by as much as 50 mm Hg. Because the gap occurs only with auscultation, it is recommended that apreliminary determination of systolic blood pressure be made by palpation and the cuff be inflated 30 mm Hg above thisvalue for auscultatory measurement of blood pressure. In some older adults, the indirect measurement using a bloodpressure cuff and the Korotkoff sounds has been shown to give falsely elevated readings compared with the directintraarterial method. This is because excessive cuff pressure is needed to compress the rigid vessels of some olderpersons. Pseudohypertension should be suspected in older adults with hypertension in whom the radial or brachial artery