Cleophas Ton J, van Marum Rob
Department of Medicine, Albert Schweitzer Hospitals, Dordrecht, The Netherlands.
Drugs Aging. 2003;20(5):313-9. doi: 10.2165/00002512-200320050-00001.
Autonomic control of blood pressure appears to decline with age giving rise to an increased risk of orthostatic hypotension and major hypotensive reactions to antihypertensive drugs. In the past few years, many workers have assessed autonomic function in the elderly and sometimes found controversial results. Baroreflex sensitivity, as measured by the steepness of the heart rate/mean pressure curve, decreases with age. However, this phenomenon does not correlate well with orthostatic impairment. Sympathetic dysfunction might be more responsible for syncopal symptoms in the elderly, a finding supported by the fact that elderly with orthostatic symptoms never collapse within a few seconds, but do so after 1 or more minutes of standing. However, the results of sympathetic function testing in the elderly indicate that sympathetic function in most elderly is not impaired and that sympathetic activity, as measured by circulating levels of catecholamines, is usually increased rather than decreased. In various populations with increased sympathetic activity, but not in the elderly, beta-adrenoceptor antagonists (beta-blockers) have been demonstrated to cause pressor effects, presumably due to alpha-adrenoceptor-mediated vasoconstriction unopposed by beta-receptor-mediated vasodilation. In the past year, large studies have been completed indicating that the same is true for the elderly, and that the depressor effect on pulse pressure upon standing in this category of patients can be offset and turned into a pressor effect by long-term beta-blocker treatment. This phenomenon could not be demonstrated with non-beta-blocker antihypertensive drugs, including ACE inhibitors, calcium channel antagonists, diuretics and angiotensin II receptor antagonists. In elderly patients beta-blockers may, therefore, be the most appropriate antihypertensive agents as they protect the elderly from orthostatic impairment.
血压的自主控制能力似乎会随着年龄的增长而下降，从而增加了体位性低血压以及对抗高血压药物出现严重降压反应的风险。在过去几年中，许多研究人员对老年人的自主功能进行了评估，有时会得出有争议的结果。通过心率/平均压力曲线的斜率来衡量的压力反射敏感性会随着年龄的增长而降低。然而，这种现象与体位性损伤的相关性并不强。交感神经功能障碍可能是老年人晕厥症状的更主要原因，这一发现得到了以下事实的支持：有体位性症状的老年人不会在几秒钟内晕倒，而是在站立1分钟或更长时间后才会晕倒。然而，对老年人交感神经功能测试的结果表明，大多数老年人的交感神经功能并未受损，而且通过儿茶酚胺循环水平来衡量的交感神经活动通常是增加而非减少。在交感神经活动增加的各类人群中（但不是老年人），β-肾上腺素能受体拮抗剂（β-阻滞剂）已被证明会引起升压作用，这可能是由于α-肾上腺素能受体介导的血管收缩未受到β-受体介导的血管舒张的对抗。在过去一年中，大型研究已经完成，结果表明老年人也是如此，而且长期使用β-阻滞剂治疗可以抵消这类患者站立时脉压的降压作用，并使其转变为升压作用。包括血管紧张素转换酶抑制剂、钙通道拮抗剂、利尿剂和血管紧张素II受体拮抗剂在内的非β-阻滞剂类抗高血压药物并未出现这种现象。因此，在老年患者中，β-阻滞剂可能是最合适的抗高血压药物，因为它们可以保护老年人免受体位性损伤。
