Muravchick S
Hospital of the University of Pennsylvania, Philadelphia 19104-4283, USA.
Acta Anaesthesiol Belg. 1998;49(2):79-84.
Aging alters both the pharmacokinetic and the pharmacodynamic aspects of anesthetic requirement. Studies of the relationship between drug concentration and effect in older adults clearly demonstrate a decline in median effective dose requirement for agents that act within the central nervous system, but there appears to be little change in the dose required for peripheral effects such as neuromuscular blockade. Most drugs also undergo somewhat slower biotransformation and demonstrate prolonged clinical effects if they require hepatic or renal degradation, although many newer agents such as remifentanil and cisatracurium have organ-independent pathways that are not affected by age. In some cases, however, the appearance of increased sensitivity to a given dose of anesthetic or opiate may actually reflect higher-than expected plasma concentrations of drug following a rapid intravenous injection. Therefore, it is impossible to completely separate the interactions between pharmacodynamic and pharmacokinetic factors associated with aging. The use of pharmacological sympathectomy with intrathecal agents and with sympatholytic adrenergic agonists may further improve outcome in a patient population at high risk because of reduced functional reserve, increased incidence of polypharmacy, and the consequences of age-related disease.
衰老会改变麻醉需求的药代动力学和药效学方面。对老年人药物浓度与效应之间关系的研究清楚地表明，作用于中枢神经系统的药物的中位有效剂量需求有所下降，但对于诸如神经肌肉阻滞等外周效应所需的剂量似乎变化不大。大多数药物的生物转化也会稍慢一些，如果它们需要肝脏或肾脏降解，则会表现出延长的临床效应，尽管许多新型药物如瑞芬太尼和顺式阿曲库铵具有不依赖器官的途径，不受年龄影响。然而，在某些情况下，对给定剂量的麻醉药或阿片类药物敏感性增加的表现实际上可能反映了快速静脉注射后药物的血浆浓度高于预期。因此，不可能完全区分与衰老相关的药效学和药代动力学因素之间的相互作用。由于功能储备减少、多药合用发生率增加以及与年龄相关疾病的后果，对于高危患者群体，使用鞘内药物和交感神经解压器官内注射进行药理学交感神经切除术可能会进一步改善治疗结果。
