老年人硬膜外阻滞应注意的问题包括() ["A．易发生呼吸抑制","B．局麻药的需要量减少","C．易发生低血压","D．穿刺操作的困难程度增加","E．强调术中给辅助药"] 老年人术中输血较多、术后呼吸肌无力，以下哪些是不可取的() ["A．吸氧","B．新斯的明","C．钙剂","D．辅助通气","E．呼吸兴奋剂"] 老年人某些手术选择局麻的优点有() ["A．减少术后中枢神经功能障碍","B．减少麻醉并发症","C．减少应激反应","D．减少术后血栓形成","E．保持循环稳定"] 老年人痛觉降低的主要原因有() ["A．躯体痛觉阈值增高","B．躯体痛觉阈值减低","C．皮肤痛觉小体减少","D．阿片受体增加","E．阿片受体减少"] 老年人中枢神经系统解剖上的改变包括有() ["A．脑体积缩小","B．脑重量减轻","C．脑脊液增加","D．脑沟增宽","E．脑神经变性"] 下列哪些因素与衰老进程有关()