3 Chapter 1 O VERVIEW 1.1 The elderly and problems related to anesthesia - surgery 1.2 Hip replacement surgery 1. 3 PCEA pain relief method 1.3.1 Epidural anesthesia 1.3.1.1 Anatomy of the epidural space 1.3.1.2 The effect of age on the distribution in the epidural space 1.3.1.3 The effect of epidural anesthesia 1.3.2 Self-controlled epidural pain relief 1.3.3 Principle of operation Figure 1.1: Changes in drug concentration in blood Jeffrey A Grass, Anesth Analg.