Comparison between patient-controlled analgesia and subcutaneous morphine in elderly patients after total hip replacement

Background. The goal of this study was to evaluate the effectiveness on postoperative pain, and cognitive impact, of patient-controlled analgesia (PCA) compared with subcutaneous (s.c.) injections of morphine in elderly patients undergoing total hip replacement (THR). Methods. Forty patients older than 70 yr were randomly assigned to two different postoperative analgesic techniques for 48 h: i.v. PCA morphine (dose, 1 mg; lockout interval, 8 min; PCA group) or regular s.c. morphine injections (SC group). Postoperative pain was assessed at rest and when moving, using a visual analogue scale (VAS) every 4 h. A Mini Mental Status (MMS) examination was used to assess cognitive functions before surgery, at 2 h, 24 h and 48 h after surgery, and at hospital discharge. Side-effects were also recorded systematically during the first 48 h after surgery. Results. The PCA group showed significantly lower pain scores than the SC group both at rest and during mobilization. However, the clinical significance of pain scores was weak. There was no intergroup difference in postoperative MMS scores. The incidence of side-effects was similar in both groups. Conclusions. We conclude that in healthy elderly subjects undergoing THR, the flexibility of the analgesic regimen is more important than the route of administration with regard to efficacy, adverse effects and recovery of cognitive function.