A comparison of patient-controlled analgesia administered by the intravenous or intranasal route during the early postoperative period

Abstract

Intranasal administration of lipophilic opioids has been shown to be an effective method of administration which is devoid of major side-effects. Whether it is as effective as intravenous administration for patient-controlled analgesia (PCA) has been investigated for fentanyl and pethidine, but not for diamorphine. This study reports a randomised controlled trial designed to compare the effectiveness of diamorphine administered as PCA utilising either the intranasal or intravenous routes. We investigated 52 consecutive patients undergoing primary lower limb joint replacement surgery. Patients were randomly allocated to receive PCA diamorphine, administered either intravenously (0.5 mg bolus, 3 min lockout) or intranasally (1.0 mg bolus, 3 min lockout). Pain was assessed using a Visual Analogue Score (VAS) at rest and on movement on five occasions over the first 36 h postoperatively. The results demonstrated that patients in the intranasal PCA group had significantly higher VAS scores than the intravenous group, both at rest (intranasal median 35.5 vs. intravenous median 20; p = 0.030) and on movement (intranasal median 64 vs. intravenous median 50; p = 0.016). However, significantly fewer patients in the intranasal group compared with the intravenous group suffered episodes of vomiting (intranasal 0/24 vs. intravenous 6/24 patients; p = 0.022). We suggest that if a maximal reduction in pain score is considered the goal of PCA management, the intravenous route is preferable to the intranasal route.