A comparison of the relative effectiveness of intravenous patient controlled-analgesia delivered morphine and morphine with fentanyl

The aim of this study is to compare the effectiveness of intravenous patient-controlled analgesia using morphine with fentanyl and morphine alone in patients undergoing gynecologic surgery. A retrospective analysis of the pain control charts of 204 patients was performed. Forty-one patients received morphine with fentanyl (GI) and 163 patients received only morphine (GII). The patients were evaluated twice each day. The degree of pain relief was assessed using a visual analogue scale (VAS). The doses used and analgesic drug-related complications including adverse effects were noted. The VAS scores in GI from postoperative days 1-3 were 2.8 ± 0.8, 1.8 ± 0.7, and 1.3 ± 0.5, respectively, and the VAS scores in GII from postoperative days 1-3 were 3.1 ± 0.9, 2.3 ± 0.8, and 1.9 ± 0.7, respectively. The difference in VAS scores between the two groups was statistically significant. The mean total dose of morphine consumed was 29.4 ± 11.6 mg in GI and 39.7 ± 33.2 mg in GII. There was no statistically significant difference in the mean total dose of morphine consumed between the two groups. The mean fentanyl dose used was 471.5 ± 180 μg in GI. Fentanyl is a synthetic opioid with an analgesic potency equivalent to about 80-100 times that of morphine. Thus, GI patients received an over-all opioid solution equivalent to 2.6 mg morphine. The mechanism of better pain relief in GI is due to the fact that patients receiving morphine and fentanyl are getting greater opioid load. This greater opioid load is it not necessarily associated with more side effects.