RESUMO
The purpose of this study was to analyze postoperative pain differences in patients undergoing peripheral arm surgery. Differences between patients' perceived pain who received 2 mg of morphine sulfate added to the standard Bier block solution and the standard Bier block solution without morphine were studied. A quasi-experimental nonequivalent control group design was utilized. Thirty adult subjects (22 men and 8 women) ages 21 to 76 years constituted the convenience sample. Pain scores were measured by a verbal descriptor scale at the following times: upon admission to the postanesthesia care unit, at 30 minutes and 60 minutes after surgery, and at 24 hours postoperatively. A two-tailed Mann-Whitney U test was used to analyze pain scores for the two groups (P < .05). No statistically significant differences were found in postoperative pain between the group receiving a Bier block solution with 2 mg of morphine sulfate and the group with a standard Bier block solution without morphine sulfate. The mean scores for the morphine sulfate group were lower in each time period measured. This study suggests a questionable benefit for adding 2 mg of morphine sulfate to a Bier block solution. A larger sample may have yielded different results. Many issues remain undecided regarding the potential role of opioids in various regional anesthetic techniques. Further studies are warranted to investigate the peripheral effects of opioids and to understand the mechanisms of action of opioid analgesics at peripheral sites.
