Analgesia
Selected Papers from the 1999 Society for Academic Emergency Medicine Meetings
CONFERENCE COVERAGE
Analgesia
Route of Analgesia and Pain Perception
The purpose of this prospective, randomized, doubleblind study was to compare the analgesic effects of IM vs. PO placebo. A convenience sample of 77 patients with acute musculoskeletal pain was given 800 mg of ibuprofen in an orange flavored drink. Thirty-nine of the subjects then received a physiologically inactive tablet resembling ibuprofen and the remaining thirty-eight subjects received a physiologically inactive IM injection resembling ketorolac 60 mg. Subjects then rated the intensity of their pain on a 100 mm visual analog scale (VAS) at baseline and 30, 60, 90, and 120 minutes after treatment.
A total of 64 patients completed the study, giving the authors the ability to detect a 20% difference in VAS score between the two groups with 90% power. After two hours, the mean VAS score had decreased from 60 to 26 for the IM group and from 59 to 27 in the PO group. There were no significant differences in the VAS scores at baseline or at each subsequent interval.
Comment by Stephanie Abbuhl, MD, FACEP
I suspect that all of us have thought, at one time or another, that at least some of the benefit from a parenteral analgesic was due to the placebo effect of the perception of a "stronger medication." The authors of this clever, but small, study have provided some initial evidence to refute this commonly held belief. Instinctively, I like this study because it reminds us of our tendency as physicians to think that pain management is more of a subjective game of manipulation than part of objective disease management. We may have again underestimated our patients.
Admittedly, it is possible that larger studies will expose some placebo effect from parenteral analgesia. In addition, there may also be clinically important differences in patient-assigned VAS scores at less than a 20% difference.1 Finally, it is also possible that certain subgroups of patients will gain a significant placebo effect from parenteral analgesics. (Source: Schwartz NA, et al. Perceived mode of NSAID/placebo administration and its effects on analgesia [abstract]. Acad Emerg Med 1999;6:505.)
Reference
1. Todd KH, et al. Clinical significance of reported changes in pain severity. Ann Emerg Med 1996;27:485-489.
In the study by Schwartz and associates on the effect of route of drug administration on pain perception, the following conclusion was drawn regarding the efficacy of the route of administration:
a. the oral route is better than the IM route.
b. the IM route is better than the oral route.
c. the IM and oral routes were equivalent.
d. the IM and oral routes were superior to the IV route.
Ketoralac vs. Meperidine for Renal Colic
This multicenter, prospective, randomized, double-blind equivalence trial examines a small area of controversy amongst many emergency physicians: Is ketoralac "better" than meperidine for analgesia in renal colic? Measurements of pain relief and functional status were taken at 60 minutes. Ketoralac patients received single intravenous bolus followed by placebo, and meperidine patients received an intravenous bolus of 50 mg followed by 25-50 mg boluses repeated every 15 minutes. The results favored ketoralac by the percentage of patients with successful pain relief and the overwhelming percentage of patients who were able to resume normal activity (44% of ketoralac patients and 10% of meperidine patients).
Comment by Richard Hamilton, MD, FAAEM, ABMT
Those of us who favor the use of ketoralac in the specific condition of renal colic will ignore the authors’ obvious bias toward the drug in developing this study, and use this study to reinforce our practice. Physicians who favor opiate analgesics would appropriately point out that the titration dosing regimen and 60-minute end point employ a suboptimal dose of meperidine as a bolus and then add additional drug at suboptimal dosing. The effect may be to cause some patients at 60 minutes to be in pain and others to be enduring the impairment of cumulative small doses of opiates. While my experience is in agreement with the authors’ hypothesis that ketoralac provides successful analgesia and earlier return of function, this study does not necessarily provide me with the support I had hoped for. A more appropriate study would be to employ 1-2 mg/kg of meperidine as a slow intravenous bolus head-to-head with ketoralac. While I believe the results would be similar, at least adequate opiate doses would be employed earlier to provide immediate complete pain relief and a period of recovery. One end point not obtained here—rapidity of onset of analgesia—is something that often favors the use of opiates in these clinical scenarios. (Source: Wood V, et al. NARC Trial: Single dose intravenous ketoralac versus titrated intravenous meperidine in acute renal colic—A randomized clinical trial [abstract]. Acad Emerg Med 1999;6:505.)
In the NARC study comparing the efficacy of ketorolac and meperidine in the treatment of acute renal colic:
a. meperidine provided better pain relief.
b. cognitive status improved significantly more in the meperidine group.
c. functional status improved significantly more in the ketorolac group.
d. the drugs were equally efficacious when given IM, but not IV.
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