Analgesia for Children with Acute Abdominal Pain

Source: Kim MK, et al. A randomized clinical trial of analgesia in children with acute abdominal pain. Acad Emerg Med 2002;9:281-287.

Recent studies have challenged the long-held belief that analgesia may mask symptoms and physical findings among adults presenting to the emergency department (ED) with acute abdominal pain. This has led to recommendations in both the surgical and emergency medicine literature to provide analgesia after initial evaluation in patients with abdominal pain. This is the first study to examine the use of analgesia among children with acute abdominal pain.

The stated goals of this randomized, double-blind, placebo-controlled study were to examine the effect of intravenous morphine (MS) on pain reduction, physical examination, and diagnostic accuracy in children with acute abdominal pain. The study included children 5-18 years of age with abdominal pain of fewer than five days duration with a pain score greater than 5 on a vertical visual analog scale (VAS), the need for vascular access, and the need for surgical consultation as determined by the pediatric emergency medicine (PEM) physician. Exclusion criteria included hypotension, morphine allergy, pregnancy, prior abdominal surgery, refusal of analgesia, sickle cell disease, inflammatory bowel disease, and suspected biliary or pancreatic problems (to account for the questionable effect of morphine on the sphincter of Oddi).

After study consent was obtained, the PEM physician and the surgical consultant independently performed and documented the physical exam and provisional diagnosis. Each marked the location of tenderness on a nine-zone grid representing the areas of the abdomen. Laboratory and other studies were ordered by agreement of the two physicians, and results were not reviewed until after the post-medication assessment and data sheets were completed. The study medication (either MS 0.1 mg/kg or normal saline) was then administered as randomized by the hospital pharmacy.

Fifteen to 30 minutes after the study medication was administered, the same physicians independently re-examined the patients and documented the location of tenderness and a final diagnosis. The final disposition was then made by the PEM physician and attending surgeon after reviewing the examination and diagnostic test results. Admitted patients were followed for complications, hospital course, and discharge diagnosis. Discharged patients received a follow-up telephone interview at 48 hours and a questionnaire, to be completed one week after ED discharge, about persistent pain and subsequent physician evaluations.

In a two-year period, 60 patients met the final study criteria (29 receiving MS and 31 receiving saline). The groups were similar in age, sex, ethnicity, pre-study VAS score, mean area of tenderness, and time interval between physician assessments. The median difference in the reduction of pain score between the two groups was 2 (p = 0.002). The decrease in the mean number of areas of tenderness with morphine was significant for the PEM physicians but not the surgeons. No decrease in mean areas of tenderness occurred in the saline group.

Twenty-one patients in the MS group and 23 patients in the saline group required exploratory laparotomy (p = NS). The mean duration of time from triage to surgery in the MS and saline groups were 7.2 and 6.6 hours (p = NS), respectively. The diagnostic accuracies between the PEM and surgical consultants pre-MS were 21/29 and 23/29, respectively. After MS, the accuracies were identical for both physician groups at 24/29. The study sample was not large enough to report significant adverse events.

The authors conclude that MS significantly decreases pain without affecting diagnostic accuracy or time to surgical intervention among children presenting to the ED with acute abdominal pain. 

Commentary by Jacob W. Ufberg, MD

This small, but well-done study demonstrates that we can expand to children (age > 5 years) what we have known to be true for adults for some time. The judicious use of analgesia among patients with abdominal pain will not obscure the diagnosis, and actually may help identify patients with nonsurgical causes of abdominal pain.

This study had one major limitation—the fact that the surgeons were able to examine patients both before and after analgesia. The surgical consultants were aware of the initial exam, and had that information when performing the post-medication exam. This does not represent a real-life situation in which the surgical consultant will have to make a decision based only on the post-MS exam.

Hopefully, this report is a stepping-stone to larger, multi-center pediatric studies that will demonstrate the benefits of analgesia to diagnostic accuracy as well as to patient comfort and satisfaction. We also must hope that some of these studies will be published where a majority of our surgical colleagues will read them.

Dr. Ufberg, Assistant Professor of Emergency Medicine, Department of Emergency Medicine, Temple University School of Medicine, Philadelphia, PA, is on the Editorial Board of Emergency Medicine Alert.