Efficacy of patient-controlled analgesia for patients with acute abdominal pain in the emergency department: a randomized trial.

OBJECTIVES

The objective was to assess the efficacy of patient-controlled analgesia (PCA) in the emergency department (ED) and to compare two PCA dosing regimens.

METHODS

A randomized controlled trial with three treatment arms was performed in an urban ED. A convenience sample of ED patients ages 18 to 65 years with abdominal pain of 7 days or less duration requiring intravenous (IV) opioid analgesia was enrolled between April 2009 and June 2010. All patients received an initial dose of 0.1 mg/kg IV morphine followed by physician-managed analgesia as needed. Patients in the PCA arms also received IV morphine with on-demand doses of 1 or 1.5 mg, with a 6-minute lockout between doses. Pain intensity was rated by patients on an 11-point numeric rating scale (NRS). Satisfaction with pain treatment, desire for the same treatment in the future, and need for additional analgesia were assessed at study end. Adverse events (O(2) sat < 92%, respiratory rate [RR] < 10/min, systolic blood pressure [sBP] < 90 mm Hg, and naloxone use) were counted. One-way analysis of variance was used to test the difference among groups in short-term pain relief, as assessed by mean change in NRS pain intensity from baseline to 30 minutes and pain over the entire 2-hour study period measured by area under the curve (AUC) of NRS pain ratings. A post hoc hierarchical linear model was used to test the observed difference in NRS between the groups between 30 and 120 minutes.

RESULTS

A total of 211 patients were enrolled. A sharp, nearly identical decline in mean NRS scores occurred from baseline to 30 minutes in the three groups (p = 0.82). Between 30 and 120 minutes, there was little further decline in the non-PCA NRS scores, while both PCA groups continued to decline (p = 0.004). The net treatment effect over the entire 2 hours was smallest in the non-PCA group and largest in the group receiving 1.5 mg of morphine (p = 0.06). The mean decline in pain from baseline to 120 minutes postbaseline in both PCA groups was 1.4 NRS units (95% confidence interval [CI] = 0.3 to 2.4) greater than the decline in patients treated without PCA. More patients in the PCA arms reported satisfaction, wanting the same pain management in the future, and not wanting further analgesics at 120 minutes than patients who did not receive PCA. There were no clinically or statistically significant differences in any outcomes between the two PCA groups. One PCA patient had a transient oxygen saturation of 88% after the initial bolus only, and one non-PCA patient had a brief drop in sBP to 87 mm Hg.

CONCLUSIONS

This study provides support for efficacy of PCA when applied to the ED setting. Future studies designed to assess implementation of this modality in the context of conditions of actual ED staffing and competing patient demands are warranted.