Open Access Open Access  Restricted Access Subscription or Fee Access

Should morphine dosing be weight based for analgesia in the emergency department?

Asad E. Patanwala, PharmD, Christopher J. Edwards, PharmD, Lori Stolz, MD, Richard Amini, MD, Amol Desai, MD, Uwe Stolz, PhD, MPH

Abstract


Objective: To determine if patient weight is predictive of the degree of analgesic response to morphine in opioid naïve patients in the emergency department (ED).
Design: Prospective observational study.
Setting: Academic, tertiary ED, designated as a level 1 trauma center.
Patients: Fifty opioid naïve adult patients who were administered a single fixed intravenous dose of 4 mg morphine on initial presentation to the ED.
Interventions: Pain was assessed at baseline and then repeated at 15- and 30-minute postdose using an 11-point (0-10) verbal numerical rating scale (NRS).
Main outcome measures: The primary outcome was maximum analgesic response, which is defined as the difference between initial pain score and lowest pain score achieved postdose at 15 or 30 minutes. Linear regression was used to analyze the relationship between maximum pain reduction and patient weight.
Results: Mean patient weight was 85.4 kg (standard deviation= ±24.2; range 47.6-170). Median initial pain score was 8 (range 6-10) and median lowest pain score achieved postdose was 4 (range 0-10). In the linear regression analysis, patient weight did not predict the degree of pain reduction on the NRS (coefficient = 0.002 [95% confidence interval (CI)= −0.029-0.032], R2 <0.001, p = 0.91). The only variable predictive of the degree of pain reduction was initial pain score (coefficient = 0.537 [95% CI = 0.013-1.061], R2 = 0.081, p = 0.045).
Conclusions: Patient weight was not significantly associated with the degree of analgesic response to morphine in opioid naïve adults. Morphine dosing based on patient weight alone is not necessary in adults in the ED.

Keywords


pain, morphine, emergency department

Full Text:

PDF

References


Niska R, Bhuiya F, Xu J: National Hospital Ambulatory Medical Care Survey: 2007 emergency department summary. National Health Statistics Reports, No. 26. Hyattsville, MD: National Center for Health Statistics, 2010.

Bijur PE, Kenny MK, Gallagher EJ: Intravenous morphine at 0.1 mg/kg is not effective for controlling severe acute pain in the majority of patients. Ann Emerg Med. 2005; 46(4): 362-367.

Birnbaum A, Esses D, Bijur PE, et al.: Randomized doubleblind placebo-controlled trial of two intravenous morphine dosages (0.10 mg/kg and 0.15 mg/kg) in emergency department patients with moderate to severe acute pain. Ann Emerg Med. 2007; 49(4): 445-453.

Chang AK, Bijur PE, Meyer RH, et al.: Safety and efficacy of hydromorphone as an analgesic alternative to morphine in acute pain: A randomized clinical trial. Ann Emerg Med. 2006; 48(2): 164-172.

Patanwala AE, Biggs AD, Erstad BL: Patient weight as a predictor of pain response to morphine in the emergency department. J Pharm Pract. 2011; 24(1): 109-113.

Hampton T: A world of pain: Scientists explore factors controlling pain perception. JAMA. 2006; 296(20): 2425-2427.

Bijur PE, Latimer CT, Gallagher EJ: Validation of a verbally administered numerical rating scale of acute pain for use in the emergency department. Acad Emerg Med. 2003; 10(4): 390-392.

American Society of Health-System Pharmacists: Morphine sulfate. In McEvoy GK (ed.): STAT!Ref System. Bethesda, MA: AHFS Drug Information, 2010.

Cohen J: A power primer. Psychol Bull. 1992; 112(1): 155-159.

Faul F, Erdfelder E, Buchner A, et al.: Statistical power analyses using G*Power 3.1: Tests for correlation and regression analyses. Behav Res Methods. 2009; 41(4): 1149-1160.

Blumstein HA, Moore D: Visual analog pain scores do not define desire for analgesia in patients with acute pain. Acad Emerg Med. 2003; 10(3): 211-214.

O’Connor AB, Zwemer FL, Hays DP, et al.: Intravenous opioid dosing and outcomes in emergency patients: A prospective cohort analysis. Am J Emerg Med. 2010; 28(9): 1041-1050.




DOI: https://doi.org/10.5055/jom.2012.0096

Refbacks

  • There are currently no refbacks.