Review of: Fleischman RJ, Frazer DG, Daya M, et al. Effectiveness and safety of fentanyl compared with morphine for out-of-hospital analgesia. Prehosp Emerg Care. 2010;14:167–175.
This retrospective before-and-after study compared the safety and effectiveness of morphine and fentanyl in the prehospital setting. In 2007, a protocol change occurred for an Oregon paramedic EMS system: switching from morphine to fentanyl. Then, EMS charts were pulled for nine months prior to the change and nine months after the change; the first three months after the change were eliminated to decrease the chances of bias occurring on the part the paramedics.
Adverse events were determined prior to the study:
- Respiratory rate <12 breaths/min;
- Pulse oximetry <92%;
- Systolic blood pressure <90 mmHg;
- Any fall in Glasgow Coma Scale score;
- Nausea or vomiting;
- Intubation; and
- Use of antiemetic agents or naloxone.
The results showed 355 patients received morphine and 363 received fentanyl. Patients in the fentanyl group received a statistically higher equivalent dose of morphine, but patients who received morphine had a higher prevalence of nausea. In conclusion, both drugs achieve pain relief and have low rates of adverse events.
Medic Marshall and Doc Wesley discuss the importance of prehospital pain management and their experiences with both medications.
Medic Marshall: Overall, I think this is a great study that points out the need to address pain in the prehospital setting and its' relative safety. Upon further examination, I found the mean starting pain score was approximately 8 out of 10—on a 0–10 scale—and generally, the pain was only decreased by approximately three points. I personally think this is being a little conservative in the management of pain. At minimum, I try to decrease pain in all of my patients by at least 50%, regardless of whether the complaint is traumatic or atraumatic.
I have the luxury of having both of these drugs at my disposal, and I use them differently. I prefer to use fentanyl for musculoskeletal injuries; it seems to work quickly, and I can give it intranasally if necessary. I use morphine for those deep pains, especially abdominal pain. Not to mention, it seems to have more of a euphoric effect than fentanyl, which I think some patients benefit from.
Doc Wesley: I congratulate the authors on furthering our understanding of the importance of prehospital pain control. This study showed clinical equivalence of morphine with fentanyl as far as pain control is concerned. My only issue with the study is their dose of fentanyl. Most services use 1 ug/kg initial dose with supplemental dosing at 0.5 ug/kg. Although this represents a doubling of the equivalent dose of morphine, my experience is that this dose is safe and poses significantly fewer side effects than administering 10mg morphine in a single IV dose.
Examining the graphs of side effects, I wonder if fentanyl would've been found to have more nausea and vomiting if the study had been powered sufficiently. However, the chief complaints of the patients who received morphine were significantly different from those who received fentanyl. The fentanyl group had a large percentage of patients with abdominal and pelvic pain, which would be associated with nausea and vomiting due to their underlying cause.
Additionally, I'd encourage future research to include pediatric patients and intranasal fentanyl administration. Although numeric pain scores are difficult with children, the data supports that they can reliably rate their pain using a visual analog score that has facial representations.
What I found especially valuable about this study was the validation that fentanyl and morphine provide equivalent periods of pain relief, but fentanyl does it faster. Fentanyl is an excellent "extrication" analgesic.
There's no reason for EMS providers to fear treating pain. This study should give provider the additional confidence that they can relieve pain with minimal concern for serious side effects.