Morphine and Fentanyl

A research article entitled “Effectiveness and safety of fentanyl compared with morphine for out-of-hospital analgesia” by Fleischman RJ, Frazer DG, Daya M, et al. appeared in the latest issue of Prehospital Emergency Care.

The bottom line of the study was there was little difference between the two drugs, (as used under the study protocol). There were very few side effects and both decreased pain by an average of three points on the 0-10 scale.

under the study protocol, the paramedics were able to give pain meds on standing orders for isolated extremity injuries, burns, and chest pain unrelieved by nitroglycerin. Morphine was given as an IV dose of 2–5 mg, repeated every 5 minutes to a maximum of 20 mg. Fentanyl was given as a 50-μg IV dose, with repeated doses of 25–50 μg every 3–5 minutes to a maximum of 200 μg. Any additional dosing required on-line medical control.

The drugs were judged to have adverse effects if any of the following happened:

Respiratory rate under 12 breaths/min
Systolic blood pressure under 90 mmHg
02 oxygen saturation (SpO2) below 92% and 5% below baseline
Any decrease in the Glasgow Coma Scale (GCS)
Nausea or vomiting

718 patients aged 13–99 years received opiates under the study protocol, 355 received morphine, 363 received fentanyl. Fentanyl patients received a higher narcotic equivalent (7.7 mg morphine equivalents for morphine, 9.2 mg for fentanyl; but the same number of doses.)

The mean initial pain scores were 8.1 for morphine and 8.3 for fentanyl. Morphine decreased pain by 2.9 points. Fentanyl decreased pain by 3.1 points. In the ED morphine patients experienced an increase in their pain scores of 0.9. The fentanyl patients experienced an increase in their pain of 0.8. The authors of the study point out that, given the size of the study sample, this small difference is not statistically significant.

5.6% of the fentanyl patients experienced an adverse effect. 9.9% of the morphine patients did. Most of the adverse effects were related to nausea. (3.8% fentanyl, 7.0% for morphine). Ten patients had their systolic blood pressures go under 90 mmHg. All resolved either spontaneously or with a fluid bolus. Ten patients had drops in their oxygen saturation or declines in their respiratory rate below 12 breaths/min, but none required anything beyond supplemental oxygen. No patients required intubation.

More significant to me than there being little difference between the two drugs (I think there are differences such as time of onset that a differently designed study would have showcased) was the documentation of very little side effects, which has been my observation with the use of morphine (The service where I work as a paramedic is still awaiting the arrival of Fentanyl), and the documentation of both the average dose and average decline in pain scales.

I did a similar (but much smaller) study of pain meds by a group of medics I oversee, and found an average morphine dose of 5.6 mg of MS and 75 ug of fentanyl with an average drop in pain scale of 2 points for morphine and 3.1 for fentanyl. My on the back of an envelope stats based on far fewer cases is hardly scientifically rigid, but seems in-line with the published study. The only documented side effects from the run forms I reviewed was occasional nausea for which zofran was given. While the dose of the drugs these medics have given seems modest, it represents a great improvement over recent years. Their use of analgesia is up almost 500% from two years ago.

I next reviewed the times I have given morpine over the last 21 months (as far as our electronic records go back). I have given morphine 69 times during this period, but I had to exclude 15 records due to the patient being unable to articulate a pain scale (some elderly with low grade dementia, pediatrics, and non-English speakers unable to understand the pain sclale). Of the 54 I was able to include, the average initial pain scale was 9.2. The average dose of morphine I gave was 7.8, and the average final pain scale was 5.4 for a 3.8 point drop in pain or 41%. My intial guess was that I would have dropped their pain scale by a greater amount, but on review there were many patients who the pain meds barely touched. 11 of my 10 of 10 pains never dropped below an 8. I only had two patients complain of nausea, and one complain of itching. No incidents of hypotension, declining mental status or desaturation.

The take home message for me is when used to treat prehospital pain morphine and fentanyl are safe. Do not be afraid to treat your patients out of fear of causing adverse effects.

There is a nice little recap of this study on by Dr. Keith Wesley, one of my EMS heroes, and Marshall Washick, an experienced paramedic.

Are Fentanyl and Morphine Equals?

I agree whole-heartedly with Marshall Washick that medics should try to drop a patient’s pain scale by at least 50%.

As i stated earlier, I was surprised to learn that despite my efforts, I am only dropping pain by about 40%.


  • Christopher says:

    Our protocols have improved somewhat with respect to pain management in NC, however, they are still fairly restrictive for Morphine and Fentanyl. Oddly enough the Dilaudid protocol is comparatively liberal.

    I’d like to see a move to weight based with higher maximums and shorter intervals for re-bolusing. Something more in line with the current research on pain management!

    NC 2009 Protocols, Pain Control:

    Ketorolac: 30mg IM/IM

    Morphine: 4mg IM/IV/IO bolus, may repeat 2mg q 5-10min to max 10mg or clinical improvement

    Fentanyl: 50-75mcg IM/IV/IO bolus, may repeat 25mcg q 20-30min to max 200mcg or clinical improvement

    Dilaudid: 1-2mg IM/IV/IO bolus, may repeat 1mg q 20-30min to max 5mg or clinical improvement

  • totwtytr says:

    Without addressing the types of problems we treat for pain (there is room for disagreement on that), the truth is that when we do treat pain, we under treat it.

    A couple of years ago I had a patient who had been doused with boiling water which had been used to cook sausage. He was covered from his neck to his waist with first and deep second degree burns and in excruciating pain.

    During the ten minute ride to the trauma center, we gave 250 mcg of Fentanyl. It controlled his pain to a tolerable level, but didn’t put him to sleep, put him in respiratory arrest, or even drop his BP.

    He thanked us profusely.

    Maybe it’s medicine in general, I don’t know. But, at least in EMS we don’t used enough pain medication when we do use it.

  • Chris in FNQ says:

    Whilst not really relevant to this research methodology, the great thing about fentanyl is that it can be given intranasally before IV access is achieved. It is great for paed’s patients in this regard (1.5mcg g / kg, some are a little more cautious at 1.2). And I’ve also taken the opportunity to site paed IV when the IN fentanyl was on board for fluid administration, no pain no tears.

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