Thursday, August 1, 2013

Paging Goldilocks to the ER: Acute Pain Management in the Emergency Department, Part I

You have a patient who presents to the emergency department with what she describes as "excruciating pain" that radiates to the lower back. The pain is sudden in onset and when you ask her to rate the pain on a scale from 1 to 10, with 10 being the worst pain, the patient responds emphatically with "15."

 

And so you decide to order morphine 4 mg IV push as a one-time dose and conduct further workup. The patient is now calm and subdued, relieved to have the ED physician finally understand and empathize enough to order an intravenous pain medication. After all, isn't that the expectation of patients when they do present to the ED?

Until 15 minutes later. You hear screams coming from the patient's room, and the nurse comes hurrying over and tells you that the patient is writhing and screaming in pain, rating it as a 12 on the pain scale. You reevaluate the patient and she tells you, "Doc, that medication did NOTHING for me. It was like 'water' in the wind. I am still in pain!" And so you go ahead and order another dose of morphine 4 mg IV push.

Another 15 minutes pass by, and you reevaluate the patient, asking her to rate her pain. She looks up at you and states, "Doc, I am still in pain. I am trying to not make a fuss about it, but I cannot help it. It's now 9 out of 10. Do you have anything stronger that you can give me? Please? That second dose did not help all that much."

Hearing this, you inform the nurse to administer a dose of hydromorphone 1 mg IV push to the patient. After 20 minutes, you reevaluate the patient, and ask her about her pain. She states, "That medication that was just given to me finally did the trick. I am in no pain. Why didn't you give that to me from the beginning?"

Why not, indeed?

This is all too common of a scenario that we encounter in the emergency department. Acute pain management in the emergency department is a beast. I often find two extremes. We may underdose patients with opioid analgesics, similar to the scenario described above, that it takes at least three or more attempts to get the pain under control. The other extreme is that we end up overshooting with the initial dose and/or with "dose-stacking" of medications, patients may experience oxygen desaturation and respiratory depression, often requiring measures and agents (such as naloxone) to reverse these effects.

Much of it has to do with a matter of convenience...or rather, inconvenience. Intravenous opioid analgesics such as morphine and hydromorphone are stocked in automated dispensing machines (ADMs) in the emergency department. With an attempt to streamline and minimize the different concentrations of these agents in these machines to prevent medication errors, some emergency departments may stock a single concentration of each of these agents. Oftentimes, you will find the following concentrations of morphine and hydromorphone respectively stocked in ADMs:



 

Where's the "Easy" button?


With these prefilled carpujects containing these medications, it makes it all too easy for clinicians to become reliant on these concentrations as initial doses for our patients.

The truth is, this is entirely not appropriate. Believe it or not, these medications, in both children and adults, are actually dosed based on weight. Here are the doses:

 

So, unless your patient happens to weigh in the neighborhood of 40 kg, that initial dose of 4 mg of IV morphine is probably not going to cut it for most of your adult patients.

In addition, there is a dosing conversion between IV morphine and IV hydromorphone that can be surmised from the table above:

10 mg morphine IV = 1.5 mg hydromorphone IV

To make it a little easier to think about, this can be rounded to the following:

7 mg morphine IV = 1 mg hydromorphone IV

In the instances where I have had appropriate weight-based initial doses of these agents being ordered by EM physicians and residents, I have had nurses come to me in a panic and state, "Can you believe Dr. [insert last name here] ordered 8 mg of morphine?! That's way too much!!" While I calmly inform them that this dose is indeed appropriate, given the patient's weight, and putting it into the perspective of the dose conversion and the fact that it is nearly equivalent to a dose of hydromorphone 1 mg IV (of which there happens to be no qualms of ordering or administering), there still exists some fear of administering such a "high dose" of morphine.

So the question now is:
How can we better optimize pain control for our patients in the emergency department? In other words, can we find a happy medium for our patients when it comes to acute pain management, as Goldilocks did in the classic tale?

The answer:
Look out for Part II, coming in the next post, which will consist of:
  • An evaluation of various studies that have investigated different methods of acute pain management using opioid analgesics for patients in the emergency department.
  • A discussion of the ways we can apply and incorporate the findings of these studies to our practice.