The problem with PRN opioids

National Inpatient Medication Chart

How often do you see an order for morphine written up as follows?

2.5 – 5 mg (per dose)

up to a total of 30 mg (per 24 hour period)

for pain (indication)

That’s a fairly common drug order in our Emergency Department. Our morphine stock consists of ampoules of either 5 or 10 mg, so this type of order often requires drawing up 5 mg and discarding 2.5 mg – which of course has to be witnessed by a second RN and legally documented in the schedule 8 drug book. I won’t ask how often ED nurses wander around with a half-filled syringe of morphine, waiting for 5 minutes to see if the first dose of 2.5 mg had any effect…. because we don’t do that, right?

So what’s the problem?

Clearly drugs such as paracetamol and ibuprofen should be written up as above, ensuring that patients receive no more than the recommended safe limits of these drugs. In contrast, however, the correct ‘maximum dose’ of morphine for one patient could be inadequate or excessive for the next. Additionally, the amount appropriate for a patient at 8pm today may be completely inappropriate for that same patient six hours later. Predicting how much opioid a patient may need throughout a 24 hour period is a guessing game at best.

“Both oversedation and undersedation of critically ill patients can have significant adverse effects.”

Safe management of opioid administration requires regular assessment not only of a patient’s pain and vital signs, but also of their level of sedation. This is clearly a nursing responsibility. Increasing sedation should be assumed to be related to opioid administration until proven otherwise. Unfortunately, a busy nurse may continue to administer 5 mg doses of morphine to a patient complaining of pain, without once evaluating their patient’s sedation level.

In my two years as an ED nurse, I have once seen the PRN morphine dose written up as follows:

2.5 – 5 mg

if sedation score <2

for pain

This led me to go searching for a sedation scale – not something I’d had to use with medication administration before. Sedation scales are commonly used to monitor patients during procedural sedation, but our acute bedside charts don’t generally leave space for regular sedation monitoring. In our department, the closest measurement is the AVPU scale on the ADDS chart – where A = alert, V = responds to voice, P = responds to pain, and U = unresponsive. This scale clearly isn’t sensitive enough to detect subtle changes in a patient’s level of sedation.

Of course, the next problem would be ensuring that all staff in a department used the same sedation scale, and understood it to mean the same thing! A quick google search for “sedation scale” shows that this might not be as simple as it sounds (eg. RASS, RS, AVRIPAS, BLOOMSBURY, ATICE, SAS, MAAS, VICS). But that’s another problem for another day.

What I learned from the rather unusual drug order quoted above, is that my job as a nurse includes careful, regular assessment of my patients’ level of sedation whenever I administer opioids. Irregardless of the sedation scale of choice, it only takes a few extra moments to document whether your patient is awake and alert, easy to rouse, unable to remain awake, or is difficult to rouse. Incorporating this as part of my vital signs assessments really isn’t all that difficult (where “pain” is the 5th vital sign, and “level of sedation” the 6th).



About tamarahills

ED nurse working on the beautiful Sunshine Coast, Australia.
This entry was posted in Featured Articles, Practice-changer and tagged , , , . Bookmark the permalink.

2 Responses to The problem with PRN opioids

  1. Pingback: The LITFL Review 084

  2. Susan says:

    I work in perioperative services in Florida and we use what is called the Aldrete scale. It is on our flow chart and is broken down into five categories: BP w/in 20% baseline ( 2 points), o2 w/in 20% baseline ( 2 points), likewise with HR measurement, able to verbally respond to questions (2 points) , able to move all extremities on command (2). . A score of at least 8 means the patient can advance to Stage 2 of recovery where discharge care is taught to the family.

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