One prehospital pain and analgesia strategy
Pain is one of the most frequent complaints amongst the patients we attend as paramedics. In managing pain, the intention for paramedics always is to exercise clinical judgement. Patients with serious pain will probably need to be addressed quickly. Some patients will have chronic pain that you might do little for or follow a well used previous plan. Some will have mild pain that may not trouble anyone out of hospital all that much.
IN Fentanyl is effective in providing analgesia. It isn’t a bad choice but should not usually be the first go to option for pain relief. It is a useful alternative where you cannot insert an IV cannula. It is a useful option for paediatric patients where IVs can prove difficult or even horrifying. Horrifying for the patient I mean but maybe for the paramedic as well. It is still an opioid, a very concentrated one at that.
If IN fentanyl cannot be administered, then there is always methoxyflurane to consider. This is a very effective drug too and great because it wears off very quickly if you take it away from the patient. This makes it an excellent option, for instance, if you have to move somebody from their bed to the ambulance trolley and that will be very painful for them but they may not need ongoing pain relief after that. You do have to invest some time in encouraging the patient to use the analgiser properly for a few minutes to get it to work fully.
These two options weren’t really meant to be stand alone for most patients. Many pain causes won’t be easily tamed and you know you will have to follow up with something more. Consider the typical patient with a limb fracture; hurts a lot, usually easy-ish to splint. You may settle the pain a bit without IV drugs but usually not completely. You know that the pain will go on well past your pre-hospital time. The real question is whether it is worth starting a non IV analgesic option like these two to provide a few minutes relief if you can just insert an IV and get analgesia started to best sort out the pain out. It is probably not the most effective strategy to start methoxyflurane early, switch to IN Fentanyl a few minutes later then start IV analgesia soon after in the ambulance. Maybe you should just start with the IV analgesia most of the time in the first place.
But, as said, neither of these options are typically the preferred first choice.
Pain management can be divided into three arms: mild, moderate and severe.
Mild pain is common enough but not always the domain of prehospital care. Lots of people have mild pain and it mostly isn’t serious. True enough, they also don’t call ambulances for it. But some do. Mild pain and opioids is not a ‘standard mix’. Instead fix the problem, use a less substantial but still effective option or let somebody else diagnose and manage the problem are all options. If the pain does need prehospital care, paracetamol, tablet or oral liquid, is perfectly reasonable. Remember there is still an underlying pain cause. The patient may still need transport to hospital or they may still have something serious going on. The pain may be only part of their overall complaint and you have to offer other management as well. Think of the dehydrated patient who has a mild headache, but would also benefit from IV fluid therapy and maybe even an antiemetic if they are vomiting. Uncommonly opioids may need to be added if the first option doesn’t work and the pain, even mild, is still a problem.
Then there is moderate pain. This is where many patients will be. Somewhere between four and say seven out of ten. Or somewhere between little pain and really big pain. Or somewhere between the patient packing their smalls for the trip to hospital and writhing on the bed with bulging, pleading eyeballs. That’s moderate pain.
Generally moderate pain is pretty serious. It typically means something is wrong and going to need fixing whether that be a medical or a traumatic problem. So the paramedic needs to be thinking of going off to hospital some time soon. It also needs to be that we should try to get rid of that pain pretty quickly. None of our options so far will cut this mustard. Now we’re talking IV options of morphine and fentanyl.
But before we launch into fixing everything with a chemical, many causes of pain have aggravating factors that you can do something about. Internal organ pain may be helped by position, such as allowing the patient to draw up their knees or adopting another position of comfort. An even more obvious option is to splint fractures and to provide compression and cooling for soft tissue sprains and strains and burns. There is a fair bit of feedback from the hospitals that paramedics underutilise these options at times. This is regardless of how far away the patient is from hospital. It is also regardless of how small the splinting situations is including even such things as the humble Colle’s fracture. It doesn’t make sense to be squirting in analgesia at one end if we are poking the patient with a hot poker at the other. To put it simply, splinting stops bone ends from moving, reducing injury to soft tissue and the local nerves being aggravated. Splinting is usually better than no splinting, even if it is only wrapping a magazine around the forearm or strapping the good leg to the one with the newly installed extra kneecap.
So you’ve done your best and it’s IV analgesia time. Opioids. Morphine or fentanyl? The choice isn’t really a big one. Morphine is usually perfectly safe. Provided the patient has enough pain receptor sites active for the opioid drug to attach to, the drug will help. It gets a bit tricky if the patient is only in mild pain and there isn’t enough pain relieving for the drug to do. Side effects come along. The same goes for the elderly who are more susceptible to the drug actions. It also has some histaminic actions so can cause a few side effects in the susceptible person anyway. But the vast majority of time it will be fine.
On the other hand, there is IV fentanyl. A synthetic opioid that is much the same as morphine in many ways. It manages to dissipate into fatty tissue pretty well though where it is rendered relatively inactive. This creates the false impression that it has a shorter duration of effect. Certainly the actions of fentanyl are shorter because of this but the drug is still in the patient’s body. This isn’t really a problem though. In fact it can be handy because prehospital analgesia can wear off faster allowing hospital patient assessment to occur if needed or unwanted complications to stop. But fentanyl does have a few advantages over morphine. It is less likely to produce the unwanted effects such as vasodilation or nausea/vomiting. As such, if these are problems the patient has then morphine might just make it worse. In truth, there is little argument for one over the other most of the time.
There really isn’t any argument for both of them at the same time. It is okay to go from IN fentanyl to IV morphine. There isn’t an IN morphine option. It is okay to change from one opioid to another if the first causes problems. It isn’t necessary though to mix both IV opioids routinely. Choose one and persist with that as needed.
So the strategy is, identify the patient is in pain and how bad it is. There is more than one way to do this. Then put the pain into the context of how sick the patient might be. The pain might be the least of the patients concerns. It wouldn’t be a great idea to spend half an hour providing pain relief to a patient with acute coronary syndrome for instance if they should be more quickly transferred to a cardiac receiving hospital. Getting rid of the pain by reperfusing a coronary artery is much wiser. Treat en-route. You might have to provide pain relief before you can move a patient or you might provide other treatment first then fall back to analgesia. Whichever, choose the analgesia option that best suits the pain severity. Finally, factor in the arguments for and against a particular drug choice. Consider your fall back options only if you have to.
Which brings us to the third arm of treatment: severe pain. In many ways this is no different to the moderate group. Once again, don’t muck around with other options if you can just get on with IV analgesia with one of the opioids. Once again, if this proves impossible due to accessing a patient or lack of available veins, IN fentanyl or methoxyflurane are good fall back options. In this case though there is another option. This one might be effective but should be considered only if none of the other options are effective and the pain really seriously needs to be addressed. This is the intramuscular opioid option. Uptake of drugs from large skeletal muscles is less predictable in unwell patients, particularly if circulation is compromised. Drug uptake will be slower and may even accumulate there until perfusion improves. The way to minimise this outcome is to choose this option last of all and restrict the doses and number of injections used. Also, give consideration to which muscle is chosen. Paramedics seem to naturally use the deltoid muscle for IM injections. That is okay but it is the least reliable of the large skeletal muscle options use for IM injection. Those in the upper leg are much better including the vastus lateralis and vastus femoris.
Finally there is the very uncommonly encountered patient who has severe over the top pain that simply just won’t go away. Think about the patient with large surface area partial thickness burns or maybe a couple of fractured femurs. In such cases, where IV opioids are just not getting on top of the pain, another heavyweight option is needed. In this case IV ketamine can be administered seeking to produce the dissociative effects to disconnect the patient from the pain sensation but without risking their vital signs otherwise.