Are we doing harm by giving morphine in chest pain?

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Have you ever given morphine to a patient with chest pain? Have you given it before trying nitroglycerin(GTN)? I know I have and the patient wasn’t hypotensive.

I consider morphine to be the gold standard of analgesia, however, now that I think about it, it really only masks the pain, doesn’t it? It doesn’t really treat the ischaemia. I’ll discuss a study shortly that shows an increased mortality with the use of morphine.

But first……..

I’m looking at the American Heart Association (AHA) guidelines for the use of morphine in Non-ST elevation (NSTEMI) and in ST elevation(STEMI) myocardial infarction and I’m confused. The use of morphine in the NSTEMI patient is Class IIa, and level B evidence, whereas in STEMI it is Class I, level C. What? isn’t the pathophysiological process the same? I need to look at this more closely.

But now here’s the paper: Meine et al. Am Heart J, 2005; 149:1043-1049.

The investigators accessed the CRUSADE registry database and looked at 57,039 patients with NSTEMI and found that those receiving morphine had an increased mortality. They had a 48% higher risk of death!

Now this is a registry study and needs a validation trial, however the point to be made is that unless there is a contraindication to GTN, this is the first drug to give. Morphine should be used if the pain cannot be controlled by GTN. This is the recommendation in the cardiac guidelines. GTN has some significant effects ie decreasing preload and afterload and resulting in vasodilatation. Morphine masks the pain.

I know I’ll be paying more attention.

 

Peter Kas

Dr Peter Kas

Emergency Physician, Educator. Key Interests: Resuscitation, Airway, Emergency Cardiology, Clinical Examination. Creator resus.com.au.

2 Comments

  1. jmjanssens on 29/11/2012 at 2:31 pm

    Hi Peter,
    I’m not sure that morphine “only” masks the pain. From it’s pharmacologic properties we can also assume that it reduces sympaethetic stimulus – witness the resolution of tachycardia and other autonomic features in patients with pain of any origin. This should have beneficial effects on myocardial workload and oxygen demand. One way of interpreting the result of the trial you coite is that intractable chest pain is a marker for severity of pathology. Patients with ongoing pain are more likely to need mrophine due to the severity of their underlying disease process. Their demise may be due to this, and not to the admnistration of morhpine per se. Morphine gets the rap though.
    I agree that GTN should be the first drug off the shelf. Faced by severe ongoing pain I would have no qualms about use of morphine or another opioid drug to reduce the suffering of the patient, confident that I am likely to be producing benefit as well.

    • Resus on 29/11/2012 at 7:51 pm

      Thanks for the comment. I agree with all you say. The point here is, and you certainly mention it, not use morphine in place of GTN. Use it as well as. The example I always use is this; If someone has a compound fracture of the femur and we give morphine and enough of it, the pain decreases significantly. It doesn’t treat the femur, but masks the pain.
      In the cardiac patient, it may very well assist in decreasing the workload and I think it does, but it doesn’t result in the vessel dilatation that has the major effect. How much resultant effect does the morphine have? We don’t really know.
      In these cases, I don’t think that the patient has any suffering. If they do, we have to rethink everything( more likely a dissection than cardiac?) It’s usually that we get the pain score down to a 1 or 2 out of 10, so they are comfortable, but have a touch of discomfort. I still think GTN should be the answer here.
      I, like you, believe that the patient in our emergency department should not be in pain, from whatever cause.

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