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Plenty of companies have started selling units that will keep EMS medications at a constant temperature, based on some earlier studies showing some breakdown of meds from heat.  However, the picture isn’t really all that clear; other studies have shown no difference.

In an effort to resolve the discrepancy (and to test a much broader range of meds), a team from Missouri exposed 23 drugs to a temperature that cycled from -6°C to 54°C–temperatures that are certainly possible over the course of the year.  Eight of the meds dropped to less than 90% of their original concentration by the end of the 28-day study, important ones all:  lidocaine, diltiazem, dopamine, NTG, ipratropium, succinylcholine, haloperidol, and naloxone.

Some of these were no surprise–diltiazem and succinylcholine are supposed to be refrigerated.  Worse yet, there was no room-temperature storage control to compare.

However, in some regions of the country, this study might actually underestimate the damage done by letting your drug box fry.  I would think that having the low temperature half the time (as done in this study) would tend to preserve the drugs; if you’re in a less-busy service in most places in the US, you might very well have your drugs baking at that upper limit better than half the time, and not necessarily cooling down during the occasional call.  By the same token, a busy service might find its ambulances assuming environmental temperatures less frequently, giving more stability.

So what does this mean to actual EMS practice?  Probably not much.  I’d be much more interested in checking the levels of drugs actually carried on an ambulance.  That’s the real test–how these things work in the field.  After all, if we find that meds are getting used before they degrade, or that the actual temperature changes of the medications themselves isn’t as great as we thought, those climate-control boxes might not be necessary–but they’ll still be great for keeping that D50 from hitting 40 degrees in the winter.

Filed under: EMS Research