Another Problem, Part II

In yesterday's case, I told you the story of how my partner and I were running an unresponsive gent with a believable report of seizure, obvious evidence of frank GI bleeding, hypotension, tachypnea, and hyperglycemia. I ran a 12-lead before departing to the hospital:

By ArcGenus41 (CC BY-SA 3.0, via Wikimedia Commons). Click to enlarge

When I saw it, I said aloud: “Oh, that’s good. Just what he needs. Another problem.” My partner glanced up from taping down the IV line and immediately saw the relevant ECG finding, as well. Did you see what we saw?

Hypothermia.

Specifically, we noted Osborn waves in pretty much every lead. The end of the QRS (or the beginning of the ST segment, depending on how you look at it) gets a sharp waveform that some people compare to a fishhook. I don’t see the fishhook shape, but I can see Osborn waves. Here are some more examples that I found online*:

By Jer5150 (CC BY-SA 3.0, via Wikimedia Commons) Source

By WikiSysop (CC BY 3.0, via Wikimedia Commons) Source

The height of Osborn waves are supposedly proportional to the degree of hypothermia, but I've not seen a solid study to back that statement up, so I take that little factoid with a grain of salt. Life In the Fast Lane has some illustrations of worsening Osborn waves, though. According to a brief article in the journal Circulation, hypothermia is initially associated with sinus tachycardia. As the core temperature drops below 32.2°C (normal body temp being 37.0°C or thereabouts), sinus bradycardia is more common. In addition to the bradycardia, all intervals commonly lengthen. As the temperature continues to fall to the range of 30.0°C and below, atrial ectopy and atrial rhythms like AFib can appear. “At this level of hypothermia [<30.0°C], 80% of patients have Osborn waves…”  

Keep in mind that ECG findings aren’t the best way to measure a patient’s temperature, just like ECGs are sub-optimal for searching out electrolyte findings. The best way to find a temperature is with a thermometer. But recognizing ECG findings can put you onto a differential diagnosis that you may not have thought of otherwise. Like in the case we were discussing here…

My experience with hypothermia is usually generally similar to this case, in that this fellow wasn’t in a cold environment. The take-home point is that hypothermia is less common during raging blizzards than it is in settings in which you wouldn’t necessarily expect cold - like seizing indoors. Even the worst urban outdoorsman usually finds shelter when it gets hard-core cold. But I have seen hypothermia in early September when a college student got a little drunk and passed out in a park. The sprinklers turned on, he got wet, and then he got cold. Another guy tried to cross a river and got wet. The coldest patient I have ever been involved in resuscitating had a core temp in the teens (I want to say 17°C, but 14°C sounds right too). He had gotten intoxicated and fell asleep in an alley. In that case, the night was admittedly pretty cold but he was well-dressed for it. He lived, by the way. 

The patient in this case study had a core temperature of 28.4°C. He died in the hospital the next day. His medical issues were complex and interrelated. 


* You should also do an image search on the Google machine for Osborn wave and check out a ton of examples that I don't have permission to share.