Working in central Victoria last week, a week in which we experienced 4 days of top temperatures over 42 degrees Celcius cooling to the mid-upper twenties by 6 am gave me a wonderful opportunity to experience the spectrum of heat related illness in Emergency Medicine (it also gave me a wonderful opportunity to experience much more effective air-com than I have at home). Here are some things that I learned.
Heat Stroke is not what I thought it was.
From the books I knew that heat stroke represented a medical emergency with loss of sweating, altered mental status and imminent death from multi-organ failure if cooling was not rapidly instituted. What I didn’t know was just how promptly it can respond to good cooling efforts.
Without going into patient details, we saw several cases of heat stroke in a single, very busy, evening shift. You know you are having one of those shifts when the nurse in charge says to you “We’ve got another hot one Putty” and you just go “ok” and shrug and head for resus. All were vulnerable people in various ways, with less luxurious accommodation, less robust physiology and possibly less decision-making resources than some other members of the community. All were found unconscious with temperatures between 41.5 and 42.7; one intubated at the scene, one GCS 6 following some nifty work with the garden hose, and the others GCS 3 on arrival. They had dry skin, tachycardia and tachypnoea. None had an abnormal BSL. All were on an antidepressant of some sort.
As each one arrived we infused 3 litres of fridge temperature Saline, put ice packs around the scalp and axillae, covered them with a wet sheet and set up our only fan to blow over them. All were rapidly cooled to below 39 degrees at which point they all started to shiver. We treated shivering with a little IV midazolam and continued cooling to normothermia during which time they all woke up properly (although a little befuddled seeming). We did not secure any airways, (except the one intubated at the scene), instead opting to stand close, ready to take the airway if required. As it happened, each one woke so rapidly as their temperature came down that there was no need to intubate anyone. Had we secured every airway early, as the exam answer would tell us to do, I do not know how we would have managed.
All of them had mild elevations of Creatinine, CK, INR, liver transaminases, Platelet count and White Cell Count but none of them progressed to multi organ failure.
It might be a small n but I now having watched this disease several times in a shift I have a much more nuanced understanding of it, particularly just how rapidly a person can be cooled with relatively simple measures and how rapidly their neurological function will respond to that cooling.
Less acute heat illness
Apart from the excitement of florid heat stroke, a heat wave also brings on a plethora of less severe illness. We had several cases that were on the way to being heat stroke (elevated core temp and confusion identified early by family members and brought to hospital in time for them to cool themselves in the air-conditioned environment. We had some heroic people working outside in environments where the ambient temp was up to 52 degrees, presenting in severe acute renal failure. One person needed urgent haemofiltration. What’s more, in a week like this you can expect countless presentations with syncope, headache, dizziness, lethargy, exacerbation of chronic renal or cardiac failure.