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Environmental Exposures

Heat stroke; heat stroke basically refers to a very high temperature, oftentimes as high as 106 or 107 degrees, where bad things begin to happen to the enzymes in your body heat stroke, smoke inhalation, carbon monoxide. How does this happen? Well, you can have increased heat generation either from pyrogens generating a fever, exercise if you go out to run a marathon across Death Valley, not surprisingly your body temperature rises. Or if you have hypothalamic disregulation problems. Some children with severe neurologic injuries don’t have good hypothalamic regulation.

What’s the pathophysiology of heat stroke? Usually you end up getting dehydrated. When you get dehydrated you have hemodynamic changes. Typically what the body would do with hypovolemia is vasoconstrict. Because your temperature is high, the body is trying to unload some of the heat, and what happens is that the body vasodilates. So you have low intravascular volume and you vasodilate. You can imagine that your hemodynamics don’t stay very good and you get very hypotensive.

Heat stroke is a medical emergency. These patients need very aggressive cooling. This may involve packing them in ice externally. It may involve administering cool fluids to every orifice and IV site to bring down their body temperature rapidly. They need to be fluid resuscitated.

Now there is a specific syndrome in young children that has been reported, of hemorrhagic shock and encephalopathy syndrome. Which is basically unexplained severe hyperthermia in young children without an infectious etiology defined, which is associated with a very significant encephalopathy. These patients develop shock, DIC and actually have a high mortality rate. In the initial series, 100% mortality rate was reported. Now survivors have been reported, but it still does have a high mortality rate. It is uncommon but has been the source of questions in the past.

Smoke inhalation; another environmental disaster. If you happen to be in a fire you get asphyxiated. Fire consumes oxygen, it leaves what you are breathing to be relatively oxygen-free, and although you are having air exchange you are not getting oxygen to your tissues. You may have a thermal injury, although this is a much less common cause of death, where you actually have flame injury to the tissues. A thermal injury with super-heated environments, gases especially if there is steam involved, you may get airway injury from the high temperatures. This is typically supraglottic. By the time it gets down to your lungs the gases have usually cooled enough that you don’t have burning all the way down your lungs. You may begin to develop airway edema. If you have a child who has stridor following a burn injury.

Carbon monoxide; combustion releases carbon monoxide. When it’s in a fire it will be associated with soot and other things. You can get carbon monoxide poisoning in other environments. Exhaust systems of furnaces may dysfunction and everyone in the home may in fact have carbon monoxide poisoning. It’s a colorless, odorless gas so they won’t know it until they are losing consciousness or having changes. We are going to talk a little about the pathophysiology, the diagnosis and the therapy.

Smoke inhalation; fires tend to release very noxious substances. If you are burning plastics or some other substances you may have very toxic smoke. Early that is going to cause bronchospasm, some lung consolidation. As you go from a day or two, you are going to start getting pulmonary edema from capillary leak in your lungs, and as you get a little bit further out you are going to tend to get bronchopneumonia.

The therapy for this is entirely supportive. If they need airway management and ventilatory support, that’s what they get. Steroids have been advocated in the past, but in controlled trials they seem to be of no benefit and may increase the risk of infection.