Toxic Or Hypoxic?
As I read through the story in the paper, I sadly recalled several similar calls I'd run on, all with tragic outcomes. The way the paper told the tale, this poor guy had been dealing with a perpetually stopped-up sink. Except in this particular episode, apparently it was really, really plugged up. In any case, he apparently tried his favorite brand of drain cleaner that had been successful in the past. Unfortunately, the desired result was not forthcoming this time. So he decided to try something else and poured a bottle of product #2 into the standing water, further adding to the chemical mix. As time passed and the water level didn't drop, he apparently figured he'd waited long enough, and now poured a third product into the sink. At this point, the chemical concoction finally reacted, quickly filling the room with lethal gas or gases. When found hours later by family, he was already dead, and the residual fumes made several other family members ill just from the short exposure they got as they searched the house. Preliminary indications were that at a minimum, some form of chlorine gas was the culprit.
Events like this pose serious challenges for EMS providers in the areas of both scene safety and patient care. This month in BTB, we look at a unique aspect of patient care that occurs on calls like this: the relationship between a toxic event and a hypoxic event.
Determining Safe Entry
Clearly, the tragedy involving the self-styled plumber initially appears to be one of toxicity, as the chemicals that came together clearly produced a noxious environment. As such, the first goal for the EMS team is to determine what safety precautions are required to allow a safe entry into the scene. Until the actual ingredients of the mix are identified, along with whatever the resulting combination is, entry into the scene is prohibited.
For some providers, it's the old "stick your nose in and sniff" method for assessing the environment. Consider one of the components of sewer gas, hydrogen sulfide. This gas has the classic "rotten egg" smell to it, but more important to know is that this gas is an olfactory desensitizer. Using the sniff method, your first sniff provides a pungent aroma, but if you step out and clear your head and then take a second sniff, it doesn't smell nearly as bad. In fact, it may hardly smell at all. But the truth is, the hydrogen sulfide has just numbed your sense of smell, and the environment is every bit as toxic as it was on the first sniff. Entry into that environment without proper protection can be deadly in a matter of seconds.
The Hypoxic Patient
Another important issue to consider is how hypoxia comes into play. Let's look at carbon monoxide poisoning. Whether it results from a faulty fireplace or furnace flue damper or trying to stay warm during a power outage by using a charcoal or gas grill for heat or cooking makes little difference--carbon monoxide is a toxic gas. Equally important, however, is that what really kills the patient is hypoxia, as the hemoglobin in the blood will pick up carbon monoxide rather than oxygen when both are available. Again in this case, the sniff method will fail to alert a provider to the danger that waits, because carbon monoxide is odorless.
Hypoxic + Toxic
Another example would be cyanide poisoning, a frequently missed diagnosis for patients with smoke inhalation. When wool, plastics or vinyl burn, the resulting smoke contains hydrogen cyanide gas, a lethal toxin at a high enough level. So that patient you're treating who was just pulled out of a house fire may well be dealing with multiple metabolic insults: the toxic effects of the cyanide as well as the hypoxia secondary to carbon monoxide binding to the hemoglobin.
The point to this discussion is to highlight the importance of recognizing that when you treat patients suffering from toxic exposure, you may have more than one battle to fight in your care efforts. Identifying the toxic agent(s) to which your patient has been exposed is clearly important in targeting your interventions. At the same time, making certain your patient is receiving high-concentration O2 therapy and any other interventions (e.g., a breathing treatment) to work collectively to correct hypoxia is also a critical element of care. Yet it is an intervention that could easily be missed if the focus is solely on the toxic aspects of the call.
In conclusion, recognize that you have basic variations of the toxic/hypoxic equation. You will see some patients who are just toxic, with hypoxia not a factor (though it should always be considered in the scheme of things). On the other side of the coin are those patients with hypoxia who have no toxic component to their situation. Then there are those patients who have both toxic and hypoxic pathologies working against them. Making certain that you work on addressing both problems is the way to reduce mortality and morbidity in your patients.
Until next month...
Mike Smith, BS, MICP, is program chair for the Emergency Medical Services program at Tacoma Community College in Tacoma, WA, and a member of EMS Magazine's editorial advisor board.
