Carbon Monoxide or Cyanide?
Vol 21 No 3
We may be approaching a good portion of our smoke inhalation victims from the wrong perspective. The traditional view is that victims of smoke and fire victims -- yes, most fire victims are NOT burned at all, dying long before the bodies can be subjected to flames -- suffered death from carbon monoxide poisoning. The latest research shows this may not be the case. The culprit may be Hydrogen Cyanide and the mechanism of the poisoning is substantially different than carbon monoxide, as are the treatment protocols. Pay attention now, as the very lives of your compatriots are also on the line here as well. Many of you get swallowed in these gas clouds on the scene of petroleum and chemical plant incidents. This information is of great importance to my industrial brothers and sisters. Much of this problem can be traced back to petroleum based products that are used in construction and everyday materials. This is nothing new. The fire service has been squawking about toxic fumes for decades. All petroleum when burned gives off Hydrogen Cyanide, from gasoline to polyurethane foam to the PVC pipe in the walls; all of it releases toxic cyanide gas, which is a killer.
The mechanisms for Carbon Monoxide and Hydrogen Cyanide are completely different. While both affect the body's ability to utilize oxygen, they do it in different ways. Oxygen and hemoglobin (a protein on the surface of the red blood cells) normally bind to one another easily at the lungs and then easily release at the cellular level once the oxygen transport has been completed. Carbon Monoxide binds to the hemoglobin much more tightly than oxygen and, in essence, refuses to break those bonds, thereby clogging the space needed by oxygen and subsequently suffocating the body. The reality in CO poisoning is the hemoglobin does not have enough space to carry oxygen molecules because it is being taken up by Carbon Monoxide. We treat this with high flow oxygen therapy and, in very severe cases, hyperbaric chambers to force out the Carbon Monoxide. This is what we have always done in the treatments of smoke inhalation victims, operating under assumption that most of them suffered CO poisoning. Hydrogen Cyanide is different. This affects the body's ability to utilize oxygen on the cellular level. The body may have excellent oxygen onboard (or even diminished levels if coupled with Carbon Monoxide poisoning, so both treatments probably should be accomplished simultaneously) but with Cyanide poisoning the body is unable to offload the oxygen at the cellular level. The Cyanide inactivates certain tissue enzymes so that the cells are unable utilize even available oxygen on that level. Cyanide poisoning requires an antidote.
There is really only one antidote that is currently available in the U.S. for Cyanide poisoning, known as the Lilly, Pasadena or Taylor kit. The basics of the kit includes Amyl Nitrite in breakable "popper-type" inhalers that are used in conjunction with a bag-valve-mask used in ventilations. This must be followed with sodium nitrite and sodium thiosulfate for intravenous administration as this will help the Cyanide release the grip on the oxygen, thereby improving eventual cellular oxygenation. Subsequent fluid administration should also follow as the toxins are then expelled by the renal system through urination. Caution should be used as some of these treatments can have some very deleterious effects on persons in cases of misdiagnosis. So prevention is going to be the key!
Was this key research done by physicians? Nope. It was done by guys like you and me in the trenches. Don Walsh, Assistant Deputy Fire Commissioner of the Chicago Fire Department, Rob Schnepp from Alemeda County Fire, Capt. Bruce Evans from my own Community College of Southern Nevada and our local Henderson Fire Department, and Rick Patrick from York, PA, co-authored the study that points to the risks of Cyanide poisoning in smoke inhalation victims. The major conclusion of the study is the realization that the risk of this poisoning is low. The potential is VERY high and the ability to treat these potential victims is virtually non-existent. They state:
? First-responder ALS providers perceived a low risk of human cyanide exposure in their services areas, eeven in counties at high risk of a cyanide event.
? Antidote supply and standard protocols for antidote use were inadequate for an effective response to ccyanide regardless of its source.
? These results emphasize the need for improved risk assessment and preparedness for cyanide poison ning across the United States. Prehospital treatment protocols should provide for the empiric treatment oof suspected cyanide poisoning and appropriate prehospital stocking of antidotes. (Walsh et. al.)
There is also significant discussion continuing about firefighters wearing their SCBAs even after the fire is out and the cleanup is continuing. Substantial gasses are still being released when the materials are smoldering, even when the fire is effectively 'out.' Even during mop-up operations firefighters should always wear their air packs. Even firefighter and engineers operating in and near the fire during the major attack operation should have breathing apparatus as many gasses given off are invisible to the naked eye yet are just as toxic as the real smoke. Just because you are not part of the major attacking battalion does not mean you should not have an SCBA on when in or near the fire ground scene. Capt. Evans states: "Remember your family when you are on the scene and wear your air pack."
To check out the latest research visit the Cyanide Poisoning Treatment Coalition (CPTC) at http://www.cyanidepoisoning.org/. This is some VERY cutting edge information and is not something that has really been explored before in the EMS arena. These guys have done the groundwork; the rest is up to us. We need to pay attention here and pass this around. Get your medical directors into the research to help get as many new treatment protocols developed as possible on this issue.
William R. Kerney, MA-EMTP-A, is a professor of emergency medical services at the Community College of Southern Nevada. His e-mail address is firstname.lastname@example.org.