Written by: Vidya Eswaran, MD (NUEM PGY-3) Edited by: Jonathan Andereck, MD (NUEM PGY-4) Expert commentary by: Matt Zuckerman, MD (University of Colorado)
Thank you, this highlights an important aspect of treating victims of smoke inhalation.
In terms of the physiology of CO I like to think of it as an acquired hemoglobinopathy at low doses, thus patients with premorbid cardiopulmonary disease may be affected at lower doses. A fair amount has been written about how absolute levels correlate poorly with clinical effects. The idea of levels correlating to symptoms seem to originate from a Bureau of Mines publication from 1923 that won’t disappear. I would suggest having a low threshold for testing anyone who might have exposure; the failure for CO is in not testing.
Additionally, cherry lips are rarely found in living patients (more commonly on autopsy event at levels below 50%) so are rarely clinically useful (J Forensic Sci. 1995 Jul;40(4):596-8).
The “consider” HBO recommendation for COHb levels >25% is very controversial and the literature is limited by heterogeneity in patients and treatment protocols. Some would argue against hyperbaric for most patients or even consider HBO for patients at lower levels. Consultation with toxicologists and hyperbaricists is likely to be helpful.
Lactic acidosis is key to cyanide poisoning. Most use a combination of smoke exposure with an elevated lactate (>10 mmol/L) to be highly suggestive of CN toxicity and an indication for empiric treatment. CN levels are rarely helpful and rarely ordered. The description of cyanide symptoms “progressing” is a bit of a misnomer as cyanide is initially rapid onset, without evolving symptoms; indeed knockdown is a common presenting symptom. Hydroxocobalamin is preferred to the antidote kit, and amyl nitrate is omitted if sodium nitrite is given. The transient hypertension associated with hydroxocobalamin is often therapeutic given the incidence of hypotension, and its important to be aware that this will discolor serum and tears and urine.
Matthew Zuckerman, MD
Assistant Professor of Emergency Medicine, University of Colorado School of Medicine
How to cite this post
[Peer-Reviewed, Web Publication] Eswaran V, Andereck J (2018, August 20). Toxic Flames. [NUEM Blog. Expert Commentary by Zuckerman M]. Retrieved from http://www.nuemblog.com/blog/toxic-flames