In support of Gov. Maggie Hassan’s recently signed proclamation naming November as Carbon Monoxide Awareness Month, it is appropriate to share the importance of this timely public health message in my first NHMS blog. 

Many years ago as an undergraduate student at UNH, I volunteered as an EMT for a newly installed hyperbaric oxygen chamber.   A donation from a New York university, the chamber was unusually large in comparison to other chambers and could contain four adults and a patient during a treatment.  I recall some of the distinct differences to the patients, really challenging cases, we treated in the chamber to those I have treated in emergency departments in large inner cities and communities as well.  The one striking commonality is not the severity of any given patient nor the tragedy for those who did not wake up or fully recover from an acute high concentrated exposure, but rather those who had presented after sustained, lower concentration exposures.

The signs and symptoms of slower more prolonged CO exposure can be challenging for patients and those around them to notice initially, and not infrequently go misdiagnosed on initial examination.  Personality changes, tremors, vague descriptions of fatigue, inability to concentrate, new onset seizures or redness of the skin may occur over several days or weeks before treatment is pursued.  This can be compounded in those with comorbid conditions that can be confusing and mask the subtle changes that develop due to carbon monoxide accumulating in the blood with partial washout periods when away from the exposure.  There should be inquiry as to whether symptoms progress or improve to some extent when the patient is away from the source.  This, in and of itself, may be the first and only indication to look for the underlying exposure.

As most clinicians learn over their careers, CO binds to hemoglobin more than 200 times the affinity of oxygen and with an even greater affinity to fetal hemoglobin, making the very young that much more susceptible.  The effect of CO binding to hemoglobin limits the amount of oxygen available for tissues and end organs.  It is described as creating a circumstance similar to what a person would experience with rapid blood loss.  Treatment modalities have been scrutinized and refined, where hyperbaric oxygen has a very narrow scope of consideration.  In general, removal of the patient from the CO source is often all that it is needed, breathing ambient air thereafter.  For those with subtle, persistent and more concerning symptoms, emergent evaluation and consideration for high concentrated oxygen should be initiated. 

Carbon monoxide toxicity remains an insidious and recurrent public health risk that is completely preventable.

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Lukas Kolm, MD, MPH

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