Tox Time: Carbon Monoxide

Leave a comment

November 21, 2017 by jtreb

Beebe Bluff is a 28 yo F brought in by EMS after a house fire. She is 5 months pregnant. ABC intact, GCS 15, dexi 130. She is currently complaining of a headache and some shortness of breath. Secondary survey shows soot on her clothes and a cherry red color to her skin, but is otherwise unremarkable.  

What: Carbon monoxide poisoning. Patients will present with a host of nonspecific symptoms including headache, nausea, dizziness, and altered mental status (ranging from confusion to coma). Myocardial injury is common as well.

 

Who:   -Victims of house fires

-Propane-powered vehicle operators

-Those with hot water heaters, indoor heaters or indoor hibachi

-Individuals in enclosed garages (accidental or suicide attempts)

 

How:  Short answer: Hemoglobin likes CO more than O2

Less short answer: Hemoglobin binds carbon monoxide with higher affinity than it does oxygen; in fact, the affinity is so high ,that oxygen can’t displace the carbon monoxide, and a left shift occurs on the oxyhemoglobin dissociation curve

 

Clues: -Normal/high SaO2 (the SaO2 only detects hemoglobin saturation, not hemoglobin saturated with oxygen)

-Normal PO2 (dissolved content of oxygen is unchanged)

-Clustered presentation (the whole family is sick, even the dog!)

-Cherry red skin color

 

Management: As always, ABCs first. Co-oximetry can detect an elevated carboxyemoglobin level, and use of an abg is preferred to a vbg. Be sure to also screen for other toxins like cyanide as well. Check an EKG and troponin to rule out myocardial injury, especially in people with a pre-existing coronary artery disease. A “classic” but rarely seen complication is hemorrhage of the basal ganglia in carbon monoxide poisoning. Contacting your local poison control is always helpful, as well.

Initial treatment involves:

-High flow oxygen via nonrebreather (to decrease the half-life of carboxyhemoglobin from 320 minutes to around 90 minutes). If necessary, intubation and ventilation with 100% oxygen is an option.

2) Hyperbaric oxygen will decrease the half-life of carboxyhemoglobin even further to around 30 minutes. Recommendations for HBO include:

-Evidence of end-organ damage

-Carboxyhemoglobin level >25 or >15 in pregnant women

-Loss of consciousness, coma, or seizures

-Evidence of myocardial ischemia or dysrhythmias

 

References:  

Centers for Disease Control and Prevention. Carbon Monoxide Poisoning. CDC 2017. Accessed at https://www.cdc.gov/co/default.htm.

Clardy P, Manaker S, and Perry H. Carbon monoxide poisoning. UpToDate 2017. Accessed at https://www.uptodate.com/contents/carbon-monoxide-poisoning?source=search_result&search=carbon%20monoxide&selectedTitle=1~150#H12.

 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: