Carbon monoxide poisoning resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief:  Vidit Bhargava, M.B.B.S [2]

## Overview

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Carbon monoxide (CO) is a colorless, odorless, tasteless, non-irritating gas, that is toxic to humans at concentrations more than 100ppm.[1]

## Causes

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### Life Threatening Causes

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Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Death can occur from almost all causes of CO poisoning and depends on CO levels in blood.

* Fire

### Common Causes

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* Boats, motor vehicles
* Charcoal grills, propane stoves, charcoal briquettes
* Gas powered generators
* Electrical cable fires
* Immediately after hurricanes and other natural calamities[2]
* Poorly functioning heating systems
* Power washers & other gas powered tools [3]

## Management

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Shown below is an algorithm summarizing the approach to Acute carbon monoxide poisoning

Characterize the symptoms:
❑ Headache
❑ Dizziness
❑ Weakness
❑ Nausea & vomiting
❑ Chest pain
❑ Altered mental status

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❑ Secure airway, breathing, circulation
❑ Intubate as needed

Check labs:
❑ CO levels in inspired air
❑ COHb levels in blood by CO-oximeter
❑ Pulse CO-oximeter
❑ Conventional oximeter not helpful
❑ Check pregnancy status in women

Strongly suggestive of poisoning[3]
❑ >2% COHb levels in non smokers
❑ >9% COHb levels in smokers

Check for concomitant cyanide poisoning

Assess for:
❑ COHb levels > 25%
❑ Check following for cardiac involvement

❑ EKG

❑ Troponins

❑ Cardiac enzymes
❑ Severe acidosis, prolonged unconsciousness
❑ Neurological impairment or abnormal neuropsychiatric testing
❑ Pt. > 36 yrs in age
❑ Pregnancy

| Yes|

| No|

Hyperbaric O2 therapy:
❑ Initiate with in 6 hrs
❑ Atleast one treatment at 2.5 to 3.0 atm

❑ Administer normobaric 100% O2 till pt is symptom free

❑ Look out for complications

❑ Educate pt before discharge
❑Instruct for possible delayed neurological complications

❑ Repeat medical & neurological exam in 2 weeks

## Do's

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* Assess for all possible high risk factors & treat with hyperbaric O2 therapy
* Use hyperbaric therapy for pregnant women irrespective of level of CO poisoning.
* Use 100% O2 therapy atleast till pt. is symptom free (4-5 hrs minimum).
* Give atleast 1 hyperbaric treatment to severe cases.
* Warn all pts. of delayed neurological complications.
* Do perform chest X-ray in all severe poisoning cases, also consider doing EKG, troponins & even CT & MRI in these cases.
* Schedule follow up visit in 2 weeks.
* Isolate pt. from the source of poisoning.
* Several pts. with mild symptoms may be safely discharged from emergency, once symptom free.

## Dont's

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* Do not rely solely on COHb levels as they are not very reliable, co-relate with clinical symptoms.
* Do not use normal pulse oximetery, it is not useful in this case.
* Do not forget to perform pregnancy test on all women in child bearing age group.
* Do not forget to isolate pt. from the source of poisoning.

## References

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1. ↑ Prockop, LD.; Chichkova, RI. (2007). "Carbon monoxide intoxication: an updated review". J Neurol Sci. 262 (1–2): 122–30. doi:10.1016/j.jns.2007.06.037. PMID 17720201. Unknown parameter `|month=` ignored (help)
2. ↑ Cukor, J.; Restuccia, M. (2007). "Carbon monoxide poisoning during natural disasters: the Hurricane Rita experience". J Emerg Med. 33 (3): 261–4. doi:10.1016/j.jemermed.2007.02.043. PMID 17976553. Unknown parameter `|month=` ignored (help)
3. ↑ 3.0 3.1 "CDC Natural Disasters". Retrieved 1 December 2013. Text " Clinical Guidance for Carbon Monoxide (CO) Poisoning After a Disaster " ignored (help)

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