Carbon Monoxide Poisoning

Andy Ketchin

History

•Mr MJ,

56 year old male.

•House fire mid morning. Patient unharmed.

•Found with GCS 4 in house 5pm same day.

•Evidence of aspiration. No evidence self harm.



Background

•PMHx No significant past.

•DHx No regular meds, or allergy.

•SHx Lives alone.
? Learning difficulties.
Unemployed.
Smoker, no alcohol.


On Examination
•A Soot Intubated
•B Reduced air entry right lower zone.
•C Hypotensive Normal ECG.
•D GCS 4 Normoglycaemic/thermic.
•E No burns/trauma.


Investigations
•U&E,CRP NAD
•FBC WCC 43, HB16.0
•ABG pH 7.26 pO2 7.9 pCO2 4.6 BE - 12.0
•Toxicology COHb 43.5% à 12.8%
•CXR Right lower zone diffuse opacity.


Problem List & Plan


CO Poisoning - Presentation
Mild – constitutional / viral symptoms.

Severe – seizures, syncope, coma myocardial ischaemia ventricular arrhythmias pulmonary oedema profound lactic acidosis

“Cherry red” insensitive


CO Poisoning - Pathophysiology

•Affinity COHb 240 : HbO2
•(Non smokers < color="#ff0000">DO = CO x CaO2

CaO2 = (k1 x Hb x SaO2) + (k2 x PaO2)

{k1 = 1.32, k2 = 0.23}


CO Poisoning - Management

Hyperbaric therapy:

•Reduced COHb t1/2

•PaO2 increased from 0.3 à 6.0 ml/dl.

Hyperbaric Therapy

Recommended:

•CO level > 40%
•CO level > 20% in pregnancy
•LOC
•Severe acidosis, pH <>
Considerations:
•Delay < 6 hr
•Logistics
•Concomitant cyanide poisoning