Carbon monoxide

what type of mechanism of toxicity is CO?

chemical asphyxiant

what is hemoglobin?

contains 4 heme groups which each contains a Fe group that binds O2

what is the MOT of CO?

CO absorbed = binds to Hg (↑ affinity than O2) = displaces O2 = hinders release of O2 from oxygenated hemes on Hg=tissue damage by binding to myoglobin and diffusing into tissue

compartments (muscle, brain)

what is the clinical presentation of mild CO toxicity?

nonspecific, Headache, Nausea, flu like Sx

how do you diagnose CO toxicity?

1. pt Hx (do they have CO monitor, did it go off)

2. carboxyhemoglobin level by co-oximetry

what is co-oximetry? when is it recommended? what levels indicated impaired O2 delivery?

-blood is put thru analysis and directly measures oxygenated and deoxygenated Hg

-Recommended in those with significant CO exposure or Sx

-↑ carboxyhemoglobin = ↑CO=↓O2 (0-5% is normal)

what is the goal of CO toxicity?

optimization of 100% O2 delivery to tissues by ↑ dissociation of deoxygenated Hg to create

room for oxygenated hemoglobin

how do you optimize O2 delivery in CO toxicity?

1. high flow tight fitting mask

2. endotracheal tube (if intubated)

3. hyperbaric oxygen therapy ("antidote" for severe)

what is hyperbaric oxygen therapy (HBO)?

provides ↑ pressure and O2 to patient to achieve ↑ arterial oxygenation to tissues and ↑elimination of CO from blood and tissues

when is the benefit of HBO the best for CO toxicity?

within 6 hr of exposure

what are the ADE of HBO? negatives?

-ADE due to ↑ pressure (seizure, middle ear barotrauma)

-not a lot of places have a HBO and transportation is risky

what are the indications for HBO with suspected or confirmed CO toxicity?

1. coma

2. seizure

3. altered mental status

4. carboxyhemoglobin >25%

5. abnormal cell fxn

6. pregnancy (carboxyhemoglobin >15%, fetal distress)

7. >35yr and >24hr exposure