Toxicology:Carbon Monoxide Poisoning

Source:

1. Gas powered engine
   1. Propane fueled forklifts
   2. Ice skating rink Zamboni
   3. Indoor tractor pulls
2. Home
   1. Furnace
   2. Indoor Heaters
      1. Home water heaters
      2. Gas heaters
      3. Pool heaters
      4. Kerosene heaters
   3. Indoor Flames
      1. Wood stoves
      2. Indoor charcoal fires
      3. Sterno fuel
   4. Tobacco smoke
      1. Smokers
         1. Carboxyhemoglobin levels may reach 9-20%
      2. Nonsmokers exposed to passive smoke
         1. Cigarette tip 2.5 fold greater CO than inhaled
3. Industrial or Occupational
   1. Steel foundry
   2. Pulp paper mill
   3. Formaldehyde and coke producing plants
   4. Fire fighters
4. Fire
   1. Building or structure fire
   2. Wilderness fire

• Pathophysiology

1. Carbon Monoxide Properties
   1. Colorless
   2. Odorless
   3. Non-irritating gas
2. Carbon monoxide inhalation
   1. High affinity for Hemoglobin
   2. Displaces Oxygen and produces carboxyhemoglobin
3. Results in excessive carboxyhemoglobin

• Symptoms

1. Headache (88%)
2. Dizziness (83%)
3. Nausea (75%)
4. Drowsiness (75%)
5. Dry Mouth (44%)

• Signs

1. Cherry-red skin and mucosa
2. Bounding Pulse
3. Hypertension
4. Muscular fasciculations
5. Stertorous breathing
6. Dilated pupils
7. Convulsions
8. Altered mental state to coma

• Symptoms and Signs per Carboxyhemoglobin level

1. Carboxyhemoglobin: 10%
   1. Frontal Headache
2. Carboxyhemoglobin: 20%
   1. Throbbing Headache
   2. Dyspnea on exertion
3. Carboxyhemoglobin: 30%
   1. Impaired judgment
   2. Nausea or Vomiting
   3. Dizziness
   4. Visual disturbance
   5. Fatigue
4. Carboxyhemoglobin: 40%
   1. Confusion
   2. Syncope
5. Carboxyhemoglobin: 50%
   1. Coma
   2. Seizures
6. Carboxyhemoglobin: 60%
   1. Hypotension
   2. Respiratory failure
7. Carboxyhemoglobin: 70%
   1. Death

• Labs

1. Blood grossly appears abnormal red color
2. Carboxyhemoglobin elevated
3. Leukocytosis

• Management
• Mild Poisoning

1. Criteria
   1. Carboxyhemoglobin <30%
   2. No Neurologic or Cardiovascular Impairment
2. Management
   1. Oxygen 100% Non-Rebreathing Mask
      1. Continue until carboxyhemoglobin <5%
   2. Admission criteria
      1. All patients with Carboxyhemoglobin >25%
      2. Underlying heart disease

• Management
• Moderate Poisoning

1. Criteria
   1. Carboxyhemoglobin: 30-40%
   2. No Neurologic Impairment
2. Management
   1. Oxygen 100% Non-Rebreathing Mask
      1. Continue until carboxyhemoglobin <5%
   2. Admission to telemetry (cardiovascular monitor)
   3. Arterial Blood Gas
      1. Determine acid-base status

• Management
• Severe Poisoning

1. Criteria
   1. Carboxyhemoglobin: >40%
   2. Neurologic Impairment
2. Management
   1. Oxygen 100% Non-Rebreathing Mask
      1. Continue until carboxyhemoglobin <5%
   2. Admission to telemetry (cardiovascular monitor)
   3. Arterial Blood Gas
      1. Follow acid-base status
   4. Hyperbaric oxygen chamber
      1. Efficacy
         1. Better short-term and long-term cognitive outcome
         2. Weaver (2002) N Engl J Med 347:1057-67
      2. Criteria
         1. Chamber immediately available OR
         2. No improvement in 4 hours
            1. Cardiovascular status
            2. Neurologic status

• Preventive Measures

1. Adequate Ventilation
2. Carbon monoxide detectors

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