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CO poisoning

CO Poisoning

The immediate and most effective treatment of CO poisoning is breathing of 100% oxygen. One to five sessions of hyperbaric oxygen therapy at pressures up to 3 atmospheres will relieve the symptoms and prevent later problems. Lower oxygen pressures are not as effective and require more time to relieve symptoms.

Signs and symptoms of CO poisoning will primarily affect organs with high blood flow and high oxygen requirement, such as brain, heart and lung.Common symptoms are headaches, nausea, vomiting and even loss of consciousness. Oxygen deprivation and cellular hypoxia can cause cerebral edema and seizures as well as chest pain, lung congestion and abnormal heart rhythms.

Hyperbaric oxygen therapy is commonly used for treatment of delayed consequences of chronic or acute exposure to carbon monoxide, carbon dioxide or cyanide.

Carbon monoxide (CO) is a by-product of all fires; it is odorless, colorless and tasteless and since competes with oxygen for binding to hemoglobin 200 to 250 times more effectively it is considered one of the most hazardous chemical exposures.

The immediate and most effective treatment of CO poisoning is breathing of 100% oxygen. One to five sessions of hyperbaric oxygen therapy at pressures up to 3 atmospheres will relieve the symptoms and prevent late neurological complications or so called DNS (delayed neurologic sequelae).

Immediate super saturation of blood with extra oxygen will rapidly reduce CO in the blood and reverse tissue hypoxia for organ preservation.

For Healthcare Practitioners: Rationale of hyperbaric oxygen therapy (HBO) in Carbon Monoxide Poisoning

  • High pressure forces oxygen transfer into tissues deprived of oxygen even where circulation is reduced
  • Immediate super saturation of plasma with oxygen to sustain (organ) life
  • Rapid reduction of CO in the blood by mass action of oxygen
  • Reduction of cerebral edema
  • Breathing 100% oxygen under hyperbaric conditions is proven to be more effective than breathing oxygen under normal atmospheric conditions
  • It assists in driving CO away from cytochrome oxidase

CO poisoning is an absolute indication for HBO in treatment of acute phase as well as prevention of late complications. Immediate super saturation of plasma with extra oxygen will reverse tissue hypoxia and rapidly reduce CO in the blood to relieve symptoms listed below:

  • Cardiac (heart) – abnormal heart rhythms and chest pain caused by heart muscle ischemia
  • Nervous System (brain) – swelling in the brain, focal necrosis and peripheral neuropathy.
  • Neurological - acute (coma, seizure caused by brain edema) and late (psychoses and dementia)
  • Pulmonary (lungs) – difficulty breathing induced by swelling in the lungs
  • Renal (kidneys) – rapid kidney failure resulting from muscle breakdown and excretion of proteins in the urine
  • Muscular- loss of blood flow to the leg leading to compartment syndrome
  • Ophthalmological (eyes) – deficits in the field of vision with bleeding in the retina
  • Auditory (ears) – hearing loss and ringing in the ears
  • Cutaneous (skin) – redness and blister formation

Benefits of hyperbaric oxygen therapy (HBO) in Carbon Monoxide Poisoning

  • Super oxygenation of the brain and the rest of the CNS minimizing swelling and acute neuro-psychological symptoms for relief of: headache, vomiting, nausea, confusion. vision problems etc
  • Reducing chronic symptoms on CNS by correction of hypoxia
  • Reversing hypoxia of the cardiac muscle and preventing further damage
  • Reducing pulmonary edema caused by hypoxia
  • Reducing muscle damage and fatigue and increasing exercise capacity
  • Eliminating sleep disturbance caused by CO
  • Improvement of microcirculation in musculoskeletal system affected by CO, relieving pain, swelling and inflammation and reducing chances of infection in necrotic muscle
  • Reducing skin damages caused by CO by promoting skin microcirculation and epithelialization
  • Improve retinal hemorrhages by vasoconstriction and promoting neo-vascularization
  • Improving numbness (peripheral neuropathy)

There is no need for direct exposure to fire to have carbon monoxide poisoning.  Improperly maintained furnaces or even engaging in fun activities like tubing behind the motor boat or snowmobiling may expose you to dangerously high CO levels.

Further reading:
  1. Lin et al. (2018): Treatment with normobaric or hyperbaric oxygen and its effect on neuropsychometric dysfunction after carbon monoxide poisoning - A systematic review and meta-analysis of randomized controlled trials, Medicine (2018) 97:39(e12456)
  2. Jain KK (2009): Textbook of hyperbaric medicine 5th Revised and Updated Ed., Ch 12: Carbon Monoxide and Other Tissue Poisons. Hogrefe & Huber Publishers, Inc., Massachusetts, USA;, pp.111 –155, 2009
  3. Kindwall EP (1999): Hyperbaric Medical Practice 2nd, Ch 20: Carbon Monoxide and Cyanide poisoning. Best Publishing Company, Arizona, USA; pp. 509–535,1999
  4. Gesell LB (2008): Hyperbaric Oxygen Therapy Indication 12th Ed., The Hyperbaric Oxygen Therapy Committee Report. Durham, NC: Undersea and Hyperbaric Medical Society, pp. 19-24

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Case file: Recovery from CO poisoning. 

24 year old female went abroad on holiday to India, where she was exposed to carbon monoxide. She fell unconscious and awoke in the hospital. On return home to Canada, she was hospitalized for 5 days, and discharged with biweekly physiotherapy and occupational therapy. The CO poisoning left her suffering from concentration and memory difficulties, right sided facial droop, and weakness of the right extremities.

Baseline cognitive testing showed deficits in concentration and delayed recall memory. Baseline motor testing showed pronounced weakness of the right hand with muscle spasm. Walking in a straight line for 20 steps took her 18 seconds, with deviations in her gait.

HBO was initiated 15 days after the insult, with 20 sessions of 90 minutes at pressures up to 2.2ATA.

After 7 HBO sessions, she was able to use her hand for everyday tasks again, and cognition was much sharper. By HBO 8 she noticed she could talk more clearly and her facial droop was gone.

By HBO 19 delayed recall and concentration greatly improved. Walking in a straight line for 20 steps took her 9 seconds, and both hands demonstrated equal strength.

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 Information contained on this site is intended for general consumer understanding and education. It should not be used as a substitute for any medical professional opinion, advice or prescribed medication nor should it serve as diagnosis or treatment of health problems.