Intoxication au monoxyde de carbone

Cited indications for hyperbaric oxygen therapy include loss of consciousness, ischemic cardiac changes, neurological deficits, significant metabolic acidosis, or carboxyhemoglobin level greater than 25%. A carboxyhemoglobin level of 50% is critical and needs to be reduced as quickly as possible. Breathing 100% oxygen at normal atmospheric pressure, this patient will clear the carboxyhemoglobin with a half-life of 90 minutes, but hyperbaric oxygen therapy will lower the half-life to 30 minutes. Also, there is considerable risk of delayed neurocognitive impairment following a severe exposure such as this, and hyperbaric oxygen is believed to lower the risk of this long-term complication, although the strength of this evidence is disputed.

Définition

• Carboxyhémoglobinémie normale: <3%
• Carboxyhémoglobinémie chez les fumeurs: 10%-15%

Physiopathologie

• Demi-vie approximative d'élimination du CO:
  • à l'air ambiant 4 heures
  • sous masque à réserve 100%: 40-50 minutes

Traitement

Carboxyhémoglobinémie inconnue

• Traitement présomptif par O2 100% durant 4-6 heures

=== Carboxyhémoglobinémie

• Patients with high levels of carboxyhemoglobin (25% and greater) and evidence of organ ischemia should be treated with hyperbaric oxygen if possible.
• Methylene blue would be recommended for toxic levels of methemoglobin, usually 20% to 30% or higher.