OXYGEN

      
   

 

      
     

What is Carbon Monoxide Poisoning?

  • Carbon monoxide causes tissue ischemia by avidly binding to hemoglobin and displacing oxygen. The treatment is 100% oxygen, and possibly HBO therapy.

Carbon monoxide (CO) binds to hemoglobin approximately 200 times more avidly than oxygen. This results in impaired oxygen transport and utilization (the oxyhemogloblin dissociation curve shifts leftwards). Conventional pulse oximetery overestimates the true saturation of hemoglobin with oxygen, and, in addition to reduced oxygen delivery to tissues, CO binds to cellular proteins and causes tissue hypoxemia.

Carbon monoxide poisoning causes cell and tissue ischemia, and can prove fatal. It has been established that breathing 100% oxygen considerably reduces the half time of COHb (carboxyhemoglobin) binding. If oxygen is delivered in a hyperbaric environment, this half time is reduced further (1). In patients with moderate to severe CO poisoning, hyperbaric oxygen may reduce late neurological sequelae as compared to normobaric oxygen (2). Although there is no compelling data to support the use of HBO in this group of patients, if facilities are available HBO should be strongly considered if the COHb is greater than 25%, there is a history of neurological impairment or the patient has evidence of cardiac abnormalities (ischemia, arrhythmias etc) (3).

References

   (1)    Moon RE, DeLong E. Hyperbaric oxygen for carbon monoxide poisoning. Med J Aust 1999; 170(5):197-199.

   (2)    Thom SR, Taber RL, Mendiguren II, Clark JM, Hardy KR, Fisher AB. Delayed neuropsychologic sequelae after carbon monoxide poisoning: prevention by treatment with hyperbaric oxygen. Ann Emerg Med 1995; 25(4):474-480.

   (3)    Piantadosi CA. The role of hyperbaric oxygen in carbon monoxide, cyanide and sulfide intoxication. Probl Respir Care 1991; 4:215-231.

        
   

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