A delayed encephalopathy with neurologic deterioration may follow carbon monoxide poisoning within a few days or weeks. Patients with one or more risk factors may benefit from more aggressive therapy and should be monitored more closely.
Risk factors for delayed encephalopathy:
(1) old age
(2) coma lasting 2 or more days
(3) persistent dizziness and fatigue after regaining consciousness
(4) concurrent events (Ellenhorn):
(4a) drug overdose
(4b) strangulation
(4c) seizures
The maximal level of carboxyhemoglobin does not appear to correlate with the development of delayed encephalopathy. Since alcoholics are involved in many fires, it would be interesting to see if chronic alcoholism would increase the risk.
Therapy for a patient at risk may include multiple cycles of hyperbaric oxygen therapy provided there are no contraindications. This has not been confirmed as useful in prospective studies (Balzan).
Monitoring may include imaging studies such as MRI to detect demyelination or other changes in the brain.
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