Carbon Monoxide Headquarters

Acute CO Poisoning:

Comparing Longterm Outcomes of NBO and HBO Therapies:

Study Title:
Trial of normobaric and hyperbaric oxygen for acute carbon monoxide intoxication

Raphael, J.C., Elkharrat, D., Jars-Guincestre, M.C., Chastang, C., Chasles, V., Vercken, J.-B., Gajdos, P.


Lancet, August 19th , pg. 414-419

The value of hyperbaric oxygen in the treatment of acute carbon monoxide intoxication was assessed in 629 adults who had been poisoned at home in the 12 hours before admission to hospital.

In patients without initial impairment of consciousness (group A) the effect of 6 hours of normobaric oxygen (NBO) (group A0, n = 170) was compared with that of 2 hours of hyperbaric oxygen (HBO) at 2 atmospheres absolute (ATA) plus 4 h NBO (group A1, n = 173).

At 1 month follow-up, 66% of A0 and 68% of A1 patients had recovered. In patients with initial impairment of consciousness, the effect of one session of HBO (group B1, n = 145) was compared with that of two sessions (group B2, n = 141); all group B patients also received 4 hours of NBO. At 1 month of follow-up, 54% of group B1 and 52% of group B2 patients had recovered. The 7 patients left with neuropsychiatric sequelae (3 B1, 4 B2) and the 4 who died (2 B1, 2 B2) had all presented with coma.

HBO was not useful in patients who did not lose consciousness during CO intoxication, irrespective of their carboxyhaemoglobin level, nor were two sessions of HBO in patients who sustained only a brief loss of consciousness. The prognosis is poorest for those presenting with coma; the trial needs to be pursued in this group of patients until the power of the study is sufficient to demonstrate the value or otherwise of HBO.

Location of Authors:
Paris, France

To Especially Note:

  • Persistent Neurologic Sequelae (PNS) was observed in many patients who had not had loss of consciousness at the time of CO poisoning
  • HBO treatment was not useful in patients who did not lose consciousness

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