Mathieu
Fewer patients with evidence of persistent neurological manifestations at 3 months following carbon monoxide intoxication following a single hyperbaric oxygen treatment.
Clinical Bottom Line: 1. Treatment with HBO resulted in fewer patients with persistent neurological manifestations at 3 months after exposure, but not 1 or 6 months.
Appraised by: Mike Bennett Dept. of Diving and Hyperbaric Medicine Prince of Wales Hospital, Sydney; Thursday, 19 November, 1998
Clinical Scenario: Non-comatose patient with carbon monoxide intoxication. Three-part Question: In non-comatose patients with CO poisoning, does the application of hyperbaric oxygen as compared to normobaric oxygen result in fewer patients with neurological manifestations? Search Terms: Hyperbaric oxygenation, carbon monoxide
The Study: Non-blinded randomised controlled trial with intention-to-treat. Adult, non-comatose patients presenting within 12 hours and with a measured HbCO of greater than 10%. Excluded if there was mixed poisoning, pregnancy or specific contraindication. Control group (N = 276; 276 analysed): 100% oxygen for 12 hours at 1ATA. Experimental group (N = 299; 299 analysed): Hyperbaric oxygen at 2.5ATA for 90 minutes.
The Evidence:
| Outcome | Time to Outcome | NBO | HBO | Relative risk reduction | Absolute risk reduction | NNT |
| Persistent neurological manifestations | 1 month | 0.26 | 0.23 | 12% | 0.030 | 33 |
| 95% CI | -16% to 39% | -0.04 to 0.10 | NNT10 to INF NNH25 to INF | |||
| PNM | 3 months | 0.15 | 0.095 | 37% | 0.055 | 18 |
| 95% CI | 1% to 72% | 0.001 to 0.11 | 9 to 746 | |||
| PNM | 12 months | 0.05 | 0.043 | 16% | 0.007 | -143 |
| 95% CI | -64% to 96% | -0.03 to 0.04 | NNT37 to INF NNH24 to INF |
Comments: 1. Interim report only with insufficient detail of outcome measures, randomisation, blinding or numbers of patients who reached final follow-up. 3. There does not appear to have been any sham treatment. 4. The effect shown is probably unreliable given nature of report.
Expiry date: August 2022
References: 1. Mathieu D, Wattel F, Mathieu-Nolf M, Durak C, Tempe JP, Bouachour G, Sainty JM. Randomized prospective study comparing the effect of HBO versus 12 hours NBO in non-comatose CO poisoned patients: results of the interim analysis. In: Proceedings of the International Joint Meeting on Hyperbaric an d Underwater Medicine, Marroni A, Oriani G, Wattel F eds. Grafica Victoria, Bolognia 1996; 331.
