Thurston
Hyperbaric oxygen may reduce mortality following myocardial infarction in a heterogenous group of patients.
Clinical Bottom Line: 1. There is significant reduction in early mortality by the addition of hyperbaric oxygen, after adjustment for severity of clinical condition.
- Appraised by: Mike Bennett, Dept of Diving and Hyperbaric Medicine
Prince of Wales Hospital, Sydney; Thursday, 17 December, 1998
- Clinical Scenario: A 56 year old man with an acute myocardial infarction.
- Three-part Question: In patients with recent acute myocardial infarction, does the addition of hyperbaric oxygen in addition to standard care, result in any reduction in mortality rate in the early post-infarction period?
- Search Terms: Hyperbaric oxygenation, myocardial infarction.
- The Study:
Non-blinded randomised controlled trial with intention-to-treat. Patients under seventy where there was a strong clinical suspicion of MI occurring within 24 hours of presentation and without specific contraindication to HBO. Control group (N = 105; 105 analysed): Full orthodox coronary care regime including oxygen by mask at 6l/min. No sham treatment. Experimental group (N = 103; 103 analysed): As above but patients were given oxygen 100% at 2ATA for two hours, followed by air for one hour in a repeating cycle for 48 hours.
The Evidence:
| Outcome | Time to Outcome | Control Rate | HBO Rate | Relative risk reduction | Absolute risk reduction | NNT |
| Mortality | 3 weeks | 0.23 | 0.17 | 28% | 0.064 | 16 |
| 95% CI: | -19% to 75% | -0.04 to 0.17 | NNT 6 to INF NNH= 23 to INF | |||
| Non-event outcomes | Time to outcome | P-value | ||||
| Regression of mortality onHBO and severity score | 3 weeks | 0.03 |
- Comments:
1. Patients of widely differing severity were included and when the mortality is adjusted for severity (using an index), there may be an important effect of hyperbaric oxygen. 2. 23 patients in the HBO group did not actually receive HBO for a variety of reasons, mainly claustrophobia. 3. 12 patients initially entered were excluded due to misdiagnosis or wrong age.
- Expiry date: June 2021
- References:
1. Thurston GJ, Greenwood TW, Bending MR, Connor H, Curwen MP. A controlled investigation into the effects of hyperbaric oxygen on mortality following acute myocardial infarction. Quarterly Journal of Medicine 1973; XLII:751-770.
