Shandling
Hyperbaric oxygen and thrombolysis in the treatment of acute myocardial infarction improved symptom resolution and may limit myocardial damage.
Clinical Bottom Line: 1.Administration of HBO and thrombolysis together is feasible and is not associated with poor outcomes. 2.Myocardial damage, as estimated by enzyme rise, may be less in the HBO group. 3.There is earlier resolution of pain associated with HBO administration. Appraised by: Mike Bennett, Dept.of Diving and Hyperbaric Medicine, Prince of Wales Hospital, Sydney Monday, 14 December, 1998
Clinical Scenario: A 55-year-old man with suspected myocardial infarction presenting to the Emergency Department. Three-part Question: In evolving myocardial infarction where thrombolysis is considered appropriate, does the addition of hyperbaric oxygenation compared to thrombolysis alone, result in any improvement in outcome? Search Terms: Hyperbaric oxygenation, myocardial infarction.
The Study: Non-blinded concealed randomised controlled trial without intention-to-treat. Presentation with suspected MI, pain duration less than six hours and considered suitable for rTPA administration. Control group (N = 41; 34 analysed): Usual cardiac care including rTPA, total dose 100mg. Experimental group (N = 41; 32 analysed): As above, but transferred immediately to hyperbaric chamber for a single session at 2ATA for 60 minutes on 100%oxygen.
The Evidence:
| Outcome | Time to Outcome | RTPA rate | HBO rate | Relative risk reduction | Absolute risk reduction | NNT |
| Death | Discharge | 0.06 | 0 | 100% | 0.059 | 17 |
| 95% CI: | -0.02 to 0.14 | NNT7 to INF NNH=49 to INF | ||||
| Revascularization | Discharge | 0.56 | 0.59 | -6% | -0.035 | -29 |
| 95% CI: | -49% to 36% | -0.27 to 0.20 | NNT5 to INF NNH=4 to INF | |||
| Balloon pump | Discharge | 0.12 | 0.03 | 74% | 0.087 | 11 |
| 95% CI: | -31% to 100% | -0.04 to 0.21 | NNT5 to INF NNH=27 to INF | |||
| Non-event outcomes | Time to outcome | rTPA group | HBO and rTPA group | P-value | ||
| CPK (activity) | 12 hours | 2,385 | 1,552 | 0.03 | ||
| Pain relief (mins) | variable | 664 | 275 | <0.001 | ||
| ST resolution (mins) | variable | 285 | 185 | >0.05 | ||
| LOS (days | variable | 9.2 | 7.4 | >0.05 |
Comments: 1. Small, pilot study without intention to treat. About 50% recruitment rate of eligible patients due to physician refusal. No attempt to blind. 2. Larger, multi-centre study with similar protocol is under way.
Expiry date: June 2021
References: 1.Shandling AH, Ellestad MH, Hart GB, Crump R, Marlow D, Van Natta B, Messenger JC, Strauss M, Stavitsky Y. Hyperbaric oxygen and thrombolysis in myocardial infarction: The "HOT MI" pilot study. American Heart Journal 1997; 134:544-550.
