Swift
Hyperbaric oxygen administration improved ventricular wall motion in patients following acute myocardial infarction.
Clinical Bottom Line: 1. The administration of hyperbaric oxygen was associated with significant improvement of ventricular wall motion compared to those patients on air.
References: 1. Swift PC, Turner JH, Oxer HF, O'Sea JP, Lane GK, Woollard KV. Myocardial hibernation identified by hyperbaric oxygen treatment and echocardiography in postinfarction patients: comparison with exercise thallium scintigraphy. American Heart Journal 1992; 124:1151-1158.
Clinical Scenario: A patient with acute myocardial infarction.
Three-part Question: In patients with hibernating myocardium following a myocardial infarction, does the administration of hyperbaric oxygen as compared to air result in improved ventricular wall contractility?
Search Terms: Myocardial infarction
The Study: Double-blinded concealed randomised controlled trial with intention-to-treat. Patients with a firm diagnosis of myocardial infarction within one week and abnormal wall motion on transoesophageal echo, who were otherwise stable.
Control group (N = 10; 10 analysed): Following transoesophageal and transthoracic echocardiography, compression to 2ATA breathing air for 30 minutes, 10 minutes decompression and repeat echocardiography.
Experimental group (N = 24; 24 analysed): As above, but compression breathing 2ATA of 100% oxygen.
The Evidence:
Outcome |
Time to Outcome |
Air group |
HBO group |
Relative risk reduction |
Absolute risk reduction |
NNT |
Ventricular contraction not improved |
1 hour |
1.0 |
0.5 |
INF |
0.5 |
2 |
95% CI: |
0.30 to 0.70 |
1 to 3 |
Non-event outcomes |
Time to outcome |
Air group |
HBO group |
P-value |
Mean arterial blood pressure change (mmHg) |
1 hour |
-3 |
-3 |
NS |
Mean heart rate change (bpm) |
1 hour |
0 |
-5 |
NS |
Comments:
1. Randomised on a 2 active to 1 control regimen.
2. Identification of hibernating myocardium may have important implications for future management, but this is unclear at this stage.
3. Much of this paper is taken with the comparison of methods of detecting hibernating myocardium and not directly with the randomised trial.
4. Steady heart rate and BP indicate no large effect of compression itself or of hyperoxia on haemodynamic parameters.
Expiry date: June 2021
Appraised by: Mike Bennett, Dept. of Diving and Hyperbaric Medicine, Prince of Wales Hospital, Sydney; Thursday, 3 June 1999