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.
Appraised
by: Mike Bennett, Dept. of Diving and
Hyperbaric Medicine, Prince of Wales Hospital
Sydney; Thursday, 3 June 1999
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 regime.
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:
October 2004
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.
