Preoperative hyperbaric oxygenation reduced psychometric dysfunction and some systemic inflammatory markers following cardiac bypass and surgery

1. Pre-operative HBOT was associated with a reduced chance of neuropsychiatric deficit when defined as a reduction of >1 standard deviation in two of seven tests
2. HBOT reduced the increase in some markers of systemic inflammation, including ICAM-1, CD-18 and heat shock protein 70, but not others.
Citation:1. Alex J, Laden G, Cale A, Bennett S, Flowers K, Madden L, Gardiner E, McCollum T, Griffin S. Pretreatment with hyperbaric oxygen and its effect on neuropsychometric dysfunction and systemic inflammatory response after cardiopulmonary bypass: A prospective randomised double-blind trial. Journal of Thoracic and Cardiovascular Surgery 2005;130(6):1623-30.
Lead author's name and fax: Joseph Alex mrjosephalex@yahoo.co.uk

Three-part Clinical Question: For patients having cardiac operations using cardiopulmonary bypass, does pre-treatment with hyperbaric oxygen versus a standard approach result in a reduction in neuropsychiatric deficit and/or systemic inflammatory response?
Search Terms: Cardiac surgical procedures, neuropsychology, inflammation mediators

The Study:Double-blinded randomised controlled trial with intention-to-treat.
The Study Patients: Adults without cerebrovascular disease or immunosuppresion having routine cardiac procedures using CPB Control group (N = 31; 31 analysed): Sham procedure at 24, 12 and 4 hours before operation breathing air at 1.5 ATA for 60 minutes
Experimental group (N = 33; 33 analysed): 100% oxygen at 2.4 ATA on the same schedule

The Evidence:

Outcome
Time to Outcome
Sham group
HBO group
Relative risk reduction
Absolute risk reduction
NNT
>1 SD deterioration in two or more NPTs
4 months
0.52
0.27
47%
0.24
4
95% Confidence Intervals:
2% to 92%
0.01 to 0.48
2 to 95

Non-Event Outcomes
Time to outcome/s
Control group
Experimental group
ANOVA for CD-18 at pre-op, 2 hrs and 24 hours post-op within each group (units unknown). No between group comparison.
24 hours
P = 0.1 (63.6 to 83.8 at 2 hours)
P = 0.001 (63.3 to 77.5 at 2 hours)

Comments:
1. Clinical significance of the effects demonstrated is not clear
2. There are logistic difficulties with three pre-operative hyperbaric sessions
3. The zero time for inflammatory mediators is after HBOT, making interpretation difficult
4. Those with previous myocardial infarction were over-represented in the HBOT group (31% versus 10%) which may bias outcome, direction unknown.
5. There is information in the abstract that does not appear in the main text and no units for the inflammatory markers6. Overall good methodological study with a result that is difficult to interpret

Appraised by: Antonia Edge & Mike Bennett, Diving and Hyperbaric Medicine, Prince of Wales Hospital, Sydney ; Friday, 26 May 2006Email: m.bennett@unsw.edu.au
Kill or Update By: July 2014


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