Caffeine
consumption lowered the peripheral transcutaneous oxygen tension increase on
hyperbaric oxygen administration in healthy volunteers.
Clinical Bottom Line:
1.
The oral consumption of caffeine in healthy volunteers resulted in a lower
tissue oxygenation in the feet under hyperbaric oxygen breathing conditions.
Appraised
by: Mike Bennett, Dept of Diving and
Hyperbaric Medicine, Prince of Wales Hospital
Sydney; Saturday, 11 September
1999
Clinical
Scenario: A patient receiving hyperbaric
oxygen therapy for a problem leg ulcer was an enthusiastic coffee drinker.
Three-part
Question: In normal human volunteers,
does the ingestion of oral caffeine result in a reduction of tissue oxygenation
achieved during hyperbaric oxygen therapy?
Search
Terms: Caffeine/administration, Blood
gas monitoring, transcutaneous
The
Study:
Double-blinded concealed
randomised controlled trial with intention-to-treat.
Healthy male volunteers, 24 to
58 years. No caffeine consumption within 12 hours.
Control group (N = 10; 10
analysed): Transcutaneous oxygen measurements were made over the chest and
dorsum of the right foot while in a standard position, breathing air. A placebo
beverage was administered and the chamber pressurised after 20 minutes to
2.36ATA and the subjects given 100% oxygen for 30 minutes.
Experimental group (N = 10; 10
analysed): As above, but a caffeine beverage was administered (3mg/kg). Subjects
were crossed-over in a random, paired fashion.
The
Evidence:
Non-Event
Outcomes
Time to outcome Control beverage
Caffeine beverage
P-value
Chest
mean absolute
PtcO2
increase (mmHg)
1hr
1,150.8
1,255.4
0.155
R
foot mean absolute
PtcO2
increase (mmHg)
1hr
836.4
568.0
0.0018
Comments:
1. Effect presumed due to
peripheral vasoconstriction.
2. Well-conducted trial.
3. Clinical significance in
problem wound patients is not known.
Expiry date: March 2003
References:
1. Stephens M, Frey M, Mohler H.
Effect of caffeine consumption on tissue oxygen levels during hyperbaric oxygen
treatment. Undersea and Hyperbaric Medicine 1999; 26:93-97.
