Stephens
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) | 1 hour | 1,150.8 | 1,255.4 | 0.155 |
| R foot mean absolute PtcO2 increase (mmHg) | 1 hour | 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: January 2022 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.
