What Researchers Did
Researchers measured how a single session of hyperbaric oxygen therapy (100% oxygen at 1.5 ATA for 60 minutes) affected brain blood flow, brain oxygen use, and pressure inside the skull in 37 patients with severe brain injuries.
What They Found
This physiological study found that hyperbaric oxygen's effects on brain blood flow and metabolism varied depending on each patient's blood flow level before treatment. In patients with reduced blood flow before treatment, both blood flow and brain oxygen metabolism (CMRO2) were higher at 1 hour and 6 hours after treatment (p less than 0.05). In patients with normal blood flow beforehand, blood flow and CMRO2 rose at 1 hour but had fallen by 6 hours. In patients with already-raised blood flow, blood flow was lower at 1 hour and 6 hours, though CMRO2 did not change. Across all patients, a marker called AVDO2 stayed constant, spinal fluid lactate levels dropped at 1 hour and 6 hours regardless of a patient's blood flow category (p less than 0.05), and intracranial pressure above 15 mm Hg decreased at 1 hour and 6 hours (p less than 0.05). The treatment's effects did not last until the next scheduled session.
Canadian Relevance
No direct Canadian connection identified.
Study Limitations
The study measured only physiological and metabolic markers over a single 6-hour window per session and did not assess clinical recovery, functional outcomes, or long-term results, and findings were based on small subgroups sorted by pre-treatment blood flow level.