A prospective trial of hyperbaric oxygen for chronic sequelae after brain injury (HYBOBI)

Some practitioners advocate hyperbaric oxygen (HBO2) for sequelae following brain injury. This study assessed recruitment, tolerance and safety in preparation for a randomized clinical trial.

Prospective, open-label feasibility study.

Hyperbaric medicine department of a tertiary academic hospital.

Participatory adult outpatients with problems from stroke (n=22), anoxia (13) or trauma (28) that occurred at least 12 months before enrollment, without contraindications to HBO2. Sixty-three participants enrolled in the study (21 females,42 males). Age was 45 +/- 16 years (18-76) and time from injury was 6.9 +/- 7.1 years (1.0-29.3). Fifty-three completed the study intervention, and 55 completed the assessment battery.

PARTICIPANTS underwent 60 daily HBO2 sessions (1.5 atm abs, 100% oxygen, 60 minutes). Assessments were conducted at baseline, after the HBO2 course, and six months later.

The prime outcome was feasibility. To estimate the immediate and long-term effects of HBO2, we assessed neuropsychological measures, questionnaires, neurologic exam and physical functioning measures. Some participants also had pre- and post-HBO2 speech evaluation (n=27) and neuroimaging (n=17).

The study met our a priori definition for feasibility for recruitment, but 44% required additional time to complete the 60 sessions (up to 105 days). HBO2-related adverse events were rare and not serious. Although many participants reported improvement in symptoms (51% memory, 51% attention/concentration, 48% balance/coordination, 45% endurance, 20% sleep) post-HBO2, and 93% reported that they would participate in the study again, no standardized testing showed clinically important improvement. In the small subset of those undergoing neuroimaging, apparent improvement was observed in auditory functional MRI (8/13), MR spectroscopy (9/17) and brain perfusionby CT angiography (5/9).

Conducting an HBO2 clinical trial in this population was feasible. Although many participants reported improvement, the lack of concurrent controls limits the strength of inferences from this trial, especially considering lack of change in standardized testing. The clinical relevance of neuroimaging changes is unknown. The findings of this study may indicate a need for caution when considering the broad application of HBO2 more than one year after brain injury due to stroke, severe TBI and anoxia, until there is more compelling evidence from carefully designed sham-controlled, blinded clinical trials.