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(Stroke. 2003;34:e153-a.)
© 2003 American Heart Association, Inc.

Letters to the Editor

Hyperbaric Oxygen Therapy

Department of Baromedicine, Memorial Medical Center, Long Beach, California

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

We applaud the authors’ efforts in attempting to use randomized controlled trials to study the effects of hyperbaric oxygen (HBO) in acute ischemic strokes. Although we agree that the pressure at which the patients were treated (2.5 atm absolute [ATA]) is appropriate, we feel that several of their other methodologies and interpretations require comments.

First: The time interval from onset of symptoms to the first HBO treatment is critical. The "golden period" from blockage of a vessel of the brain by thrombus or embolus with onset of neurological dysfunction is 3 hours.¹ This is defined as the first reperfusion period. The second reperfusion period occurs from 3 to 5 hours² after the occlusion. Successful outcomes in the treatment of cerebral gas embolism with HBO during the second reperfusion have been observed.³ Hence, any study using HBO has to consider these 2 reperfusion times.

Second: The complication of cerebral edema associated with the treatment of arterial gas embolism has been observed^4,5 even with immediate HBO treatment. We have reported evidence of a post-HBO exposure vasodilatation occurring in otherwise healthy volunteers.⁶ We do not feel these observations are a cause of morbidity.

Third: The minimum of a 1-hour HBO exposure at 2 ATA is required to saturate the mixed venous hemoglobin return to the right atrium in normal resting males.⁷ An additional 30 minutes is needed to saturate the other tissues of the body. Treatment duration less than this would not be expected to give optimal results.

Fourth: For . . . [Full Text of this Article]

Daniel E. Rusyniak, MD for the Hot Stroke Study Group

Departments of Emergency Medicine, Pharmacology & Toxicology & Neurology, Indiana University School of Medicine, Indianapolis, Indiana