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Effects of Hyperbaric Oxygen on Neurologic Outcome for Cerebral Ischemia in Rats
Author(s) -
Roos Joel A.,
JacksonFriedman Cathy,
Lyden Patrick
Publication year - 1998
Publication title -
academic emergency medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.221
H-Index - 124
eISSN - 1553-2712
pISSN - 1069-6563
DOI - 10.1111/j.1553-2712.1998.tb02569.x
Subject(s) - medicine , anesthesia , ischemia , hyperbaric oxygen , occlusion , randomized controlled trial , middle cerebral artery , clinical trial , surgery
Objective: To evaluate the effect of hyperbaric oxygen (HBO) therapy on neurologic outcome (assessed by the quantal bioassay approach) following acute focal cerebral ischemia in rats. Methods: Two separate experimental trials were conducted. Trial 1, a nonblinded experiment, used 38 rats. Trial 2, a blinded experiment, used 59 rats. Focal cerebral ischemia was induced with a surgically placed intraluminal occlusion of the left middle cerebral artery; subsequent removal allowed reperfusion. Arterial occlusion times were varied from 5 to 90 minutes in trial 1, and from 3 to 45 minutes in trial 2. The control groups were maintained at ambient pressure for the duration of each trial. The trial 1 treatment group received a single 30‐minute HBO treatment at 2.0 atmospheres absolute (ATA) on the initial day of ischemia. The trial 2 treatment group received 30‐minute HBO treatments at 2.0 ATA daily for 4 consecutive days. The animals underwent daily 5‐point neurologic examinations. A computerized quantal bioassay was used to determine the ET 50 —the occlusion time required to cause a neurologic abnormality in half of the animals. The control and treatment ET 50 values were compared in each trial using a 2‐tailed t‐test. An increased ET 50 for the treatment vs the control group implied a beneficial effect of HBO; a decrease, the opposite. The study had a power of 80% to detect a difference of 11.4 minutes in the ET 50 for a 2‐sided α= 0.05. Results: For trial 1: the HBO ET 50 was 18.1 ± 21.9 minutes and the control ET 50 was 22.8 ± 25.0 minutes (p > 0.2). For trial 2: the HBO ET 50 was 9.49 ± 17.4 minutes and the control ET 50 was 14.9 ± 14.2 minutes (p < 0.2). Conclusion: HBO therapy showed no apparent benefit in a rat model as a treatment modality for acute cerebral ischemia with reperfusion.