title: Hyperbaric oxygen reduces infarct volume in rats by increasing oxygen supply to the ischemic periphery.
abstract: OBJECTIVE
  Hyperbaric oxygen (HBO) increases oxygen supply to anoxic areas. To examine the therapeutic effect of HBO on ischemic stroke, we measured infarct volume as well as cerebral blood flow (CBF), oxygen supply, and lipid peroxidation in the ischemic periphery.
  
  
  METHODS
  Prospective experimental study in rats.
  
  
  METHODS
  Experimental laboratory in a university teaching hospital.
  
  
  METHODS
  Thirty-eight adult rats.
  
  
  METHODS
  The rats were anesthetized (1% halothane) and intubated. Focal ischemia was induced by ligating the right middle cerebral and right common carotid arteries. Nineteen animals were exposed to 2 hrs of HBO (100% oxygen, 3 atmospheres absolute), initiated 10 mins after the onset of ischemia. The remaining animals were kept at ambient pressure and used as controls.
  
  
  RESULTS
  At the initiation of ischemia, CBF measured by a laser-Doppler flow probe placed in the ischemic periphery was reduced to 47%+/-11% and 51%+/-15% of normal levels in animals exposed or not to HBO, respectively. These altered values were not affected further by administration of HBO and remained stable throughout a 2-hr observation period. Arterial oxygen pressure and content were significantly increased to 1571+/-130 torr (209.41+/-17.32 kPa; p < .0001) and 1.03+/-0.04 mmol/dL (p < 0.0001), respectively, in HBO-treated animals compared with nontreated animals (139+/-14 torr [18.53+/-1.87 kPa] and 0.86+/-0.04 mmol/dL, respectively). The calculated increase in the oxygen supply to the ischemic periphery was 20%. The infarct volume of HBO-treated animals measured 24 hrs after the onset of focal cerebral ischemia was significantly reduced by 18% (HBO-treated, 132+/-13 mm3 vs. nontreated, 161+/-29 mm3; p = .02). Lipid peroxidation was unchanged after 120 mins of HBO administration in the cerebral cortex where the laser-Doppler flow probe was placed.
  
  
  CONCLUSIONS
  HBO at 3 atmospheres absolute reduced infarct volume by increasing oxygen supply to the ischemic periphery without aggravating lipid peroxidation, suggesting that HBO can be useful in treating stroke victims.
authors.affiliation: Department of Anesthesiology and Resuscitology, Okayama University Medical School, Okayama City, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sunami
authors.forename: Y
authors.initials: Y
authors.lastname: Takeda
authors.forename: M
authors.initials: M
authors.lastname: Hashimoto
authors.forename: M
authors.initials: M
authors.lastname: Hirakawa
mesh_terms: D000818:Animals; D002544:Cerebral Infarction / Q000628:therapy*; D002560:Cerebrovascular Circulation; D006931:Hyperbaric Oxygenation; D011446:Prospective Studies; D051381:Rats