Effects of hyperbaric hyperoxia on cardiac and regional hemodynamics in conscious dogs.
BACKGROUND
Although evidence of systemic vasoconstriction has been reported both in animal models and in humans, the regional hemodynamic effects of hyperbaric hyperoxia have not been well characterized.


METHODS
In the present study, we report the effects of hyperoxia (normobaric and hyperbaric) on simultaneous measurements of cardiac and regional hemodynamics in the chronically instrumented conscious dog.


RESULTS
Hyperbaric hyperoxia (202 kPa) produced significant decreases in heart rate (12%) and cardiac output (20%) and a significant increase in systemic vascular resistance (30%). Carotid artery blood flow decreased significantly (18%) whereas coronary, hepatic, renal and mesenteric flows remained unchanged.


CONCLUSIONS
Our data show that the hyperoxic vasoconstriction is limited to the cerebral and peripheral vascular beds. Additionally, blood flow to major organs is well preserved in the face of hyperoxia-induced decreases in cardiac output. Consequently, we postulate that a redistribution of blood flow from peripheral vascular beds (e.g., skin, muscle, bone) to major organs occurs during hyperbaric hyperoxia.
Department of Anesthesiology, University of Texas-Houston Medical School, USA.
J M
JM
Berry
M F
MF
Doursout
B D
BD
Butler
D000818:Animals; D002302:Cardiac Output; D003326:Coronary Circulation; D004285:Dogs; D005260:Female; D006321:Heart / Q000503:physiopathology*; D018496:Hyperoxia / Q000503:physiopathology*; D008297:Male; D012039:Regional Blood Flow