Redistribution of cardiac output and oxygen delivery in the hypoxemic fetal lamb.
In hypoxia, fetal cardiac output and the product arterial O2 content x blood flow to the fetal heart and central nervous system (CNS) tend to remain constant. As a consequence the percentage of cardiac output directed to the heart and CNS increases hyperbolically in inverse relation to the oxygen content of the fetal ascending aorta, [O2]as. The fetal lamb maintains [O2]as approximately 0.45 mM (0.45 +/- 0.02 SEM) higher than the O2 content in the abdominal aorta, [O2]ab, over a wide range of oxygenation. When [O2]as decreases below the 2 mM level, the [O2]as--[O2]ab difference (delta O2) decreases also. A mathematical model of the fetal circulation shows that delta O2 is a function of the ratio oxygen consumption of fetal upper body/abdominal aorta blood flow (VU/FA). The behavior of delta O2 in hypoxia can be explained by assuming that the VU/FA ratio is maintained in moderate hypoxia and decreases in sever hypoxia.
D000818:Animals; D001012:Aorta, Abdominal / Q000503:physiopathology; D001775:Blood Circulation; D002302:Cardiac Output; D002490:Central Nervous System / Q000098:blood supply; D005260:Female; D005315:Fetal Diseases / Q000503:physiopathology*; D005318:Fetal Heart / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology*; D008955:Models, Cardiovascular; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D011247:Pregnancy; D012039:Regional Blood Flow; D012756:Sheep
D010100:Oxygen