Hyperoxia after hypoxia on the Cardiac Output Distribution (COD)

Abstract 18

Routine use of oxygen shortly after birth might cause extra oxidative stress. This study investigates the changes of fraction of COD to different organs during reoxygenation under hyperoxic conditions after exposure to acute hypoxia. Fertile White Leghorn eggs were studied at two incubation time groups (TG1, d14-16 (n=13) and TG2, D17-19 (n=12), total incubation time is 21d). A branch of the chorioallantoic vein was catheterized. The cardiac output distribution was measured with fluorescent microspheres injected during normoxia, at the end of 5 minutes period hypoxia (100% N₂) and after 5 minutes of hyperoxic reoxygenation (100%O₂). Results are presented in the table. Hypoxia caused a redistribution of the cardiac output in favour of the brain, heart and lungs. Contrary to reoxygenation with 21% O₂, when the CO is redistributed in favour of the brain and intestine only.

Table 1 Table: Mean percentage (%) of the fraction of COD during hypoxia and reoxygenation. (*p<0.05 increased compared to normoxia;**p< 0.05 decreased compared to normoxia).