Hypoxia-Ischemia, BrainAnoxiaAnimals, NewbornPlethysmography, Whole BodyHypoxia, BrainIschemiaRats, Sprague-DawleyBrain IschemiaCell HypoxiaPia MaterMortalityHypercapniaNeuroprotective AgentsMyocardial IschemiaHypotensionBrainCerebrovascular CirculationCell DeathDisease Models, AnimalRats, WistarHospital MortalityReperfusion InjuryNeuronsInfant MortalityTime Factors