Regional Blood Flow Changes in Neonatal Pigs in Response to Hypercapnia, Hemorrhage and Sciatic Nerve Stimulation

Regional blood flow changes in response to hypercapnia, hemorrhage, and sciatic nerve stimulation were studied in 22 newborn piglets. Femoral, renal and/or carotid arterial flows were recorded simultaneously with aortic pressure and heart rate in piglets lightly anesthetized with halothane. Observations were made while ventilation was regulated to maintain arterial pH and pCO₂ within the normal range, and when ventilation was adjusted to produce increased pCO₂ and decreased pH uncomplicated by hypoxia. The ability of the neonate to respond to low or high frequency and intensity sciatic nerve stimulation was studied during control, hypercapnia, and hypercapnia complicated by hemorrhage. The results indicate immaturity of the mechanisms normally utilized to compensate for these stresses.