Restricted cardiovascular and cerebral performance of intra-uterine growth retarded newborn piglets during severe hypoxia.

In 7 term born two-day-old intra-uterine growth retarded (IUGR) piglets cardio- and cerebrovascular, metabolic and EEG reactions were studied at rest and during severe hypoxia in comparison to 17 normal-weight piglets. In IUGR piglets even in control conditions a distinct cerebral blood flow (CBF) elevation, lower cerebrovascular resistance and oxygen consumption in the higher perfused brain regions at diminished arterial blood pressure were observed. Also the arterial glucose concentration was in the borderline hypoglycemic range, however, cerebral glucose delivery was nearly maintained. IUGR piglets survived a 1-h hypoxic period (paO2 = 25-30 mmHg) less frequently. The main reason was the distinctly restricted emergency reaction with a lack of arterial blood pressure increase and blood glucose elevation as well as a reduced (higher perfused brain regions) or absent CBF increase (lower perfused brain regions). Thereby, even in the early stage of hypoxia cerebral oxygen delivery in both brain compartments and oxygen consumption in the latter were decreased followed by a further decrease of the arterial blood pressure. The latter factor was essential for acute cardio-vascular-cerebral insufficiency.