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Pre- and postnatal risk factors for cardiovascular instability in VLBW infants at 36-40 wks postconceptional age. 118

Signs of autonomic instability such as episodes of bradycardia are frequently observed in VLBW infants at age close to term. The clinical implications of these events as well as the underlying physiological mechanisms continue to be a matter of controversy. The aim of this study was to examine what factors might predispose to an instability of heart rate (HR) blood pressure (BP) and peripheral blood flow (PBF) in VLBW infants at age close to term. The integrated responses of HR, BP and PBF to a 45° head-up tilt test were used to evaluate the cardiovascular stability. A decrease in PBF, rise in BP and decrease in HR are the normal responses in term infants and older children.