Reduced postnatal cerebral glucose metabolism measured by PET after asphyxia in near term fetal lambs

The effects of fetal asphyxia on cerebral function and development, involve the transition from fetal to neonatal life. Changes in cerebral glucose me tabolism may be an early postnatal indicator of fetal asphyxia. The objecti ve is to develop an experimental lamb model involving the transition from f etal to neonatal life and to examine the effect of fetal asphyxia with cere bral hypoxic ischemia on early postnatal cerebral glucose metabolism. Fetal asphyxia was induced by total umbilical cord occlusion in eight near-term fetal lambs (134-138 days) with the ewe under isoflurane-opiate anesthesia. The mean occlusion time until cardiac arrest was 14.5 (4.2) min (SD). Lamb s were immediately delivered and standardized resuscitation was instituted after 2 min asystole. At 4 hr postnatal age, [18-F]Fluoro-2-deoxy-glucose ( 18-FDG) was injected intravenously in eight asphyxiated lambs and in eight controls. Cerebral glucose metabolism was examined by positron emission tom ography (PET). As a result the mean arterial blood pressure, acid-base valu es, blood glucose and serum lactate at 4 hr postnatal age did not differ si gnificantly between lambs subjected to umbilical cord occlusion and control s. EEG was abnormal in all lambs subjected to cord occlusion and normal in the controls at 4 hr postnatal age. Global cerebral metabolic rate (CMRgl) as determined by PET was significantly lower in lambs subjected to cord occ lusion mean/median (SD) 22.2/19.6 (8.4) mu mol/min/100 g) than in controls mean/median (SD) 37.8/35.9 (6.1); P < 0.01). Global CMRgl is significantly reduced in newborn lambs 4 hr after fetal asphyxia induced by umbilical cor d occlusion. A reduction in CMRgl is an early indicator of global hypoxic c erebral ischemia. (C) 2001 Wiley-Liss, Inc.