摘要:

ABSTRACTSPrevious studies in mature fetal sheep have shown that alcohol depresses cerebral blood flow (CBF), cerebral O2consumption (CMRO2), and cerebral glucose consumption (CMRglu). This effect earlier in gestation might contribute to the pathogenesis of fetal alcohol syndrome. Physiologic studies of immature fetal sheep have demonstrated lower CBF, CMRO2, and CMRglu as well as a blunted vasodilatory response to hypoxia compared with mature fetal sheep. The purpose of this study was to determine whether immature fetal responses to alcohol are blunted compared with near-term fetal responses. We studied seven immature fetal sheepin uteroat 92 ± 1 d gestation (term = 147 d) 2 d after placement of vascular catheters. Pure ethanol (1 g/kg) was infused i.v. to the mother over 1 h. We measured CBF and myocardial blood flow by radioactive microspheres and calculated CMRO2and CMRglu using arterial and sagittal sinus O2and glucose concentrations. At a fetal ethanol concentration of 33 + 8 mmol/L (150 ± 37 mg/dL), there were no significant changes in CBF, CMRO2, or CMRglu. There was mild hypoglycemia (glucose concentration = 1.05 ± 0.2versus1.33 ± 0.2 mM baseline) and lactic acidemia (lactate concentration = 1.29 ± 0.3versus1.07 ± 0.2 mM baseline). Cardiovascular variables were unchanged as was myocardial blood flow. The immature fetal sheep brain shows no significant cerebrovascular and metabolic response to acute alcohol intoxication compared with mature fetal sheep. Mild hypoglycemia and lactic acidemia did develop. The reason for the developmental differences in response to alcohol and their relationship to fetal alcohol syndrome remain to be elucidated. (Pediatr Res31: 645–648, 1992)

ISSN:0031-3998    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTSThe temporal relationship between changes in cerebral Doppler flow velocity wave forms, ductal patency, blood gases, and blood pressure during the transition from intrauterine to newborn life was assessed longitudinally in 16 healthy term fetuses and newborns. Doppler flow velocity wave forms were obtained from fetal cerebral arteries (anterior cerebral, internal carotid, and basilar) before birth, within 8 h after birth, and again at 24 and 48 h after birth. The resistance index was used as a measure of vascular resistance. The resistance index of the cerebral arteries studied increased significantly between the antenatal and 8-h study periods. This was followed by a significant decrease below fetal levels by the 24-h study period, with little change thereafter. We conclude that in the newborn human, as in the newborn lamb, the transition from fetal to immediate newborn life is associated with an increase in cerebral vascular resistance and thus a decrease in cerebral blood flow in response to the increase in arterial oxygenation. The subsequent decrease in the cerebral resistance index between 8 and 24 h of life cannot be explained by a loss of ductal shunting nor by associated changes in newborn blood gases or blood pressure, but may rather reflect a remodeling of the circulation due to impedance matching. (Pediatr Res31: 649–652, 1992)

ISSN:0031-3998    

出版商:OVID    

年代:1992

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1992

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1992

数据来源: OVID