Covert R F, Schreiber M D, Torgerson L J, Torgerson R W, Miletich D J
Department of Pediatrics, Pritzker School of Medicine, Chicago, IL, USA.
Reprod Fertil Dev. 1996;8(1):157-62. doi: 10.1071/rd9960157.
To determine whether common carotid artery blood flow measured with an ultrasonic flow transducer would predict brain blood flow in fetal sheep, we measured unilateral common carotid artery blood flow and compared this to simultaneous measurements of total brain blood flows made by radioisotope-labelled microsphere techniques. We studied anaesthetized, exteriorized fetal sheep with intact umbilical circulation after ligation of extracranial, extracerebral arteries and placement of a common carotid artery flow transducer; five fetuses at 120 d gestation had 19 total comparison measurements. As measured by microsphere technique, mean basal blood flow during undisturbed conditions to regional brain areas were similar to normal values reported for the exteriorized ovine fetus; these flows were highly correlated to fetal PaCO2 and successfully varied over a wide range (total brain 9.1-200.4 ml/min/100g and total cortex 6.1-153.1 ml/min/100g) in subsequent experimental conditions of hypercapnia or occluded blood flow. Blood flow as measured by flow transducer significantly correlated (P < or = 0.01) with microsphere measurements of blood flow to total brain (r = 0.56) and total cortex (r = 0.62); regional flow to cerebellum (r = 0.70) and thalamus (r = 0.60) also correlated to transducer measurements. Stronger correlations were observed at low-flow conditions to total brain (r = 0.83) and to total cortex (r = 0.90). As measured by microsphere technique, right and left cortical blood flows were highly correlated (P = 0.0001, r = 0.97), indicating that the flow transducer or surgical manipulation did not disturb the distribution of cerebral blood flow. The mean values for zero flow reference of the transducer were < 1.5% of mean basal flow values. It is concluded that the common carotid artery flow transducer technique developed in this study provides an accurate prediction of blood flow to total brain and total cortex over a wide range of values in fetal sheep. This technique provides a methodologic advantage to sequential experimental interventions and may prove advantageous to studies of fetal sheep cerebral circulation.
为了确定用超声流量传感器测量的颈总动脉血流是否能预测胎羊的脑血流，我们测量了单侧颈总动脉血流，并将其与用放射性同位素标记微球技术同时测量的全脑血流进行比较。我们研究了在结扎颅外、脑外动脉并放置颈总动脉流量传感器后，具有完整脐循环的麻醉、体外化胎羊；5只妊娠120天的胎儿进行了19次总对比测量。通过微球技术测量，在未受干扰的情况下，区域脑区的平均基础血流与已报道的体外化绵羊胎儿的正常值相似；这些血流与胎儿的动脉血二氧化碳分压高度相关，并且在随后的高碳酸血症或血流阻断的实验条件下，成功地在很宽的范围内变化（全脑9.1 - 200.4毫升/分钟/100克，全皮质6.1 - 153.1毫升/分钟/100克）。通过流量传感器测量的血流与微球测量的全脑血流（r = 0.56）和全皮质血流（r = 0.62）显著相关（P≤0.01）；小脑（r = 0.70）和丘脑（r = 0.60）的区域血流也与传感器测量值相关。在低血流条件下，观察到与全脑（r = 0.83）和全皮质（r = 0.90）的相关性更强。通过微球技术测量，左右皮质血流高度相关（P = 0.0001，r = 0.97），表明流量传感器或手术操作并未干扰脑血流的分布。传感器零流量参考的平均值小于平均基础流量值的1.5%。结论是，本研究中开发的颈总动脉流量传感器技术能够在很宽的数值范围内准确预测胎羊全脑和全皮质的血流。该技术为连续的实验干预提供了方法学优势，可能对胎羊脑循环研究有利。
