Résumé
Objective To investigate the protective effect of dexamethasone on stress response induced by intraute-rine balloon aortic valvuloplasty (IUBAV) in a fetal lamb model. Methods Twenty-four near term twin pregnant goats were randomly assigned to control group (n=12) and dexamethasone group (intracardiac injection of dexamethasone) (n=12). Ultrasound guided IUBAV model was established. According to the combination of treatment and operation, 48 fetal lambs were divided into four groups. The following parameters were dynamically monitored by ultrasound, which were fetal and neonatal heart rate (HR), cardiac rhythm, aortic resistance index (RI) and pulsatility index (PI). On established IUBAV model, blood samples and liver tissue specimens were taken from fetal/neonatal goats for detection of blood glucose (Glu), lactate acid (LA), plasma epinephrine (E), norepinephrine (NE), cortisol (Cort), hepatic glycogen staining. Results IUBAV resulted in increased values of Glu, LA, E, NE and Cort levels, and decreased pH value, there were significant differences between pre-and 3h-post procedure (P<0.05), and significant differences were also existed in these values between pre-and 3d-post procedure (P<0.05). After administrating dexamethasone, the changes of Glu, LA, E, NE, Cort and pH levels were suppressed effectively. Fetal hepatic glycogen was consumed in large amounts due to IUBAV while recovered 3 days after IUBAV by glycogen staining. After administrating dexamethasone, hepatic glycogen consumption related to IUBAV was obviously inhibited. After IUBAV, fetal aortic RI was increased, and there was significant differences compared with pre-procedure (P<0.05). Up to 3d-post procedure, the values of RI recovered to some extent, but statistical difference was exist-ed compared with pre-procedure (P<0.05). After administrating of dexamethasone, increased aortic RI was effectively sup-pressed. Conclusions IUBAV could lead to reversible stress response and increased aortic RI in a fetal lamb model which could be alleviated by dexamethasone.
Résumé
Objective To study the effects of fetal lamb cardiac bypass on the fetal cardiac function.Methods Eight ewes at gestation of 120 to 140 days have nine fetus which were randomly divided into control group (n = 4) and fetal bypass group (n = 5). Control group underwent sham procedure that fetal stemotomy was performed.Bypass group underwent fetal cardiac bypass with cen- trifugal pump and placenta for 30 minutes.Fetal mean blood pressure,heart rate and bleed gas data were recorded before bypass,30 minutes during bypass,1 hour after cessation of bypass,2 hour after cessation of bypass.Tei index of two ventricles and pulse index of umbilical arteries were recorded with ultrasonography.Plasma troponin I was assayed.Ultrastructure of fetal myocardium was recorded,Results Fetal mean blood pressure and heart rate of two groups have no changes during the experiment time.The umbilical pulse index of bypass group elevated significantly compared with control group (P
Résumé
Massive bleeding during pregnancy has a significant effect on the mother and the fetus. To evaluate the safety of hemodilution as a therapy for hemorrhage during pregnancy, the author compared maternal and fetal hemodynamics and oxygen carrying capacity at varying conditions in gravid ewes. Six Corriedale-breed, near-term pregnant ewes (120-140 days gestation) were anesthetized with nitrous oxide, halothane and oxygen. After the vital signs became stable, the maternal and fetal parameters of hemodynamics and oxygen carrying capacity were measured as control values. After then, 15% of total estimated matemal blood volume (12.5 ml/kg) was removed over approximately 15 minutes and infusion of the same amount of a mixture of lactated Ringer's solution and 10% pentastarch was done simultaneously (15% bleeding). Twenty minutes later the same parameters were measured. After then, a second phlebotomy was performed to remove an additional 15% of the total estimated maternal blood volume and infusion of the same amount of a mixture of the same solutions was done simultaneously (30% bleeding). And the same parameters were measured. Data collections included matemal heart rate, systolic, diastolic and mean arterial pressure, central venous pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, hemoglobin, hematocrit, serum lactate, arterial and mixed venous pH, oxygen tension, carbon dioxide tension, oxygen saturation, and fetal heart rate, systolic, diastolic and mean arterial pressure, hemoglobin, hematocrit, serum lactate, and umbilical arterial and venous blood gas analysis. Matemal arterial blood pressure, heart rate, central venous pressure, pulmonary artery pressure, pulmonary capillary wedge pressure and carfiac output revealed no significant changes, and there was neither hypoxemia nor acidosis in gravid ewes. Serum lactate concentration at 30% bleeding increased significantly but within normal range. Oxygen flux, oxygen consumption and oxygen extraction ratio revealed no significant differences. In fetal lamb blood pressure was not changed, but heart rate, serum lactate concentration and oxygen extraction ratio were revealed significant increases in 15% bleeding and 30% bleeding cases. In conclusion, gravid ewe was well tolerated to acute hemodilution, and.fetal lamb was well compensated.