Fauza D O, Fishman S J
Harvard Center for Minimally Invasive Surgery and the Department of Surgery, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
J Pediatr Surg. 1998 Dec;33(12):1737-40. doi: 10.1016/s0022-3468(98)90274-3.
BACKGROUND/PURPOSE: Intracranial bleeding has been reported as one of the complications of both open and minimally invasive fetal surgery and putatively attributed to intraoperative fluctuations of carotid blood flow. The aim of this study was to look at fetal carotid blood flow and its relationship with umbilical blood flow, blood pressure, oxygen delivery, and acid-base status in the fetus at various intraamniotic pressures with both liquid and gas media during fetoscopic surgery.
Six 115- to 130-day-gestation ewes underwent continuous invasive systemic blood pressure monitoring in the descending aorta. A hysterotomy was performed. A 6-mm ultrasonic blood flow probe was placed around the common umbilical artery at its origin from the fetal aorta. This was followed by placement of a double-lumen, 4F catheter in the fetal descending aorta through a femoral artery. A 4-mm ultrasonic blood flow probe was then placed around the fetal left common carotid artery. A pressure-monitoring, multiperforated catheter was placed inside the amniotic cavity. The fetus was repositioned inside the uterus, which was then closed. The abdominal wall was closed loosely. No further manipulation was performed for 1 hour. Intraamniotic pressure was raised from 0 to 30 mm Hg at 5-mm Hg intervals by infusing either warmed saline or medical air. Common umbilical artery and left carotid artery blood flows, blood pressure, blood gases, bicarbonate, sodium, and hematocrit were recorded in all fetuses at each 5-mm Hg interval. Maternal systemic blood pressure, O2 saturation, and temperature were kept constant.
Carotid blood flow remained stable within the intra-amniotic pressure range studied (0 to 30 mm Hg), despite the significant drop in common umbilical artery blood flow uniformly observed above 20 mm Hg when saline was infused and above 15 mm Hg when air was infused. There was fetal hypoxemia and hypercarbia concomitant with decreased common umbilical artery blood flow (however, without fetal acidosis, because of compensatory elevation of bicarbonate). Within the intraamniotic pressure range studied, fetal aortic blood pressure, sodium, and hematocrit did not vary significantly, even when there was decreased umbilical blood flow.
Fetal carotid blood flow is protected, possibly autoregulated, remaining stable even after umbilical blood flow decreases as a consequence of elevated intrauterine pressures up to 30 mm Hg during videofetoscopy. These data suggests that perioperative intracranial bleeding related to videofetoscopic surgery is caused by factors other than fluctuations of cerebral blood flow.
背景/目的：颅内出血已被报道为开放性和微创性胎儿手术的并发症之一，据推测与术中颈动脉血流波动有关。本研究的目的是在胎儿镜手术期间，观察不同羊膜腔内压力下，使用液体和气体介质时，胎儿颈动脉血流及其与脐血流、血压、氧输送和酸碱状态的关系。
对6只妊娠115至130天的母羊进行降主动脉连续有创系统血压监测。进行子宫切开术。在脐动脉从胎儿主动脉发出的起始处周围放置一个6毫米的超声血流探头。随后通过股动脉将一根双腔4F导管置入胎儿降主动脉。然后在胎儿左颈总动脉周围放置一个4毫米的超声血流探头。将一个压力监测、多孔导管置入羊膜腔内。将胎儿重新安置在子宫内，然后关闭子宫。腹壁松散缝合。1小时内不再进行进一步操作。通过注入温热盐水或医用空气，将羊膜腔内压力以5毫米汞柱的间隔从0升高至30毫米汞柱。在每个5毫米汞柱间隔时，记录所有胎儿的脐动脉和左颈动脉血流、血压、血气、碳酸氢盐、钠和血细胞比容。母体系统血压、血氧饱和度和体温保持恒定。
在所研究的羊膜腔内压力范围内（0至30毫米汞柱），颈动脉血流保持稳定，尽管当注入盐水时，在20毫米汞柱以上，以及当注入空气时，在15毫米汞柱以上，均观察到脐动脉血流显著下降。脐动脉血流减少时伴有胎儿低氧血症和高碳酸血症（然而，由于碳酸氢盐的代偿性升高，没有胎儿酸中毒）。在所研究的羊膜腔内压力范围内，即使脐血流减少，胎儿主动脉血压、钠和血细胞比容也没有显著变化。
胎儿颈动脉血流受到保护，可能存在自身调节，即使在胎儿镜检查期间子宫内压力升高至30毫米汞柱导致脐血流减少后，仍保持稳定。这些数据表明，与胎儿镜手术相关的围手术期颅内出血是由脑血流波动以外的因素引起的。
