超声波多普勒隔水管气侵监测系统设计与海上测试

为了研究超声波多普勒隔水管气侵监测测量原理的正确性和海上应用的可行性,开展了室内实验和现场试验。通过室内实验,得到了油基钻井液在不同含气情况下超声波多普勒信号与含气率之间的关系,验证了利用多普勒信号畸变进行气侵识别的有效性和适用性;通过开展陆上井现场试验,确定了隔水管气侵监测系统设计的关键参数,验证了超声波多普勒设备对大壁厚环空内部流动监测的可行性;设计并加工了隔水管气侵监测系统样机。通过在海上钻井过程中的实际应用,测试了监测系统的稳定性,得到了隔水管内部流动状态的监测信号,验证了隔水管气侵监测系统在海上现场应用的可行性。     

The normal fetus of an acardiac twin pregnancy: Perinatal management based on echocardiographic and sonographic evaluation

Experience with three prenatally diagnosed pregnancies complicated by an acardiac twin reveals that ultrasonography and echocardiography are helpful in detecting early signs of in-utero congestive heart failure in the normal twin. The use of Doppler blood flow analysis to determine direction of blood flow, post-mortem placental and fetal angiography, and umbilical cord blood gas determination provided proof that retrograde arterial perfusion occurs in the acardiac fetus. In a fourth pregnancy, an experimental approach to occlude the acardiac twin's umbilical cord was attempted, but was unsuccessful.     

Favourable outcome of a tight constriction band secondary to amniotic band syndrome

Amniotic band syndrome or amniotic disruption complex is a well-known congenital limb abnormality, which occurs in 1 in 1200 to 1 in 15 000 live births. In cases of an isolated band constriction, it has been speculated that the bands lead to decreased blood flow in the constricted limb and subsequent natural amputation. Fetal surgery could be considered in these situations in order to release the constriction band in threatened limb amputation. We present a case of a tight constriction ring secondary to amniotic band syndrome with a favourable outcome, despite the failure of an attempted surgical procedure. Copyright © 2004 John Wiley & Sons, Ltd.     

Is unexplained third trimester intrauterine death of fetuses with gastroschisis caused by umbilical cord compression due to acute extra-abdominal bowel dilatation?

We report on a case of gastroschisis in which sudden dilatation of extra-abdominal bowel at 34+1 weeks was followed by an unusual umbilical flow velocity waveform (diastolic notching). The condition was associated with normal umbilical Doppler indices, brain sparing effect and a non-reactive cardiotocograph (CTG). Findings at postnatal surgery strongly suggested severe cord compression by the herniated dilated bowel. The significance of notching in the umbilical artery waveform is discussed, as is the potential importance of this sign in the prepartum management of fetuses with gastroschisis. Copyright © 2002 John Wiley & Sons, Ltd.     

First-trimester ultrasonic diagnosis of twin reversed arterial perfusion sequence

Twin reversed arterial perfusion (TRAP) syndrome sequence is a rare specific anomaly of twin gestation with fused placentae and umbilical anastomosis. This syndrome occurs once in very 35 000–48 000 births and has been described in the second trimester (23-29 weeks of gestation). We report on early sonographic diagnosis (10 and 12 weeks' gestation) of two cases of TRAP sequence, together with their umbilical cord Doppler studies.