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J A Deprest

Publications and source records attributed to J A Deprest.

44 records · Page 3Linked to original sources
PubMed1994

A model for fetal surgery through intrauterine endoscopy.

Video-endoscopic technology may offer new hope for the future of fetal surgery. Ten time-dated pregnant ewes (95 to 105 days; term, 145 days) were used to develop a model of fetal surgery through intrauterine endoscopy. Special 5-mm ports were designed with short, flexible, balloon-tipped shafts. The cannulas were inserted through purse-stringed hysterostomies. Amnioinfusion of warmed physiological fluid (Hartmann) was used as the work medium. Fetal heart rate and oxygen saturation (pulse oximetry), temperature, and amniotic pressure were monitored continuously through endoscopically placed sensors. Surgical procedures included subcutaneous dissection of the abdominal wall and ligation of the urethra in the male fetus (n = 7), ligation of the urachus within the umbilical cord (n = 8), and endoscopy of the fetal esophagus and trachea (n = 6). Bloodless surgery was achieved with a novel coagulation device that allows bipolar cutting and coagulation in an electrolyte-rich fluid medium. The mean fetal operative time was 147 minutes (range, 130 to 195). The intraamniotic temperature was maintained between 38.0 +/- 0.9 degrees C and 41.7 +/- 1.7 degrees C throughout the procedure. Oxygen saturation ranged from 51 +/- 20% to 72 +/- 14%, and fetal heart rate from 120 to 140 beats per minute. In conclusion, intrauterine endoscopy in a fluid medium allows fully monitored surgical procedures, lasting more than 2 hours, to be performed on the fetal lamb.

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PubMed1994

Fetoscopy-guided fetal endoscopy in a sheep model.

Video-endoscopic surgical treatment of the fetus may, in the future, become an alternative to open fetal operation. Six 95-day-old fetal lambs were examined through intrauterine endoscopy using amnioinfusion and specially designed balloon-tipped cannulas. The fetuses were monitored endoscopically for oxygen saturation, heart rate and temperature throughout the procedure. With a rigid 5 millimeter telescope and a flexible 3 millimeter endoscope, the respiratory and upper gastrointestinal tracts could be examined. No mucosal or other trauma was noted upon completion of the endoscopy; all lambs survived the procedure. While the applications of fetal endosurgery are likely to be similar to those of open fetal operation, fetal endoscopy (looking in the fetus) is a new entity for which clinical relevance (rather than mere feasibility) remains to be demonstrated. This technique, however, could become a valuable research tool to study fetal gastrointestinal and pulmonary physiologic factors in situ.

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PubMedDate not supplied

Fetoscopy in the pregnant rabbit at midgestation.

OBJECTIVE: To develop a small animal model for fetoscopy. METHODS: In 12 time-dated pregnant rabbits at 22 days' gestational age (term 32 days) one amniotic sac in each uterine horn (n = 24) was used for a fetoscopic procedure. After laparotomy, a 2- to 3-mm microsurgical myometrial incision was made to expose the chorionic and amniotic membrane. Under microscopic control, a 2-mm needle was inserted into the amniotic sac. Through this a 1.2-mm endoscope was passed to carry out fetoscopy during maximally 10 min, using 5-10 ml saline amnioinfusion. Mean outcome measurements were ability to visualize the placenta, umbilical cord and the different fetal elements during fetoscopy, as well as fetal survival and weight at second-look operation at 30 days. The untreated amniotic sacs served as negative controls. RESULTS: In all cases, fetoscopy could be carried out successfully, and all fetuses survived till delivery without significant influence on fetal birth weight. CONCLUSION: The midgestational rabbit can be used to perform fetoscopy.

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PubMedDate not supplied

Infrared fetoscopy in the sheep.

The strong light sources used in fetoscopy and embryoscopy may cause eye injuries to the fetus. To circumvent this potential hazard, we have successfully used an infrared light source and infrared video camera to perform 'night vision' fetoscopy in a fetal lamb model.

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PubMedDate not supplied

Underwater Nd:YAG laser coagulation of blood vessels in a rat model.

Endoscopic coagulation of placental and umbilical cord vessels has been suggested as a treatment for selected cases of twin-twin transfusion syndrome and of acardiac twin. The feasibility, safety and hemostatic effect of neodymium:yttrium-aluminium-garnet (Nd:YAG) laser in an underwater environment were experimentally studied in an in vivo model, mimicking the in utero situation and fetoplacental vessels. In 10 male Wistar rats, immersed in normal saline at 38 degrees C, femoral vessels, carotid artery, abdominal aorta and vena cava were coagulated under endoscopic control. A 100-Watt Nd:YAG laser was used in continuous mode with a 600-micron fiber. Outcome measurements were vascular diameter, total energy (joules) used to obtain visual coagulation and subsequent vascular obliteration. Overall failure rate was 32% and perforation of the vessel occurred in 7.7% of cases.

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PubMedDate not supplied

Amnioinfusion with Hartmann's solution: a safe distention medium for endoscopic fetal surgery in the ovine model.

In this study, we have investigated the maternal effects of distending the uterine cavity with Hartmann's solution in 2nd trimester equivalent pregnant sheep. In 7 pregnant ewes, double endoscopic cannulation of the amniotic cavity was performed under general anesthesia, and 1 liter of Hartmann's solution at 38 degrees C, radiolabeled with 99mTc-red blood cells, was infused. Maternal central venous pressure, hematocrit, serum and amniotic fluid osmolarity, and amniotic fluid volume were measured at nine time points within a 2-hour period. Over this time interval, no significant fluid shift to the maternal compartment was observed. We detected no adsorption of radioactivity to the fetus or membranes, and no diffusion of radioactivity to maternal or fetal tissues was noticed. We conclude from these experiments that following double cannulation and intra-amniotic infusion of Hartmann's solution into the 2nd-trimester pregnant ovine uterus, no significant shift of fluid to the maternal compartment was observed over a 2-hour time period.

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PubMedDate not supplied

Matrix metalloproteinases-2 and -9 and their endogenous tissue inhibitors in tissue remodeling after sealing of the fetal membranes in a sheep model of fetoscopic surgery.

OBJECTIVES: We studied collagen plugging of the fetoscopic access site in an in vivo fetal lamb model for fetoscopic surgery and possible role for matrix metalloproteinase (MMP)-2 and -9 and tissue inhibitors (TIMPs). METHODS: Eight ewes had fetoscopic balloon occlusion of the trachea as an experimental treatment for congenital diaphragmatic hernia between days 88 and 99 of gestation (term 145 days) with sampling of amniotic, allantoic, and tracheal fluid. Nonoperated cotwins were used as controls. The fetoscopy port was closed using a collagen plug. Ten days (range 9-12) later, fluids were sampled and plug sites collected for histologic analysis. Activity of MMP-2 (72 kDa, gelatinase A) and MMP-9 (92 kDa, gelatinase B) was determined in the fluids by zymography and secretion of TIMPs (27-30 kDa; TIMP-1, glycosylated TIMP-3 and TIMP-4, 24 kDa; unglycosylated TIMP-3, 21 kDa; TIMP-2) by reverse zymography and quantified by densitometric analysis. RESULTS: No pregnancy was complicated by amniorhexis or preterm labor. At cesarean, normal volumes of amniotic and allantoic fluid were present in all cases. Histology of the plug sites revealed good integration of the collagen plug without complete restoration of membrane integrity. MMP-2, MMP-9, and TIMPs were detected in all fluids. In the operated animals, significantly (P <.05) higher activity of MMP-9 was found in amniotic fluid, with lower concentrations of TIMPs in allantoic fluid (P <.01). Tracheal occlusion was associated with a significant (P <.02) increase in both MMP-2 and -9 in tracheal fluid. CONCLUSION: Collagen plugging of the fetoscopic access port sites in sheep resulted in functionally effective sealing of the fetal membranes. Changes in MMP-2, MMP-9, and TIMPs suggest an active remodeling of both the fetal lung and the fetal membranes.

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