Creation of experimental urethral obstruction in utero: evaluation of fetal renal function.

Management of obstructive uropathy diagnosed in utero would be markedly enhanced by the availability of a simple, safe and quantitative fetal renal function test to predict postnatal renal function. In order to allow experimental evaluation of such a parameter, we adjusted a model of complete urethral obstruction with urachal ligation in 30 fetal lambs at 79 or 99 days of gestation. The method described allows obstruction in male and female fetuses as early as 79 days of gestation, with an overall high survival rate (control: 12/14; obstructed: 23/29), although lower (6/12) when obstruction is performed early (79 days) during gestation. Consequences of obstruction were examined on the 121st day of gestation. Severe hydronephrosis, ureteral and calyceal dilatation, with or without ascites and pulmonary hypoplasia were observed in all fetuses; creatinine clearance determined in utero was decreased in both groups with obstruction (early and late) vs control group: 1.15 +/- 0.5, NS, and 0.58 +/- 0.4, p < 0.01 vs 1.61 +/- 0.8 ml/min/kg respectively. In both obstructed groups, fetuses with ascites displayed lower plasma creatinine concentration and higher creatinine clearance values when compared to fetuses without ascites. In conclusion, the experimental model of obstructive uropathy described appears efficient and easily reproducible, allowing therefore the evaluation of a predictive parameter of postnatal renal function. Our preliminary results suggest that renal fetal function is more dependent on the degree of obstruction than on the term of its creation.

Motility of the transplanted small bowel: a manometric study in the piglet.

Complete transection of sympathic and parasympathic nerves is an inevitable consequence of intestinal transplantation. The aim of this experiment was to study if extrinsic denervation alters the motor function of the graft. Ten large-white piglets were used. In Group 1 control (5 animals), a segment of distal ileum was isolated on its intact neurovascular pedicle as a Thirty-Vella loop. In Group 2 study (5 animals), a Thiry-Vella loop of distal ileum was transplanted as a free autograft. The motility of intestinal loops was studied by intraluminal pressure recording at the 8th and 15th postoperative days, on conscious animals fasted for 24 hours. The measured patterns were period (P), duration (D), maximal amplitude (A) and speed of migration (S) of phases III of migratory myoelectric complexes (MMCs). One hundred and seven MMCs were recorded and compared between Group 1 and Group 2. The results were as follows: mean (+/- sem) of Group 1 vs mean (+/- sem) of Group 2. P (min) = 68.5 (+/- 8.1) vs 54.2 (+/- 3.2)(NS); D (min) = 5.9 (+/- 0.2) vs 5.9 (+/- 0.1) (NS); A (cmH2O) = 73.9 (+/- 4.1) vs 83.4 (+/- 3.2) (NS); S (cm/min) = 5 (+/- 1.1) vs 6.2 (+/- 1) (NS). The motor function of the loops was studied following intraluminal perfusion of a cholinergic compound (carbachol) at doses of 1, 2, 3, 4 and 5 mg. The mean and the maximal pressures were recorded during 3 minutes from the 2nd minute following injection of carbachol.(ABSTRACT TRUNCATED AT 250 WORDS)

High-frequency ventilation in newborn lambs after intra-uterine creation of diaphragmatic hernia.

Infants with congenital diaphragmatic hernia (CDH) die, because their lungs are hypoplastic and their pulmonary vascular resistance remains elevated after birth. In human newborns, it is difficult to appreciate the benefit of new therapeutic approaches, because the pathological findings are not uniform, the disease is rare and the clinical criteria for poor prognosis with conventional therapy are uncertain. To study the benefit of high-frequency ventilation (HFV) the use of Tolazoline in CDH, we created a diaphragmatic defect in sheep fetuses at 0.6 gestation and studied full-term newborns after a caesarian section. A sternotomy was performed to place catheters and flow probes on the aorta and pulmonary artery and to clamp the ductus arteriosus and the left pulmonary artery. Twins were used as control, and the CDH lambs were either ventilated with conventional ventilation (CV) or HFV. 23 ewes were operated upon with a 22% abortion rate and 31 newborn lambs (10 controls and 21 CDH) were studied. A complete gasometric and hemodynamic study was performed in 23 lambs (7 controls, 8 CDH with CV and 8 CDH with HFV). Clinical and pathological findings of the lambs with CDH were very similar to severe CDH in humans with bilateral lung hypoplasia, severe respiratory distress, high pulmonary vascular resistance and severe hypoxemia. HFV dramatically improved CO2 elimination, allowed less aggressive ventilation, and was associated with higher flows and lower systemic and pulmonary vascular resistance. However, HFV did not improve oxygenation leaving the newborn with severe hypoxemia associated with massive intrapulmonary foramen ovale shunting from right to left.

[Surgery of the esophagus under thoracoscopy. Study of feasibility]. / Chirurgie de l'oesophage par thoracoscopie. Etude de faisabilité.

An experimental study of thoracoscopic surgery on the esophagus was conducted in 11 animals. Complete dissection of the esophagus was carried out in the ten last cases. Other procedures performed included mode picking, truncal vagotomies, and myotomies. The thoracoscopic esophageal surgery might allow to decrease the morbidity of thoracotomy. Its interest, compared with other methods of dissection without thoracotomy, has to be evaluated.

Laparoscopic splenectomy: initial laboratory experience.

An experimental study was conducted in an animal model to test the feasibility of laparoscopic splenectomy. Twelve pigs were operated on. The splenectomy was feasible in 10 cases. However, a splenic injury occurred in five cases and the average blood loss was 80 ccm. We concluded that laparoscopy is feasible in an experimental model but is not a safe and easy procedure. Clinical applications should probably be limited to selected cases.

Thoracoscopic dissection of the esophagus: an experimental study.

In order to reduce the respiratory morbidity of thoracotomy in esophageal surgery, several methods have been used, such as blunt dissection and endoscopic dissection through mediastinoscopy. It seems that the latter reduces drastically the morbidity but does not allow full visualization of the esophageal wall, a disadvantage in some circumstances. We describe a thoracoscopic dissection of the esophagus which gives a large and magnified view of the pleural cavity, of the mediastinum, and of the esophagus.