Pulmonary effects of in utero tracheal occlusion are dependent on gestational age in a rabbit model of diaphragmatic hernia

Purpose: The authors investigated the effect of gestational age on lung development and maturation after in utero tracheal occlusion (TO) in a rabbit model of congenital diaphragmatic hernia (CDH). Methods: In 46 fetal rabbits, CDH was created at 23 days' gestational age (GA; term, 31 days), corresponding to the pseudoglandular phase of lung development. A second intervention was performed at either 26, 27, or 28 days on 6 fetuses in each GA group. At that time, either TO (CDH + TO), or a sham operation (CDH + sham) was performed. Nonoperated littermates served as internal normal controls (CTR). All fetuses were delivered by cesarean section at 30 days GA to assess lung response by lung-to-body-weight ratio, pulmonary morphometry, and the density of type II pneumocytes. Results: After TO, the lungs were significantly larger than in CDH animals; their weight was proportional to the duration of TO. Pulmonary morphometry in TO fetuses was comparable with that of controls. The density of type II cells was inversely related to the gestational age at which TO was performed, with normal values with TO at GA at 28 days. Conclusion: Timing of TO is critical to subsequent pulmonary development: early in gestation TO leads to pulmonary overgrowth and type II pneumocyte depletion, whereas normal values are obtained when TO is delayed till 28 of 32 days.     

The mouse as a model to study adhesion formation following endoscopic surgery: a preliminary report.

Our aim was to investigate the feasibility of a mouse model to study adhesion formation following endoscopic surgery. Following preliminary studies to establish anaesthesia and pneumoperitoneum pressure, a prospective randomized study was carried out to investigate the effect of CO2 pneumoperitoneum on postoperative adhesions. In group I (control group), the duration of pneumoperitoneum was shorter than 5 min. In groups II, III and IV, pneumoperitoneum was maintained for 60 min without flow, with a continuous low flow (1 ml/min) and a continuous high flow (10 ml/min) through the abdominal cavities of the mice using non-humidified CO2, respectively. Adhesions were scored after 7 days by laparotomy. The total adhesion scores were 0.9 +/- 0.8 (n = 15) in control group, 2.4 +/- 0.8 (n = 15) (P < 0.001 versus control group) in group II with no flow, 2.6 +/- 1.3 (n = 15) (P < 0.001 versus control group) in group III with a continuous low flow and 4.3 +/- 0.9 (n = 15) (P < 0.001 versus control group and P < 0.001 versus group II and III) in group IV with a continuous high flow. In conclusion, the mouse can be used as a model to study adhesion formation following endoscopic surgery. Duration of CO2 pneumoperitoneum is a co-factor in adhesion formation.