Abstract
ObjectivesWe aimed to develop a more representative model for neonatal congenital diaphragmatic hernia repair in a large animal model, by creating a large defect in a fast-growing pup, using functional pulmonary and diaphragmatic read outs.BackgroundGrafts are increasingly used to repair congenital diaphragmatic hernia with the risk of local complications. Growing animal models have been used to test novel materials.Methods6-week-old rabbits underwent fiberoptic intubation, left subcostal laparotomy and hemi-diaphragmatic excision (either nearly complete (n = 13) or 3*3cm (n = 9)) and primary closure (Gore-Tex patch). Survival was further increased by moving to laryngeal mask airway ventilation (n = 15). Sham operated animals were used as controls (n = 6). Survivors (90 days) underwent chest X-Ray (scoliosis), measurements of maximum transdiaphragmatic pressure and breathing pattern (tidal volume, Pdi). Rates of herniation, lung histology and right hemi-diaphragmatic fiber cross-sectional area was measured.ResultsRabbits surviving 90 days doubled their weight. Only one (8%) with a complete defect survived to 90 days. In the 3*3cm defect group all survived to 48 hours, however seven (78%) died later (16–49 days) from respiratory failure secondary to tracheal stricture formation. Use of a laryngeal mask airway doubled 90-day survival, one pup displaying herniation (17%). Cobb angel measurements, breathing pattern, and lung histology were comparable to sham. Under exertion, sham animals increased their maximum transdiaphragmatic pressure 134% compared to a 71% increase in patched animals (p<0.05). Patched animals had a compensatory increase in their right hemi-diaphragmatic fiber cross-sectional area (p<0.0001).ConclusionsA primarily patched 3*3cm defect in growing rabbits, under laryngeal mask airway ventilation, enables adequate survival with normal lung function and reduced maximum transdiaphragmatic pressure compared to controls.
Highlights
Congenital diaphragmatic hernia (CDH) occurs in 2,6/10,000 live births [1]
In the 3*3cm defect group all survived to 48 hours, seven (78%) died later (16–49 days) from respiratory failure secondary to tracheal stricture formation
A primarily patched 3*3cm defect in growing rabbits, under laryngeal mask airway ventilation, enables adequate survival with normal lung function and reduced maximum transdiaphragmatic pressure compared to controls
Summary
Once the initial problems of ventilatory insufficiency and pulmonary hypertension due to pulmonary hypoplasia are managed, the defect requires surgical closure This can be undertaken primarily for small defects or in the case of larger defects a patch repair may be required. To improve long term outcomes, more biocompatible and functional diaphragmatic substitutes are needed, to overcome problems such as recurrence, small bowel obstruction, adhesions and gastro esophageal reflux disease [10]. Most of these problems occur in the first two years of life. Growing animal models have been used to test novel materials
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