Esophageal anastomosis: an experimental model to study anastomotic healing and the use of lyophilized collagen

This experimental study assessed the use of lyophilized collagen to reinforce cervical esophageal anastomosis in rabbits. Twenty New Zealand White rabbits weighing 2.3-3.2 kg were used. In group I (n = 10) a 1-cm-long segment of the esophagus was excised and the two free edges anastomosed, to mimic the conditions found in newborn esophageal atresia. Group II (n = 10) had a segmental esophageal resection and end-to-end anastomosis as in group I but the anastomotic site was circumferentially covered with lyophilized type I collagen film. The resected segments were processed immediately and served as controls for the postoperative tissue in each animal. The animals were starved for the first 24 h and water was given on the 2nd postoperative day; on the 3rd postoperative day the animals were allowed a normal diet. Two rabbits in group II died on the 7th and 8th postoperative days because of a fistula. All the rabbits were killed on the 10th postoperative day and 4-cm segments of esophagus with the anastomosis at the centre were removed. At this time gross leakage was detected in four animals (one in group I and three in group II). Each anastomosis was evaluated for bursting pressure, collagen content, and histologic appearance. Bursting pressure was higher in group I. Collagen (measured as hydroxyproline) levels in anastomotic and adjoining 1-cm segments were compared with concentrations in control segments resected during operation. In group II animals there was a significant reduction in the lowering of hydroxyproline concentrations around the anastomosis. Microscopic evaluation revealed no significant differences between the two groups. This experiment showed no demonstrable benefit from the use of lyophilized collagen in preventing the esophageal anastomotic leakage that occurs in repaired esophageal atresia.