Zinc deficiency impairs wound healing of colon anastomosis in rats.

BACKGROUND: Anastomotic leakage is a relevant surgical complication. The aim of the study was to investigate the influence of a controlled preoperative zinc deficiency on the extracellular matrix composition of colon anastomosis. MATERIALS AND METHODS: Forty male Wistar rats were randomized to either a zinc deficiency group (n = 20) or a control group (n = 20). In each animal, a transverse colonic end-to-end anastomosis was performed. On postoperative day 7, the surface of the mucosal villi, expression of matrix metalloproteinases (MMP) 2, 8, 9, and 13, and both the number of proliferating cells (Ki67) and apoptotic cells, as well as the collagen types I/III ratio were analyzed. Within the anastomotic area the mesenterial region and the antimesenterial region were analyzed separately. RESULTS: In each group, one anastomotic leakage was detected. Expression of both MMP 2, 9, and 13 was significantly higher, and expression of Ki67 was significantly reduced in the zinc deficient group both mesenterial and antimesenterial. The collagen types I/III ratio was reduced in the zinc deficiency group by trend, without statistical significance neither mesenterial nor antimesenterial. Likewise, zinc deficiency affected neither the expression of MMP 8 nor the rate of apoptotic cells, respectively. Analyses of the surface of the mucosal villi revealed no significant differences comparing the groups with neither mesenterial nor antimesenterial. CONCLUSIONS: Our study constitutes the known negative effect of zinc deficiency on wound healing. Zinc deficiency significantly increased the activity of MMPs (2, 9, and 13), caused a reduced collagen type I/III ratio, and delayed cell proliferation and quality of intestinal wound healing.

Different tissue reaction of oesophagus and diaphragm after mesh hiatoplasty. Results of an animal study.

BACKGROUND: Laparoscopic mesh-reinforcement of the hiatal region in the treatment of gastroesophageal reflux disease (GERD) and paraesophageal hernia (PEH) reduces the risk of recurrence. However, there are still controversies about the technique of mesh placement, shape, structure and material. We therefore compared tissue integration and scar formation after implantation of two different polypropylene-meshes in a rabbit model. METHODS: A total of 20 female chinchilla rabbits were included in this study. Two different meshes (Polypropylene PP, Polyglecaprone 25 Composite PP-PG) were implanted on the abdominal diaphragm around the oesophagus. After 3 months the implanted meshes were excised en-bloc. Histological and morphological analyses were carried out accordingly proliferation rate, apoptosis and collagen type I/III ratio. RESULTS: Regarding proliferation rate of oesophagus PP (9.31 +/- 3.4%) and PP-PG (13.26 +/- 2.54%) differ in a significant (p = 0.0097) way. In the diaphragm we found a significant (p = 0.00066) difference between PP (9.43 +/- 1.45%) and PP-PG (18.73 +/- 5.92%) respectively. Comparing oesophagus and diaphragm we could prove a significant difference within PP-PG-group (p = 0.0195). Within PP-group the difference reached no statistical significance (p = 0.88). We found analogous results regarding apoptosis.Furthermore, there is a significant (p = 0.00013) difference of collagen type I/III ratio in PP-PG (12.28 +/- 0.8) compared to PP (8.44 +/- 1,63) in case of oesophageal tissue. Concerning diaphragm we found a significant difference (p = 0.000099) between PP-PG (8.85 +/- 0.81) and PP (6.32 +/- 1.07) as well. CONCLUSION: The histologic and morphologic characteristics after prosthetic enforcement of the hiatus in this animal model show a more distinct tissue integration using PP-PG compared to PP. Additionally, different wound healing and remodelling capability influence tissue integration of the mesh in diaphragm and oesophagus.

Postoperative peridural analgesia increases the strength of colonic contractions without impairing anastomotic healing in rats.

BACKGROUND AND AIMS: Peridural analgesia (PDA) is a common treatment in postoperative management after abdominal surgery to shorten postoperative ileus and to permit early postoperative nutrition. There are conflicting opinions on the effect of early peristalsis on healing of colonic anastomoses. PATIENTS AND METHODS: A short segment of the distal colon was resected in 32 Wistar rats. Two strain gauge transducers were placed on the serosa proximal to the anastomosis to measure the strength and periodicity of bowel contractions. A peridural catheter was placed between lumbar vertebra 7 and the sacral crest. The animals received 4, 16, 20, and 24 h after operation an injection of either 0.03 ml ropivacaine 0.75%/kg body weight or the same amount of sodium chloride (controls). After 3 and 10 days the colonic anastomoses were resected to measure the bursting pressure. The anastomoses were prepared for histopathological examination and determination of relative collagen content. RESULTS: Postoperative PDA led to an increasing amplitude of phasic and tonic contractions while the frequency of contractions was not significantly affected. None of the groups presented with any anastomotic complications. The bursting pressure after 3 and 10 days was similar in the two groups. The relative amount of collagen I in the anastomotic area was significantly higher after treatment with peridural ropivacaine. CONCLUSION: Postoperative PDA with ropivacaine increases the strength of colonic contractions. The increase in phasic contractions suggests a better propulsive bowel function. The significantly higher amount of collagen I in the anastomosis of animals in the PDA group supports the idea that healing of colonic anastomoses is improved rather than diminished by PDA.

Influence of postoperative epidural analgesia with bupivacaine on intestinal motility, transit time, and anastomotic healing.

Epidural application of bupivacaine has been suggested to have a sympatholytic effect on spinal reflex mechanisms that shortens postoperative paralysis and leads to an improved transit time. The influence on anastomitic healing remains controversial. Laparotomy was performed in eight dogs. A short segment of the distal colon was resected and five electrodes were fixed on the serosa to measure the myoelectric activity (e.g., Migrating Myoelectric Complex--MMC). After operation a peridural catheter was placed between L7 and the sacral crest. One milliliter of bupivacaine 0.25% for each 3 kg of body weight was injected every 4 hours. Barium pellets coated in wax were placed into the stomach to allow radiographic representation of transit time. After 5 days the colon anastomosis was resected to measure the bursting pressure. In the peridural analgesia group (PDA) we found one small bowel intussusception and one covered anastomotic leakage. Postoperative PDA led to early and severe myoelectric activity but did not influence the time until the first MMC occurred (44 +/- 0.8 h, PDA; 44.6 +/- 1.5 h,control). Neither the transit time to the colon (50.2 +/- 1.9h, PDA; 51.7 +/- 5.5 h, control) nor the anastomotic healing was influenced (bursting pressure: 176 +/- 21.1 mmHg, PDA; 152 +/- 27.7 mmHg, control). Postoperative epidural analgesia with bupivacaine shortens intestinal paralysis. Early myoelectric activity with a lack of propulsive activity can cause complications like small bowel intussusception. Hence early postoperative enteral nutrition after epidural analgesia is risky. Because the influence of epidural analgesia on propulsive motility remains unclear, it seems reasonable to recommend its limited use in colon surgery.