Functional assessment of a new staple line reinforcement in lung resection

Maximum resistance pressure at the time of lung tissue rupture after porcine lung transection using automatic linear staplers with different reinforcement methods

PURPOSES

Polyglycolic acid (PGA) sheets, fibrin glue, and staple line reinforcement are frequently used to prevent air leakage during lung resection. However, the optimal staple-line reinforcement method remains unclear.

METHODS

Cranial lung lobes of pigs were used to evaluate different staple line reinforcement methods (n = 6). Ventilator-assisted manometry was used to measure the maximum resistance pressure at the time of rupture of the lung tissue after stapling.

RESULTS

The mean maximum resistance pressures at the time of lung tissue rupture after using the stapler alone, stapler with PGA sheet and fibrin glue, and stapler with reinforcement were 38.0 cmH2O, 51.3 cmH2O, and 62.7 cmH2O, respectively. A significant increase in the maximum resistance pressure was observed with stapler reinforcement (P < 0.001), while the differences between the other groups were not statistically significant (P = 0.055, P = 0.111). A histological assessment revealed disruption of alveolar structures near the needle-stitching site in the stapler alone, and in the stapler with PGA sheet and fibrin glue groups. Pleural rupture near the staple line was observed in the stapler with reinforcement group.

CONCLUSIONS

The maximum resistance pressure before air leakage was significantly higher when using a stapler with reinforcement than when using a stapler alone.

Synthetic Pressure Sensitive Adhesives for Biomedical Applications

Pressure sensitive adhesives are components of everyday products found in homes, offices, industries, and hospitals. Serving the general purpose of fissure repair and object fixation, pressure sensitive adhesives indiscriminately bind surfaces, as long as contact pressure is administered at application. With that being said, the chemical and material properties of the adhesive formulation define the strength of a pressure sensitive adhesive to a particular surface. Given our increased understanding of the viscoelastic material requirements as well as the intermolecular interactions at the binding interface required for functional adhesives, pressure sensitive adhesives are now being explored for greater use. New polymer formulations impart functionality and degradability for both internal and external applications. This review highlights the structure-property relationships between polymer architecture and pressure sensitive adhesion, specifically for medicine. We discuss the rational, molecular-level design of synthetic polymers for durable, removable, and biocompatible adhesion to wet surfaces like tissue. Finally, we examine prevalent challenges in biomedical wound closure and the new, innovative strategies being employed to address them. We conclude by summarizing the progress of current research, identifying additional clinical opportunities, and discussing future prospects.

Polyglutamic Acid-Based Elastic and Tough Adhesive Patch Promotes Tissue Regeneration through In Situ Macrophage Modulation

Adhesive patches are advanced but challenging alternatives to suture, especially in treating fragile internal organs. So far there is no suture-free adhesive patch based on metabolizable poly(amino acid) materials with excellent mechanical strength as well as immunomodulation functionality. Here, a polyglutamic acid-based elastic and tough adhesive patch modified by photosensitive groups on the surface to achieve robust light-activated adhesion and sealing of flexible internal organs is explored. With the porous internal morphology and excellent biodegradability, the patches promote regeneration through a macrophage-regulating microenvironment. Treated rabbits achieve rapid full-thickness gastric regeneration with complete functional structure within 14 d, suggesting its robust tissue adhesion and repair-promoting ability.

Extracellular matrix powder protects against bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis refers to a group of lung diseases characterized by inflammation, fibroblast proliferation, and excessive collagen deposition. Although the mechanisms underlying pulmonary fibrosis are poorly understood, current evidence suggests that epithelial injury contributes to the development of fibrosis. Regenerative medicine approaches using extracellular matrix (ECM) scaffolds have been shown to promote site-specific tissue remodeling. This led to the hypothesis that particulate ECM would promote normal tissue repair and attenuate bleomycin-induced pulmonary fibrosis. C57BL/6 mice were treated intratracheally with bleomycin or saline with or without a particulate form of ECM scaffold from porcine urinary bladder matrix (UBM-ECM) or enzymatically digested UBM-ECM. Mice were sacrificed 5 and 14 days after exposure. Compared to control mice, bleomycin-exposed mice had similar increases in inflammation in the bronchoalveolar lavage fluid regardless of UBM-ECM treatment. However, 14 days after exposure, lung histology and collagen levels revealed that mice treated with bleomycin and the particulate or digested UBM-ECM had negligible fibrosis, whereas mice given only bleomycin had marked fibrosis. Administration of the particulate UBM-ECM 24 h after bleomycin exposure also significantly protected against pulmonary injury. In vitro epithelial cell migration and wound healing assays revealed that particulate UBM-ECM promoted epithelial cell chemotaxis and migration. This suggests that promotion of epithelial wound repair may be one mechanism in which UBM-ECM limits pulmonary fibrosis.

A comparison of gastrojejunal anastomoses with or without buttressing in a porcine model

INTRODUCTION

The addition of staple-line reinforcements on circular anastomoses has not been well studied. We histologically and mechanically analyzed circular- stapled anastomoses with and without bioabsorbable staple-line reinforcement (SeamGuard, W. L. Gore & Associates, Flagstaff, AZ) in a porcine model.

METHODS

Gastrojejunal anastomoses were constructed using a #25 EEA Proximate ILS (Ethicon Endo-Surgery, Cincinnati, OH) mechanical stapling device with and without Bioabsorbable SeamGuard (BSG). Gastrojejunal anastomoses were resected acutely and at 1 week, and burst-pressure testing and histological analysis were performed. Standardized grading systems for inflammation, collagen deposition, vascularity, and serosal inflammation were used to compare the two anastomosis types.

RESULTS

Acute burst pressures were significantly higher with BSG than with staples alone (1.37 versus 0.39 psi, p=0.0075). Burst pressures at 1 week were significantly lower with BSG than with staples alone (2.24 versus 3.86 psi, p=0.0353); however, both readings were above normal physiologic intestinal pressures. There was no statistical difference in inflammation (13.4 versus 15.6, p=0.073), width of mucosa (3.2 mm versus 3.2 mm, p=0.974), adhesion formation (0 versus 0.5, p=0.575), number of blood vessels (0.5 versus 1.0, p=0.056), or serosal inflammation (2.0 versus 1.0, p=0.27) between the stapled anastomoses and those buttressed with BSG. Stapled-only anastomoses had statistically more collagen (2.0 versus 1.0, p=0.005) than the anastomoses supported with BSG.

CONCLUSIONS

The addition of BSG as a staple-line reinforcement acutely improves the burst strength of a circular anastomosis but not at 1 week. At 1 week, a decrease in collagen content with the BSG-buttressed stapled anastomosis was the only difference in the histologic parameters studied with no difference in vascularity, adhesions, or inflammation. The long-term effect of BSG on anastomotic strength or scarring is yet to be determined. The clinical implications may include decreased stricture formation and also decreased strength at anastomoses.

Reinforcement does not necessarily reduce the rate of staple line leaks after sleeve gastrectomy. A review of the literature and clinical experiences

BACKGROUND

Laparoscopic sleeve gastrectomy (SG) is an accepted bariatric procedure, with an advantaged by a low complication rate. A feared complication is stapler line leak. Buttressing materials have been suggested as a means of reducing staple line leak rates. We analyzed the leak rates from published series to help in demonstrating a potential cause.

METHODS

The study was institutional review board (IRB) approved retrospectively. A Medline search using the key words sleeve gastrectomy and bariatric surgery obtained 54 articles. Attention was restricted to 11 articles written in English that listed numbers of gastrectomy procedures and leaks. Poisson regression assessed the possibility that patients who received buttressing materials had a reduced rate of leaks.

RESULTS

Thirty-five patients were evaluated from Greece (15) and the United States (20); two patients developed staple line leaks that appeared to be related to problems associated with buttressing materials. Eleven prior studies and the present series yielded 1,589 procedures, 15 (0.94%) of which were complicated by leaks. The leak rate for patients who were known to have received reinforcement of some sort was 1.45 (95% confidence interval 0.41-3.43) times that for other patients. To detect a difference between 1% and 0.5% as statistically significant in 80% of cases, with a two tailed test and alpha set at 0.05, would require 9,346 procedures.

CONCLUSIONS

There is no reason to believe, at this point, that reduction in leak rates occur because reinforcement is used. Because the leak rate is small, the routine reinforcement of the staple line after sleeve gastrectomy is questionable at best, although a decrease in hemorrhage has been reported.

Buttressing staples with cholecyst-derived extracellular matrix (CEM) reinforces staple lines in an ex vivo peristaltic inflation model

BACKGROUND

Staple line leakage and bleeding are the most common problems associated with the use of surgical staplers for gastrointestinal resection and anastomotic procedures. These complications can be reduced by reinforcing the staple lines with buttressing materials. The current study reports the potential use of cholecyst-derived extracellular matrix (CEM) in non-crosslinked (NCEM) and crosslinked (XCEM) forms, and compares their mechanical performance with clinically available buttress materials [small intestinal submucosa (SIS) and bovine pericardium (BP)] in an ex vivo small intestine model.

METHODS

Three crosslinked CEM variants (XCEM0005, XCEM001, and XCEM0033) with different degree of crosslinking were produced. An ex vivo peristaltic inflation model was established. Porcine small intestine segments were stapled on one end, using buttressed or non-buttressed surgical staplers. The opened, non-stapled ends were connected to a peristaltic pump and pressure transducer and sealed. The staple lines were then exposed to increased intraluminal pressure in a peristaltic manner. Both the leak and burst pressures of the test specimens were recorded.

RESULTS

The leak pressures observed for non-crosslinked NCEM (137.8 +/- 22.3 mmHg), crosslinked XCEM0005 (109.1 +/- 14.1 mmHg), XCEM001 (150.1 +/- 16.0 mmHg), XCEM0033 (98.8 +/- 10.5 mmHg) reinforced staple lines were significantly higher when compared to non-buttressed control (28.3 +/- 10.8 mmHg) and SIS (one and four layers) (62.6 +/- 11.8 and 57.6 +/- 12.3 mmHg, respectively) buttressed staple lines. NCEM and XCEM were comparable to that observed for BP buttressed staple lines (138.8 +/- 3.6 mmHg). Only specimens with reinforced staple lines were able to achieve high intraluminal pressures (ruptured at the intestinal mesentery), indicating that buttress reinforcements were able to withstand pressure higher than that of natural tissue (physiological failure).

CONCLUSIONS

These findings suggest that the use of CEM and XCEM as buttressing materials is associated with reinforced staple lines and increased leak pressures when compared to non-buttressed staple lines. CEM and XCEM were found to perform comparably with clinically available buttress materials in this ex vivo model.

Staple line reinforcement reduces postoperative pancreatic stump leak after distal pancreatectomy

Pancreatic stump leak is the major source of morbidity after stapled distal pancreatectomy. We hypothesized that reinforcement of the stapler system with a buttress mat can improve leak rates when compared to standard stapling alone. We performed 13 consecutive distal pancreatectomies using our reinforced stapler system, forming our experimental group. A historical control group was composed of 18 patients undergoing stapled pancreatic closure without reinforcement. The main outcome measure was pancreatic leak in the postoperative period. Pancreatic leaks included fistulas and fluid collections (sterile or infected). Hospital length of stay was recorded as a secondary measure. Postoperative pancreatic leak rate was zero in the experimental group, but 39% in the control group (P = 0.025). Development of a pancreatic leak resulted in prolonged hospital stays: 13.6 vs 8.3 days (P < 0.03). We conclude that staple line reinforcement is a simple and effective method of reducing pancreatic stump leakage after distal pancreatectomy. The economic impact of lower leak rates is reflected in significantly shorter hospital stays. The results of our study should be validated in a randomized controlled trial.