title: Pericardium matrix buttressing hinders the stapled bronchial stump healing.
abstract: BACKGROUND
  Biomechanical and histological properties of stapled bronchi with and without bovine pericardial matrix plus collagen reinforcement are analyzed.
  
  
  METHODS
  Pneumonectomy with mechanical bronchial suture was performed in the swine model. Pigs were randomly assigned to three groups: three-row staplers without reinforcement (Traditional), with reinforcement (Buttressed) and control "wild type", non-resected normal bronchus (Normal). Intraoperative test was carried for air leaks at 20/30/40 mm Hg endobronchial pressure. After 60 d, tracheobronchial specimen was harvested, stocked, and analyzed. Tensile test was performed using INSTRON 5965 loading frame machine. Maximal strain resistance value, length of elongation at rupture parameter, and stiffness coefficient (K) were evaluated. Histological analysis was performed. Sample size calculation was assessed (four per group), and the Student t-test was used to statistically evaluate differences in biomechanical variables.
  
  
  RESULTS
  No fistula occurred. Biomechanical analysis showed that maximal strain resistance is 41.22 ± 2.11 N (Traditional), 24.53 ± 3.47 N (Buttressed), and 30.91 ± 0.29 N (Normal); elongation at rupture is 16.01 ± 1.82 mm (Traditional), 12.89 ± 0.48 mm (Buttressed), and 9.32 ± 0.11 mm (Normal). Finally, K is 2.59 ± 0.16 N/mm (Traditional), 1.91 ± 0.33 N/mm (Buttressed), and 3.32 ± 0.01 N/mm (Normal). Stumps without reinforcement proved higher resistance and length of elongation than reinforced ones. Normal bronchial tissue shows the highest stiffness coefficient. Statistical analysis produced significant values for each biomechanical feature. Group Buttressed stumps show greater thickness and a substantial inflammatory reaction with granulation tissue along the whole scar and around areas of discontinuity within the scar, not yet healed.
  
  
  CONCLUSIONS
  Reinforcing the mechanical suture line of bronchial stump with bovine pericardial matrix plus collagen shows suboptimal biomechanical and histological characteristics compared to using the stapler alone.
authors.affiliation: Department of Thoracic Surgery, University of Perugia Medical School, Perugia, Italy. Electronic address: jacopovannucci@tiscali.it.
authors.forename: Jacopo
authors.initials: J
authors.lastname: Vannucci
authors.affiliation: Istituto di Ricerca Traslazionale per l'Apparato Locomotore Nicola Cerulli-LPMRI, Arezzo, Italy.
authors.forename: Gian Luca
authors.initials: GL
authors.lastname: Gervasi
authors.affiliation: Istituto di Ricerca Traslazionale per l'Apparato Locomotore Nicola Cerulli-LPMRI, Arezzo, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Freddolini
authors.affiliation: Anatomy Section, Department of Surgery and Biomedical Sciences, University of Perugia Medical School, Perugia, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pistilli
authors.affiliation: Department of Veterinary Sciences, University of Perugia, Perugia, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: De Monte
authors.affiliation: Department of Veterinary Sciences, University of Perugia, Perugia, Italy.
authors.forename: Antonello
authors.initials: A
authors.lastname: Bufalari
authors.affiliation: Anatomy Section, Department of Surgery and Biomedical Sciences, University of Perugia Medical School, Perugia, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Rende
authors.affiliation: Department of Thoracic Surgery, University of Perugia Medical School, Perugia, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Puma
mesh_terms: D000818:Animals; D002417:Cattle; D003094:Collagen / Q000009:adverse effects*; D011013:Pneumonectomy / Q000379:methods*; D011897:Random Allocation; D017792:Surgical Stapling; D013552:Swine; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D003094:Collagen
keywords: Biomechanical tests; Bronchus; Fistula; Lobectomy; Lung; Pulmonary resection; Stapler; VATS