title: Influence of clamping stress and duration on the trauma of liver tissue during surgery operation.
abstract: BACKGROUND
  Tissue grasping damage often occurs in minimally invasive surgery, which would increase the postoperative recovery time and the risk of surgical complications. The purpose of this study was to evaluate the relationship between liver tissue trauma and compression stress magnitude and duration during tissue clamping operation.
  
  
  METHODS
  The clamping experiments of liver tissues in vivo were conducted by using a universal soft tissue mechanical testing machine under different clamping stress magnitudes and durations. The rabbit liver was used to simulate human liver. A minimally invasive surgery grasper was used in these tests to simulate the real tissue-surgical operation condition. A pathological grading system was created to quantitatively assess the trauma within the liver tissue. The hyperbolic regression models were utilized to predict the trauma degree of liver tissue.
  
  
  RESULTS
  Obvious hyperemia, hemorrhage, hepatic capsule rupture and inflammatory cell infiltration appeared in the clamping sites of the liver. Assessment results indicated that the trauma degree increased nonlinearly with the increasing clamping stress and duration time. There exist safe thresholds, in which the severe trauma of the studied tissue can be avoided during grasping operation.
  
  
  CONCLUSIONS
  The results could provide the safety margins and the trauma prediction models for surgeons during grasping and palpation tasks in minimally invasive surgery.
authors.affiliation: Tribology Research Institution, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Cheng Du 610031, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.affiliation: Tribology Research Institution, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Cheng Du 610031, China.
authors.forename: Qing-Yuan
authors.initials: QY
authors.lastname: Yu
authors.affiliation: Tribology Research Institution, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Cheng Du 610031, China. Electronic address: liweijiani@home.swjtu.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Tribology Research Institution, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Cheng Du 610031, China.
authors.forename: Bing-Rui
authors.initials: BR
authors.lastname: Wang
authors.affiliation: Tribology Research Institution, Key Laboratory for Advanced Technology of Materials of Ministry of Education, Southwest Jiaotong University, Cheng Du 610031, China.
authors.forename: Zhong-Rong
authors.initials: ZR
authors.lastname: Zhou
mesh_terms: D000818:Animals; D003250:Constriction; D006801:Humans; D007431:Intraoperative Complications / Q000473:pathology*; D008099:Liver / Q000293:injuries* / Q000473:pathology / Q000601:surgery*; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D023421:Models, Animal; D011817:Rabbits
keywords: Compression; Laparoscopic grasper; Pathological assessment; Rabbit liver; Trauma