title: Sternal stability at different negative pressures during vacuum-assisted closure therapy.
abstract: BACKGROUND
  Vacuum-assisted closure (VAC) is a widely used therapy in patients with poststernotomy mediastinitis. The aim of this study was to evaluate sternal stability during VAC application at seven negative pressures (-50 to -200 mm Hg) in a porcine wound model.
  
  
  METHODS
  Six pigs underwent median sternotomy and 2 steel wires were fixed at each sternal side and connected to a traction device. The device was connected to a force transducer linked to a force recorder. VAC therapy was applied to the wound. At each negative pressure, the length and width of the wound were measured before and after traction was started. Traction was increased stepwise up to 400 N.
  
  
  RESULTS
  The diastasis induced by a certain lateral force was similar in wounds treated with -75, -125, and -175 mm Hg. At -75 mm Hg, a significant improvement (p < 0.01) in sternal stability was seen compared with the open-chest setting. This was not further improved at -125 or -175 mm Hg. High negative pressures (-150 to -200 mm Hg) in combination with a high lateral force (>200 N) increased the risk of separation of the foam from the wound edges, with air leakage or organ rupture as a result.
  
  
  CONCLUSIONS
  Our results suggest that low negative pressures (-50 to -100 mm Hg) stabilize the sternum as efficiently as high negative pressures (-150 to -200 mm Hg). Low negative pressures (-50 to -100 mm Hg) were more beneficial, however, because no air leakage or organ rupture was observed at these pressures.
authors.affiliation: Department of Cardiothoracic Surgery, Lund University Hospital, Lund, Sweden. arash.mokhtari@med.lu.se
authors.forename: Arash
authors.initials: A
authors.lastname: Mokhtari
authors.forename: Rainer
authors.initials: R
authors.lastname: Petzina
authors.forename: Lotta
authors.initials: L
authors.lastname: Gustafsson
authors.forename: Johan
authors.initials: J
authors.lastname: Sjögren
authors.forename: Malin
authors.initials: M
authors.lastname: Malmsjö
authors.forename: Richard
authors.initials: R
authors.lastname: Ingemansson
mesh_terms: D000818:Animals; D001864:Bone Wires; D008480:Mediastinitis / Q000628:therapy; D011312:Pressure; D013249:Sternum / Q000601:surgery*; D013314:Stress, Mechanical; D013530:Surgical Wound Infection / Q000628:therapy; D034421:Sus scrofa; D014143:Traction; D014160:Transducers, Pressure; D014618:Vacuum