title: Idiopathic postpneumonectomy pulmonary edema: hyperinflation of the remaining lung is a potential etiologic factor, but the condition can be averted by balanced pleural drainage.
abstract: OBJECTIVE
  Idiopathic postpneumonectomy pulmonary edema is a leading cause of mortality after pneumonectomy. Postoperative hyperinflation of the remaining lung is an etiologic factor. We have demonstrated avoidance of postpneumonectomy pulmonary edema solely by changing management of the pneumonectomy space to a balanced drainage system. In sheep, we tested the following hypothesis: (1) Postoperative induced hyperinflation of the remaining lung can cause postpneumonectomy pulmonary edema. (2) A balanced drainage system can prevent its development.
  
  
  METHODS
  We performed 37 right-sided pneumonectomies in adult sheep. In experiment 1, after surgery, 10 sheep had continuous suction (5 kPa) applied through an intercostal catheter placed in the empty hemithorax to induce mediastinal shift and hyperinflation of the left lung without adverse hemodynamic sequelae. In experiment 2, 27 sheep were randomly allocated into 3 equal groups regarding management of the residual empty right hemithorax: balanced drainage, no intercostal drainage, and clamp-release intercostal underwater drainage. A fourth group of 9 sheep served as a sham controls placebo with the same anesthetic and a right thoracotomy.
  
  
  RESULTS
  All sheep tolerated surgery without adverse event. In experiment 1, there was significant mediastinal shift at necropsy in all sheep and 60% (n = 6) had postpneumonectomy pulmonary edema develop in the left lung (P = .023 vs sham). In experiment 2, incidences of postpneumonectomy pulmonary edema were as follows: 0 in balanced group (P = .057 vs other groups), 3 (30%) in no-drainage group, and 3 (30%) in clamp-release group. Only the 12 sheep with postpneumonectomy pulmonary edema had respiratory distress; the rest had uneventful recoveries.
  
  
  CONCLUSIONS
  In a sheep model of postpneumonectomy pulmonary edema, hyperinflation from mediastinal shift is an etiologic factor. A balanced drainage system averts postpneumonectomy pulmonary edema. This is the first time such a causal relationship has been demonstrated, supporting our continued use of balanced drainage after pneumonectomy.
authors.affiliation: Department of Cardiothoracic Surgery, Sir Charles Gairdner Hospital, Perth, W. Australia, Australia. John.Alvarez@health.wa.gov.au
authors.forename: John M
authors.initials: JM
authors.lastname: Alvarez
authors.forename: Jeremy
authors.initials: J
authors.lastname: Tan
authors.forename: Nand
authors.initials: N
authors.lastname: Kejriwal
authors.forename: Karim
authors.initials: K
authors.lastname: Ghanim
authors.forename: Mark A J
authors.initials: MA
authors.lastname: Newman
authors.forename: Amanda
authors.initials: A
authors.lastname: Segal
authors.forename: Greg
authors.initials: G
authors.lastname: Sterret
authors.forename: Max K
authors.initials: MK
authors.lastname: Bulsara
mesh_terms: D000818:Animals; D004322:Drainage / Q000379:methods; D011013:Pneumonectomy / Q000009:adverse effects*; D011654:Pulmonary Edema / Q000209:etiology* / Q000517:prevention & control*; D011897:Random Allocation; D012756:Sheep; D013396:Suction