title: Selective diaphragm muscle weakness after contractile inactivity during thoracic surgery.
abstract: BACKGROUND
  Postoperative pulmonary complications are significant contributors to morbidity in patients who have undergone upper abdominal, thoracic, or cardiac surgery. The pathophysiology of these complications might involve postoperative inspiratory muscle weakness. The nature of postoperative inspiratory muscle weakness is unknown.
  
  
  OBJECTIVE
  To investigate the effect of surgery on the functioning of the diaphragm, the main muscle of inspiration.
  
  
  METHODS
  Serial biopsies from the diaphragm and the latissimus dorsi muscle were obtained from 6 patients during thoracotomy for resection of a tumor in the right lung. Biopsies were taken as soon as the diaphragm had been exposed (t(0)) and again after 2 hours (t(2)). The contractile performance of demembranated muscle fibers, as well as fiber morphology and markers for proteolysis, was determined.
  
  
  RESULTS
  In all patients, the force-generating capacity of diaphragm muscle fibers at t(2) was significantly reduced (~35%) compared with that at t(0), with a more pronounced force loss in type 2 fibers compared with type 1 fibers. Diaphragm weakness was not part of a generalized muscle weakness as contractile performance of latissimus dorsi fibers was preserved at t(2). Diaphragm fiber size and myofibrillar structure were not different at t(2) compared with t0, but myosin heavy chain type 2 was significantly reduced at t(2) and MuRF-1 mRNA and protein levels were elevated at t(2).
  
  
  CONCLUSIONS
  Only 2 hours of thoracic surgery causes marked, and selective, diaphragm muscle fiber weakness.
authors.affiliation: Department of Surgery, VU University Medical Center/Institute for Cardiovascular Research, The Netherlands.
authors.forename: Willem N
authors.initials: WN
authors.lastname: Welvaart
authors.forename: M A
authors.initials: MA
authors.lastname: Paul
authors.forename: Ger J M
authors.initials: GJ
authors.lastname: Stienen
authors.forename: Hieronymus W H
authors.initials: HW
authors.lastname: van Hees
authors.forename: Stephan A
authors.initials: SA
authors.lastname: Loer
authors.forename: Ra
authors.initials: R
authors.lastname: Bouwman
authors.forename: Hans
authors.initials: H
authors.lastname: Niessen
authors.forename: Frances S
authors.initials: FS
authors.lastname: de Man
authors.forename: Christian C
authors.initials: CC
authors.lastname: Witt
authors.forename: Henk
authors.initials: H
authors.lastname: Granzier
authors.forename: Anton
authors.initials: A
authors.lastname: Vonk-Noordegraaf
authors.forename: Coen A C
authors.initials: CA
authors.lastname: Ottenheijm
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D015153:Blotting, Western; D064211:Connectin; D003964:Diaphragm / Q000473:pathology*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000601:surgery*; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D009124:Muscle Proteins / Q000032:analysis; D018908:Muscle Weakness / Q000473:pathology*; D018482:Muscle, Skeletal / Q000473:pathology; D018995:Myosin Heavy Chains / Q000032:analysis; D011183:Postoperative Complications / Q000473:pathology*; D011494:Protein Kinases / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D044843:SKP Cullin F-Box Protein Ligases / Q000032:analysis; D013908:Thoracotomy; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases / Q000032:analysis
chemical_list: D064211:Connectin; D009124:Muscle Proteins; C577285:TTN protein, human; D000070584:Tripartite Motif Proteins; C440907:FBXO32 protein, human; D044843:SKP Cullin F-Box Protein Ligases; C440908:TRIM63 protein, human; D044767:Ubiquitin-Protein Ligases; D011494:Protein Kinases; D018995:Myosin Heavy Chains