title: Effects of short vs. prolonged mechanical ventilation on antioxidant systems in piglet diaphragm.
abstract: OBJECTIVE
  Prolonged controlled mechanical ventilation (MV) is known to induce diaphragmatic oxidative stress that seems to be an important factor reducing force-generating capacity. To better understand the cellular mechanisms involved, this work examined the effect of short vs. prolonged MV on antioxidant defense in the diaphragm.
  
  
  METHODS
  Prospective, randomized, controlled animal study in a university laboratory.
  
  
  METHODS
  Eleven piglets (15-20 kg) were assigned to one of two groups: a long-MV group (n=6) ventilated for 3 days or a short-MV group (n=5) ventilated for 3 h. Force frequency curves of the transdiaphragmatic pressure (Pdi) were obtained in vivo by phrenic nerve pacing. Oxidative stress was evaluated by thiobarbituric reactive substance (TBARs) content and the enzymatic antioxidant activity of both superoxide dismutase (SOD) and glutathione peroxidase (GPx) in samples of diaphragm.
  
  
  RESULTS
  Pdi decreased in the long-MV group by 30-35% over the 3 days at all frequencies compared to the short-MV group. Diaphragm TBARs content was significantly higher and SOD activity lower in long-MV animals than in short-MV animals after 72 h. GPx activity tended to be lower in diaphragms from long-MV animals, but this difference was not significant.
  
  
  CONCLUSIONS
  This study shows that 3 days of MV in piglets is associated with a decrease in antioxidant activity which could emphasize oxidative stress and both contribute to the diaphragm dysfunction caused by MV.
authors.affiliation: Intensive Care Unit, Department of Anesthesiology: DAR B, CHU de Montpellier, Hôpital Saint Eloi, 80 avenue Augustin Fliche, 34295 Montpellier, France. s-jaber@chu-montpellier.fr
authors.forename: Samir
authors.initials: S
authors.lastname: Jaber
authors.forename: Mustapha
authors.initials: M
authors.lastname: Sebbane
authors.forename: Christelle
authors.initials: C
authors.lastname: Koechlin
authors.forename: Maurice
authors.initials: M
authors.lastname: Hayot
authors.forename: Xavier
authors.initials: X
authors.lastname: Capdevila
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Eledjam
authors.forename: Christian
authors.initials: C
authors.lastname: Prefaut
authors.forename: Michèle
authors.initials: M
authors.lastname: Ramonatxo
authors.forename: Stefan
authors.initials: S
authors.lastname: Matecki
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure; D003964:Diaphragm / Q000502:physiology*; D009119:Muscle Contraction; D018384:Oxidative Stress; D012121:Respiration, Artificial / Q000009:adverse effects*; D013552:Swine; D013997:Time Factors; D015300:Ventilator Weaning