Effects of short vs. prolonged mechanical ventilation on antioxidant systems in piglet diaphragm.
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.
Jaber
Samir
S
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
Sebbane
Mustapha
M
Koechlin
Christelle
C
Hayot
Maurice
M
Capdevila
Xavier
X
Eledjam
Jean-Jacques
JJ
Prefaut
Christian
C
Ramonatxo
Michèle
M
Matecki
Stefan
S
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