title: Blood markers of oxidative stress predict weaning failure from mechanical ventilation.
abstract: Patients undergoing mechanical ventilation (MV) often experience respiratory muscle dysfunction, which complicates the weaning process. There is no simple means to predict or diagnose respiratory muscle dysfunction because diagnosis depends on measurements in muscle diaphragmatic fibre. As oxidative stress is a key mechanism contributing to MV-induced respiratory muscle dysfunction, the aim of this study was to determine if differences in blood measures of oxidative stress in patients who had success and failure in a spontaneous breathing trial (SBT) could be used to predict the outcome of MV. This was a prospective analysis of MV-dependent patients (≥72 hrs; n = 34) undergoing a standard weaning protocol. Clinical, laboratory and oxidative stress analyses were performed. Measurements were made on blood samples taken at three time-points: immediately before the trial, 30 min. into the trial in weaning success (WS) patients, or immediately before return to MV in weaning failure (WF) patients, and 6 hrs after the trial. We found that blood measures of oxidative stress distinguished patients who would experience WF from patients who would experience WS. Before SBT, WF patients presented higher oxidative damage in lipids and higher antioxidant levels and decreased nitric oxide concentrations. The observed differences in measures between WF and WS patients persisted throughout and after the weaning trial. In conclusion, WF may be predicted based on higher malondialdehyde, higher vitamin C and lower nitric oxide concentration in plasma.
authors: Biophysics Department, Program of Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Rio Grande do Sul, Brazil.
authors: Cléber
authors: C
authors: Verona
authors: Biophysics Department, Program of Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Rio Grande do Sul, Brazil.
authors: Fernanda S
authors: FS
authors: Hackenhaar
authors: Department of Critical Care, Moinhos de Vento Hospital, Rio Grande do Sul, Brazil.|Federal University of Health Sciences of Porto Alegre - UFCSPA Medical School, Rio Grande do Sul, Brazil.
authors: Cassiano
authors: C
authors: Teixeira
authors: Biophysics Department, Program of Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Rio Grande do Sul, Brazil.
authors: Tássia M
authors: TM
authors: Medeiros
authors: Biophysics Department, Program of Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Rio Grande do Sul, Brazil.
authors: Paulo V
authors: PV
authors: Alabarse
authors: Biophysics Department, Program of Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Rio Grande do Sul, Brazil.
authors: Tiago B
authors: TB
authors: Salomon
authors: Biophysics Department, Program of Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Rio Grande do Sul, Brazil.
authors: Ártur K
authors: ÁK
authors: Shüller
authors: Department of Critical Care, Moinhos de Vento Hospital, Rio Grande do Sul, Brazil.
authors: Juçara G
authors: JG
authors: Maccari
authors: Clínicas Hospital of Porto Alegre, Rio Grande do Sul, Brazil.
authors: Robledo Leal
authors: RL
authors: Condessa
authors: Department of Critical Care, Moinhos de Vento Hospital, Rio Grande do Sul, Brazil.|Federal University of Health Sciences of Porto Alegre - UFCSPA Medical School, Rio Grande do Sul, Brazil.
authors: Roselaine P
authors: RP
authors: Oliveira
authors: Clínicas Hospital of Porto Alegre, Rio Grande do Sul, Brazil.
authors: Silvia R
authors: SR
authors: Rios Vieira
authors: Biophysics Department, Program of Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Rio Grande do Sul, Brazil.
authors: Mara S
authors: MS
authors: Benfato
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001205:Ascorbic Acid / Q000097:blood; D015415:Biomarkers / Q000097:blood*; D002374:Catalase / Q000097:blood; D005260:Female; D005978:Glutathione / Q000097:blood; D019803:Glutathione Disulfide / Q000097:blood; D005979:Glutathione Peroxidase / Q000097:blood; D006801:Humans; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood; D009573:Nitrites / Q000097:blood; D017063:Outcome Assessment, Health Care / Q000379:methods; D018384:Oxidative Stress; D011237:Predictive Value of Tests; D012121:Respiration, Artificial / Q000379:methods*; D013482:Superoxide Dismutase / Q000097:blood; D015300:Ventilator Weaning / Q000379:methods*
chemical_list: D015415:Biomarkers; D009573:Nitrites; D009569:Nitric Oxide; D008315:Malondialdehyde; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005978:Glutathione; D001205:Ascorbic Acid; D019803:Glutathione Disulfide
keywords: Oxidative stress; intensive care units; malondialdehyde; mechanical ventilation; nitric oxide; vitamin C; weaning