title: T-piece improves arterial and central venous oxygenation in trachestomized patients as compared to continuous positive airway pressure/pressure support ventilation.
abstract: BACKGROUND
  T-piece has been widely used as T-piece trial to identify patients who are ready for extubation but it is seldom used as a weaning tool. Our objective was to investigate the effects of breathing via T-piece on gas exchange as compared to continuous positive airway pressure with pressure support (CPAP+PS) and CPAP with automatic tube compensation (CPAP+ATC) as it has not been evaluated yet.
  
  
  METHODS
  Tracheostomized, "ready to be weaned" critically ill patients were enrolled in this prospective, auto-control clinical trial. Arterial oxygen tension (PaO2) was determined on CPAP+PS (t0), 15 minutes later on CPAP+ATC (t1), then on T-piece at 15, 30 and 60 minutes (t2-4). ScvO2 was measured at t0 and t4. Settings of fraction of inspired oxygen (FiO2) and positive end-expiratory pressure (PEEP) were kept constant throughout the investigation.
  
  
  RESULTS
  Twenty-five patients were enrolled. T-piece trial was interrupted in 4 cases after t2, due to pulmonary oedema, hypertension or fatigue. PaO2/FiO2 was significantly higher on T-piece (t3,4) then on CPAP (t0,1), P<0.05, PaO2/FiO2 did not change significantly on CPAP+PS (t0) vs. CPAP+ATC (t1) modes: median=208 (interquartile range: 175-266) vs. 223 (186-290) mmHg, P=0.102, but significantly increased from t0-t4: 208 (175-266) vs. 249 (215-325) mmHg, P=0.003, respectively. ScvO2 was significantly higher on T-piece at t4: 80% (75-82%) than on CPAP+PS at t0: 73% (71-78%), P<0.001.
  
  
  CONCLUSIONS
  On the same FiO2 and PEEP setting, breathing via T-piece improved oxygenation and resulted in increased ScvO2 as compared to breathing on CPAP with PS. Our observations suggest a potential role of T-piece during weaning from mechanical ventilation.
authors.affiliation: Department of Anaesthesiology and Intensive Therapy, Faculty of Medicine, University of Szeged, Szeged 6722, Hungary. lovas.andras@med.u-szeged.hu
authors.forename: A
authors.initials: A
authors.lastname: Lovas
authors.forename: Z
authors.initials: Z
authors.lastname: Molnár
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D045422:Continuous Positive Airway Pressure / Q000295:instrumentation* / Q000379:methods; D016638:Critical Illness; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology*; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D014139:Tracheostomy / Q000295:instrumentation* / Q000379:methods; D015300:Ventilator Weaning / Q000379:methods*
chemical_list: D010100:Oxygen