title: Automatic tube compensation-assisted respiratory rate to tidal volume ratio improves the prediction of weaning outcome.
abstract: OBJECTIVE
  To assess whether the respiratory rate to tidal volume ratio (RVR) measured while receiving automatic tube compensation (ATC) [RVRATC] would have a better predictive value as a weaning measure than unassisted RVR.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  General ICU of a tertiary-care university hospital.
  
  
  METHODS
  Forty-three patients who received mechanical ventilation for > 24 h and were considered ready for weaning.
  
  
  METHODS
  All patients underwent a 60-min spontaneous breathing trial (SBT) [positive end-expiratory pressure of 5 cm H(2)O; ATC, 100%]. Patients tolerating the trial (n = 35) were extubated immediately. The following parameters were measured at the onset and end of the SBT: RVR, RVRATC, peak airway pressure (Paw), airway occlusion pressure, and minute ventilation. The outcome measure was successful extubation (ability to maintain spontaneous breathing for > 48 h).
  
  
  RESULTS
  Median age was 55 years (range, 25 to 88 years), median APACHE (acute physiology and chronic health evaluation) II score was 15.5 (range, 3 to 29), and median duration of mechanical ventilation prior to the SBT was 7 days (range, 1 to 40 days). Extubation was successful in 25 patients (72%). There were no significant differences in baseline characteristics between patients successfully extubated (group 1) and those requiring reintubation. On multivariate analysis, RVRATC measured at 60 min (RVR(60)ATC) was most predictive of successful extubation (p = 0.03). The area under the receiver operator characteristic curve was also highest for RVR(60)ATC (0.81 +/- 0.03) as compared to RVR (0.77 +/- 0.03), RVRATC (0.75 +/- 0.04), and RVR measured at 60 min (0.69 +/- 0.05). The ratio of RVR(60)ATC to Paw was the best predictor (0.84 +/- 0.02).
  
  
  CONCLUSIONS
  RVRATC measured at the end of the SBT was the best predictor of successful extubation. A new ratio (ratio of RVRATC to Paw) was most predictive and deserves further study.
authors.affiliation: Department of General Intensive Care, Rabin Medical Center, Beilinson Campus, Petah Tiqva, and Sackler Faculty of Medicine, Tel Aviv University, Israel. cohenjon@post.tau.ac.il
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Cohen
authors.forename: Maury
authors.initials: M
authors.lastname: Shapiro
authors.forename: Elad
authors.initials: E
authors.lastname: Grozovski
authors.forename: Pierre
authors.initials: P
authors.lastname: Singer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012129:Respiratory Function Tests; D012131:Respiratory Insufficiency / Q000628:therapy*; D013990:Tidal Volume; D015300:Ventilator Weaning / Q000379:methods*