title: Serial measurements of the rapid-shallow-breathing index as a predictor of weaning outcome in elderly medical patients.
abstract: OBJECTIVE
  To determine the usefulness of serial measurements of the rapid-shallow-breathing index (f/VT) as a predictor for successfully weaning elderly medical patients from mechanical ventilator support using a threshold value (< or =130) derived specifically for this population.
  
  
  METHODS
  Prospective observational study using parameters suggested from retrospective analysis.
  
  
  METHODS
  Medical ICUs of a university-affiliated private teaching hospital.
  
  
  METHODS
  Using data obtained from a retrospective analysis of 10 medical patients > or =70 years old who had failed weaning, 49 additional medical patients older than 70 years were studied prospectively.
  
  
  METHODS
  Standard weaning parameters were determined using a hand-held spirometer. Respiratory rate (f, breaths/min) and tidal volume (VT, liters) were measured at the beginning of a spontaneous breathing trial and hourly thereafter for up to 5 h using the same hand-held spirometer.
  
  
  RESULTS
  Retrospective analysis showed that the published threshold value for f/VT (< or =105) had poor predictability for weaning success when measured at the beginning of the weaning trial. In the 9 of 10 patients who failed to wean in the retrospective review, the f/VT increased to > 130 as the trial progressed over 2 to 3 h. Using an f/VT < or =130 as the threshold value for prospectively predicting successful weaning, the diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value increased from 84%, 92%, 57%, 87%, and 67%, respectively, when measured at the beginning of the weaning trial to 92%, 93%, 89%, 97%, and 80%, respectively, when measured 3 h later. The area under the receiver operating characteristic curve for f/VT also improved from 0.81 to 0.93.
  
  
  CONCLUSIONS
  Serial measurements of the rapid-shallow-breathing index in medical elderly patients during a period of spontaneous breathing can accurately predict the ability to be successfully weaned from mechanical ventilator support.
authors.affiliation: Division of Pulmonary Intensive Care, Mount Sinai Medical Center, Miami Beach, Fla, USA.
authors.forename: B P
authors.initials: BP
authors.lastname: Krieger
authors.forename: J
authors.initials: J
authors.lastname: Isber
authors.forename: A
authors.initials: A
authors.lastname: Breitenbucher
authors.forename: G
authors.initials: G
authors.lastname: Throop
authors.forename: P
authors.initials: P
authors.lastname: Ershowsky
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001145:Arrhythmias, Cardiac / Q000503:physiopathology; D002245:Carbon Dioxide / Q000097:blood; D005544:Forecasting; D006801:Humans; D007022:Hypotension / Q000503:physiopathology; D008451:Maximal Voluntary Ventilation / Q000502:physiology*; D017063:Outcome Assessment, Health Care; D010100:Oxygen / Q000097:blood; D011175:Positive-Pressure Respiration; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012372:ROC Curve; D012119:Respiration / Q000502:physiology; D015656:Respiratory Mechanics / Q000502:physiology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013147:Spirometry; D013610:Tachycardia / Q000503:physiopathology; D013990:Tidal Volume / Q000502:physiology; D013997:Time Factors; D015300:Ventilator Weaning
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen