title: Evaluation of the diagnostic performance and cut-off value for the rapid shallow breathing index in predicting extubation failure.
abstract: OBJECTIVE
  To evaluate the diagnostic performance of the rapid shallow breathing index (RSBI) in predicting extubation failure among adult patients in the intensive care unit and to determine the appropriateness of the classical RSBI cut-off value.
  
  
  METHODS
  This was a prospective study conducted in the adult intensive care unit of the Botucatu School of Medicine Hospital das Clínicas. The RSBI was evaluated in 73 consecutive patients considered clinically ready for extubation.
  
  
  RESULTS
  The classical RSBI cut-off value (105 breaths/min/L) presented a sensitivity of 20% and a specificity of 95% (sum = 115%). Analysis of the receiver operator characteristic (ROC) curve revealed a better cut-off value (76.5 breaths/min/L), which presented a sensitivity of 66% and a specificity of 74% (sum = 140%). The area under the ROC curve for the RSBI was 0.78.
  
  
  CONCLUSIONS
  The classical RSBI cut-off value proved inappropriate, predicting only 20% of the cases of extubation failure in our sample. The new cut-off value provided substantial improvement in sensitivity, with an acceptable loss of specificity. The area under the ROC curve indicated that the discriminative power of the RSBI is satisfactory, which justifies the validation of this index for use.
authors.affiliation: Faculdade de Medicina de Botucatu, Universidade Estadual Paulista - UNESP - CEP 18618-970, Botucatu, SP, Brasil. ardanaga@yahoo.com.br
authors.forename: Aline Roberta
authors.initials: AR
authors.lastname: Danaga
authors.forename: Ana Lúcia
authors.initials: AL
authors.lastname: Gut
authors.forename: Letícia Cláudia de Oliveira
authors.initials: LC
authors.lastname: Antunes
authors.forename: Ana Lúcia dos Anjos
authors.initials: AL
authors.lastname: Ferreira
authors.forename: Fábio Akio
authors.initials: FA
authors.lastname: Yamaguti
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Christovan
authors.forename: Ubirajara
authors.initials: U
authors.lastname: Teixeira
authors.forename: Cristina Aparecida Veloso
authors.initials: CA
authors.lastname: Guedes
authors.forename: Ana Beatriz
authors.initials: AB
authors.lastname: Sasseron
authors.forename: Luis Cuadrado
authors.initials: LC
authors.lastname: Martin
mesh_terms: D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012015:Reference Standards; D012129:Respiratory Function Tests; D012131:Respiratory Insufficiency / Q000628:therapy; D056152:Respiratory Rate; D012680:Sensitivity and Specificity; D015300:Ventilator Weaning / Q000009:adverse effects*