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Respir Care. 2011 Oct;56(10):1500-5. doi: 10.4187/respcare.00768. Epub 2011 Feb 9.

Preliminary evaluation of a new index to predict the outcome of a spontaneous breathing trial.

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Respiratory Therapy Department, Hôpital du Sacré-Coeur, Montréal, Québec, Canada.



The available predictors of spontaneous-breathing-trial (SBT) success/failure lack accuracy. We devised a new index, the CORE index (compliance, oxygenation, respiration, and effort).


To compare the CORE index to the CROP index (compliance, rate, oxygenation, and pressure), airway-occlusion pressure 0.1 s after the start of inspiratory flow (P(0.1)), and rapid shallow breathing index (RSBI) for predicting SBT success/failure in a critical care environment.


With 47 mechanically ventilated patients recovering from respiratory failure, of various causes, we prospectively examined the SBT success/failure prediction accuracy and calculated receiver operating characteristic curves, sensitivity, specificity, and likelihood ratios of CORE, CROP, P(0.1), and RSBI.


The specificities were CORE 0.95, P(0.1) 0.70, CROP 0.70, and RSBI 0.65. The sensitivities were CORE 1.00, CROP 1.00, P(0.1) 0.93, and RSBI 0.89. The areas under the receiver operating characteristic curve were CORE 1.00 (95% CI 0.92-1.00), CROP 0.91 (95% CI 0.79-0.97), P(0.1) 0.81 (95% CI 0.67-0.91), and RSBI 0.77 (95% CI 0.62-0.88). The positive likelihood ratios were CORE 20.0, CROP 3.3, P(0.1) 3.1, and RSBI 2.5. The negative likelihood ratios were CORE 0.0, CROP 0.0, P(0.1) 0.1, and RSBI 0.2.


The CORE index was the most accurate predictor of SBT success/failure.

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