"Weaning from Mechanical Ventilation: Predictive Indices".The New England Journal of Medicine. 1991. 324(21):1445-1450.PubMed•Full text•PDFContents1Clinical Question2Bottom Line3Major Points4Guidelines5Design6Population6.1Inclusion Criteria6.2Exclusion Criteria6.3Baseline Characteristics7Interventions8Outcomes8.1Primary Outcome8.2Secondary Outcomes9Funding10Further ReadingClinical QuestionWhat are the most accurate predictors for successful weaning from mechanical ventilation in patients who are clinically stable and considered ready for a weaning trial?Bottom LineRapid shallow breathing, as reflected by the ratio of respiratory frequency to tidal volume (f/VT), is the most accurate predictor of failure, and its absence is the most accurate predictor of success, in weaning patients from mechanical ventilation.Major PointsTwo new predictive indices were developed for weaning outcomes from mechanical ventilation: the f/VT ratio, quantifying rapid shallow breathing, and the CROP index_gpt, integrating thoracic compliance, respiratory rate, arterial oxygenation, and maximal inspiratory pressure (PImax).In a study divided into two phases, optimal threshold values differentiating successful weaning from weaning failure were first determined in a "training set" and then prospectively tested in a "prospective-validation set."The f/VT ratio demonstrated higher accuracy compared to traditional indices like VE and PImax, making it a reliable and effort-independent predictor for weaning outcomes.GuidelinesAs of the last knowledge update for this summary, no specific guidelines have been described reflecting the results of this study.DesignProspective, cohort study involving 100 patients who were clinically stable and undergoing a weaning trial from mechanical ventilationTesting of new predictive indices for weaning outcomesSetting: Medical intensive care units of the University of Texas Health Science CenterPopulationInclusion CriteriaClinically stable patients considered ready for a weaning trial from mechanical ventilationExclusion CriteriaPatients not meeting specific study criteriaPatients in whom weaning decisions were made without consideration of study design or measurementsPatients for whom clinical judgment dictated continuation of mechanical ventilation independent of predictive indicesBaseline CharacteristicsAverage patient age: 59.6 yearsAverage duration of ventilator support: 8.2 daysDiagnoses included adult respiratory distress syndrome, pneumonia, obstructive airway disease, central nervous system disorders, congestive heart failure, pulmonary fibrosis, and othersInterventionsMeasurement of the f/VT ratio while patients breathed spontaneously for one minuteFormulation of the CROP index_gpt—calculating dynamic and static compliance, PImax, and arterial blood gas analysisOutcomesPrimary OutcomeSuccessful weaning—ability to sustain spontaneous breathing for ≥24 hoursUnsuccessful weaning—reinstitution of mechanical ventilation at the end of a weaning trial or within 24 hours of extubationSecondary OutcomesObjective criteria for weaning failure including carbon dioxide levels, pH, and oxygenation levelsSubjective criteria for weaning failure including clinical signs such as diaphoresis, increased effort, tachycardia, arrhythmias, or hypotension during spontaneous breathingFundingSupported in part by the American Lung Association and the Veterans Affairs Research ServiceFurther ReadingN/A