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Centre for Evidence-
Based Medicine

Diagnosis: Clinical Scenario

You admit a 77 year old female with community acquired pneumonia to the ICU. She was admitted from the emergency department with hypoxemia that is refractory to supplemental oxygen. She is intubated but this required fiber optic intubation because she could not be intubated by direct laryngoscopy. She was placed on antibiotics and required . She does not have other significant past medical history. Two days later, her fraction of inspired oxygen is 40% and she is off positive end expiratory pressure. You decide she is ready to be extubated but the critical care fellow expresses concern that she will fail extubation and will not be able to be reintubated. You state that you would like to use some diagnostic test to help predict if she will be successfully extubated. Your fellow states that the respiratory rate to tidal volume ratio can be used to predict successful extubation and her ratio is 50.

You from the question: In mechanically ventilated patients, can the respiratory rate to tidal volume ratio be used to predict successful extubation? You perform a MEDLINE search using the Mesh terms 'extubation' and 'sensitivity' and 'specificity' and find an article about predictors of successful extubation (NEJM 1991:324:1445-1450.)

Read the article and decide:

  1. Are the results of this diagnostic test valid?
  2. Are the results of this diagnostic test important?
  3. Can you apply this valid, important evidence about a diagnostic test in caring for your patient?

Continue to completed worksheet