Critical Illness: Yang Tobin Study 1991

Question 1

Yang-Tobin Clinical Q

Answer 1

In mechanically ventilated patients, what predictors determine success or failure of weaning patients from mechanical ventilation?

Question 2

Yang-Tobin Bottom Line

Answer 2

The rapid shallow breathing index (RSBI) is the ratio of respiratory rate to tidal volume (f/VT). RSBI >105 accurately predicts weaning failure, while RSBI <105 is associated with weaning success.

Question 3

Yang-Tobin Primary Outcome

Answer 3

ventilation weaning success

-first sgep was validating RSBI

Question 4

Yang-Tobin Inclusion Criteria

Answer 4

• Medical (ie, non-surgical) patients
• Clinically stable mechanically ventilated patients in an ICU
• Patients considered by their physicians to be ready to undergo a weaning trial

Question 5

Yang-Tobin Interventions

Answer 5

• RSBI: f/VT, where f=respiratory rate (breaths/min) and VT=tidal volume (liters)
• CROP: integrates compliance, respiratory rate, oxygenation, and maximal inspiratory pressure

Question 6

Yang-Tobin Criticisms

Answer 6

• Positive and negative predictive values are not optimal measures for assessing the quality of a predictor, since they vary according to the prevalence or pretest probability of weaning success. However, likelihood ratios independent of pretest probability were calculated from the original data. The LR+ was 2.7 and the LR- was 0.05. This suggests that RSBI >105 was better at identifying weaning failure than an RSBI <105 is at identifying weaning success.
• As a result, while RSBI can guide decisions about extubation, a RSBI <105 should not prompt extubation, especially in the face of clinical judgment suggesting extubation could be harmful.