Rapid Shallow Breathing Index (RSBI)
Why Use
Helps clinicians identify patients at risk for failed extubation. Provides an easily interpretable binary result: positive (<105) predicts success and negative (>105) predicts failure.
When to Use
Intubated patients who are breathing spontaneously, such as during a spontaneous breathing trial, and meet other clinical criteria for weaning from mechanical ventilation.
Formula
Pearls / Pitfalls
The RSBI is one component of a clinical assessment that may help predict success versus failure of extubation. Applies only to patients who are breathing spontaneously, since the formula is based on respiratory rate and tidal volume, which would be artificially dictated by vent settings in modes such as assist control and pressure control. More sensitive than specific (positive RSBI predicts successful extubation better than negative RSBI predicts unsuccessful extubation). Data show that women are more likely than men to have a negative RSBI (predicting failure) independent of actual extubation outcome. Clinicians can use the positive RSBI as an additional supporting data point to for the decision to extubate. Although the RSBI is generally accepted as helpful in predicting success of extubation, there is a dearth of convincing evidence that its application in decision-making leads to a change in outcomes. The RSBI should not be the sole determinant of extubation. Consider other data points before attempting extubation, including: Spontaneous awakening trials (SAT) and spontaneous breathing trials (SBT). Adequacy of gas exchange. Absence of copious secretions. Strength of cough. Hemodynamic stability. Resolution/improvement of pathology that necessitated intubation in the first place.
Management
Patients with RSBI <105 (“positive”): If the patient otherwise meets criteria for liberation from the ventilator, a positive RSBI means they are likely to have successful extubation. Clinicians can use the positive RSBI as an additional supporting data point for the decision to extubate. Patients with RSBI >105 (“negative”): These patients are more likely to fail extubation. However, there are multiple confounding factors that make a patient more likely to have a negative RSBI, including female gender, smaller endotracheal tube size, and active suctioning during spontaneous breathing. If a patient has a negative RSBI, but in all other respects is ready for extubation, consider potential confounding factors at play resulting in an inflated RSBI value (i.e., a negative RSBI should not necessarily deter clinicians from deciding to extubate).
Critical Actions
The RSBI is only applicable to patients that are clinically ready for weaning from the ventilator. It is not meant to answer the question of whether a patient is ready for extubation. Rather, it helps to predict the outcome after extubation.
More Information
Interpretation: RSBI Interpretation <105 Likely successful wean to extubation (97% sensitive, original study), "positive" >105 Likely to fail extubation, "negative" Note: in the original study, a value of 105 was not specified as being positive or negative. As always, use clinician judgment in borderline cases.