RSBI Calculator
Calculate the Rapid Shallow Breathing Index (RSBI) to assess readiness for weaning from mechanical ventilation. Free RSBI calculator with Yang-Tobin threshold of 105 and visual charts.
About This Calculator
About the Rapid Shallow Breathing Index (RSBI) Calculator
The Rapid Shallow Breathing Index (RSBI) — also known as the Yang-Tobin Index — is a clinical tool used by intensivists, pulmonologists, and respiratory therapists to predict whether a patient on mechanical ventilation can be successfully weaned and extubated. First described by Yang and Tobin in 1991, RSBI remains one of the most widely used bedside weaning predictors in intensive care units worldwide.
RSBI is calculated as the ratio of respiratory frequency (f) to tidal volume (VT) measured in liters: RSBI = f / VT(L). A score below 105 suggests the patient's breathing pattern is not dangerously rapid or shallow, indicating a higher probability of successful extubation. A score of 105 or above indicates rapid shallow breathing, which correlates with weaning failure. Lower values indicate a better prognosis, with scores below 60 suggesting excellent weaning readiness.
The measurement is typically obtained during a spontaneous breathing trial (SBT) after disconnecting the ventilator but leaving the endotracheal tube in place. The patient breathes spontaneously for one minute while a spirometer records the tidal volume, and the respiratory therapist counts the number of breaths. This calculator performs the RSBI computation instantly and color-codes the result against the 105 threshold.
Important Clinical Considerations
RSBI is a valuable screening tool, but it should never be used in isolation for extubation decisions. Clinicians must also evaluate airway patency, cough strength, secretion volume, hemodynamic stability, consciousness level, and the results of a formal spontaneous breathing trial. The RSBI was originally validated in adult medical ICU patients and may have different predictive value in surgical, pediatric, or neurological populations.
Regional Usage
United States: RSBI is a standard component of weaning assessment protocols in most American ICUs, often used alongside rapid shallow breathing assessment during SBTs. The 105 threshold is universally accepted.
United Kingdom: UK critical care guidelines (ICS and NICE) recognize RSBI as a useful adjunct but emphasize that it should be interpreted in the context of the full clinical picture. Many UK ICUs incorporate RSBI into daily weaning rounds.
India: RSBI is widely used in Indian ICUs as a simple, low-cost bedside tool. Indian studies have confirmed the 105 threshold is applicable, though some research suggests a slightly lower cutoff (around 100) may improve specificity in certain populations.
Frequently Asked Questions
What is the Rapid Shallow Breathing Index (RSBI)?
The Rapid Shallow Breathing Index (RSBI) is a clinical parameter used to predict successful weaning from mechanical ventilation. It is calculated as the ratio of respiratory frequency (breaths per minute) to tidal volume (in liters). An RSBI below 105 suggests a higher probability of successful extubation.
How is RSBI calculated?
RSBI is calculated by dividing the respiratory rate (f) by the tidal volume (VT) in liters: RSBI = f / VT(L). For example, a patient breathing 24 times per minute with a tidal volume of 350 mL would have an RSBI of 24 / 0.350 = 68.6, which is below the 105 threshold and suggests weaning is likely to succeed.
What does an RSBI below 105 mean?
An RSBI below 105 indicates that the patient's breathing pattern is not excessively rapid or shallow, suggesting that weaning from mechanical ventilation is likely to be successful. Values below 60 indicate an excellent prognosis for extubation.
What does an RSBI above 105 indicate?
An RSBI of 105 or above suggests rapid, shallow breathing, which indicates that the patient may have difficulty sustaining spontaneous breathing after extubation. In such cases, clinicians often consider alternative weaning strategies or delay extubation.
What is the normal range for tidal volume?
In healthy adults at rest, tidal volume typically ranges from 500 to 600 mL. However, in mechanically ventilated patients, tidal volume is often set between 350 and 500 mL depending on lung compliance, ideal body weight, and the lung-protective ventilation strategy being used.
What is the origin of the RSBI cutoff of 105?
The RSBI cutoff of 105 was established by Yang and Tobin in their landmark 1991 study published in the New England Journal of Medicine. They prospectively evaluated several weaning predictors and found that an RSBI below 105 had the highest predictive accuracy for successful extubation.
Can RSBI alone determine extubation readiness?
No, RSBI should not be used in isolation to determine extubation readiness. Clinicians typically combine RSBI with other assessments including the spontaneous breathing trial (SBT), airway patency, cough effectiveness, secretion burden, hemodynamic stability, and overall clinical judgment.
How is tidal volume measured for RSBI calculation?
Tidal volume for RSBI measurement is obtained using a spirometer connected to the endotracheal tube after disconnecting the patient from the ventilator. The patient breathes spontaneously for one minute, and the average tidal volume is recorded. This measurement is typically performed as part of a spontaneous breathing trial.