Prediction of Weaning Outcome from Mechanical Ventilation using Diaphragmatic Rapid Shallow Breathing Index

Background: Diaphragmatic dysfunction has been increasingly documented to play a critical role to determine ventilator dependency and failure of weaning. Objective: The goal was to study the diagnostic accuracy of diaphragmatic rapid shallow breathing index (D-RSBI) as a predictor of weaning outcomes in comparison to RSBI. Methods: A prospective observational study on consecutively admitted patients who were intubated and mechanically ventilated for a duration of at least 48 hours was carried out. The right hemidiaphragm displacement [diaphragm displacement (DD)] was calculated by M-mode ultrasonography, and respiratory rate (RR) and tidal volume (TV) were documented from the ventilator readings. Rapid shallow breathing index (RSBI) was measured as RR/TV (in liters); D-RSBI was calculated as RR/DD (in millimeters) and expressed as breath/minute/millimeter. Extubation failure was defined as the reinstitution of mechanical ventilation at the end of; or during the spontaneous breathing trial (SBT); re-intubation or the need of noninvasive ventilation (NIV) for the patient within 48 hours of extubation. Results: Of 101 screened patients, 50 patients met the inclusion criteria, of whom 45 patients had successful SBT, and finally, 41 patients could be successfully extubated. Hence, the overall rate of weaning failure in the study population was 18%. The areas under the receiver operator characteristic (ROC) curves for D-RSBI and RSBI were 0.97 and 0.70, respectively (p <0.0001). The Pearson's correlation among RSBI and D-RSBI was 0.81 (p-value <0.001). Conclusion: Diaphragmatic rapid shallow breathing index has a positive correlation and greater diagnostic accuracy than RSBI, the conventional weaning index.