Rapid Shallow Breathing Index and Ultrasonographic Diaphragmatic Parameters as Predictors of Weaning Outcome in Critically Ill Patients on Mechanical Ventilation.

Background: Successful weaning is a crucial element in care toward critically ill patients on mechanical ventilation. An attempt was made to propose and assess a reliable predictor of weaning outcome.

Materials and methods: A prospective observational study was conducted on 76 patients on mechanical ventilation, assessed by Acute Physiology and Chronic Health Evaluation II (APACHE II) score. For all these patients we calculate Rapid shallow breathing index (RSBI), Ultrasonographic diaphragmatic parameters namely diaphragmatic excursion (DEx), diaphragmatic thickening fraction (DTF) and diaphragmatic contraction velocity (DCV). Values were compared among patients with two groups of successful and failed weaning outcomes, respectively, and statistically analyzed.

Results: Of 76 patients included in the study, with ultrasonographic diaphragmatic parameters being measured 30 min into SBT, 71 patients tolerated spontaneous breathing test (SBT) for 2 h and were extubated. Of these, 61 patients did not require reintubation or any form of ventilatory support within 48 h after extubation. There was a statistically significant difference in APACHE II scores, duration of ventilation, oxygen saturation levels, RSBI, DEx, DTF, and DCV between groups of patients who showed successful and failed weaning from mechanical ventilation. There were a significant positive correlation between the duration of ventilation and the RSBI and a significant negative correlation between DEx, DCV, DTF, and duration of ventilation. As predictors of weaning outcome, RSBI showed the best validity, followed by DCV, DTF, and DEx.

Conclusion: RSBI can be reliably used as a predictor of weaning outcome in critically ill patients on mechanical ventilation.