Rapid Shallow Breathing Index as a Predictor for Intubation and Mortality in Acute Respiratory Failure

BACKGROUND: Noninvasive ventilation (NIV) is one of the most important therapeutic tools in patients with acute respiratory failure. However, in case of incorrect patient selection it can delay necessary intubation and is associated with complications and even mortality. Patient selection, therefore, plays a key role in therapeutic success. The purpose of this study was to determine the value of the rapid shallow breathing index (RSBI) in predicting the failure of NIV.

METHODS: This prospective observational study was conducted in the emergency department (ED) of a tertiary hospital. Adults presenting to the ED with acute respiratory failure were included in the study. The success of RSBI values measured initially (RSBI 1) and at 30 min (RSBI 2) and the difference between these 2 values (Δ RSBI) in predicting subjects’ intubation requirement and survival was tested using multivariate logistic regression analysis.

RESULTS: Two hundred sixty-seven subjects were included in the study. RSBI 1, RSBI 2, and Δ RSBI values differed significantly between the intubated and non-intubated subjects. According to the multivariate model, RSBI 1 and RSBI 2 > 105, Δ RSBI < 19, heart rate > 100 beats/min, and S_pO2 < 92% were significantly associated with intubation requirement. RSBI 1, RSBI 2, and Δ RSBI values also differed significantly between subjects with a fatal course and surviving individuals. According to the multivariate model, RSBI 2 > 105, Δ RSBI < 19, heart rate > 100, and increasing age were associated with in-hospital mortality.

CONCLUSIONS: RSBI can be a successful marker in predicting the failure of NIV and predicting in-hospital mortality in patients admitted to the ED with acute respiratory failure.