Regional Flow Index may predict weaning outcomes in patients under prolonged mechanical ventilation

Abstract Background Regional flow index based on electrical impedance tomography (EIT) may estimate patients' regional inspiratory efforts. The aim of the study was to explore its value in predicting weaning outcomes. Method A total of 26 patients with prolonged mechanical ventilation were analyzed retrospectively. They received spontaneous breathing trials (SBT) in automatic tube compensation (ATC) mode for two hours. The global flow index was calculated by fitting the airway flow and time waveform. Regional flow index was calculated by substituting the airway flow with the derivative of regional impedance measured with EIT. Receiver operating characteristic curve analyses were performed to evaluate the predictive effectiveness of the EIT-based regional flow index. Results Weaning was successful in 19 patients but failed in 7. The global flow index calculated with EIT-based impedance and ventilator-recorded airway flow was significantly correlated (r = 0.436, P = 0.024). The regional flow index of the dorsal region group (1.97 ± 1.55) is higher than that of the ventral region (1.21 ± 1.30) at the end of the first hour during ATC (P = 0.01). The dorsal flow index at the beginning of SBT was greater in patients who were successfully weaned (P = 0.02). The area under the curve of this parameter was 0.797, and the sensitivity and specificity for predicting weaning success were 73.7% and 85.7%, respectively. Conclusion The dorsal flow index may assess the patient’s respiratory efforts during SBT. The EIT-based regional flow index may be used to predict the success of weaning.