The ratio of respiratory rate to diaphragm thickening fraction for predicting extubation success

BACKGROUND: Several parameters are used to predict successful extubation but their accuracy varies among studies. We hypothesized that combining conventional and diaphragmatic parameters would be more effective than using just one. Our primary objective was to evaluate the performance of the respiratory rate in relation to the diaphragm thickening fraction (RR/DTF) ratio to predict the success of extubation. METHODS: We enrolled 130 adult patients who required invasive mechanical ventilation, planned to be extubated, and used a spontaneous breathing trial (SBT) in the intensive care unit from July 2020 to April 2022. We measured the conventional parameters and the diaphragmatic parameters 2 h after SBT. The RR/DTF was calculated by dividing the respiratory rate (RR) by the diaphragm thickening fraction (DTF). The definition of weaning success is successful extubation within 48 h. RESULTS: Of 130 patients, 8 patients (6.2%) were reintubated within 48 h. The RR/DTF was significantly lower in the successful extubation group than in the extubation failure group (right hemidiaphragm; 0.47 (0.33–0.64) vs 1.1 (0.6–2.32), p < 0.001 and left hemidiaphragm; 0.45 (0.31–0.65) vs 0.78 (0.48–1.75), p < 0.001). The right RR/DTF using a cut-off point at ≤ 0.81 had a sensitivity of 87.7%, a specificity of 75%, and areas under the receiver operating characteristic curve (AUROC) of 0.762 for predicting successful extubation (p = 0.013). The sensitivity, specificity, and AUROC for predicting extubation success of right DTF at a cut-off point of ≥ 26.2% were 84.3%, 62.5%, and 0.775, respectively (p = 0.009). CONCLUSION: The RR/DTF ratio is a promising tool for predicting extubation outcome. Additionally, using RR/DTF was more reliable than conventional or diaphragmatic parameters alone in predicting extubation success. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12890-023-02392-w.