The predictive value of ultrasonic measurement of the diaphragmatic thickening fraction combined with the maximal inspiratory pressure in mechanical ventilation patients

Abstract

Objective: To evaluate the value of the diaphragmatic thickening fraction (DTF) combined with the maximum inspiratory pressure (MIP) for the prediction of weaning success in mechanically ventilated patients. Methods: Patients admitted to the intensive care unit (ICU) of Yijishan Hospital of Wannan Medical College and on mechanical ventilation for 24 hours from June 2018 to April 2019 were selected as the study subjects. A low-level pressure support ventilation (PSV) method was applied to conduct a spontaneous breathing test (SBT) for 30 minutes after the patients met the screening conditions for clinical weaning; and the patients were weaned when they met the clinical weaning criteria. Before weaning, the patient's MIP was measured. The right hemidiaphragmatic excursion (DE) and the thickness of the diaphragm at the end of inspiration and at the end of exhalation were measured by ultrasound, and the DTF was calculated. The statistical relationship between the DTF, DE and MIP was analyzed. The predictive value for the success of weaning was calculated with the DTF, DE and MIP and was evaluated by the area under the receiver operating characteristic curve (AUC). Results: A total of 73 patients were included in this study, including 57 patients who were successfully weaned, and 16 patients who experienced failure. The DTF of the successful weaning group (35%, 8%) was significantly higher than that of the failed weaning group (25%±5%), and the difference was statistically significant (t=6.401, P<0.01). The MIP (34±9 cmH(2)O) in the successful weaning group was significantly higher than that in the failed weaning group (23±3 cmH(2)O), and the difference was statistically significant (t=7.186, P<0.01). The ROCs for the DTF, MIP, and diaphragmatic displacement were 0.907, 0.896, and 0.749, respectively. A DTF ≥ 27.78%, with a sensitivity of 92.98%, a specificity of 81.25%, and an AUC of 0.907 (95% CI: 0.816-0.963), was used as the standard to predict the success of weaning. An MIP>26.5 cmH(2)O, with a sensitivity of 80.7%, a specificity of 93.75%, and an AUC of 0.896 (95% CI: 0.803-0.955), was used as the standard to predict the success of weaning. The AUC of DTF ≥ 27.78% and MIP ≥ 26.5 cmH(2)O was 0.920 (95% CI:0.832-0.971), and the specificity increased to 87.7%, but the sensitivity was slightly reduced to 87.5%. Conclusions: The DTF and MIP play a crucial role in determining the appropriate time and predicting the outcome of weaning of mechanical ventilation patients. Compared with the DTF and MIP alone, the DTF combined with MIP greatly improved the accuracy of predicting successful weaning.