Abstract

This study investigated dyspnea intensity and respiratory muscles ultrasound early after extubation to predict extubation failure. It was conducted prospectively in two intensive care units in France and Canada. Patients intubated for at least 48 hours were studied within 2 hours after an extubation following a successful spontaneous breathing trial. Dyspnea was evaluated by the Dyspnea-Visual Analog Scale from 0 to 10 cm (VAS) and the Intensive Care - Respiratory Distress Observational Scale (range 0 – 10). The ultrasound thickening fraction of the parasternal intercostal and the diaphragm were measured; limb muscle strength was evaluated using the Medical Research Council score (MRC) (range 0 – 60). Extubation failure occurred in 21 of the 122 enrolled patients (17%). Dyspnea-VAS and Intensive Care - Respiratory Distress Observational scale were higher in patients with extubation failure vs. success: 7 (5 – 9) cm versus 3 (1 – 5) cm respectively (p<0.001) and 4.4 (2.5 – 6.5) versus 2.4 (2.1 – 2.8) respectively (p<0.001). The ratio of intercostal muscle to diaphragm thickening fraction was significantly higher and MRC was lower in patients with failure (0.9 [0.4 – 3.0] vs. 0.3 [0.2 – 0.5], p<0.001, and 45 [36 – 50] versus 52 [44 – 60], p=0.012). The thickening fraction of the intercostal and its ratio to diaphragm thickening showed the highest area under the receiver operating characteristic curves for an early prediction of extubation failure (0.81). Areas under the receiver operating characteristic curves of Dyspnea-VAS and Intensive Care - Respiratory Distress Observational scale reached 0.78 and 0.74 respectively. Respiratory muscle ultrasound and dyspnea measured within two hours after extubation predict subsequent extubation failure.