Sonometric assessment of cough predicts extubation failure. SonoWean: a proof-of-concept study

Background: Extubation failure is associated with increased mortality. Cough ineffectiveness may be associated with extubation failure but its quantification for patients undergoing weaning from invasive mechanical ventilation (IMV) remains challenging. Methods: patients under IMV for more than 24 hours completing a successful spontaneous T-tube breathing trial (SBT) were included. At the end of the SBT, we performed quantitative sonometric assessment of three successive coughing efforts using a sonometer. The mean of the 3-cough volume in decibels was named Sonoscore. Results: During a 1-year period, 106 patients were included. Median age was 65 [51–75] years, mainly men (60%). Main reasons for IMV were acute respiratory failure (43%), coma (25%) and shock (17%). Median duration of IMV at enrollment was 4 [3–7] days. Extubation failure occurred in 15 (14%) patients. Baseline characteristics were similar between success and failure extubation groups, except percentage of simple weaning which was lower and MV duration which was longer in extubation failure patients. Sonoscore was significantly lower in patients who failed extubation (58 [52–64] vs. 75 [70–78] dB, P  < 0.001). After adjustment on MV duration and comorbidities, Sonoscore remained associated with extubation failure. Sonoscore was predictive of extubation failure with an area under the ROC curve of 0.91 (IC 95% [0.83–0.99], P  < 0.001). A threshold of Sonoscore < 67.1 dB predicted extubation failure with a sensitivity of 0.93 IC 95% [0.70–0.99] and a specificity of 0.82 IC 95% [0.73–0.90]. Conclusion: Sonometric assessment of cough strength might be helpful to identify patients at risk of extubation failure in patients undergoing IMV.