Objective:To analyze the effect of transtracheal pressure (TTP) on the application of a speaking valve in critically ill patients after tracheostomy.Methods:A retrospective analysis was conducted of 50 patients wearing a speaking valve after tracheostomy. Patients who had been wearing a speaking valve for 30min or more were the tolerance group, while those with less than 30min were the intolerance group. Transtracheal pressure was monitored during resting breathing, forced expiration and speaking. Linear regression models were evaluated to isolate the factors best predicting tolerance. The changes in respiratory muscle contraction before and after wearing a speaking valvs were evaluated using ultrasound. The patients′ satisfaction with wearing a speaking valve was also recorded.Results:TTP during speaking significantly predicted tolerance. The baseline values of diaphragmatic thickening fraction and physical functioning also positively predicted tolerance. Acute physiology and chronic health (APACHE II) score was a significant negative predictor. After wearing the speaking valve, the average contraction of the rectus abdominis, external oblique, internal oblique and transverse abdominis muscles increased significantly. Both groups expressed high satisfaction with the speaking valves.Conclusions:Transtracheal pressure during speaking can help predict the tolerance for wearing a speaking valve among critically ill patients after a tracheostomy. Baseline diaphragmatic thickening fraction, physical functioning and APACHE II score can predict the duration of speaking valve tolerance.