Controlled twitch mouth pressure reliably predicts twitch esophageal pressure.

The present study hypothesized that twitch mouth pressure (TwPmo) can reliably predict intrathoracic pressure swings reflected by twitch esophageal pressure (TwPes) using a controlled and automated trigger technique. TwPmo, TwPes, and transdiaphragmatic pressure (TwPdi) following bilateral anterior magnetic phrenic nerve stimulation were measured in 21 healthy subjects using an inspiratory pressure trigger (0.5kPa, experiment 1), an expiratory pressure trigger (0.5kPa, experiment 2), an inspiratory flow trigger (40ml/s, experiment 3), and no trigger at relaxed functional residual capacity (experiment 4). TwPmo and TwPes were correlated as follows: r=0.99, p<0.0001 (experiment 1); r=0.67, p=0.001 (experiment 2); r=0.96, p<0.0001 (experiment 3); no correlation (experiment 4). Bland and Altman analysis revealed most narrow limits of agreement for TwPmo and TwPes in experiment 1: bias (range) 0.15kPa (-0.03 to 0.32). TwPmo is an excellent predictor for TwPes when using a fully automated and controlled inspiratory pressure trigger. Thus, measurement of TwPmo could become a standard means assessing inspiratory muscle strength.