Abstract

Background: Twitch transdiaphragmatic pressure (twPdi) following magnetic stimulation (MS) of the phrenic nerves is the gold standard for non-volitional assessment of diaphragm strength. Expiratory muscle function can be investigated using MS of the abdominal muscles and measurement of twitch gastric pressure (twPgas). Objectives: To investigate whether twitch pressures following MS of the phrenic and lower thoracic nerve roots can be predicted noninvasively by diaphragm ultrasound parameters and volitional tests of respiratory muscle strength. Methods: Sixty-three healthy subjects underwent standard spirometry, measurement of maximum inspiratory (PI<sub>max</sub>) and expiratory pressure (PE<sub>max</sub>), and diaphragm ultrasound. TwPdi following cervical MS of the phrenic nerve roots and twPgas after lower thoracic MS (twPgas-Thor) were measured using esophageal and gastric balloon catheters inserted transnasally. Using surface electrodes, compound muscle action potentials (CMAP) were simultaneously recorded from the diaphragm or obliquus abdominis muscles, respectively. Results: Forced expiratory flow (FEF<sub>25–75</sub>) was significantly correlated with twPdi (r = 0.37; p = 0.003) and its components (twPgas and twitch esophageal pressure, twPes). Diaphragm excursion velocity during tidal breathing was correlated to twPes (r = 0.44; p = 0.02). No prediction of twitch pressures was possible from CMAP amplitude, forced vital capacity (FVC), or PI<sub>max</sub>. TwPgas-Thor was correlated with FEF<sub>25–75</sub> (r = 0.46; p = 0.05) and diaphragm thickness at total lung capacity (r = 0.38; p = 0.04) but could not be predicted from CMAP amplitude, FVC, or PE<sub>max</sub>. Conclusions: TwPdi and twPgas-Thor cannot be predicted from volitional measures of respiratory muscle strength, diaphragm and abdominal CMAP, or diaphragm ultrasound. Invasive recording of esophageal and gastric pressures following MS remains indispensable for objective assessment of respiratory muscle strength.

Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.