The aims of the current study are as follows:

i) Investigate the relationships between indices derived from ultrafast ultrasound imaging and Pditw, ii) Investigate the relationships between indices derived from ultrafast ultrasound imaging and diaphragm EMG, iii) Investigate the performance of ultrafast ultrasound for the diagnosis of diaphragm dysfunction, iv) Investigate the ability of ultrafast ultrasound imaging to decipher the cause of diaphragm dysfunction i.e. contractility alteration and/or phrenic nerves conduction defect.

The Neuromuscular Physiology and Evaluation Laboratory of the Institute of Myology recently reported that artificially stimulated diaphragm contraction may be captured and quantified using ultrafast ultrasound imaging. By filming the diaphragm at very high frame rate, one may extract ultrasound indices such as diaphragm thickening fraction and diaphragm tissue velocity. The same team showed that these indices, in particular, maximal diaphragm tissue velocity were strongly reliable and related to Pditw in healthy subjects. This approach bridges the gap between non-volitional (that are commonly combined with internal pressure measurements) and non-invasive procedures. Whether the relationships between indices derived from ultrafast ultrasound and Pditw exist in patients presenting with actual or suspicion of diaphragm dysfunction remains to be specifically investigated. Similarly, the potential of this approach for the diagnosis of phrenic conduction abnormalities remains to be assessed as it may help to circumvent confounding factors associated with surface EMG.

Inclusion Criteria:

• > 18 years old
• Patients with confirmed diaphragm dysfunction or suspicion
• Written informed consent
• Able to comply with all protocol requirements
• Affiliate or beneficiary of a social security scheme

Exclusion Criteria:

• Known allergy to latex
• Known allergy to Lidocaine or similar product
• Pacemaker
• Guardianship/trusteeship
• Pregnant or nursing women