Assessment of Human Diaphragm Strength by Magnetic and Electric Stimulation After Ultrasonography Phrenic Nerve Tracking

In intensive care unit, various forms of sepsis, undernutrition, surgery, global inflammation, iatrogeny, and mechanical ventilation, contribute to the overall muscular involvement including the diaphragm.

Assessment of diaphragm dysfunction is a critical issue for patients under mechanical ventilation, providing prognosis information and leading to the best therapeutic choices.

Up to now, for sedated ventilated critical care patient, expensive magnetic phrenic nerve stimulation equipment is needed to evaluate diaphragm strength.

In this study, the investigators aim to develop an affordable easy-to-use phrenic nerve stimulation tool, with ultrasonography and a nerve stimulator usually used for neuromuscular transmission monitoring. Hypothesis is that phrenic pacing using this new method is equivalent to the Gold Standard.

Inclusion criteria

• ICU patient with invasive mechanical ventilation
• Sedated patient with a Richmond Agitation-Sedation Scale of -4 or -5

Exclusion criteria

• Contraindication for magnetic stimulation (Pacemaker)
• Hemodynamic or respiratory instability : PaO2/FiO2 < 200 mmHg, noradrenaline > 0,3 µg/kg/min, dobutamine > 10 µg/kg/min
• Neuromuscular disease or recent use of neuromuscular blocking agents (2h30) with a TOF ratio below 4/4 95%.
• Refusal of study participation or to pursue the study by the patient, no consent
• Pregnancy or breastfeeding
• Absence of coverage by the French statutory healthcare insurance system