Non-invasive phrenic nerve stimulation to avoid ventilator-induced diaphragm dysfunction in critical care

Area of Science:

• Biomedical Engineering
• Respiratory Physiology
• Neuromuscular Electrical Stimulation

Background:

• Diaphragm muscle atrophy occurs rapidly within 24 hours of mechanical ventilation, leading to adverse clinical outcomes.
• Invasive phrenic nerve stimulation shows potential for maintaining diaphragm function but has limitations.
• Non-invasive stimulation presents a valuable alternative to overcome the risks and complexities of invasive methods.

Purpose of the Study:

• To investigate the feasibility of non-invasive electrical stimulation of the phrenic nerve.
• To characterize stimulation parameters for inducing diaphragm contractions.
• To assess the efficacy of non-invasive stimulation in healthy volunteers.

Main Methods:

• Non-invasive electrical stimulation applied to the phrenic nerve in healthy volunteers.
• Systematic variation of electrode positions and stimulation parameters.
• Assessment of diaphragmatic response using respiratory measurements, electromyography, mechanomyography, and ultrasound.

Main Results:

• Feasible non-invasive phrenic nerve capture using surface electrodes was demonstrated.
• Optimal electrode positions were identified and characterized.
• Stimulation parameters were defined to reliably produce diaphragm contractions exceeding 600ml inspired volume.

Conclusions:

• Non-invasive phrenic nerve stimulation is a viable method for inducing diaphragm contractions.
• This approach offers potential for developing systems to maintain diaphragm function in intensive care.
• Minimal specialist skills are required for setup, facilitating wider application.