Electromagnetic Stimulation of the Phrenic Nerve in Critically Ill Mechanically Ventilated Patients (STIMIT-II)

Electromagnetic Stimulation of the Phrenic Nerve to Generate Contraction of the Diaphragm in Critically Ill Mechanically Ventilated Patients - a Proof-of-concept Study (STIMIT-II)

Ventilator-induced diaphragmatic dysfunction is a common issue in critically ill patients. Muscle stimulation has shown to have beneficial effects in muscle groups on the extremities. A non-invasive way to stimulate the diaphragm would be the electromagnetic stimulation but it is currently unclear if that is feasible.

In this proof-of-concept trial the primary aim is to show that it is possible to induce a diaphragmatic contraction in critically ill ICU patients via an external electromagnetic stimulation of the phrenic nerve, leading to an inspiration (i) with a sufficient tidal volume (3-6 ml/kg ideal body weight) and (ii) with verifiable muscular diaphragmatic contraction through ultrasound imaging.

During the time of first spontaneous breathing trial 60% of mechanically ventilated patients present with diaphragmatic weakness or also know as ventilator-induced diaphragmatic dysfunction (VIDD). The damage to the diaphragm in terms of muscle atrophy has been shown as early as 12 hours after initiation of mechanical ventilation. Recently, a correlation between diaphragmatic atrophy and mortality could be established.

Induction of diaphragmatic contractions via stimulation of the phrenic nerve would be a possible method to prevent or treat VIDD. A possible modality would be the non-invasive electromagnetic stimulation but feasibility has not been established.

In this proof-of-concept trial the primary aim is to show that it is possible to induce a diaphragmatic contraction in critically ill ICU patients via an external electromagnetic stimulation of the phrenic nerve, leading to an inspiration (i) with a sufficient tidal volume (3-6 ml/kg ideal body weight) and (ii) with verifiable muscular diaphragmatic contraction through ultrasound imaging.

Inclusion Criteria:

• Patients between 18 and 60 years old, hospitalized in ICU
• Mechanical ventilation < 36 h
• Prone to stay ventilated > 72 h

Exclusion Criteria:

• Known neurological condition affecting motor neuron or muscle (e.g. ALS)
• Known paralysis of the phrenic nerve
• Proven or suspected spinal cord injury that contraindicates weight bearing on the spinal cord
• Conditions that limit diaphragm movement (high intra-abdominal pressure, ascites, obesity)
• Not able to read and understand the national language German
• Patients with Implanted cardiac support systems (pacemaker, implanted defibrillator)
• Patients with implanted medical pumps
• Pregnant patients
• Patients with skin lesions, infections or strictures in throat/neck area
• Patients with metallic implants