Electromagnetic Stimulation of the Phrenic Nerve of Intubated Patients With Obesity

Electromagnetic Stimulation of the Phrenic Nerve to Generate Contraction of the Diaphragm in Anesthetized and Intubated Patients With Obesity - a Proof-of-concept Study

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 leading to an inspiration with a sufficient tidal volume via an external electromagnetic stimulation of the phrenic nerve in obese patients.

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 leading to an inspiration with a sufficient tidal volume via an external electromagnetic stimulation of the phrenic nerve in obese patients

Inclusion Criteria:

• ≥ 18 years of age
• American Society of Anaesthesiologists Classification I or II
• Planned anesthesia with intubation
• Adipositas Grade II-III

Exclusion Criteria:

• Chronic lung disease
• Preexisting diaphragmatic weakness
• Neurologic disease with known motor weakness
• Paralysis of the phrenic nerve
• Contraindication for any movement in the cervical vertebrae
• Conditions that limit the movement of the diaphragm e.g. ascites, increased intraabdominal pressure.
• Inability to communicate in the official language
• Infections, lesions or stricture in the neck area
• Implanted cardiac devices e.g. pace maker, defibrillator, event recorder
• Implanted medical pumps e.g. left ventricular assist device
• Metal implants in the upper body
• Preganancy