Electromagnetic Stimulation of the Phrenic Nerve of Intubated Patients With Obesity (STIMIT-IA)

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

When the stimulation locus is changed according to protocol the change of the triggered tidal volume is measured in % to the original location

Time between first successful N. phrenicus stimulation and identification of the optimal stimulation locus in seconds

Variation of stimulated tidal volumes and diaphragm contraction using mean and standard deviation of each stimulation intensity

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