Electromagnetic Stimulation of the Phrenic Nerve of Intubated Patients With Obesity

Study Overview
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Brief Summary
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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.

Detailed Description
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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

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

Conditions
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General Anaesthesia, Muscle Weakness

Intervention / Treatment
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* Device: Electromagnetic stimulation


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Electromagnetic stimulation<br>Electromagnetic stimulation of the phrenic nerve. | Device: Electromagnetic stimulation<br>* Electromagnetic stimulation of the phrenic nerve<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 1.Tidal volume generated by electromagentical stimulation of the phrenic nerve (ml) | Mean tidal volume of 10 consecutively stimulations of the phrenic nerve | approximately 15 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Max inspiratory flow after stimulation | The maximal air flow created in the duct following stimulation of the N. phrenicus (meter / second) | approximately 15 minutes | 
| Abdominal extension maximum | Extension of the abdomen in centimeter measured via abdominal belt | approximately 15 minutes | 
| Air pressure during each breath | Change in pressure in the duct from expiration to inspiration (mbar) | approximately 15 minutes | 
| Diaphragmatic thickening fraction | Diaphragmatic contractility measured by ultrasound after N. phrenicus stimulation | approximately 15 minutes | 
| Feedback/Stimulation locus relation | When the stimulation locus is changed according to protocol the change of the triggered tidal volume is measured in % to the original location | approximately 15 minutes | 
| Latency between stimulation and feedback | Time between start and end of the stimulation in seconds | approximately 15 minutes | 
| Intensity/Contractility relation | Correlation between the simulation intensity and the diaphragmatic contractility | approximately 15 minutes | 
| Time to find the optimal stimulation point of the N. phrenicus | Time between first successful N. phrenicus stimulation and identification of the optimal stimulation locus in seconds | approximately 15 minutes | 
| Distance between anatomical landmarks and optimal stimulation locus | Distance between anatomical landmarks and optimal stimulation locus | approximately 15 minutes | 
| Reproducibility of stimulation answer | Variation of stimulated tidal volumes and diaphragm contraction using mean and standard deviation of each stimulation intensity | approximately 15 minutes | 
| Incidence of Adverse Events during stimulation | Adverse Events elicited by the electromagnetic stimulation | approximately 15 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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VIDD, ICUAW, muscle weakness