Electromagnetic Stimulation of the Phrenic Nerve of Intubated Patients

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.

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.

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

Conditions
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Muscle Weakness, General Anaesthesia

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 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, adipositas. 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

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 |
| --- | --- | --- |
| Tidal volume generated by electromagentical stimulation of the phrenic nerve (ml) | Mean tidal volume of 10 consecutively stimulations of the phrenic nerve | Study duration (approximately 10 minutes) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Tidal volume per breath | Tidal volume | Study duration (approximately 10 minutes) | 
| Max inspiratory flow after stimulation | The maximal air flow created in the duct following stimulation of the N. phrenicus (meter / second) | Study duration (approximately 10 minutes) | 
| Abdominal extension maximum | Extension of the abdomen measured via in abdominal belt | Study duration (approximately 10 minutes) | 
| Air pressure during each breath | Change in pressure in the duct from expiration to inspiration (mbar) | Study duration (approximately 10 minutes) | 
| Diaphragmatic thickening fraction | Diaphragmatic contractility measured by ultrasound after N. phrenicus stimulation | Study duration (approximately 10 minutes) | 
| Feedback/Stimulation locus relation | When the stimulation locus is changed according to protocol the change of the triggered breath is measured in % to the original location. | Study duration (approximately 10 minutes) | 
| Latency between stimulation and feedback | Time between start and end of the stimulation in seconds | Study duration (approximately 10 minutes) | 
| Intensity/Contractility relation | Correlation between the simulation intensity and the diaphragmatic contractility | Study duration (approximately 10 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 | Study duration (approximately 10 minutes) | 
| Distance between anatomical landmarks and optimal stimulation locus | Distance between anatomical landmarks and optimal stimulation locus | Study duration (approximately 10 minutes) | 
| Reproducibility of stimulation answer | Variation of stimulated tidal volumes and diaphragm contraction | Study duration (approximately 10 minutes) | 
| Incidence of Treatment-Emergent Adverse Events [Safety and Tolerability] | Adverse Events elicited by the electromagnetic stimulation | Study duration (approximately 10 minutes) | 

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