Breath Synchronized Abdominal Muscle Stimulation to Facilitate Ventilator Weaning: a Pilot Study

Study Overview
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Brief Summary
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The primary objective of this study is to determine whether neuromuscular electrical stimulation applied to the abdominal wall muscles in synchrony with exhalation can increase the strength of the respiratory muscles in prolonged mechanical ventilation patients.

Detailed Description
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In the U.S. over 500,000 patients have difficulty weaning from mechanical ventilation every year. These patients cost the health care system $16 billion annually and have an increased risk of medical complications and morbidity. A major factor responsible for weaning failure is the imbalance between decreased respiratory muscle strength and excessive respiratory load. This study includes an investigational device that applies electrical stimulation to the abdominal muscles in synchrony with exhalation. This is hypothesized to improve the strength of the respiratory muscles. The long term goal of this project is to determine whether this approach can reduce the number of days taken for patients to wean from mechanical ventilation.

Official Title
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Breath Synchronized Abdominal Muscle Stimulation to Facilitate Ventilator Weaning: a Pilot

Conditions
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Electric Stimulation, Respiration, Artificial, Ventilator Weaning

Intervention / Treatment
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* Device: Breath synchronized abdominal NMES
* Device: Sham breath synchronized abdominal NMES


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients who have been mechanically ventilated for at least fourteen days. Clinically stable: oxygen saturation > 90% with a fractional inspired oxygen ≤ 0.40, external positive end expiratory pressure ≤ 5 centimeters water, temperature ranging from 35.5 to 38.5 degrees celsius, no intravenous administration of vasoactive agents. Exclusion Criteria: Patients in whom Neuromuscular Electrical Stimulation (NMES) does not elicit a palpable contraction of the abdominal muscles. Patients with broken or irritated skin on the abdominal wall Patients with a history of neuromuscular disease Body Mass Index (BMI) > 35 kg/m2 Patients who are not medically stable Patients with a pacemaker Female patients who are pregnant Patients under the age of 18 Patients who are expected to die within four weeks Patients who are unable to follow verbal instructions Patients with epilepsy Patients with an abdominal wall hernia Patients with anoxic encephalopathy Patients with history of, or active, substance abuse

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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: VentFree Stimulation<br>Breath synchronized abdominal NMES | Device: Breath synchronized abdominal NMES<br>* VentFree prototype (VF03) that delivers electrical stimulation pulses to the abdominal muscles during exhalation with a frequency of 30 Hz, a pulse width of 350 µs and 90% of the maximum current that the participant can tolerate. These stimulation parameters were selected to cause a tetanic (continuous) contraction of the abdominal muscles, without pain for the patient. Stimulation will be administered for 30 minutes 2 times per day, 5 days per week, for 6 weeks; or until the patient is weaned from mechanical ventilation.<br>* Other names: VentFree;|
| Sham Comparator: Sham Stimulation<br>Sham breath synchronized abdominal NMES | Device: Sham breath synchronized abdominal NMES<br>* Modified VentFree prototype (VF03) that delivers stimulation pulses to the abdominal muscles during exhalation with a frequency of 10 Hz, a pulse width of 100 µs and current set to 10 milliamp. These stimulation parameters were chosen to cause a twitch contraction of the abdominal wall muscles. Stimulation will be administered for 30 minutes, 2 times per day, 5 days per week, for 6 weeks; or until the patient is weaned from mechanical ventilation.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Maximum Expiratory Pressure From Baseline to Extubation | Maximum expiratory pressure was measured from total lung capacity | Change from baseline to first extubation, an expected average of 4 weeks | 
| Change in Maximum Inspiratory Pressure From Baseline to Extubation | Maximum inspiratory pressure was measured from end expiratory lung volume. | Change from baseline to first extubation, an expected average of 4 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Thickness of the Transverse Abdominis Muscle From Baseline to Extubation | Thickness of transverse abdominis muscle as measured by ultrasound | Change from baseline to first extubation, an expected average of 4 weeks | 
| Change in Thickness of the External Oblique Muscle From Baseline to Extubation | Thickness of the external oblique muscle as measured by ultrasound | Change from baseline to first extubation, an expected average of 4 weeks | 
| Change in Thickness of the Internal Oblique Muscle From Baseline to Extubation | Thickness of the internal oblique muscle as measured by ultrasound | Change from baseline to first extubation, an expected average of 4 weeks | 
| Thickness of the Rectus Abdominis Muscle | Thickness of the rectus abdominis muscle as measured by ultrasound | Change from baseline to first extubation, an expected average of 4 weeks | 
| Thickness of the Diaphragm | Thickness of the diaphragm as measured by ultrasound | Change from baseline to first extubation, an expected average of 4 weeks | 
| Weaning Success | Defined as free from ventilator support for more than 72 hours | The earlier of 6 weeks or first extubation, an expected average of 4 weeks | 
| Number of Days Taken to Wean |  | The earlier of 6 weeks or first extubation, an expected average of 4 weeks | 
| Change in Cough Peak Flow From Baseline to Extubation | Cough peak flow was measured from total lung capacity | Change from baseline to first extubation, an expected average of 4 weeks | 
| Change in Spontaneous Tidal Volume From Baseline to Final Visit or First Extubation |  | Change from baseline to final study visit or first extubation, an expected average of 4 weeks | 
| Change in Spontaneous Respiratory Rate From Baseline to Final Study Visit |  | Change from baseline to final study visit, an expected average of 4 weeks | 
| Change in Spontaneous Minute Ventilation From Baseline to Final Study Visit |  | Change from baseline to final study visit, an expected average of 4 weeks | 
| Maximum Sensation of Stimulation Experienced by Patient | Measured using the behavioral pain scale | Through study completion, an expected average of 4 weeks | 
| Number of Adverse Events That Are Related to Treatment | This includes any adverse event that was graded as having a possible, probable or definite relationship to the study intervention. | Though study completion, an expected average of 4 weeks |