The scientific study is intended to show that external non-invasive electromagnetic stimulation can be used to safely and effectively stimulate the phrenic nerve in awake healthy subjects as well as in ventilated, anesthetized patients and that the stimulation can generate a diaphragmatic contraction that generates significant breath volume - a Controlled Own Breath (COB). Also of interest is the reproducibility of the generated diaphragmatic movements and the reliability of different feedback signals for detecting the generated diaphragmatic contraction. This applies to inspiration and expiration detection for subsequent synchronization mechanisms of the magnetic stimulator for patient-initiated breathing as well as to contraction intensity. Further, the characterization of the position finding process is of great importance, so that technical developments can further simplify the process of coil positioning in the future. The possible occurrence of discomfort and pain sensation will also be investigated in awake healthy volunteers. Different stimulation protocols will be used. Finally, it will be investigated whether an adjusted coil position still triggers reproducible diaphragmatic contractions after removal and repositioning in the same configuration. The knowledge gained will be used to further develop the technique and to prepare a study in critically ill, ventilated patients where the diaphragmatic muscle is to be treated preventively by stimulating the phrenic nerve, in order to prevent atrophy of the muscle.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
OTHER
Masking
NONE
Enrollment
10
The Stimit Activator Device is composed of three components. 1. A magnetic stimulator generating current pulses 2. A novel Stimit coil design optimized for phrenic nerve stimulation 3. A coil positioning device for quick, easy and reproducible coil positioning
Swiss Paraplegic centre
Nottwil, Switzerland
Change in airway pressure / endpoint Group 1:
The primary outcome / endpoint is the change in airway pressure at the mouth during stimulation as seen with or without the use of the ventilator
Time frame: During stimulation
Discomfort / pain during stimulation measured by Visual Analogue Scale / endpoint Group 1:
The primary outcome / endpoint is the level of discomfort / pain during stimulation, measured by Visual Analogue Scale(0-100, with 100 being worst pain / discomfort)
Time frame: During stimulation
Change in airway pressure / endpoint Group 2:
The primary outcome / endpoint is the change in airway pressure during stimulation as seen with or without the use of the ventilator during stimulation.
Time frame: During stimulation
Diaphragmatic contraction
Diaphragmatic contraction at 20 percent / 30 percent / 40 percent stimulation intensity at the optimal stimulation site, at 25 Hz and 2s stimulation time
Time frame: During stimulation
Feedback signals
Change of the maximum value of the feedback signals in percent of the maximum depending on the coil position (in 0.5 cm steps; at least 3 steps in each direction)
Time frame: During stimulation
Time stimulation start to end
Time (mean value \& standard deviation) between stimulation start and stimulation end (trigger signal start and end) until the feedback signals from: * the abdominal belt, * the Diaphragm Thickening Fraction ((TFdi) according to standard procedure, measured via ultrasound during stimulation), and * the Diaphragm Excursion Signal "respons" (measured by ultrasound during stimulation)
Time frame: During stimulation
Correlation stimulation intensity and diaphragm contraction
Correlation between stimulation intensity (power output in percent) and diaphragm contraction, measured by tidal volume, at the optimal coil position at given frequency (25 Hz) and given stimulation duration
Time frame: During stimulation
Optimal stimulation site - distance
Distance from anatomical landmark (a) to optimal stimulation site (b) and phrenic nerve (c) using ultrasound and between b and c
Time frame: During stimulation
Optimal stimulation site - time
Time from the start of coil positioning to finding a coil positioning which produces the maximum diaphragmatic contraction at a given stimulation intensity and frequency of 25 Hz
Time frame: During stimulation
Tidal volumes
The mean and standard deviation of generated tidal volumes for ten stimulations performed without the subject being ventilated
Time frame: During stimulation
Skin reactions / musle activation
For Group 1: evaluation of stimulation-induced local skin reactions or muscle activation leading to paresthesia in the dental area
Time frame: During stimulation
Safety outcome
The safety outcome/ endpoint is the occurrence of the following events during stimulation: * Device related Adverse Events * Device related Serious Adverse Events
Time frame: During stimulation and postoperatively, usually within 2-3 hours
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