Transcutaneous electrical phrenic nerve stimulation (TEPNS) and transcutaneous electrical diaphragm stimulation (TEDS) are modalities that use surface electrodes placed on the patients' skin to generate action potentials and contractions of the muscle fibers of the diaphragm. The primary objective will be to evaluate the efficacy of TEPNS and TEDS in healthy adult individuals. Secondary objectives will be to assess the feasibility, safety, and level of discomfort reported by the individual resulting from the application of TEPNS and TEDS.
Age between 18 and 60 years;
Normal pulmonary function test, without alterations, assessed through spirometry;
Body Mass Index (BMI) between 18.5 and 24.9 kg/m2.
Smokers or former smokers;
Individuals with previously known cardiopulmonary diseases (restrictive lung diseases, chronic obstructive pulmonary disease - COPD, asthma, cystic fibrosis, among other pathologies);
Presence of implanted electrical devices (pacemaker, implantable cardioverter-defibrillator, among others);
Individuals who have contraindications to undergo evaluation and/or application of transcutaneous electrical stimulation of the diaphragm muscle, such as: altered sensitivity, wounds at the site of application, deformities, among other conditions.
Crossover
Transcutaneous electrical phrenic nerve stimulation (TEPNS)
Other interventionThe characteristics of the electrical current: biphasic waves, set at a stimulation frequency of 10 Hz, pulse width of 200 μs, rise time of 1.0 second, on time of 1.0 second, fall time of 1.0 second, and off time of 2 seconds, resulting in 12 stimuli per minute. The application of "TEPNS" will initially be performed by defining the trajectory of the phrenic nerve in the cervical region. The negative pole (active point), a stick with a spherical tip for micro-current of 2 mm will be positioned with slight pressure in the region of the phrenic nerve pathway between the two heads of the sternocleidomastoid muscle. Additionally, at the positive pole (passive point), a self-adhesive electrode sized (2.0 x 2.0 cm) will be positioned on the skin in the shoulder region. The intensity, measured in milliamperes (mA), will be adjusted to the maximum tolerated by the patient. The total stimulation time will be 10 minutes, applied continuously in a single session.
Transcutaneous electrical diaphragm stimulation (TEDS)
Other interventionThe characteristics of the electrical current are: biphasic waves, set at a stimulation frequency of 30 Hz, pulse width of 400 μs, rise time of 1.0 second, on time of 1.0 second, fall time of 1.0 second, and off time of 2 seconds, resulting in 12 stimuli per minute. Two self-adhesive electrodes sized (5.0 x 5.0 cm) will be used, positioned in the bilateral parasternal region next to the xiphoid process and the other electrode in the intercostal space between the 6th and 7th ribs bilaterally, at the mid-axillary line. The intensity, measured in milliamperes (mA), will be adjusted to the maximum intensity tolerated by the patient until diaphragmatic contraction is observed with the naked eye, without contraction of other muscles in the abdominal region. The total stimulation time will be 10 minutes, applied continuously in a single session.
Diaphragm mobility
The assessment of diaphragmatic mobility will use a "convex" type transducer (2-6 MHz), positioned in the right subcostal space, at the midclavicular line, tilted in the cephalic direction. The B-mode visualization window will initially be used to locate the diaphragmatic hemi-dome. Upon acquiring a good quality image, respiratory excursions will be measured in M-mode, using the inferior vena cava and the gallbladder as anatomical parameters. Diaphragmatic mobility measurement will be considered as the distance, in centimeters, between the baseline at expiration and its greatest vertical displacement at inspiration produced by diaphragmatic movement.
Diaphragm thickness
Diaphragm thickness (Tdi) will be obtained using a high-frequency "linear" type transducer (7-13 MHz), positioned over the zone of apposition (ZA) of the diaphragm muscle. The approximate location is between the 8th and 9th intercostal space, between the anterior axillary line and the midaxillary line, 0.5 to 2.0 cm below the costophrenic angle. The depth will be 1.5 to 3.0 cm, and the diaphragm muscle will be identified as the innermost portion of the hypoechoic muscular layer bounded by two hyperechoic membranes, the pleura - superficial line, and the peritoneum - deeper line. "Tdi" will be measured from the inner edge of the pleural line to the inner edge of the peritoneal line at the end of expiration (Tdi-exp); and at the end of inspiration (Tdi-insp).
Thickening fraction
The thickening fraction will be obtained using a high-frequency "linear" type transducer (7-13 MHz), positioned over the zone of apposition (ZA) of the diaphragm muscle. The approximate location is between the 8th and 9th intercostal space, between the anterior axillary line and the midaxillary line, 0.5 to 2.0 cm below the costophrenic angle. The depth will be 1.5 to 3.0 cm, and the diaphragm muscle will be identified as the innermost portion of the hypoechoic muscular layer bounded by two hyperechoic membranes, the pleura - superficial line, and the peritoneum - deeper line. The localization of structures and measurements will be performed in B-mode. The diaphragm thickening fraction will be calculated as the percentage of thickness increment during inspiration relative to the thickness at the end of expiration.
Evaluation of sensory discomfort
The assessment of reported sensory discomfort will be measured through the application of the horizontal numerical scale of sensory discomfort. The numerical scale will be presented to participants in its printed version, on standardized paper measuring 10 centimeters in length. The value "0" (zero) will be assigned to the concept of "absence of discomfort," and the value "10" (ten) will be assigned to the concept of "greatest imaginable discomfort."
Safety of TEPNS and TEDS application
Safety criteria will be measured through the occurrence of the number of adverse events, including: Mean arterial pressure \< 65 mmHg; heart rate \> 140 bpm or \< 50 bpm; arrhythmias occurrence; oxygen saturation dropping below 88%; temperature increase (above 37.7°C); presence of reported pain above 7 on the visual analog pain scale; presence of burns at the site where electrodes were placed for electrostimulation. The numbers of adverse events will be recorded, along with their classification according to the World Health Organization Patient Safety Document as follows: no harm, minor, moderate, severe, and death.
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Hospital Sirio-Libanes
Lead sponsor
Hospital Israelita Albert Einstein
Collaborator
