Could a gentle zap on the face help COPD patients breathe easier?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Arm1 - Healthy Volunteers Inclusion Criteria: * Adults aged 18-50 years * BMI 18-30 kg/m² * Ability to provide informed consent and complete study procedures in English Exclusion Criteria: * Current daytime respiratory impairment such as uncontrolled asthma, uncontrolled COPD, pneumonia, or interstitial lung disease * Use of supplemental oxygen * Pregnancy or breastfeeding * Current use of acetazolamide, Sodium-glucose cotransporter-2 (SGLT2) inhibitors, or daily opioids * History of claustrophobia or panic disorder * Metallic implants in the craniofacial or cervical region that may interfere with electrode placement or electrical stimulation * Implanted cardiac or neuroelectric device (e.g., pacemaker, implantable cardioverter-defibrillator (ICD), deep brain stimulator, vagus nerve stimulator, implanted drug pump) * Open, broken, inflamed, infected, or healing skin lesions at or near facial electrode placement sites * Resting heart rate \<60 Beats Per Minute * History of seizure disorder or epilepsy Arm 2 -COPD Inclusion Criteria: * Adults aged 40-75 years * Confirmed diagnosis of COPD by spirometry (post-bronchodilator Forced Expiratory Volume (FEV1) /Forced Vital Capacity (FVC) \<0.70) or provider documentation in medical records * Modified Medical Research Council (mMRC) dyspnea grade ≥2 * Stable COPD (no exacerbation requiring hospitalization, systemic corticosteroids, or antibiotic therapy within the preceding 6 weeks) * On stable COPD therapy for at least 4 weeks prior to enrollment * Ability to provide informed consent and complete questionnaires in English * Resting Peripheral Capillary Oxygen Saturation (SpO₂) ≥88% on room air or prescribed supplemental oxygen Exclusion Criteria: * Unstable cardiovascular disease (e.g., unstable angina, decompensated heart failure, recent MI within 6 months, uncontrolled arrhythmia) or peripheral vascular disease * Patients with cardiovascular disease, including chest pain, heart failure, and aortic stenosis * Resting heart rate \<60 BPM * Implanted cardiac or neuroelectric device (e.g., pacemaker, ICD, deep brain stimulator, vagus nerve stimulator, implanted drug pump) * Metallic implants in the craniofacial or cervical region that may interfere with electrode placement or stimulation * Open, broken, inflamed, infected, or healing skin lesions at or near facial electrode placement sites * Active trigeminal neuralgia or other cranial neuropathy * History of seizure disorder or epilepsy * Severe or uncontrolled psychiatric disorder (e.g., psychosis, severe untreated anxiety or panic disorder) that would impair the ability to participate * Pregnancy or breastfeeding * COPD exacerbation requiring hospitalization, systemic corticosteroids, or antibiotics within the preceding 3 months * Musculoskeletal pain, injury, or any other condition that precludes the use of a stationary bike for Cardiopulmonary Exercise Test (CPET) * Any condition that, in the opinion of the investigator, would compromise participant safety or data integrity