Heart Rate Variability (HRV)

High-flow nasal cannula is a type of non-invasive respiratory support that helps patients breathe more comfortably. Because the flow is high, it can deliver more oxygen to the lungs and make breathing easier by reducing the effort needed to breathe. However, the best strategy to determine the best oxygen flow rate remains uncertain. Reducing flow rates prematurely can increase work of breathing and prolong ICU stay, while unnecessary prolongation can increase costs. Currently, evidence to guide titration is limited. Heart rate variability is the natural variation in the time between each heartbeat. Heart rate variability reflects the level of autonomic nervous system activity in response to stress. The autonomic nervous system is the part of the nervous system that automatically controls how heart rate speeds up and slows down. When heart rate variability is higher, it indicates that the system is able to adjust to changes in the body, including stress. However, when heart rate variability is low, it indicates that the system is constrained and in a state of stress. The VARIATION study is designed to characterize how heart rate variability goal of this observational study is to learn whether heart rate variability can serve as a marker of the appropriateness of high flow nasal cannula flow support during flow titration in patients with respiratory failure. The main question it aims to answer is: Does heart rate variability change before other conventional respiratory signs when there are changes in respiratory function due to inadequate flow rate? Participants already on high flow nasal cannula as part of their regular medical care will: 1. Undergo a stepwise decrease in high flow nasal cannula flow rate. 2. Be recorded continuously with electrocardiogram and electrical impedance tomography.

The goal of this randomized crossover trial is to compare the differences in psychological and physiological effects of walking in two different outdoor environments (urban/suburban commercial environments vs. urban/suburban nature areas/preserves) in adults with prediabetes. The main questions it aims to answer are: * Do psychological measures of stress, anxiety, and affect improve more in one type of outdoor environment over the other? * Do physiological measures of stress improve more in one type of outdoor environment over the other? As this is a crossover trial, participants will serve as their own controls. Researchers will compare both the psychological and physiological effects walking in the two types of outdoor environments. Participants will: * Walk 150-minutes per week for six weeks in each of the two outdoor conditions. * Visit the clinic four times, including before and after each six-week walking period. * Collect saliva samples immediately proceeding or following the four clinic visits. * Return to their pre-study level of physical activity for a 5-week washout period between each of the two walking interventions.

This is a randomized, controlled study. ACS follow- up patients aged 18 to 80 years old with hemodynamic stability, who are 14 days to 1 year after PCI, are screened through the HAMD score and the HAMA score. Patients with a HAMD score greater than 7 points and a HAMD score higher than that of the HAMA, are included in this study. Patients were allocated to the active taVNS group or sham taVNS group with a 1:1 ratio. Both groups received the stimulation for 20 minutes each time, twice a day with an 8-week treatment and a 8-week follow-up. All treatments were self-administered by the patients at home after they received training from the hospitals. The primary observation endpoints include the depression scores of the HAMD. The secondary observation endpoints include the HAMA 、GAD、 response and remission rates of HAMD ，as well as the PCL-C for post-traumatic stress disorder. We also observed the cardiac function indexes measured by echocardiography and the B-type natriuretic peptide .

This research study examines recovery after a sports-related concussion or mild head injury. Many athletes experience lingering problems with thinking, balance, and mood months after a concussion. We are testing a new home-based program called BraW-Day™ (Brain \& Walk Exercise Every Day). This 14-day program uses a mobile app on your smartphone and combines simple brain exercises (like counting backwards) with walking exercises. The idea is that doing these tasks together may help your brain and body recover more effectively. What You'll Do: * Two in-person visits at UNLV (baseline and after 14 days) for assessments * Daily 15-minute exercises at home using the BraW-Day app * Provide a small saliva sample for biomarker testing * Complete brief questionnaires about your symptoms and health Potential Benefits: You may experience improvements in thinking, balance, or mood. Even if you don't benefit directly, your participation will help researchers understand how to better support athletes recovering from concussion. Who Can Join: * Ages 18-40 * Had a sports-related concussion or mild head injury within the past 3-12 months * Have a smartphone and can safely do light walking and simple tasks This study is registered at ClinicalTrials.gov and approved by the UNLV Institutional Review Board to protect your safety and rights.

Background and Rationale: Sleep-disordered breathing and nocturnal hypoxemia are highly prevalent in patients with precapillary pulmonary hypertension (PH), and current guidelines recommend systematic sleep assessment in this population. In obstructive sleep apnea, nocturnal hypoxic burden-defined as the area under the SpO₂ desaturation curve associated with respiratory events (%.min/h)-has demonstrated strong prognostic value for cardiovascular morbidity and mortality. However, its role in precapillary PH has not yet been investigated. Evaluating hypoxic burden in this population may refine indications and therapeutic targets for nocturnal oxygen therapy. In addition, pulmonary hypertension is characterized by autonomic nervous system (ANS) dysfunction, including increased sympathetic tone, reduced heart rate variability (HRV), and a higher incidence of cardiac arrhythmias, all associated with worse prognosis. The reduction in HRV is particularly deleterious when occurring during restorative slow-wave sleep (N3), a phase marked by predominant parasympathetic activity essential for cardiovascular recovery and homeostasis. A better understanding of the interaction between nocturnal hypoxemia and ANS modulation may provide new prognostic markers and potential therapeutic targets in PH. Objectives: 1. To describe the evolution of nocturnal hypoxic burden over time in patients with precapillary pulmonary hypertension (at baseline, 12 months, and 24 months). 2. To describe the longitudinal evolution of HRV parameters (RMSSD, LF/HF ratio, HF) at baseline, 12 months, and 24 months. 3. To evaluate cross-sectional correlations (at baseline, M12, and M24) between HRV parameters, hypoxic burden, oxygen desaturation, apnea-hypopnea index (AHI), and clinical status. 4. To evaluate longitudinal correlations between changes in HRV parameters, hypoxic burden, desaturation, AHI, and clinical status between baseline and M12, and between baseline and M24. 5. To assess the 2-year prognostic value of HRV parameters and hypoxic burden for adverse clinical outcomes. Study Design and Population: This is a prospective, single-center observational cohort study conducted at the Pulmonary Hypertension Referral Center of Rouen University Hospital. The cohort design allows longitudinal assessment of HRV, hypoxic burden, and clinical status, enabling both cross-sectional and longitudinal correlation analyses, as well as prognostic evaluation. A total of 60 adult patients (≥18 years) with precapillary pulmonary hypertension confirmed by right heart catheterization and requiring pulmonary arterial vasodilator therapy will be included. Participants will undergo full overnight polysomnography (PSG) at: * Baseline (inclusion) * 12 months (M12) * 24 months (M24) For incident cases, baseline PSG will be performed prior to initiation of vasodilator therapy. All patients will continue to receive standard-of-care management according to current European guidelines for pulmonary hypertension. Descriptive analyses and cross-sectional correlations will pool repeated measures (excluding incident baseline values for generalization to prevalent cases). Intra-subject correlation will be accounted for using bootstrap methods. Longitudinal analyses will assess changes over time and prognostic associations. The prognostic value of HRV and hypoxic burden will be evaluated over a 2-year follow-up period. This study explores an original dimension of precapillary pulmonary hypertension pathophysiology by investigating the interaction between nocturnal oxygenation, autonomic dysfunction, and clinical evolution. Identification of hypoxic burden and HRV as prognostic markers may contribute to improved risk astratification and therapeutic optimization in this high-risk population.

This prospective observational study aims to evaluate whether preoperative heart rate variability (HRV) and anxiety are associated with, and can help predict, emergence agitation in adult patients undergoing elective septorhinoplasty under general anesthesia. Preoperative anxiety will be assessed using a visual analog scale (VAS) and the State-Trait Anxiety Inventory (STAI-1). Resting HRV will be recorded preoperatively using a chest-strap heart rate monitor and HRV metrics (e.g., SDNN, RMSSD, LF/HF) will be derived. Emergence agitation will be assessed in the post-anesthesia care unit (PACU) using the Richmond Agitation-Sedation Scale (RASS) during the early recovery period. Secondary observations will include early postoperative events such as postoperative nausea and vomiting (PONV) and laryngospasm. The study is planned to enroll approximately 100 participants.

The goal of this study is to learn how different amounts of supervised indoor cycling training change gut health (gut bacteria, the substances gut bacteria make, and the gut barrier integrity), and how these changes relate to changes in fitness, muscle health, and signs of doing too much training (a state called 'overreaching'). The study includes healthy, recreationally active men aged 18 to 45 years. The primary questions, for which the study is powered (sufficient participants included), are: 1. Does moderate load training change blood and faecal levels of butyrate (a short-chain fatty acid made by gut bacteria) after eight weeks compared with a control group? 2. Compared to moderate load training, do higher training loads lead to different responses in blood and faecal levels of butyrate? Researchers will compare: * A control group that does not complete structured training; * A moderate-load training group that completes eight weeks of supervised cycling (4x/week); * A high-load training group that completes four weeks of moderate-load training followed by four weeks of higher training load (twice the number of training sessions). Participants will: * Be randomly assigned to one of the three groups; * Complete 8 weeks of supervised indoor cycling sessions if assigned to a training group; * Complete four study assessment periods (baseline, after week four, after week eight, and after a short taper (rest period); * Provide blood, stool, skeletal muscle, urine, saliva, and breath samples during the assessment periods; * Complete fitness and performance tests and questionnaires during the assessment periods.

This study aims to investigate the effects of music intervention on subjective anxiety and physiological indicators, including heart rate, blood pressure, and heart rate variability, in first-time ambulatory surgery patients, and to compare the differential effects between self-selected and standardized music interventions.

A randomized, parallel, double-blind, controlled, clinical trial. Two groups of participants will be included, both receiving a therapeutic exercise intervention and an educational session on the importance of proper breathing over a 6-week period. One of the groups will additionally perform a home-based controlled breathing exercise protocol. Pre- and post-intervention assessments (6 weeks) will be conducted, along with a follow-up evaluation 4 weeks after completion of the intervention. The goal is to determine the effectiveness of adding a controlled breathing exercise program to a therapeutic exercise intervention on cardiorespiratory variables in individuals with multiple myeloma.

The goal of this action research project is to develop and implement nature- and activity-based group interventions across health care, school and leisure settings in Southern Norway. The interventions are tailored to support the mental health, self-efficacy and daily life functioning of children and youth in the Agder region, with a particular focus on youngsters who struggle due to neurodivergence, such as Attention Deficit Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD) or Tourette's syndrome. The main questions we aim to answer are: 1. To what extent does nature- and activity-based outdoor education contribute to improvements in children's quality of life? 2. To what extent does nature- and activity-based interventions in a health care setting improve children's self-efficacy, self-esteem and quality of life? 3. Is there a difference in physiological reactions between nature-based provision of education or therapy and traditional indoor provision of education or therapy? Participants will take part in a 12-week school-based or health care intervention.

Introduction: Long COVID is characterized by persistent symptoms that persist for weeks or months after the acute phase of infection, with a significant impact on the cardiovascular and autonomic systems. Objectives: This study aims to evaluate the effects of a physiotherapeutic rehabilitation protocol on cardiovascular autonomic modulation and on inflammatory and cardiac biomarkers in patients with Long COVID. Methodology: This is a controlled clinical trial, carried out in a cardiorespiratory rehabilitation outpatient clinic, involving individuals with a clinical diagnosis of Long COVID undergoing a protocol of 20 aerobic, anaerobic and respiratory rehabilitation sessions. Heart rate variability (HRV) variables will be analyzed using linear and non-linear methods, in addition to serum levels of CKMB, LDH, ferritin and C-reactive protein. Expected results: Rehabilitation is expected to provide an improvement in autonomic function and a reduction in inflammatory and cardiac markers, contributing to the understanding of the pathophysiological mechanisms of Long COVID and helping to propose evidence-based therapeutic strategies.