Yoga Breath Training to Improve Cardiorespiratory Synchrony in Spinal Cord Injury

Primary outcomes

1. Ventilatory pattern after regular Ujjayi breathing

   Time frame: Change in ventilatory pattern, Time Frame: Baseline, Week 6

   Ventilatory patterns measured as rate and regularity by breathing belts (pneumobelts). A normal respiratory rate for an adult at rest is 12 to 18 breaths per minute.

2. Pulmonary function after regular Ujjayi breathing

   Time frame: Change in pulmonary function, Time Frame: Baseline, Week 6

   Pulmonary function measured by spirometry, maximal voluntary ventilation, and maximum inspiratory and expiratory pressures. Results will be reported as forced vital capacity (FVC), Forced Expiratory Volume in 1 second (FEV1), FEV1/FVC ratio, Peak Expiratory Flow (PEF), and Forced Expiratory Flow (FEF) 25%-75%. An absolute range cannot be provided as it depends on various factors such as injury level, completeness of injury, age, race, and sex. In healthy adults, MVV is typically around 120-170 liters per minute (L/min).

3. Central and peripheral chemosensitivity after regular Ujjayi breathing

   Time frame: Change in central and peripheral chemosensitivity, Time Frame: Baseline, Week 6

   The Read rebreathing method assesses neural drive to breathe and CO2 sensitivity (central chemosensitivity). A three-way valve connects the breathing circuit to room air or 95% O2-5% CO2. Subjects exhale to functional residual capacity, then rebreathe until PETCO2 reaches 55 mmHg, they can't continue, SPO2 drops below 95%, or 10 minutes elapse. Peripheral chemosensitivity uses brief exposures to hypercapnic (10% CO2, 21% O2) or hypoxic gas (pure nitrogen). Ventilatory response is measured over up to 30 seconds, followed by room air. Each test takes about 15 minutes. Tests are conducted seated and supine. Chemosensitivity is measured by plotting ventilation against pulmonary gas levels.

4. Ventilatory perfusion after regular Ujjayi breathing

   Time frame: Change in ventilatory perfusion, Time Frame: Baseline, Week 6

   Ventilatory perfusion will be calculated from mixed expired and end tidal CO2 measures. The V/Q ratio in healthy lungs is close to 1- this means that ventilation (V) matches perfusion (Q) almost perfectly in well-ventilated alveoli. Certain pathologies could increase or decrease the V/Q ratio.

5. Sleep quality after regular Ujjayi breathing

   Time frame: Change in sleep quality, Time Frame: Baseline, Week 6

   Sleep quality is assessed using two methods: the PROMIS Sleep Disturbance Short Form and NoxA1 polysomnography. The PROMIS survey provides raw scores that are converted into T-scores. T-scores falling between 40 and 59 indicate average sleep disturbance levels, considered within the normal range. Scores above 60 suggest more sleep disturbances than average, while scores below 39 indicate less disturbance compared to average.

   NoxA1 polysomnography records several parameters including EEG waves for sleep stages, wake after onset, nocturnal disturbances, maximum and minimum heart rates at rest, breathing rates, limb movements, teeth grinding (monitored via chin movement sensors), blood oxygen saturation, and respiratory patterns.