This project seeks to investigate the effects of a single acute intermittent hypoxia (AIH) session on respiratory and non-respiratory motor function and EMG (electromyography) activity on patients with ALS (amyotrophic lateral sclerosis) and healthy controls.
Most ALS patients survive less than 5 years after diagnosis, and the main cause of death is respiratory failure. The investigators are interested in the therapeutic potential of acute intermittent hypoxia (AIH) for individuals with neuromuscular diseases, such as ALS. More than two decades of research indicates AIH elicits meaningful respiratory and non-respiratory motor recovery. Acute intermittent hypoxia (AIH) consists of alternating periods of breathing mildly hypoxic (lowered oxygen concentration) and normoxic (normal oxygen concentration) air. The investigators propose to study mechanisms of respiratory plasticity associated with a single presentation of mild AIH. The fundamental hypothesis guiding this proposal is that even a single AIH trial improves respiratory (and non-respiratory) motor function in ALS patients procedure. Participants will then be asked to breathe air with reduced oxygen for short periods of time, for a duration of 45 minutes. The activity of your muscles and your heart function will be monitored throughout the procedure.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
29
AIH entails continuous breathing as the level of oxygen in the air is decreased, then returned to normal. Participants will alternate between breathing normal air and breathing hypoxic air (air that has less oxygen). Participants will complete a single 45 minute session of acute intermittent hypoxia (AIH). Breathing, muscle activity and heart activity will be monitored before, during and after the procedure. The intervals will last 1 minute each.
Participants will complete the sham acute intermittent hypoxia, consisting of a single 45 minute session of breathing air with normal oxygen levels. All aspects of this procedure will otherwise be the same as for the AIH procedure. Breathing, muscle activity and heart activity will be monitored before, during and after the procedure.
UF Clinical Research Center
Gainesville, Florida, United States
University of Florida
Gainesville, Florida, United States
Percent Change in Maximal Inspiratory Pressure (MIP)
MIP is a maximal voluntary static contraction of the inspiratory muscles against a closed valve, measured at the mouth. The test will be repeated until 3 measurements are obtained within 10% variability and an average of the three trials is reported. The change in MIP will be the percent difference in pressure between the averaged baseline MIP and the averaged follow-up measure, which is tested 60 minutes after the gas intervention.
Time frame: 3 Hours
Percent Change in Maximal Voluntary Grip Force
Maximal static voluntary handgrip contractions will be evaluated in a seated position with the arm at the side and elbow flexed to 90 degrees. The test will be repeated until 3 measurements are obtained within 10% variability and then averaged. The change in grip will be the percent difference in force between the averaged baseline grip and the averaged follow-up grip measure, which is tested 60 minutes after the gas intervention.
Time frame: 3 Hours
Percent Change in Sniff Nasal Inspiratory Pressure
Maximal voluntary contractions of the inspiratory muscles measured with a pressure sensor placed in the nare. The test will be repeated until 3 measurements are obtained within 10% variability and then averaged. The change in sniff nasal inspiratory pressure will be the percent difference in pressure between the averaged baseline sniff nasal inspiratory pressure and the averaged follow-up measure, which is tested 60 minutes after the gas intervention.
Time frame: 3 Hours
Percent Change in Minute Ventilation
Minute ventilation is measured using a pneumotachograph connected to the face mask to record breath-by-breath volume and breathing rate, which is then multiplied to calculate minute ventilation. After achieving a stable tidal volume, 5 minutes of resting minute ventilation will be recorded and then averaged. The change in minute ventilation will be the percent difference in volume between the averaged baseline ventilation and the averaged follow-up ventilation, which is tested 60 minutes after the gas intervention.
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Time frame: 3 Hours
Occlusion Pressure (P0.1)
P0.1 is measured with a pressure transducer connected to a face mask and represents the pressure generated against a transiently occluded airway in the first 0.1 sec of inspiration. The generated during this initial period of inspiration is resistant to learning or sensory bias and is considered a clinical estimate of inspiratory drive. Five measurements will be conducted and then averaged, with 5-15 un-occluded breaths between each P0.1 measurement. The averaged pressures at baseline and 60 minutes post-gas intervention will be reported and will be expressed in cm H2O.
Time frame: 3 Hours
Percentage Change in Respiratory EMG Vector Magnitude
EMG vector magnitude represents the composite surface EMG activity expressed from eight respiratory muscles (bilateral scalene, sternocleidomastoid, 2nd parasternal, and 8th external intercostal/diaphragm). The vector magnitude was calculated for each participant from the root mean square (RMS) values from each EMG channel, as the square root of the sum of the individual squared EMG channel amplitudes.
Time frame: 3 Hours