The Role of Heliox in Respiratory Control
ConditionWork of Breathing
Trial statusRecruiting
Trial phasePhase 4
Trial typeInterventional
Biological sexAll
Age18-40
SponsorIndiana University
About this trial
Warfighters are frequently exposed to environments and life-support systems that increase breathing resistance and the work of breathing (WOB), such as aircraft on-board oxygen generation systems and underwater breathing apparatuses. Elevated WOB increases the perception of breathing difficulty (dyspnea) and has been associated with impaired cognitive performance, including slower reaction time and reduced accuracy during attention-demanding tasks. These effects are particularly concerning in operational settings that require rapid decision-making and precise motor responses.
Despite growing recognition of this issue, critical gaps remain regarding strategies to mitigate the perceptual and cognitive consequences of elevated inspiratory resistance, especially under realistic operational stressors. The objective of this study is to determine whether reducing mechanical WOB alters breathing perception and cognitive performance during inspiratory resistance. Participants will breathe either normal-density air or a low-density helium-oxygen gas mixture (heliox) to determine whether reducing mechanical WOB lowers perceived breathing effort and improves cognitive function.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Between the ages of 18-40 years old.
English speaking and reading.
Self-reported weekly activity of at least 120 minutes/week of high intensity exercise for the previous 2 years.
Normal pulmonary function assessed by a resting forced expiratory volume in 1 second over forced vital capacity (FEV1/FVC) > 75% of predicted.
Disqualifiers
History of smoking or recreational smoking, cardiovascular disease, renal disease, pulmonary disease (including asthma or exercise-induced asthma), neurological disease, and metabolic disease.
Are pregnant or could possibly be pregnant by self-report.
Are color blind.
Known allergy or hypersensitivity latex.
Trial design
Design model
Crossover
Treatments tested in this trial
Heliox inspirate
DrugThis intervention corresponds to Arm 1 titled "room air and heliox inspirate". This corresponds with the first phase/period of this study.
Treatment groups
15 Participants
are divided into 2 treatment groupsGroup A: Room Air, then Heliox InspirateActive comparator 1 intervention
Group B: Heliox Inspirate, then Room AirActive comparator 1 intervention
Trial outcomes
Primary outcomes
1
Change in Stroop Color-Word Test Time Performance
Time performance on the Stroop Color-Word Test (min:sec) will be measured every 10 minutes during each breathing task.
Time frame
Before and after each Day 1 breathing task (approximately 60 minutes in duration)2
Change in Stroop Color-Word Test Error Performance
The number of errors on the Stroop Color-Word Test will be measured will be measured every 10 minutes during each breathing task.
Time frame
Before and after each Day 1 breathing task (approximately 60 minutes in duration)3
Change in Perception of Dyspnea Intensity
Participants will rate perception of dyspnea (breathing) intensity on a visual analog scale (VAS) every 5 minutes during each breathing task. The participant will draw a vertical marker line on a horizontal line (100mm),indicating their breathing perception from "not noticeable" (0mm) to "maximal imaginable intensity" (100mm).
Time frame
Before and after each Day 1 breathing task (approximately 60 minutes in duration)4
Change in Perception of Dyspnea Unpleasantness
Participants will rate perception of dyspnea (breathing) unpleasantness on a visual analog scale (VAS) every 5 minutes during each breathing task. The participant will draw a vertical marker line on a horizontal line(100mm), indicating their breathing perception from "not unpleasant"(0mm) to "maximal imaginable unpleasantness" (100mm).
Time frame
Before and after each Day 1 breathing task (approximately 60 minutes in duration)Secondary outcomes
1
Change in Work of Breathing - Esophageal Pressure
Heliox-induced reduction in WOB will be summarized by pre- and post-values of pressure (unit: cmH2O) via esophageal balloon pressures during the heliox condition.
Time frame
Before and after each Day 1 breathing task (approximately 60 minutes in duration)2
Change in Work of Breathing - Mouth Pressure
Heliox-induced reduction in WOB will be summarized by pre- and post-values of pressure (unit: cmH2O) via esophageal balloon pressures, mouth pressure, and dynamic lung volumes during the heliox condition.
Time frame
Before and after each Day 1 breathing task (approximately 60 minutes in duration)3
Change in Work of Breathing - Dynamic Lung Volume
Heliox-induced reduction in WOB will be summarized by pre- and post-values of pressure (unit: cmH2O) via dynamic lung volumes during the heliox condition.
Time frame
Before and after each Day 1 breathing task (approximately 60 minutes in duration)4
Change in Cerebral Blood Velocity
Bilateral transcranial Doppler Ultrasound will be used to continuously measure middle and posterior cerebral artery blood velocity during each breathing task. The ultrasound transducers will be placed on both sides of the head at the temporal windows and the positions will be fixed using a transducer holder.
Time frame
Before and after each Day 1 breathing task (approximately 60 minutes in duration)Sponsors and contacts
Click on the lead sponsor to view all of their trials.
Indiana University
Lead sponsor
United States Department of Defense
Collaborator
Source ClinicalTrials.gov