An interventional study of VIH in Acute Mountain Sickness, sponsored by Institute of Sport - National Research Institute, Poland. Active, not recruiting at 1 site in Poland. Open to participants aged 18 Years to 39 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-08-20.
Sponsored by Institute of Sport - National Research Institute, Poland · Not applicable, Interventional, and Basic science
This study investigates the effects of a brief Voluntary Isocapnic Hyperpnoea (VIH) on Acute Mountain Sickness (AMS) symptoms, SpO₂, blood pressure, and blood gas homeostasis in normobaric hypoxia, to evaluate whether such respiratory modulation may serve as a viable strategy to alleviate AMS symptoms. The investigation seeks to explore the physiological mechanisms underlying VIH in severe hypoxia (4200m asl) and furnish insight regarding practical means of providing immediate relief from AMS symptoms. Furthermore, given the scarcity of relevant literature, this investigation may serve as a pilot study and lay the foundation for future research.
The present investigation employed a randomized crossover design. The study was conducted in the Institute of Sport - National Research Institute in Warsaw, Poland, in July and August 2025. Across 2 consecutive days, the participants underwent two 2-hour sessions under hypoxia of 4200m asl (FiO2 = 12.8%) in a normobaric chamber (Air Sport, Międzyzdroje, Poland). The sessions were held at the same time of day, between 17:00 and 19:00. Temperature (approximately 21 °C), humidity (45-50%), and gas concentration were centrally controlled and maintained at stable levels throughout the exposure period. During the control session, the participants remained seated without any activity. During the experimental session, they additionally performed a 5-minute VIH session (20 breaths/minute) after 1 hour of hypoxic exposure. Isocapnic BreathWayBetter devices (Isocapnic Technologies Inc., Kelowna, British Columbia, Canada) equipped with 6-liter breathing bags were employed to perform VIH. The accompanying Isocapnic mobile app was used to guide breathing rhythm and monitor session duration. The order of sessions was determined using block randomization within subgroups of 4-6 individuals to ensure balanced exposure to each condition. Multiple measurements were taken, including blood pressure, heart rate, SpO2, blood gasometry, and the 2018 Lake Louise AMS Score.
Blood gas analysis was conducted using a Radiometer™ ABL90 FLEX (Radiometer Medical ApS, Brønshøj, Denmark). The following parameters were assessed: hydrogen ion concentration (pH), bicarbonate ion concentration (HCO₃-), partial pressure of oxygen (pO₂), and partial pressure of carbon dioxide (pCO₂). All measurements were taken in duplicate using 45 µL capillary blood samples collected from the fingertip. Analyses were performed immediately following collection by a trained technician following the manufacturer's instructions.
Peripheral blood pressure was measured digitally using the OMRON M2 monitor (OMRON Healthcare, Kyoto, Japan).
SpO₂ was estimated at the fingertip using a pulse oximeter (NONIN Onyx Vantage 9590, Nonin Medical, Inc., Plymouth, MN, USA).
The 2018 Lake Louise AMS Score questionnaire was presented to the participants before the experiment for familiarization and then used to evaluate symptoms of AMS based on a combination of subjective self-reports and clinical findings.
All the measurements were performed by qualified and experienced specialists. The participants were blinded to the obtained results, except for the 2018 Lake Louise AMS Score, which was self-reported.
216 studies on the registry are indexed under Altitude Sickness; 46 are open to participants now.
This study's planned enrollment of 20 is below the median of 34 across 178 interventional studies indexed under Altitude Sickness.
Browse Altitude Sickness studies →Institute of Sport - National Research Institute, Poland is the lead sponsor of 6 studies on the registry; 1 is open to participants now.
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The inclusion criteria comprised:
Exclusion criteria included:
Across 2 consecutive days, the participants underwent two 2-hour sessions under hypoxia of 4200m asl (FiO2 = 12.8%) in a normobaric chamber (Air Sport, Międzyzdroje, Poland). The sessions were held at the same time of day, between 17:00 and 19:00. Temperature (approximately 21 °C), humidity (45-50%), and gas concentration were centrally controlled and maintained at stable levels throughout the exposure period. During the control session, the participants remained seated without any activity.
Across 2 consecutive days, the participants underwent two 2-hour sessions under hypoxia of 4200m asl (FiO2 = 12.8%) in a normobaric chamber (Air Sport, Międzyzdroje, Poland). The sessions were held at the same time of day, between 17:00 and 19:00. Temperature (approximately 21 °C), humidity (45-50%), and gas concentration were centrally controlled and maintained at stable levels throughout the exposure period. During the experimental session, they additionally performed a 5-minute VIH session (20 breaths/minute) after 1 hour of hypoxic exposure. Isocapnic BreathWayBetter devices (Isocapnic Technologies Inc., Kelowna, British Columbia, Canada) equipped with 6-liter breathing bags were employed to perform VIH. The accompanying Isocapnic mobile app was used to guide breathing rhythm and monitor session duration.
Behavioral: VIH
During the experimental session, they additionally performed a 5-minute VIH session (20 breaths/minute) after 1 hour of hypoxic exposure. Isocapnic BreathWayBetter devices (Isocapnic Technologies Inc., Kelowna, British Columbia, Canada) equipped with 6-liter breathing bags were employed to perform VIH. The accompanying Isocapnic mobile app was used to guide breathing rhythm and monitor session duration.
SpO₂
Arterial oxygen saturation (SpO₂)
Time frame: Day 1 and Day 2 of the study.
AMS LL
2018 Lake Louise Acute Mountain Sickness Score
Time frame: Day 1 and Day 2 of the study.
pH
hydrogen ion concentration
Time frame: Day 1 and Day 2 of the study.
pO₂
partial pressure of oxygen (pO₂)
Time frame: Day 1 and Day 2 of the study.
pCO₂
partial pressure of carbon dioxide (pCO₂)
Time frame: Day 1 and Day 2 of the study.
HCO₃-
bicarbonate ion concentration (HCO₃-)
Time frame: Day 1 and Day 2 of the study.
Plan to share: No — Privacy reasons.
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Institute of Sport - National Research Institute, Poland