Voluntary Isocapnic Hyperpnea in Hypoxia to Mitigate Acute Mountain Sickness

NCT07126834 | Active Not Recruiting

• 2 other identifiers: 2025/TK/1102.39/2025
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Acute Mountain Sickness

Keywords

acute mountan sickness; breathing; hyperpnoea; blood gas analysis; lake louis scale

Outcome Measures

Primary Outcomes (6)

• SpO₂

  Arterial oxygen saturation (SpO₂)

  Day 1 and Day 2 of the study.

• AMS LL

  2018 Lake Louise Acute Mountain Sickness Score

  Day 1 and Day 2 of the study.

• pH

  hydrogen ion concentration

  Day 1 and Day 2 of the study.

• pO₂

  partial pressure of oxygen (pO₂)

  Day 1 and Day 2 of the study.

• pCO₂

  partial pressure of carbon dioxide (pCO₂)

  Day 1 and Day 2 of the study.

• HCO₃-

  bicarbonate ion concentration (HCO₃-)

  Day 1 and Day 2 of the study.

Study Arms (2)

Control

NO INTERVENTION

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.

Experimental

EXPERIMENTAL

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

Interventions

VIH BEHAVIORAL

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.

Experimental

Eligibility Criteria

• Age: 18 Years - 39 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• age between 18 and 39 years,
• meeting the World Health Organization's minimum physical activity guidelines, defined as 150-300 minutes of moderate-intensity aerobic activity per week, 75-150 minutes of vigorous-intensity activity, or an equivalent combination of both (Bull et al. 2020).

You may not qualify if:

• exposure to hypoxia within the past three months,
• any chronic or acute medical condition within the same timeframe,
• current use of any medication,
• known allergic reactions,
• pregnancy,
• smoking.

Sponsors & Collaborators

• Institute of Sport - National Research Institute, Poland: lead

Study Sites (1)

Institute of Sport - National Research Institute, Warsaw, Poland

Warsaw, 01-982, Poland

Location

MeSH Terms

Conditions

Altitude Sickness; Respiratory Aspiration; Hyperventilation

Condition Hierarchy (Ancestors)

Respiration Disorders; Respiratory Tract Diseases; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms, Respiratory; Signs and Symptoms

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator - Research Associate

Study Record Dates

• First Submitted: August 6, 2025
• First Posted: August 17, 2025
• Study Start: June 1, 2025
• Primary Completion: June 15, 2025
• Study Completion: August 31, 2025
• Last Updated: August 20, 2025

Record last verified: 2025-08

Data Sharing

• IPD Sharing: Will not share

Locations

PL (1)