Assessment of Pulmonary Function and Physiological Adaptation of Lung Transplant Recipients at Extreme Altitude: The Mount Aconcagua (6971 m) Expedition
Trial Snapshot
- Phase
- Not Applicable
- Status
- Active, not recruiting
- Sponsor
- Medical University of Vienna
- Enrollment
- 30
- Locations
- 1
- Primary Endpoint
- Change in peripheral oxygen saturation (SpO₂) as a marker of physiological adaptation
Study Overview
Brief Summary
This prospective observational study investigates the effects of intermittent hypoxic conditioning and real high-altitude exposure in lung transplant recipients compared with healthy controls.
The study includes an eight-week home-based preparatory phase during which participants use a normobaric hypoxic tent with reduced oxygen concentration. Prior to this phase, all participants receive standardized training on the safe use of the equipment. During the preparatory period, daily vital parameters, including heart rate, oxygen saturation, and heart rate variability, are recorded using a sports watch and a pulse oximeter. Symptoms, adverse events, and subjective well-being are documented daily in an electronic diary. All data are transmitted to the study team via encrypted electronic systems, allowing continuous remote monitoring. At the end of the preparatory phase, participants undergo a clinical evaluation to confirm fitness for the expedition phase.
The expedition phase consists of a monitored ascent of Aconcagua (6,971 meters). Before departure, all participants are required to attend a comprehensive safety, protection, and first aid training conducted jointly by the study team and professional expedition providers. The expedition is planned and led by an experienced international expedition company in cooperation with a local provider specializing in high-altitude mountaineering.
The expedition includes arrival in Mendoza, preparatory procedures such as equipment checks and permits, followed by a staged ascent to base camp. Subsequent days involve rest periods and acclimatization hikes with the establishment of progressively higher camps. A summit attempt is planned after sufficient acclimatization, followed by descent to high camp. A weather-dependent buffer period is included before the final descent to the valley and return to Mendoza, where the expedition concludes.
Total study participation is expected to last approximately 15 weeks, including about eight weeks of home-based preparation and approximately three weeks at altitude. A final follow-up examination is conducted 2 to 4 weeks after completion of the expedition, marking the end of study participation.
Study Design
- Study Type
- Observational
- Observational Model
- Cohort
- Time Perspective
- Prospective
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •Lung transplant recipients:
- •Age ≥ 18 years
- •> 1 years after lung transplantation
- •Stable lung function over 6 month prior to inclusion, FEV1 +/-10% from baseline
- •VO2peak of more than 25 ml/min/kg
- •Physical and mental fitness, defined as the ability to complete strenuous day trips lasting 8 to 10 hours independently without suffering from a fear of heights, an altitude exposure of at least 2500m must be confirmed.
- •Negative pregnancy test for women of childbearing age
- •Written informed consent
- •Healthy volunteers:
- •Age ≥ 18 years
- •VO2peak of more than 25 ml/min/kg
- •Physical and mental fitness, defined as the ability to complete strenuous day trips lasting 8 to 10 hours independently without suffering from a fear of heights
- •Negative pregnancy test for women of childbearing age
- •Written informed consent
Exclusion Criteria
- •Lung transplant recipients:
- •Age < 18 years
- •Refusal to participate in the study
- •Pregnancy
- •Healthy controls:
- •Age < 18 years
- •Refusal to participate in the study
- •Pregnancy
- •Chronic obstructive pulmonary disease (COPD)
Arms & Interventions
Lung transplant recipients
Healthy volunteers
Outcomes
Primary Outcomes
Change in peripheral oxygen saturation (SpO₂) as a marker of physiological adaptation
Time Frame: From enrollment to the end of the expedition at 3 weeks
Change in forced expiratory volume in one second (FEV₁)
Time Frame: From enrollment to the end of the expedition at 3 weeks
Secondary Outcomes
- Heart Rate Variability (HRV)(From enrollment to the end of the expedition at 3 weeks)
- Blood gas analysis (BGA)(From enrollment to the end of the expedition at 3 weeks)
- Acute mountain sickness (AMS)(From enrollment to the end of the expedition at 3 weeks)
- Level of immunosuppression(From enrollment to the end of the expedition at 3 weeks)
- Level of Torque Teno Virus (TTV)(Before enrollment until approx. 4 weeks after the end of the expedition)
- Voice analysis(Prior to enrollment to the end of the expedition at 3 weeks)
- Gut Microbiota Dynamics(Prior to enrollment to the end of the expedition at 3 weeks)
- Transthoracic echocardiography(Prior to enrollment to the end of the expedition at 3 weeks)
- Lung Ultrasound Score(Prior to enrollment to the end of the expedition at 3 weeks)
- Renin-angiotensin-aldosterone system(Prior to enrollment to the end of the expedition at 3 weeks)
- End-tidal CO₂ measurements(Prior to enrollment to the end of the expedition at 3 weeks)
- Continuous glucose monitoring(Prior to enrollment to the end of the expedition at 3 weeks)
Investigators
Jakob Mühlbacher, MD
M.D, PhD
Medical University of Vienna