Acute Exposure to High Altitude on Blood and Tissue Oxygenation (ABGA, NIRS)

Study Overview
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Brief Summary
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Randomized crossover Trial in patients with Pulmonary Hypertension (PAH, CTEPH) to assess the acute response to High Altitude (2500m above sea level) on blood and tissue oxygenation (ABGA, NIRS).

Detailed Description
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Low altitude baseline measurements will be performed in Zurich (460m asl) including Echocardiography, Right heart catheterization, 6MWT, pulmonary function test, clinical assessment and blood gas Analysis. Randomly assigned to the order of testing, the participants will be tested in Low Altitude (Zurich, 470m) and at High Altitude (2500m). At rest and under exercise data from ABGA and NIRS will be compared at low altitude and High Altitude.

Official Title
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Acute Exposure to Hypoxia in Precapillary Pulmonary Hypertension: Physiological and Clinical Effects at Rest and During Exercise

Conditions
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Pulmonary Hypertension

Intervention / Treatment
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* Other: Low altitude: 470m above sea level
* Other: Säntis; 2500m above sea level


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Informed consent PH diagnosed according to internation Guidelines: mPAP ≥ 25 mmHg along with a PAWP ≤15 mmHg during right heart catheterization at the time of Initial diagnosis PH class 1 (PAH) or 4 (CTEPH) Stable condition, on the same medication for > 4 weeks Patient live permanently at an altitude < 1000m asl. Exclusion Criteria: Resting PaO2 ≤7.3 kPA corresponding to the requirement of long-term oxygen therapy > 16hour daily (nocturnal oxygen therapy alone is allowed) Severe daytime hypercapnia (pCO2 > 6.5 kPa) Susceptibility to high altitude related diseases (AMS, HAPE, etc.) based on previous experienced discomfort at altitudes. Exposure to an altitude >1500m for ≥3 nights during the last 4 weeks before the study participation Residence > 1000m above sea level Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, neurological or orthopedic problems with Walking disability Women who are pregnant or breast feeding

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Including a baseline assessment and assessments at Low altitude and High altitude
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Order A<br>The participants will be tested in Zurich (Low altitude: 470m above sea level) and consecutively at High Altitude(Säntis; 2500m above sea Level) | Other: Low altitude: 470m above sea level<br>* Assessment at Low Altitude (in Zurich; 470m above sea level) in order to compare this data with High altitude exposure<br>Other: Säntis; 2500m above sea level<br>* Exposure to High Altitude (Säntis; 2500m above sea level) for approximately 5 hours<br>|
| Experimental: Order B<br>The participants will be tested at High Altitude (Säntis; 2500m above sea level) and consecutively in Zurich (Low altitude; 470m above sea level). | Other: Low altitude: 470m above sea level<br>* Assessment at Low Altitude (in Zurich; 470m above sea level) in order to compare this data with High altitude exposure<br>Other: Säntis; 2500m above sea level<br>* Exposure to High Altitude (Säntis; 2500m above sea level) for approximately 5 hours<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Arterial blood oxygenation at High Altitude (2500m above sea level) | Difference in arterial blood oxygenation at Low Altitude (Zurich, 470m above sea level) and High Altitude (Säntis; 2500m above sea level) | within 5 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Near infrared spectroscopy at High Altitude (2500m) | Difference in cerebral tissue oxygenation and muscle tissue oxygenation measured by near infrared spectroscopy at low Altitude (Zurich) and High Altitude (Säntis, 2500m) | within 5 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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High Altitude, arterial blood gas analysis, near infrared spectroscopy