Acute Exposure of Simulated Hypoxia 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 arterial hypertension (PAH) and chronic thromboembolic pulmonary Hypertension (CTEPH) to assess the acute response to simulated altitude (FiO2:15.1, equivalent to 2500m above sea level) on blood and tissue oxygenation (ABGA, near infrared spectroscopy)

Detailed Description
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Low altitude baseline measurements will be performed in Zurich (460m asl) including Echocardiography, Right heart catheterization, six-minute walk test (6MWT), pulmonary function test, clinical assessment and blood gas analysis. Randomly assigned to the order of testing, the participants will be tested under simulated altitude (FiO2: 15.1% with the AMC altitrainer) and shamed altitude with the same device. At rest and under exercise data from ABGA and near infrared spectroscopy will be compared under simulated altitude and shamed 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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* Device: Simulated Altitude (FiO2: 15.1%)
* Device: Shamed Hypoxia (FiO2: 20.9)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Informed consent PH diagnosed according to internation Guidelines: mean pulmonary artery pressure (mPAP) ≥ 25 mmHg along with a pulmonary artery wedge pressure (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 partial Oxygen pressure (PaO2) ≤7.3 kilopascal (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, high-altitude pulmonary edema (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 under simulated altitude and normoxia.
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Order air-hypoxia<br>The participants will be exposed to shamed hypoxia (FiO2: 20.9% equivalent to sea level and consecutively to simulated altitude (FiO2: 15.1% equivalent to 2500m above sea level) administered by an altitude Simulator (Altitrainer, SMTEC), simulated altitude (FiO2: 15.1%), with a facemask. | Device: Simulated Altitude (FiO2: 15.1%)<br>* Inhalation of deoxygenated air through a altitude simulator (Altitrainer), for approx. 1 hour. given by a facemask.<br>Device: Shamed Hypoxia (FiO2: 20.9)<br>* Inhalation of unmodified air through an altitude Simulator (Altitrainer) for approximately 1 hour given by a facemask<br>|
| Experimental: Order hypoxia-air<br>The participant will be exposed to hypoxia (FiO2, 15.1% equivalent to 2500m above sea level), simulated altitude (FiO2: 15.1%), and consecutively to shamed hypoxia (FiO2, 20.9%) administered by an altitude simulator (Altitrainer, SMTEC) with a facemask. | Device: Simulated Altitude (FiO2: 15.1%)<br>* Inhalation of deoxygenated air through a altitude simulator (Altitrainer), for approx. 1 hour. given by a facemask.<br>Device: Shamed Hypoxia (FiO2: 20.9)<br>* Inhalation of unmodified air through an altitude Simulator (Altitrainer) for approximately 1 hour given by a facemask<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| arterial blood oxygenation under simulated altitude at rest (FiO2: 15.1) | Difference in arterial blood oxygenation under simulated altitude (FiO2: 15.1%) and shamed hypoxia (FiO2: 20.9%) at rest. | 2 hours | 
| arterial blood oxygenation under simulated altitude at the time of exhaustion (FiO2: 15.1) | Difference in arterial blood oxygenation under simulated altitude (FiO2: 15.1%) and shamed hypoxia (FiO2: 20.9%) at the time of exhaustion | 2 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Near infrared spectroscopy under simulated altitude at rest (FiO2: 15.1) | Difference in cerebral tissue oxygenation and muscle tissue oxygenation under simulated altitude (FiO2: 15.1%) and shamed hypoxia (FiO2: 20.9%) at rest | 2 hours | 
| Near infrared spectroscopy under simulated altitude at rest (FiO2: 15.1) | Difference in cerebral tissue oxygenation and muscle tissue oxygenation under simulated altitude (FiO2: 15.1%) and shamed hypoxia (FiO2: 20.9%) | 2 hours | 

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