Effect of High Altitude Exposure, Acclimatization and Re-exposure on Nocturnal Breathing Pattern in Lowlanders

Study Overview
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Brief Summary
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Prospective interventional trial in lowlanders evaluating the effect of acute exposure, acclimatization and re-exposure of high altitude on nocturnal breathing pattern.

Detailed Description
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Respiratory polygraphies will be performed in Santiago de Chile, 520 m, over the course of 3 days. Participants will then travel by commercial airline (5 h flight) and by bus (3 h ride) to the ALMA base camp located at 2900 m near San Pedro de Atacama, northern Chile. Participants will stay there for the next 7 nights and respiratory polygraphies will be performed on night 1 and 6. They will be spend the days (6-8 h daily) at the telescope station at 5050 m while undergoing physiological testing. Daily transports from 2900 to 5050 m will be by car (1 h ride, one way). After the first 8 day altitude sojourn participants will return to the Santiago area (520 m) for a 6 day recovery period. A second altitude sojourn with an identical schedule as the one described above and a final low altitude stay of 3 days will follow.

Official Title
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Effect of High Altitude Exposure, Acclimatization and Re-exposure on Nocturnal Breathing Pattern in Lowlanders

Conditions
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Effect of High Altitude

Intervention / Treatment
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* Other: Altitude exposure


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: born, raised and currently living <800m No overnight stay at altitudes >1500 m 4 weeks before the study Exclusion Criteria: Previous altitude intolerance to altitude <3000 m Pregnancy Health impairment, which requires regular treatment

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Altitude exposure<br>Acute high altitude exposure followed by 8 day acclimatization and re-exposure after 6 days at low altitude | Other: Altitude exposure<br>* Altitude exposure<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean nocturnal oxygen saturation measured by pulse oximetry | Change in mean nocturnal oxygen saturation over the course of high altitude exposure during 2 sojourns at 5050 m compared to low altitude | first sojourn at 5050 m, night 1, 6; second sojourn at 5050 m, night 1, 6; low altitude sojourn at 520 m, night 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Apnea-/hypopnea index measured by respiratory polygraphy | Change in apnea-/hypopnea index over the course of high altitude exposure during 2 sojourns at 5050 m compared to low altitude | first sojourn at 5050 m, night 1, 6; second sojourn at 5050 m, night 1, 6; low altitude sojourn at 520 m, night 1 | 
| Oxygen desaturation index measured by respiratory polygraphy | Change in oxygen desaturation index over the course of high altitude exposure during 2 sojourns at 5050 m compared to low altitude | first sojourn at 5050 m, night 1, 6; second sojourn at 5050 m, night 1, 6; low altitude sojourn at 520 m, night 1 | 
| Acute mountain sickness measured by the Environmental Symptom questionnaire cerebral score (AMSc) | Incidence of acute mountain sickness (AMSc score >= 0.7) over the course of high altitude exposure during 2 sojourns at 5050 m compared to low altitude | first sojourn at 5050 m, day 2, 7; second sojourn at 5050 m, day 2,7; low altitude sojourn at 520 m, day 2 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Altitude, Nocturnal breathing pattern