Acute Mountain Sickness (AMS)NCT07148674
Efficacy of Positive Expiratory Pressure on Acute Mountain Sickness
A study testing Positive Expiratory Pressure (10cmH2O) in hypobaric hypoxia in people with Acute Mountain Sickness (AMS), run by BiALP - Alpine, Disaster and Wilderness Medicine.
Trial summary
This pilot study aims to evaluate the efficacy of positive expiratory pressure (PEP) therapy at 10 cmH₂O in improving peripheral oxygen saturation (SpO₂) and mitigating symptoms of acute mountain sickness (AMS) in healthy individuals exposed to extreme altitude conditions. Read more about this study
- Who is it for?
- Ages 18 to 99 yearsHealthy volunteers can take part
- Conditions the study is for
- Acute Mountain Sickness (AMS)
- What is being tested?
- Positive Expiratory Pressure (10cmH2O) in hypobaric hypoxia
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 3 participants
- Where
- No sites listed yet
- Study dates
- 5 Sep 2025to 31 Dec 2025
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 99 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Healthy volunteers without ongoing medical conditions
- Over 18 years of age
- Volunteers with the physical and technical skills necessary to undertake a mountaineering expedition on Mount Aconcagua, Argentina, and with previous experience at extreme altitudes
Who cannot join
- Subjects with any ongoing medical conditions
- Under 18 years of age
- Subjects without previous mountaineering experience at extreme altitudes and without adequate physical and technical preparation necessary to undertake a mountaineering expedition on Mount Aconcagua, Argentina
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: Efficacy of Positive Expiratory Pressure on Acute Mountain Sickness, a Pilot Crossover Trial at 6000 Meters
This pilot study aims to evaluate the efficacy of positive expiratory pressure (PEP) therapy at 10 cmH₂O in improving peripheral oxygen saturation (SpO₂) and mitigating symptoms of acute mountain sickness (AMS) in healthy individuals exposed to extreme altitude conditions.
Three male participants will be monitored during an ascent of Mount Aconcagua, Argentina, at elevations of 4,300 m, 5,560 m, and 6,000 m above sea level. The study involves three sequential phases of 10 minutes each: baseline breathing without PEP, breathing with PEP applied via a mechanical face mask, and post-PEP breathing.
Primary outcomes include changes in SpO₂ and Lake Louise Score (LLS) to assess AMS severity. Findings will provide preliminary data on the potential role of PEP as a non-pharmacological intervention in high-altitude medicine.
- Conditions
- Acute Mountain Sickness (AMS)
- Being tested
- Positive Expiratory Pressure (10cmH2O) in hypobaric hypoxia
- Medical subject headings
- Altitude Sickness
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Positive Expiratory Pressure (10cmH2O) in hypobaric hypoxiaDevice
The intervention under investigation will be the application of positive expiratory pressure (PEP) at 10 cmH₂O using an Ambu mask. The mask will allow participants to inspire freely while generating a controlled expiratory pressure. The PEP device is a non-pharmacological medical device whose uses in both hospital and pre-hospital settings are part of everyday medical practice.
| Study group | Role | What they receive |
|---|---|---|
| Intervention | Experimental | Pilot trial of positive expiratory pressure for acute mountain sickness.
1 single arm with 3 phases:
* 1: Baseline Breathing (No PEP) Participants breathe normally without any device for 10 minutes in supine position, serving as control.
* 2: Positive Expiratory Pressure (PEP) Breathing Participants breathe through a face mask with a mechanical PEP device set at 10 cmH₂O expiratory pressure for 10 minutes supine. Inspiration is unrestricted; expiration occurs against resistance to improve oxygenation and reduce AMS symptoms.
* 3: Post-PEP Breathing (No PEP) After PEP, participants breathe normally for 10 minutes supine.
Each phase is consecutive at altitudes 4,300 m, 5,560 m, and 6,000 m Receives: Device: Positive Expiratory Pressure (10cmH2O) in hypobaric hypoxia |
What is being measured
The primary outcome is the main question the study is designed to answer.
Peripheral Oxygen Saturation (SpO2)
Measured: During the 3 weeks of expedition on Mount Aconcagua, after arrival of participants at 4300masl, 5560masl and 6000 masl.
Secondary outcomes (1)
Lake Louise Score
The Lake Louise Score (LLS) is a standardized tool to diagnose Acute Mountain Sickness (AMS). It combines self-reported symptoms (headache, gastrointestinal upset, fatigue/weakness, dizziness/lightheadedness) rated from 0 (none) to 3 (severe). AMS is diagnosed when headache is present plus at least one other symptom, with a total score ≥3. Higher scores reflect greater symptom severity: 3-5 mild AMS, 6-9 moderate, ≥10 severe. The LLS is used in research and expeditions to quantify altitude illness and monitor response to acclimatization or treatment.
Measured: During the 3 weeks of expedition on Mount Aconcagua, after arrival of participants at 4300masl, 5560masl and 6000 masl.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Aug 2025
- Study start5 Sep 2025 (estimated)
- Primary completion31 Dec 2025 (estimated)
- Study completion31 Dec 2025 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (15)Papers the sponsor has linked to this study.
- Other trials for Acute Mountain Sickness (AMS)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 3 participants (estimated)
Sponsor and investigators
- Lead sponsor
- BiALP - Alpine, Disaster and Wilderness Medicine
- Sponsor type
- University, hospital or other
- Collaborators
- Società Italiana Medicina degli Ambienti Estremi
- Responsible party
- Principal investigator, Paolo Rodi, BiALP - Alpine, Disaster and Wilderness Medicine
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07148674
- Sponsor's protocol ID
- 6962
- Status last verified
- Aug 2025
- First submitted
- 6 Aug 2025
- Last updated
- 29 Aug 2025
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Mellor A. Research at high altitudes. J R Army Med Corps. 2011 Mar;157(1):5-7. doi: 10.1136/jramc-157-01-01.
PubMed 21465903Wu J, Wu Y, Wang L, Ye H, Lu J, Li Y. Challenges and Advances in Rechargeable Batteries for Extreme-Condition Applications. Adv Mater. 2024 Jan;36(4):e2308193. doi: 10.1002/adma.202308193. Epub 2023 Nov 28.
PubMed 37847882Nespoulet H, Rupp T, Bachasson D, Tamisier R, Wuyam B, Levy P, Verges S. Positive expiratory pressure improves oxygenation in healthy subjects exposed to hypoxia. PLoS One. 2013 Dec 23;8(12):e85219. doi: 10.1371/journal.pone.0085219. eCollection 2013.
PubMed 24376872Johnson PL, Johnson CC, Poudyal P, Regmi N, Walmsley MA, Basnyat B. Continuous positive airway pressure treatment for acute mountain sickness at 4240 m in the Nepal Himalaya. High Alt Med Biol. 2013 Sep;14(3):230-3. doi: 10.1089/ham.2013.1015.
PubMed 24067184Rupp T, Saugy JJ, Bourdillon N, Verges S, Millet GP. Positive expiratory pressure improves arterial and cerebral oxygenation in acute normobaric and hypobaric hypoxia. Am J Physiol Regul Integr Comp Physiol. 2019 Nov 1;317(5):R754-R762. doi: 10.1152/ajpregu.00025.2019. Epub 2019 Sep 18.
PubMed 31530174Rupp T, Maufrais C, Walther G, Esteve F, Macdonald JH, Bouzat P, Verges S. MEDEX 2015: Prophylactic Effects of Positive Expiratory Pressure in Trekkers at Very High Altitude. Front Physiol. 2021 Sep 21;12:710622. doi: 10.3389/fphys.2021.710622. eCollection 2021.
PubMed 34621182Fagevik Olsen M, Lannefors L, Westerdahl E. Positive expiratory pressure - Common clinical applications and physiological effects. Respir Med. 2015 Mar;109(3):297-307. doi: 10.1016/j.rmed.2014.11.003. Epub 2014 Nov 12.
PubMed 25573419Gabry AL, Ledoux X, Mozziconacci M, Martin C. High-altitude pulmonary edema at moderate altitude (< 2,400 m; 7,870 feet): a series of 52 patients. Chest. 2003 Jan;123(1):49-53. doi: 10.1378/chest.123.1.49.
PubMed 12527602Agostoni P, Caldara G, Bussotti M, Revera M, Valentini M, Gregorini F, Faini A, Lombardi C, Bilo G, Giuliano A, Veglia F, Savia G, Modesti PA, Mancia G, Parati G; HIGHCARE Investigators. Continuous positive airway pressure increases haemoglobin O2 saturation after acute but not prolonged altitude exposure. Eur Heart J. 2010 Feb;31(4):457-63. doi: 10.1093/eurheartj/ehp472. Epub 2009 Nov 10.
PubMed 19903683Wang C, Wang X, Chi C, Guo L, Guo L, Zhao N, Wang W, Pi X, Sun B, Lian A, Shi J, Li E. Lung ventilation strategies for acute respiratory distress syndrome: a systematic review and network meta-analysis. Sci Rep. 2016 Mar 9;6:22855. doi: 10.1038/srep22855.
PubMed 26955891Roach RC, Hackett PH, Oelz O, Bartsch P, Luks AM, MacInnis MJ, Baillie JK; Lake Louise AMS Score Consensus Committee. The 2018 Lake Louise Acute Mountain Sickness Score. High Alt Med Biol. 2018 Mar;19(1):4-6. doi: 10.1089/ham.2017.0164. Epub 2018 Mar 13.
PubMed 29583031Luks AM, Beidleman BA, Freer L, Grissom CK, Keyes LE, McIntosh SE, Rodway GW, Schoene RB, Zafren K, Hackett PH. Wilderness Medical Society Clinical Practice Guidelines for the Prevention, Diagnosis, and Treatment of Acute Altitude Illness: 2024 Update. Wilderness Environ Med. 2024 Mar;35(1_suppl):2S-19S. doi: 10.1016/j.wem.2023.05.013. Epub 2023 Dec 27.
PubMed 37833187Woods P, Alcock J. High-altitude pulmonary edema. Evol Med Public Health. 2021 Jan 6;9(1):118-119. doi: 10.1093/emph/eoaa052. eCollection 2021.
PubMed 33732460Hackett PH, Rennie D, Levine HD. The incidence, importance, and prophylaxis of acute mountain sickness. Lancet. 1976 Nov 27;2(7996):1149-55. doi: 10.1016/s0140-6736(76)91677-9.
PubMed 62991Netzer N, Strohl K, Faulhaber M, Gatterer H, Burtscher M. Hypoxia-related altitude illnesses. J Travel Med. 2013 Jul-Aug;20(4):247-55. doi: 10.1111/jtm.12017. Epub 2013 Mar 11.
PubMed 23809076
Study at a glance
From the registry record, last updated by the sponsor on 29 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Efficacy of Positive Expiratory Pressure on Acute Mountain Sickness, a Pilot Crossover Trial at 6000 Meters
- ClinicalTrials.gov ID
- NCT07148674
- Acronym / sponsor ID
- 6962
- Conditions
- Acute Mountain Sickness (AMS)
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 3 participants (estimated)
- Lead sponsor
- BiALP - Alpine, Disaster and Wilderness MedicineUniversity, hospital or other
- Collaborators
- Società Italiana Medicina degli Ambienti Estremi
- Study start
- 5 Sep 2025 (estimated)
- Primary completion
- 31 Dec 2025 (estimated)
- Study completion
- 31 Dec 2025 (estimated)
- First posted
- 29 Aug 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This pilot study aims to evaluate the efficacy of positive expiratory pressure (PEP) therapy at 10 cmH₂O in improving peripheral oxygen saturation (SpO₂) and mitigating symptoms of acute mountain sickness (AMS) in healthy individuals exposed to extreme altitude conditions.
Three male participants will be monitored during an ascent of Mount Aconcagua, Argentina, at elevations of 4,300 m, 5,560 m, and 6,000 m above sea level. The study involves three sequential phases of 10 minutes each: baseline breathing without PEP, breathing with PEP applied via a mechanical face mask, and post-PEP breathing.
Primary outcomes include changes in SpO₂ and Lake Louise Score (LLS) to assess AMS severity. Findings will provide preliminary data on the potential role of PEP as a non-pharmacological intervention in high-altitude medicine.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Intervention | Experimental | Device: Positive Expiratory Pressure (10cmH2O) in hypobaric hypoxiaPilot trial of positive expiratory pressure for acute mountain sickness. 1 single arm with 3 phases: * 1: Baseline Breathing (No PEP) Participants breathe normally without any device for 10 minutes in supine position, serving as control. * 2: Positive Expiratory Pressure (PEP) Breathing Participants breathe through a face mask with a mechanical PEP device set at 10 cmH₂O expiratory pressure for 10 minutes supine. Inspiration is unrestricted; expiration occurs against resistance to improve oxygenation and reduce AMS symptoms. * 3: Post-PEP Breathing (No PEP) After PEP, participants breathe normally for 10 minutes supine. Each phase is consecutive at altitudes 4,300 m, 5,560 m, and 6,000 m |
Who may qualify
- Ages
- 18 to 99 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Healthy volunteers without ongoing medical conditions
- Over 18 years of age
- Volunteers with the physical and technical skills necessary to undertake a mountaineering expedition on Mount Aconcagua, Argentina, and with previous experience at extreme altitudes
Key exclusion criteria (3 listed)
- Subjects with any ongoing medical conditions
- Under 18 years of age
- Subjects without previous mountaineering experience at extreme altitudes and without adequate physical and technical preparation necessary to undertake a mountaineering expedition on Mount Aconcagua, Argentina
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Positive Expiratory Pressure (10cmH2O) in hypobaric hypoxiaThe intervention under investigation will be the application of positive expiratory pressure (PEP) at 10 cmH₂O using an Ambu mask. The mask will allow participants to inspire freely while generating a controlled expiratory pressure. The PEP device is a non-pharmacological medical device whose uses in both hospital and pre-hospital settings are part of everyday medical practice. | Device | Intervention |
Primary outcome
Peripheral Oxygen Saturation (SpO2)
Time frame: During the 3 weeks of expedition on Mount Aconcagua, after arrival of participants at 4300masl, 5560masl and 6000 masl.
1 secondary outcome
Lake Louise Score
Time frame: During the 3 weeks of expedition on Mount Aconcagua, after arrival of participants at 4300masl, 5560masl and 6000 masl.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Aug 2025.
- Background: PubMed 21465903Mellor A. Research at high altitudes. J R Army Med Corps. 2011 Mar;157(1):5-7. doi: 10.1136/jramc-157-01-01.
- Background: PubMed 37847882Wu J, Wu Y, Wang L, Ye H, Lu J, Li Y. Challenges and Advances in Rechargeable Batteries for Extreme-Condition Applications. Adv Mater. 2024 Jan;36(4):e2308193. doi: 10.1002/adma.202308193. Epub 2023 Nov 28.
- Background: PubMed 24376872Nespoulet H, Rupp T, Bachasson D, Tamisier R, Wuyam B, Levy P, Verges S. Positive expiratory pressure improves oxygenation in healthy subjects exposed to hypoxia. PLoS One. 2013 Dec 23;8(12):e85219. doi: 10.1371/journal.pone.0085219. eCollection 2013.
- Background: PubMed 24067184Johnson PL, Johnson CC, Poudyal P, Regmi N, Walmsley MA, Basnyat B. Continuous positive airway pressure treatment for acute mountain sickness at 4240 m in the Nepal Himalaya. High Alt Med Biol. 2013 Sep;14(3):230-3. doi: 10.1089/ham.2013.1015.
- Background: PubMed 31530174Rupp T, Saugy JJ, Bourdillon N, Verges S, Millet GP. Positive expiratory pressure improves arterial and cerebral oxygenation in acute normobaric and hypobaric hypoxia. Am J Physiol Regul Integr Comp Physiol. 2019 Nov 1;317(5):R754-R762. doi: 10.1152/ajpregu.00025.2019. Epub 2019 Sep 18.
- Background: PubMed 34621182Rupp T, Maufrais C, Walther G, Esteve F, Macdonald JH, Bouzat P, Verges S. MEDEX 2015: Prophylactic Effects of Positive Expiratory Pressure in Trekkers at Very High Altitude. Front Physiol. 2021 Sep 21;12:710622. doi: 10.3389/fphys.2021.710622. eCollection 2021.
- Background: PubMed 25573419Fagevik Olsen M, Lannefors L, Westerdahl E. Positive expiratory pressure - Common clinical applications and physiological effects. Respir Med. 2015 Mar;109(3):297-307. doi: 10.1016/j.rmed.2014.11.003. Epub 2014 Nov 12.
- Background: PubMed 12527602Gabry AL, Ledoux X, Mozziconacci M, Martin C. High-altitude pulmonary edema at moderate altitude (< 2,400 m; 7,870 feet): a series of 52 patients. Chest. 2003 Jan;123(1):49-53. doi: 10.1378/chest.123.1.49.
- Background: PubMed 19903683Agostoni P, Caldara G, Bussotti M, Revera M, Valentini M, Gregorini F, Faini A, Lombardi C, Bilo G, Giuliano A, Veglia F, Savia G, Modesti PA, Mancia G, Parati G; HIGHCARE Investigators. Continuous positive airway pressure increases haemoglobin O2 saturation after acute but not prolonged altitude exposure. Eur Heart J. 2010 Feb;31(4):457-63. doi: 10.1093/eurheartj/ehp472. Epub 2009 Nov 10.
- Background: PubMed 26955891Wang C, Wang X, Chi C, Guo L, Guo L, Zhao N, Wang W, Pi X, Sun B, Lian A, Shi J, Li E. Lung ventilation strategies for acute respiratory distress syndrome: a systematic review and network meta-analysis. Sci Rep. 2016 Mar 9;6:22855. doi: 10.1038/srep22855.
- Background: PubMed 29583031Roach RC, Hackett PH, Oelz O, Bartsch P, Luks AM, MacInnis MJ, Baillie JK; Lake Louise AMS Score Consensus Committee. The 2018 Lake Louise Acute Mountain Sickness Score. High Alt Med Biol. 2018 Mar;19(1):4-6. doi: 10.1089/ham.2017.0164. Epub 2018 Mar 13.
- Background: PubMed 37833187Luks AM, Beidleman BA, Freer L, Grissom CK, Keyes LE, McIntosh SE, Rodway GW, Schoene RB, Zafren K, Hackett PH. Wilderness Medical Society Clinical Practice Guidelines for the Prevention, Diagnosis, and Treatment of Acute Altitude Illness: 2024 Update. Wilderness Environ Med. 2024 Mar;35(1_suppl):2S-19S. doi: 10.1016/j.wem.2023.05.013. Epub 2023 Dec 27.
- Theoretical underpinningLink provided by the sponsor.
- Theoretical underpinningLink provided by the sponsor.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Questions about this trial
What is this clinical trial studying?
A study testing Positive Expiratory Pressure (10cmH2O) in hypobaric hypoxia in people with Acute Mountain Sickness (AMS), run by BiALP - Alpine, Disaster and Wilderness Medicine.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 29 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Paolo Rodi, MD (+41766992164, paolorodi95@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Peripheral Oxygen Saturation (SpO2) (time frame: During the 3 weeks of expedition on Mount Aconcagua, after arrival of participants at 4300masl, 5560masl and 6000 masl.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07148674, which also lists 15 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Aug 2025.