High AltitudeNCT06446427
The Effect of Acute High Altitude Exposure on Rescuer Performance and Patient Care
A study testing Acute high altitude exposure, Acute high altitude exposure, with supplementary oxygen and Subacute high altitude exposure, after having spent a night at high altitude in people with High Altitude and Hypobaric Hypoxia, run by Insel Gruppe AG, University Hospital Bern at 2 sites in Switzerland.
Trial summary
Rescue services in mountainous regions are frequently called to missions at altitudes >3000 m. Under the difficult conditions of acute exposure to altitude, the crews then have to undertake demanding medical and rescue measures. Read more about this study
- Who is it for?
- Ages 18 to 80 yearsHealthy volunteers can take part
- Conditions the study is for
- High Altitude, Hypobaric Hypoxia, Risk Reduction
- What is being tested?
- Acute high altitude exposure, Acute high altitude exposure, with supplementary oxygen and Subacute high altitude exposure, after having spent a night at high altitude
- How many people
- 20 participants
- Where
- 2 sitesSwitzerland
- Study dates
- 2 Aug 2024to 3 Jul 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 80 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Medical doctors with certification and experience in preclinical emergency medicine, defined as (all must apply):
- 2 or more years of training in anaesthesiology
- 3 or more months of preclinical work
- 50 or more cases as the lead preclinical physician with potential danger to the patient's life (with a National Advisory Committee for Aeronautics score (NACA) of 4 or more)
- A valid preclinical certification (Swiss "Notarztkurs" or similar)
- Written informed consent to participate in the study
Who cannot join
- Any medical condition known to place the participant at higher risk for hypoxia-induced adverse events (cardiovascular, pulmonary, neurological, otherwise).
- Pre-acclimatisation to high altitude, defined as travel to above 2500 m in the 4 weeks previous to the study
Trial locations and contacts
2 sites in 1 country.
Switzerland2 sites
Berner Simulations- und CPR-Zentrum BeSiC
Bern, 3010
High Altitude Research Station Jungfraujoch
Bern, 3012
About this study
Rescue services in mountainous regions are frequently called to missions at altitudes >3000 m. Under the difficult conditions of acute exposure to altitude, the crews then have to undertake demanding medical and rescue measures. Previous studies in non-medical personnel, such as astronauts, aircraft pilots, and military helicopter pilots have found that the lack of oxygen associated with acute exposure to altitude may impair cognitive functions. No data exists on the effect this may have on the performance of medical staff in terms of patient examination, communication, decision-making, planning, and overall patient care. This study aims to close this knowledge gap. The investigators of this study aim to make rescue missions to high altitude safer for both the patients and the rescuers.
To assess the effect of high altitude on patient care, the investigators recruit highly trained medical specialists who will perform patient care in simulated scenarios both at high altitude and at low altitude. These scenarios will be recorded and the performance of the medical specialists judged by independent reviewers.
The medical specialists will also perform in simulated scenarios at high altitude two more times: once with supplementary oxygen, and once after spending a night at high altitude. the investigators do this to evaluate whether supplementary oxygen improves their performance, and whether symptoms of acute mountain sickness (which usually develop after spending the first night at high altitude) decreases their performance further.
Read the detailed description
Rescue services in mountainous regions are frequently called to missions at altitudes >3000 m. Under the difficult conditions of acute exposure to altitude, the crews then have to undertake demanding medical and rescue measures, such as an emergency induction of anaesthesia, resuscitation, treatment of polytraumatized patients, or a winch manoeuvre by helicopter in exposed, fall-prone terrain.
The exponential decrease in barometric pressure at altitude results in hypobaric hypoxia (HH), leading to a reduction in the partial pressure of oxygen at every point along the oxygen transport chain from the ambient air to tissue mitochondria. If the body's adaptive mechanisms fail to compensate for the lack of oxygen, symptoms like headache, nausea, fatigue, and dizziness may occur. In addition, HH may impair higher cortical functions. Individuals affected by high altitude frequently do not recognise a decline in cognitive function and overall performance, which can lead to incidents and even fatal consequences.
Previous studies in non-medical personnel, such as astronauts, aircraft pilots, and military helicopter pilots have explored the influence of HH on multiple cognitive domains. Impairment of working memory was described during hypoxia awareness trainings and in pilots while others reported no effects. Some studies have reported reduced psychomotor vigilance, while others found no effects. To counteract these impairments, the European Union Aviation Safety Agency (EASA) mandates simulated hypoxia training for pilots flying rescue missions to above 4000 m.
Studies in medical personnel are few and mostly focused on the quality of cardiopulmonary resuscitation (CPR) at (simulated) high altitude. High-quality CPR, which can be physically demanding for rescuers even under normoxic conditions, leads to rescuer fatigue faster under HH. Two recent studies have shown that HH leads to a lower quality of CPR at simulated and natural high altitude. A smaller study found simulated altitude to have a negative effect on the quality of ventilation but not on chest compression. A recent study reported a slower reaction time in medical personnel at simulated high altitude. Particularly noteworthy is the fact that rescuers did neither notice the reduced cognitive function nor the decreased quality of CPR they provided under HH, even though they were highly trained helicopter emergency medical services personnel. To the investigators' knowledge, CPR at high altitude has only been studied as an isolated skill. No data exist on the performance of medical staff in terms of patient examination, communication, decision-making, planning, and overall patient care. This study aims to close this knowledge gap. The findings of this study may help to broaden the understanding of HH, and lay the ground for further research in high altitude rescue.
As the primary endpoint of this study, the investigators evaluate medical performance and patient care using validated scores for medical skills and non-technical skills (Modified Simulation Team Assessment Tool (STAT), Concise Assessment of Leader Management (CALM), Team Emergency Assessment Measure (TEAM). These three scores are averaged (25% STAT, 25% CALM, 50% TEAM) to form a composite score. Scores are assessed by an analysis of video recordings of the simulated scenarios by independent outside assessors.
Secondary endpoints are described in detail elsewhere. They involve the measurement of reaction speed, risk assessment ability, cognitive function, the presence/absence of acute mountain sickness (AMS), the self-assessment of cognitive capacity, and basic vital functions. The concrete tests and measurements the investigators imply are:
- Psychomotor Vigilance Test (PVT)
- Balloon Analogue Risk Task (BART)
- Digit Symbol Substitution Test (DSST)
- Lake Louis Score (LLS), AMS is present at a score of three or higher
- Self-Assessment of Cognitive Capacity on a scale of 1-10
- Heart rate, Blood-pressure, peripheral blood oxygen saturation (SpO2) as measured by non-invasive means
The investigators will assess medical performance (and all other tests and measurements mentioned above) at four time points (baseline, interventions 1-3).
Testing at 30 minutes after arrival by train at high altitude (the High Altitude Research Station Jungfraujoch, 3450 m, "intervention 1") and at low altitude (Bern, 540 m, "baseline") are performed to answer the main hypothesis; whether acute rescuer exposure to high altitude impairs patient care.
To answer the additional research questions, additional testing will be performed at high altitude 4 hours after arrival with supplemental oxygen (4 litres/min, nasal) ("intervention 2") and after spending the night at 3450 m ("intervention 4").
At the four time points of measurement, the participants will have to run through one of the following four scenarios of simulated patient care:
- A polytraumatised 35 y.o. patient who fell 12 metres. Adequate treatment will entail: anamnesis, immobilisation of the cervical spine, treatment of a tension pneumothorax, installation of analgosedation.
- A 64 y.o. patient with acute abdominal pain and nausea due to an acute myocardial infarction. Adequate treatment will entail: Anamnesis, performing and interpreting a 12-lead electrocardiogram, resuscitation.
- A 35 y.o. mother with her 5 m.o. child who is experiencing a seizure. Adequate treatment will entail: Anamnesis, treatment of the epileptic seizure, recognition of impeding respiratory failure and consequent assisted ventilation.
- A 19 y.o. hypothermic patient. Adequate treatment will entail: Anamnesis, recognition of likely hypothermia and taking measures to avoid afterdrop, resuscitation according to hypothermia protocols, adequate care after return of spontaneous circulation.
All four scenarios are designed to be of equal difficulty. However, the order of the scenarios is randomised electronically before the start of the study, so that different participants go through different scenarios at all points of measurements (baseline, interventions 1-3). This is done to avoid skewing of performance due to some scenarios being inadvertently more difficult or easier than others.
Before each scenario, the participants undergo all tests and measurements outlined above (PVT, BART, DSST, LLS, Self-Assessment of Cognitive Capacity on a scale of 1-10, Heart rate, Blood-pressure, peripheral blood oxygen saturation).
Supplemental application of oxygen during intervention 2 might bias the participants. Therefore, they will receive air via nasal cannula at the same flow rate during all other scenarios (baseline, interventions 1 and 3) in the sense of a "placebo administration".
- Conditions
- High Altitude, Hypobaric Hypoxia, Risk Reduction
- Being tested
- Acute high altitude exposure, Acute high altitude exposure, with supplementary oxygen, Subacute high altitude exposure, after having spent a night at high altitude
- Keywords
- High Altitude, Hypobaric Hypoxia, Patient Care, Patient Safety, Rescuer Safety, Emergency Medicine, Anaesthesia
- Medical subject headings
- Altitude Sickness, Risk Reduction Behavior
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Acute high altitude exposureOther
Also called Intervention 1
Thirty minutes after arrival at the Research Station Jungfraujoch by train, a simulated scenario of patient care ("intervention 1", high altitude at 3450 masl) is performed.
Acute high altitude exposure, with supplementary oxygenOther
Also called Intervention 2
4 hours after arrival at the Research Station Jungfraujoch by train, a simulated scenario of patient care ("intervention 2", high altitude at 3450 masl) is performed, while the participants receive 4 litres / minute of oxygen via nasal route.
Subacute high altitude exposure, after having spent a night at high altitudeOther
Also called Intervention 3
After having spent a night at the Research Station Jungfraujoch, a simulated scenario of patient care ("Intervention 3", high altitude at 3450 masl) is performed.
What is being measured
The primary outcome is the main question the study is designed to answer.
The effect of acute high altitude exposure on medical performance, measured by the STAT score
The investigators asses the quality of patient care at low and high altitude exposure.
The primary outcome of the study - a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT) - will be analysed by means of a linear mixed-effect regression model to account for the longitudinal study design. In particular, each of the four time points represents a fixed effect (implemented with a factor variable) and a random offset for each participants is included in the model allowing to represent the repeated measurements and associated covariance structure.
The analysis of the primary endpoint - the difference in the composite score between baseline and after acute altitude exposure (intervention 1) - will be performed by assessing the pairwise contrast of the estimated marginal means of the linear mixed-effect regression model.
Measured: Baseline, intervention 1 (30 minutes after arriving at high altitude)
The effect of acute high altitude exposure on medical performance, measured by the CALM score
The investigators asses the quality of patient care at low and high altitude exposure.
The primary outcome of the study - a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT) - will be analysed by means of a linear mixed-effect regression model to account for the longitudinal study design. In particular, each of the four time points represents a fixed effect (implemented with a factor variable) and a random offset for each participants is included in the model allowing to represent the repeated measurements and associated covariance structure.
The analysis of the primary endpoint - the difference in the composite score between baseline and after acute altitude exposure (intervention 1) - will be performed by assessing the pairwise contrast of the estimated marginal means of the linear mixed-effect regression model.
Measured: Baseline, intervention 1 (30 minutes after arriving at high altitude)
The effect of acute high altitude exposure on medical performance, measured by the TEAM score
The investigators asses the quality of patient care at low and high altitude exposure.
The primary outcome of the study - a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT) - will be analysed by means of a linear mixed-effect regression model to account for the longitudinal study design. In particular, each of the four time points represents a fixed effect (implemented with a factor variable) and a random offset for each participants is included in the model allowing to represent the repeated measurements and associated covariance structure.
The analysis of the primary endpoint - the difference in the composite score between baseline and after acute altitude exposure (intervention 1) - will be performed by assessing the pairwise contrast of the estimated marginal means of the linear mixed-effect regression model.
Measured: Baseline, intervention 1 (30 minutes after arriving at high altitude)
Secondary outcomes (5)
The effect of supplementary oxygen on medical performance during acute high altitude exposure, measured as a composite of STAT, CALM, and TEAM scores
The investigators asses any changes to the quality of patient care when participants receive supplementary oxygen during acute high altitude exposure. Since acute effects of high altitude exposure are mainly due to hypobaric hypoxia, supplementary oxygen might improve patient care. Patient care is measured through a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT).
The investigators use the same linear mixed-effect regression model as described under the primary outcome for the assessment of this outcome, but comparing intervention 2 (4 hours after arrival at high altitude, with supplementary oxygen) to baseline) and intervention 1 (at 30 minutes after arrival at high altitude).
Measured: Baseline, intervention 1 (30 minutes after arriving at high altitude), intervention 2 (4 hours after arriving at high altitude, with supplementary oxygen)
The effect of subacute high altitude exposure on medical performance, measured as a composite of STAT, CALM, and TEAM scores
The investigators asses the quality of patient care under subacute high altitude exposure, i.e. after having spent a night at high altitude. At the altitude at which the study takes place, 30-40% of participants are expected to develop mild to moderate symptoms of acute mountain sickness, which might impair the quality of patient care they provide. The presence and severity of AMS will be assessed by the Lake Louis Score. AMS is present at a score of 3 or higher. Patient care is measured through a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT).
The investigators use the same linear mixed-effect regression model as described under the primary outcome for the assessment of this outcome, but comparing intervention 3 (after having spent a night at high altitude, no supplementary oxygen) to baseline and intervention 1 (at 30 minutes after arrival at high altitude).
Measured: Baseline, intervention 1 (30 minutes after arriving at high altitude), intervention 3 (after having spent a night at high altitude)
The effect of gender and age on medical performance during low altitude, acute and subacute high altitude exposure, measured as a composite of STAT, CALM, and TEAM scores
The impact of age and sex on medical performance during all points of testing (baseline, interventions 1-3) will be analysed by including the interactions of two variables (age and sex) with the fixed effect (representing the four time points) in the linear mixed-effect regression model described under the primary outcome. The statistical significance of the interaction will be assessed with a likelihood ratio test.
Patient care is measured through a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT).
Measured: Baseline, intervention 1 (30 minutes after arriving at high altitude), intervention 2 (4 hours after arriving at high altitude, with supplementary oxygen), intervention 3 (after having spent a night at high altitude)
The correlations between psychomotor test results (PVT, BART, DSST, self-assessment of cognitive function) and medical performance during low altitude, acute and subacute high altitude exposure, measured as a composite of STAT, CALM, and TEAM scores
Cognitive functions, such as measured by the psychomotor tests the investigators imply, can be impaired by high altitude exposure. The Psychomotor Vigilance Test (PVT) measures reaction speed in milliseconds. The Balloon Analogue Risk Task (BART) measures risk-taking behaviour in three numerical outcome variables. The Digit Symbol Substitution Test (DSST) measures cognitive performance and has a number of correct answers the participant found as its outcome. Participants will also self-assess their cognitive function on a scale of 1 to 10.
The investigators will look for statistical correlations between the results of psychomotor testing (PVT, BART, DSST) and the self-assessment of cognitive capacity, and the quality of patient care at all four time points (baseline, interventions 1-3). Patient care is measured through a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT).
Measured: Baseline, intervention 1 (30 minutes after arriving at high altitude), intervention 2 (4 hours after arriving at high altitude, with supplementary oxygen), intervention 3 (after having spent a night at high altitude)
The correlations between vital parameters (blood pressure, heart rate, peripheral blood oxygen saturation) and medical performance during low altitude, acute and subacute high altitude exposure, measured as a composite of STAT, CALM, and TEAM scores
The investigators will measure basic vital parameters of participants (blood pressure, heart rate, and peripheral blood oxygen saturation) by non-invasive means at all time points of testing (baseline, interventions 1-3). They will look for correlations between those parameters and the medical performance. Patient care is measured through a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT).
Measured: Baseline, intervention 1 (30 minutes after arriving at high altitude), intervention 2 (4 hours after arriving at high altitude, with supplementary oxygen), intervention 3 (after having spent a night at high altitude)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Jun 2024
- Study start2 Aug 2024
- Primary completion9 Feb 2025
- Study completion3 Jul 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (36)Papers the sponsor has linked to this study.
- Other trials for High AltitudeStudies of the same condition, open and under way.
- More trials run by Insel Gruppe AG, University Hospital BernThe sponsor's other registered studies.
- 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
- Health services research
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- The investigators imply a repeated measures design. A group of 20 participants will perform in simulated medical scenarios sequentially under four different circumstances (baseline, interventions 1-3)
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- Insel Gruppe AG, University Hospital Bern
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Juergen Knapp, PD, MD, Principal investigator, University Hospital of Bern (Inselspital), Department of Anaesthesiology and Pain Medicine
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06446427
- Sponsor's protocol ID
- 2024-00237
- Status last verified
- Dec 2024
- First submitted
- 15 May 2024
- Last updated
- 29 Apr 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: No individual participant data (IPD) will be shared in the primary publication(s). IPD can be made available at a reasonable request.
Publications
Luks 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 37833187McMorris T, Hale BJ, Barwood M, Costello J, Corbett J. Effect of acute hypoxia on cognition: A systematic review and meta-regression analysis. Neurosci Biobehav Rev. 2017 Mar;74(Pt A):225-232. doi: 10.1016/j.neubiorev.2017.01.019. Epub 2017 Jan 19.
PubMed 28111267Shaw DM, Cabre G, Gant N. Hypoxic Hypoxia and Brain Function in Military Aviation: Basic Physiology and Applied Perspectives. Front Physiol. 2021 May 17;12:665821. doi: 10.3389/fphys.2021.665821. eCollection 2021.
PubMed 34093227Bouak F, Vartanian O, Hofer K, Cheung B. Acute Mild Hypoxic Hypoxia Effects on Cognitive and Simulated Aircraft Pilot Performance. Aerosp Med Hum Perform. 2018 Jun 1;89(6):526-535. doi: 10.3357/AMHP.5022.2018.
PubMed 29789086Falla M, Hufner K, Falk M, Weiss EM, Vogele A, Jan van Veelen M, Weber B, Brandner J, Palma M, Dejaco A, Brugger H, Strapazzon G. Simulated Acute Hypobaric Hypoxia Effects on Cognition in Helicopter Emergency Medical Service Personnel - A Randomized, Controlled, Single-Blind, Crossover Trial. Hum Factors. 2024 Feb;66(2):404-423. doi: 10.1177/00187208221086407. Epub 2022 May 31.
PubMed 35640630Walsh JJ, Drouin PJ, King TJ, D'Urzo KA, Tschakovsky ME, Cheung SS, Day TA. Acute aerobic exercise impairs aspects of cognitive function at high altitude. Physiol Behav. 2020 Sep 1;223:112979. doi: 10.1016/j.physbeh.2020.112979. Epub 2020 May 29.
PubMed 32479806Bolmont B, Thullier F, Abraini JH. Relationships between mood states and performances in reaction time, psychomotor ability, and mental efficiency during a 31-day gradual decompression in a hypobaric chamber from sea level to 8848 m equivalent altitude. Physiol Behav. 2000 Dec;71(5):469-76. doi: 10.1016/s0031-9384(00)00362-0.
PubMed 11239664Kryskow MA, Beidleman BA, Fulco CS, Muza SR. Performance during simple and complex military psychomotor tasks at various altitudes. Aviat Space Environ Med. 2013 Nov;84(11):1147-52. doi: 10.3357/asem.3245.2013.
PubMed 24279227Narahara H, Kimura M, Suto T, Saito H, Tobe M, Aso C, Nishihara F, Saito S. Effects of cardiopulmonary resuscitation at high altitudes on the physical condition of untrained and unacclimatized rescuers. Wilderness Environ Med. 2012 Jun;23(2):161-4. doi: 10.1016/j.wem.2012.02.001.
PubMed 22656663Niederer M, Tscherny K, Burger J, Wandl B, Fuhrmann V, Kienbacher CL, Schreiber W, Herkner H, Roth D, Egger A. Influence of high altitude after a prior ascent on physical exhaustion during cardiopulmonary resuscitation: a randomised crossover alpine field experiment. Scand J Trauma Resusc Emerg Med. 2023 Oct 24;31(1):59. doi: 10.1186/s13049-023-01132-7.
PubMed 37875893Sato T, Takazawa T, Inoue M, Tada Y, Suto T, Tobe M, Saito S. Cardiorespiratory dynamics of rescuers during cardiopulmonary resuscitation in a hypoxic environment. Am J Emerg Med. 2018 Sep;36(9):1561-1564. doi: 10.1016/j.ajem.2018.01.029. Epub 2018 Jan 8.
PubMed 29352676Suto T, Saito S, Tobe M, Kanamoto M, Matsui Y. Reduction of Arterial Oxygen Saturation Among Rescuers During Cardiopulmonary Resuscitation in a Hypobaric Hypoxic Environment. Wilderness Environ Med. 2020 Mar;31(1):97-100. doi: 10.1016/j.wem.2019.10.008. Epub 2020 Feb 7.
PubMed 32044210Egger A, Niederer M, Tscherny K, Burger J, Fuhrmann V, Kienbacher C, Roth D, Schreiber W, Herkner H. Influence of physical strain at high altitude on the quality of cardiopulmonary resuscitation. Scand J Trauma Resusc Emerg Med. 2020 Mar 6;28(1):19. doi: 10.1186/s13049-020-0717-0.
PubMed 32143653Vogele A, van Veelen MJ, Dal Cappello T, Falla M, Nicoletto G, Dejaco A, Palma M, Hufner K, Brugger H, Strapazzon G. Effect of Acute Exposure to Altitude on the Quality of Chest Compression-Only Cardiopulmonary Resuscitation in Helicopter Emergency Medical Services Personnel: A Randomized, Controlled, Single-Blind Crossover Trial. J Am Heart Assoc. 2021 Dec 7;10(23):e021090. doi: 10.1161/JAHA.121.021090. Epub 2021 Dec 2.
PubMed 34854317Carballo-Fazanes A, Barcala-Furelos R, Eiroa-Bermudez J, Fernandez-Mendez M, Abelairas-Gomez C, Martinez-Isasi S, Murciano M, Fernandez-Mendez F, Rodriguez-Nunez A. Physiological demands of quality cardiopulmonary resuscitation performed at simulated 3250 meters high. Am J Emerg Med. 2020 Dec;38(12):2580-2585. doi: 10.1016/j.ajem.2019.12.048. Epub 2019 Dec 24.
PubMed 31911060
Study at a glance
From the registry record, last updated by the sponsor on 29 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Acute High Altitude Exposure on Rescuer Performance and Patient Care
- ClinicalTrials.gov ID
- NCT06446427
- Acronym / sponsor ID
- 2024-00237
- Conditions
- High Altitude, Hypobaric Hypoxia, Risk Reduction
- Keywords
- High Altitude, Hypobaric Hypoxia, Patient Care, Patient Safety, Rescuer Safety, Emergency Medicine, Anaesthesia
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 20 participants (actual)
- Lead sponsor
- Insel Gruppe AG, University Hospital BernUniversity, hospital or other
- Study start
- 2 Aug 2024 (actual)
- Primary completion
- 9 Feb 2025 (actual)
- Study completion
- 3 Jul 2025 (actual)
- First posted
- 6 Jun 2024 (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.
Rescue services in mountainous regions are frequently called to missions at altitudes >3000 m. Under the difficult conditions of acute exposure to altitude, the crews then have to undertake demanding medical and rescue measures. Previous studies in non-medical personnel, such as astronauts, aircraft pilots, and military helicopter pilots have found that the lack of oxygen associated with acute exposure to altitude may impair cognitive functions. No data exists on the effect this may have on the performance of medical staff in terms of patient examination, communication, decision-making, planning, and overall patient care. This study aims to close this knowledge gap. The investigators of this study aim to make rescue missions to high altitude safer for both the patients and the rescuers.
To assess the effect of high altitude on patient care, the investigators recruit highly trained medical specialists who will perform patient care in simulated scenarios both at high altitude and at low altitude. These scenarios will be recorded and the performance of the medical specialists judged by independent reviewers.
The medical specialists will also perform in simulated scenarios at high altitude two more times: once with supplementary oxygen, and once after spending a night at high altitude. the investigators do this to evaluate whether supplementary oxygen improves their performance, and whether symptoms of acute mountain sickness (which usually develop after spending the first night at high altitude) decreases their performance further.
Detailed description
Rescue services in mountainous regions are frequently called to missions at altitudes >3000 m. Under the difficult conditions of acute exposure to altitude, the crews then have to undertake demanding medical and rescue measures, such as an emergency induction of anaesthesia, resuscitation, treatment of polytraumatized patients, or a winch manoeuvre by helicopter in exposed, fall-prone terrain.
The exponential decrease in barometric pressure at altitude results in hypobaric hypoxia (HH), leading to a reduction in the partial pressure of oxygen at every point along the oxygen transport chain from the ambient air to tissue mitochondria. If the body's adaptive mechanisms fail to compensate for the lack of oxygen, symptoms like headache, nausea, fatigue, and dizziness may occur. In addition, HH may impair higher cortical functions. Individuals affected by high altitude frequently do not recognise a decline in cognitive function and overall performance, which can lead to incidents and even fatal consequences.
Previous studies in non-medical personnel, such as astronauts, aircraft pilots, and military helicopter pilots have explored the influence of HH on multiple cognitive domains. Impairment of working memory was described during hypoxia awareness trainings and in pilots while others reported no effects. Some studies have reported reduced psychomotor vigilance, while others found no effects. To counteract these impairments, the European Union Aviation Safety Agency (EASA) mandates simulated hypoxia training for pilots flying rescue missions to above 4000 m.
Studies in medical personnel are few and mostly focused on the quality of cardiopulmonary resuscitation (CPR) at (simulated) high altitude. High-quality CPR, which can be physically demanding for rescuers even under normoxic conditions, leads to rescuer fatigue faster under HH. Two recent studies have shown that HH leads to a lower quality of CPR at simulated and natural high altitude. A smaller study found simulated altitude to have a negative effect on the quality of ventilation but not on chest compression. A recent study reported a slower reaction time in medical personnel at simulated high altitude. Particularly noteworthy is the fact that rescuers did neither notice the reduced cognitive function nor the decreased quality of CPR they provided under HH, even though they were highly trained helicopter emergency medical services personnel. To the investigators' knowledge, CPR at high altitude has only been studied as an isolated skill. No data exist on the performance of medical staff in terms of patient examination, communication, decision-making, planning, and overall patient care. This study aims to close this knowledge gap. The findings of this study may help to broaden the understanding of HH, and lay the ground for further research in high altitude rescue.
As the primary endpoint of this study, the investigators evaluate medical performance and patient care using validated scores for medical skills and non-technical skills (Modified Simulation Team Assessment Tool (STAT), Concise Assessment of Leader Management (CALM), Team Emergency Assessment Measure (TEAM). These three scores are averaged (25% STAT, 25% CALM, 50% TEAM) to form a composite score. Scores are assessed by an analysis of video recordings of the simulated scenarios by independent outside assessors.
Secondary endpoints are described in detail elsewhere. They involve the measurement of reaction speed, risk assessment ability, cognitive function, the presence/absence of acute mountain sickness (AMS), the self-assessment of cognitive capacity, and basic vital functions. The concrete tests and measurements the investigators imply are:
- Psychomotor Vigilance Test (PVT)
- Balloon Analogue Risk Task (BART)
- Digit Symbol Substitution Test (DSST)
- Lake Louis Score (LLS), AMS is present at a score of three or higher
- Self-Assessment of Cognitive Capacity on a scale of 1-10
- Heart rate, Blood-pressure, peripheral blood oxygen saturation (SpO2) as measured by non-invasive means
The investigators will assess medical performance (and all other tests and measurements mentioned above) at four time points (baseline, interventions 1-3).
Testing at 30 minutes after arrival by train at high altitude (the High Altitude Research Station Jungfraujoch, 3450 m, "intervention 1") and at low altitude (Bern, 540 m, "baseline") are performed to answer the main hypothesis; whether acute rescuer exposure to high altitude impairs patient care.
To answer the additional research questions, additional testing will be performed at high altitude 4 hours after arrival with supplemental oxygen (4 litres/min, nasal) ("intervention 2") and after spending the night at 3450 m ("intervention 4").
At the four time points of measurement, the participants will have to run through one of the following four scenarios of simulated patient care:
- A polytraumatised 35 y.o. patient who fell 12 metres. Adequate treatment will entail: anamnesis, immobilisation of the cervical spine, treatment of a tension pneumothorax, installation of analgosedation.
- A 64 y.o. patient with acute abdominal pain and nausea due to an acute myocardial infarction. Adequate treatment will entail: Anamnesis, performing and interpreting a 12-lead electrocardiogram, resuscitation.
- A 35 y.o. mother with her 5 m.o. child who is experiencing a seizure. Adequate treatment will entail: Anamnesis, treatment of the epileptic seizure, recognition of impeding respiratory failure and consequent assisted ventilation.
- A 19 y.o. hypothermic patient. Adequate treatment will entail: Anamnesis, recognition of likely hypothermia and taking measures to avoid afterdrop, resuscitation according to hypothermia protocols, adequate care after return of spontaneous circulation.
All four scenarios are designed to be of equal difficulty. However, the order of the scenarios is randomised electronically before the start of the study, so that different participants go through different scenarios at all points of measurements (baseline, interventions 1-3). This is done to avoid skewing of performance due to some scenarios being inadvertently more difficult or easier than others.
Before each scenario, the participants undergo all tests and measurements outlined above (PVT, BART, DSST, LLS, Self-Assessment of Cognitive Capacity on a scale of 1-10, Heart rate, Blood-pressure, peripheral blood oxygen saturation).
Supplemental application of oxygen during intervention 2 might bias the participants. Therefore, they will receive air via nasal cannula at the same flow rate during all other scenarios (baseline, interventions 1 and 3) in the sense of a "placebo administration".
Study design
- Primary purpose
- Health services research
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- Double blind (participant, outcomes assessor)
- Model description
- The investigators imply a repeated measures design. A group of 20 participants will perform in simulated medical scenarios sequentially under four different circumstances (baseline, interventions 1-3)
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- Medical doctors with certification and experience in preclinical emergency medicine, defined as (all must apply):
- 2 or more years of training in anaesthesiology
- 3 or more months of preclinical work
- 50 or more cases as the lead preclinical physician with potential danger to the patient's life (with a National Advisory Committee for Aeronautics score (NACA) of 4 or more)
- A valid preclinical certification (Swiss "Notarztkurs" or similar)
Key exclusion criteria (2 listed)
- Any medical condition known to place the participant at higher risk for hypoxia-induced adverse events (cardiovascular, pulmonary, neurological, otherwise).
- Pre-acclimatisation to high altitude, defined as travel to above 2500 m in the 4 weeks previous to the study
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 |
|---|---|---|
| Acute high altitude exposureAlso: Intervention 1Thirty minutes after arrival at the Research Station Jungfraujoch by train, a simulated scenario of patient care ("intervention 1", high altitude at 3450 masl) is performed. | Other | – |
| Acute high altitude exposure, with supplementary oxygenAlso: Intervention 24 hours after arrival at the Research Station Jungfraujoch by train, a simulated scenario of patient care ("intervention 2", high altitude at 3450 masl) is performed, while the participants receive 4 litres / minute of oxygen via nasal route. | Other | – |
| Subacute high altitude exposure, after having spent a night at high altitudeAlso: Intervention 3After having spent a night at the Research Station Jungfraujoch, a simulated scenario of patient care ("Intervention 3", high altitude at 3450 masl) is performed. | Other | – |
Primary outcome
The effect of acute high altitude exposure on medical performance, measured by the STAT score
Time frame: Baseline, intervention 1 (30 minutes after arriving at high altitude)
The investigators asses the quality of patient care at low and high altitude exposure. The primary outcome of the study - a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT) - will be analysed by means of a linear mixed-effect regression model to account for the longitudinal study design. In particular, each of the four time points represents a fixed effect (implemented with a factor variable) and a random offset for each participants is included in the model allowing to represent the repeated measurements and associated covariance structure. The analysis of the primary endpoint - the difference in the composite score between baseline and after acute altitude exposure (intervention 1) - will be performed by assessing the pairwise contrast of the estimated marginal means of the linear mixed-effect regression model.
The effect of acute high altitude exposure on medical performance, measured by the CALM score
Time frame: Baseline, intervention 1 (30 minutes after arriving at high altitude)
The investigators asses the quality of patient care at low and high altitude exposure. The primary outcome of the study - a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT) - will be analysed by means of a linear mixed-effect regression model to account for the longitudinal study design. In particular, each of the four time points represents a fixed effect (implemented with a factor variable) and a random offset for each participants is included in the model allowing to represent the repeated measurements and associated covariance structure. The analysis of the primary endpoint - the difference in the composite score between baseline and after acute altitude exposure (intervention 1) - will be performed by assessing the pairwise contrast of the estimated marginal means of the linear mixed-effect regression model.
The effect of acute high altitude exposure on medical performance, measured by the TEAM score
Time frame: Baseline, intervention 1 (30 minutes after arriving at high altitude)
The investigators asses the quality of patient care at low and high altitude exposure. The primary outcome of the study - a composite score comprising three previously validated scores (25% CALM, 25% TEAM, 50% STAT) - will be analysed by means of a linear mixed-effect regression model to account for the longitudinal study design. In particular, each of the four time points represents a fixed effect (implemented with a factor variable) and a random offset for each participants is included in the model allowing to represent the repeated measurements and associated covariance structure. The analysis of the primary endpoint - the difference in the composite score between baseline and after acute altitude exposure (intervention 1) - will be performed by assessing the pairwise contrast of the estimated marginal means of the linear mixed-effect regression model.
5 secondary outcomes
The effect of supplementary oxygen on medical performance during acute high altitude exposure, measured as a composite of STAT, CALM, and TEAM scores
Time frame: Baseline, intervention 1 (30 minutes after arriving at high altitude), intervention 2 (4 hours after arriving at high altitude, with supplementary oxygen)
The effect of subacute high altitude exposure on medical performance, measured as a composite of STAT, CALM, and TEAM scores
Time frame: Baseline, intervention 1 (30 minutes after arriving at high altitude), intervention 3 (after having spent a night at high altitude)
The effect of gender and age on medical performance during low altitude, acute and subacute high altitude exposure, measured as a composite of STAT, CALM, and TEAM scores
Time frame: Baseline, intervention 1 (30 minutes after arriving at high altitude), intervention 2 (4 hours after arriving at high altitude, with supplementary oxygen), intervention 3 (after having spent a night at high altitude)
The correlations between psychomotor test results (PVT, BART, DSST, self-assessment of cognitive function) and medical performance during low altitude, acute and subacute high altitude exposure, measured as a composite of STAT, CALM, and TEAM scores
Time frame: Baseline, intervention 1 (30 minutes after arriving at high altitude), intervention 2 (4 hours after arriving at high altitude, with supplementary oxygen), intervention 3 (after having spent a night at high altitude)
The correlations between vital parameters (blood pressure, heart rate, peripheral blood oxygen saturation) and medical performance during low altitude, acute and subacute high altitude exposure, measured as a composite of STAT, CALM, and TEAM scores
Time frame: Baseline, intervention 1 (30 minutes after arriving at high altitude), intervention 2 (4 hours after arriving at high altitude, with supplementary oxygen), intervention 3 (after having spent a night at high altitude)
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Apr 2026.
- 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.
- Background: PubMed 28111267McMorris T, Hale BJ, Barwood M, Costello J, Corbett J. Effect of acute hypoxia on cognition: A systematic review and meta-regression analysis. Neurosci Biobehav Rev. 2017 Mar;74(Pt A):225-232. doi: 10.1016/j.neubiorev.2017.01.019. Epub 2017 Jan 19.
- Background: PubMed 34093227Shaw DM, Cabre G, Gant N. Hypoxic Hypoxia and Brain Function in Military Aviation: Basic Physiology and Applied Perspectives. Front Physiol. 2021 May 17;12:665821. doi: 10.3389/fphys.2021.665821. eCollection 2021.
- Background: PubMed 29789086Bouak F, Vartanian O, Hofer K, Cheung B. Acute Mild Hypoxic Hypoxia Effects on Cognitive and Simulated Aircraft Pilot Performance. Aerosp Med Hum Perform. 2018 Jun 1;89(6):526-535. doi: 10.3357/AMHP.5022.2018.
- Background: PubMed 35640630Falla M, Hufner K, Falk M, Weiss EM, Vogele A, Jan van Veelen M, Weber B, Brandner J, Palma M, Dejaco A, Brugger H, Strapazzon G. Simulated Acute Hypobaric Hypoxia Effects on Cognition in Helicopter Emergency Medical Service Personnel - A Randomized, Controlled, Single-Blind, Crossover Trial. Hum Factors. 2024 Feb;66(2):404-423. doi: 10.1177/00187208221086407. Epub 2022 May 31.
- Background: PubMed 32479806Walsh JJ, Drouin PJ, King TJ, D'Urzo KA, Tschakovsky ME, Cheung SS, Day TA. Acute aerobic exercise impairs aspects of cognitive function at high altitude. Physiol Behav. 2020 Sep 1;223:112979. doi: 10.1016/j.physbeh.2020.112979. Epub 2020 May 29.
- Background: PubMed 11239664Bolmont B, Thullier F, Abraini JH. Relationships between mood states and performances in reaction time, psychomotor ability, and mental efficiency during a 31-day gradual decompression in a hypobaric chamber from sea level to 8848 m equivalent altitude. Physiol Behav. 2000 Dec;71(5):469-76. doi: 10.1016/s0031-9384(00)00362-0.
- Background: PubMed 24279227Kryskow MA, Beidleman BA, Fulco CS, Muza SR. Performance during simple and complex military psychomotor tasks at various altitudes. Aviat Space Environ Med. 2013 Nov;84(11):1147-52. doi: 10.3357/asem.3245.2013.
- Background: PubMed 22656663Narahara H, Kimura M, Suto T, Saito H, Tobe M, Aso C, Nishihara F, Saito S. Effects of cardiopulmonary resuscitation at high altitudes on the physical condition of untrained and unacclimatized rescuers. Wilderness Environ Med. 2012 Jun;23(2):161-4. doi: 10.1016/j.wem.2012.02.001.
- Background: PubMed 37875893Niederer M, Tscherny K, Burger J, Wandl B, Fuhrmann V, Kienbacher CL, Schreiber W, Herkner H, Roth D, Egger A. Influence of high altitude after a prior ascent on physical exhaustion during cardiopulmonary resuscitation: a randomised crossover alpine field experiment. Scand J Trauma Resusc Emerg Med. 2023 Oct 24;31(1):59. doi: 10.1186/s13049-023-01132-7.
- Background: PubMed 29352676Sato T, Takazawa T, Inoue M, Tada Y, Suto T, Tobe M, Saito S. Cardiorespiratory dynamics of rescuers during cardiopulmonary resuscitation in a hypoxic environment. Am J Emerg Med. 2018 Sep;36(9):1561-1564. doi: 10.1016/j.ajem.2018.01.029. Epub 2018 Jan 8.
- Background: PubMed 32044210Suto T, Saito S, Tobe M, Kanamoto M, Matsui Y. Reduction of Arterial Oxygen Saturation Among Rescuers During Cardiopulmonary Resuscitation in a Hypobaric Hypoxic Environment. Wilderness Environ Med. 2020 Mar;31(1):97-100. doi: 10.1016/j.wem.2019.10.008. Epub 2020 Feb 7.
- Individual participant dataSharing planned: No. No individual participant data (IPD) will be shared in the primary publication(s). IPD can be made available at a reasonable request.
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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. This study is not recruiting at the moment.
Juergen Knapp, PD, MD principal investigator
University Hospital of Bern (Inselspital), Department of Anaesthesiology and Pain Medicine
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Acute high altitude exposure, Acute high altitude exposure, with supplementary oxygen and Subacute high altitude exposure, after having spent a night at high altitude in people with High Altitude and Hypobaric Hypoxia, run by Insel Gruppe AG, University Hospital Bern at 2 sites in Switzerland.
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 6 inclusion and 2 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: finished, as of the sponsor's last update on 29 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
The effect of acute high altitude exposure on medical performance, measured by the STAT score (time frame: Baseline, intervention 1 (30 minutes after arriving at high altitude)). The study lists 3 primary outcomes in all. 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 NCT06446427, which also lists 36 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 Apr 2026.