Cognition at Altitude in HEMS - Part II

Study Overview
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Brief Summary
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The aim of the current study is to evaluate under blinded conditions, both in a simulated environment and during helicopter flight, the effect of a rapid (within 20 minutes) exposure to altitude (4000 m asl) on physiological parameters and selected cognitive domains, in providers operating in helicopter emergency medical service (HEMS) exposed to hypobaric hypoxia or to hypobaric normoxia (H0: cognitive effects under hypobaric hypoxia = cognitive effects under hypobaric normoxia). Simulated environment will allow to control different factors. The parallelism between a study branch conducted in a simulated environment and another one conducted under a real-life condition will allow to evaluate the additive effects on additional stressor factors (processive and systemic ones). Simulation branch: each participant will take part in three research sessions: a familiarization session and two experimental sessions in simulation facility called terraXcube (test 1 and 2). On test 1 and test 2 each group will be exposed twice to the simulated altitude of 4000 m asl (under hypobaric hypoxia or hypobaric normoxia conditions) according to the randomization protocol. Participants will perform the neurocognitive tests three times on each of the two tests: before the ascent (TC0), after 5 min from the end of the ascent (TC1) and after around 30 min (TC2), to investigate European Union Aviation Safe Agency (EASA) proposed recommendations. After completing each neurocognitive test session, participants will be asked to rate their performance using a visual analogue scales (VAS). All participants will wear the vital parameters monitoring system during the entire duration of the tests inside the chamber, as well as the cerebral oxygen saturation (ScO2) sensor. Samples will be collected by saliva, urine and/or capillary blood. The same schedule is repeated in each test session. In-field branch: each participant will take part in three research sessions: a familiarization session and two experimental sessions during helicopter flights (test 1 and 2). On test 1 and test 2 each group will be exposed twice to the altitude of 4000 m (under hypobaric hypoxia or hypobaric normoxia conditions) according to the randomization protocol. Participants will perform the neurocognitive test two times on each test: before the ascent (TC0), after around 5 min from the end of the ascent (TC1). After completing each neurocognitive tests, participants will be asked to rate their performance using a visual analogue scales (VAS). All participants will wear the vital parameters monitoring system during the entire duration of the tests. Samples will be collected. The same schedule is planned in each test session.

Official Title
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Cognitive Performance After Acute Exposure to Altitude - Part II

Conditions
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Emergency Medicine, Hypobaric Hypoxia, Hypobaric Normoxia, Cognitive Performance, Stress Physiology

Intervention / Treatment
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* Other: Altitude exposure in hypobaric normoxic condition
* Other: Altitude exposure in hypobaric hypoxic condition


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: members of emergency medical services (EMS) and search and rescue (SAR) services with an occupational licence; an age between 18 and 60 years; an American Society of Anaesthesiologists (ASA) physical status class I; provided informed and written consent; no current COVID 19 symptoms and temperature ≤ 37.5°on test days, not being tested positive for COVID-19, ideally COVID-19 vaccinated. Exclusion Criteria: members under the age of 18 years; an ASA physical status class II or more; a medical history of psychiatric disorders and neurological diseases; previous high altitude pulmonary oedema (HAPE) or high altitude cerebral oedema (HACE) or severe acute mountain sickness (AMS) (defined as a Lake Louise Score (LLS) > 9) occurred at altitudes similar to the ones tested in the study; no informed consent; current COVID 19 symptoms, being tested positive for COVID-19 or symptoms and body temperature ≥ 37.5°on test days.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 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: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Interventional, non-pharmacological, randomized, controlled, double-blinded, cross-over
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Hypobaric normoxia<br>Altitude exposure in hypobaric normoxic condition | Other: Altitude exposure in hypobaric normoxic condition<br>* Altitude exposure with oxygen supplementation to achieve normoxia at altitude<br>|
| Sham Comparator: Hypobaric hypoxia<br>Altitude exposure in hypobaric hypoxic condition | Other: Altitude exposure in hypobaric hypoxic condition<br>* Altitude exposure with air supplementation to obtain a sham comparator arm<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Psychomotor Vigilance Test - PVT | Changes in reaction time using a computer-based test (PVT) | Changes from baseline (T0) to altitude measurement (respectively after 5 min - T1 and after 30 min - T2) | 
| Digit-Symbol Substitution Task - DSST | Changing in processing speed using a computer based test (DSST) | Changes from baseline (TC0) to altitude measurement (respectively after 5 min - TC1 and after 30 min - TC2) | 
| 2-back Test | Changing in working memory using a computer based test (2-back test) | Changes from baseline (TC0) to altitude measurement (respectively after 5 min - TC1 and after 30 min - TC2) |