The Effects of Intermittent Hypoxia on Acute Hypoxic Injury

Study Overview
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Brief Summary
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This study intends to further reveal the effectiveness of intermittent hypoxia in preventing acute hypoxic injury.

Detailed Description
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Acute exposure to hypoxia can induce acute hypoxic injury (AHI), according to the severity of the injury, it can be divided into acute mountain sickness (AMS), high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). AMS is the most common type, it mostly occurs within 6-12 hours after rapidly entering the altitude above 2500m, sometimes within 1h, and can be manifested as headache, nausea, diarrhea, sleep disorders, etc. The incidence of AMS at the altitude of 2500-3000m is 10-20%, which reaches 50-85% at 4500-5000m above sea level. Intermittent hypoxia (IH) refers to periodic hypoxic-normoxic training performed with brief exposure to hypoxia. Previous studies have found that short-term intermittent hypoxia can increase the sensitivity of hypoxia and reduce the severity of acute hypoxia injury, and alleviate acute hypoxia injury by reducing the inflammatory response caused by hypoxia. Therefore, this study aims to conduct a randomized controlled trial to further reveal the effectiveness of IH and explore its potential mechanisms.

Official Title
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The Effects of Intermittent Hypoxia on Acute Hypoxic Injury

Conditions
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Acute Mountain Sickness

Intervention / Treatment
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* Other: Intermittent Hypoxia
* Other: Sham Intermittent Hypoxia


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Informed written consent from the volunteers. Healthy volunteers between ages of 18 and 45 years, body mass index (BMI) of 19.0 and 24.9 kg/m2. Long-term residence at flatland (altitude of <100 m), not having been to an altitude ≥1500 m in 30 days. Resting peripheral oxygen saturation of more than 90%, cerebral oxygen saturation between 58%-82%, heart rate between 60 bpm and 100 bpm, and blood pressure within the normal range (90-130/60-80 mmHg). Exclusion Criteria: History of cardiovascular, cerebrovascular, pulmonary, hepatic, dermatologic, or hematologic diseases. History of substance abuse. The use of medications or medical devices. Pregnancy, hypertension, diabetes mellitus, obesity, sleep apnea and neurological disorders.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 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
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: IH group<br>Participants will receive 10 times intermittent hypoxia (oxygen concentration: 13%) intervention before exposure to acute hypoxia environment. | Other: Intermittent Hypoxia<br>* The intermittent hypoxia protocol refers to four cycles of 10 minutes hypoxia inhaling interval by 5 minutes normoxia, which is performed twice a day (at least 6 hours apart) in 5 days.<br>|
| Sham Comparator: Control group<br>Participants will receive 10 times sham-hypoxia (oxygen concentration: 21%) intervention in 5 days before exposure to acute hypoxia environment. | Other: Sham Intermittent Hypoxia<br>* The sham intermittent hypoxia protocol refers to 55 minutes normoxia inhaling, which is performed twice a day (at least 6 hours apart) in 5 days.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of acute mountain sickness between IH group and control group | A questionnaire called 2018 Lake Louise Scoring System (LLSS) score [0-12] will be used in this primary outcome assessment. The higher LLS scores mean the worse symptoms of acute mountain sickness (AMS). | After the 6-hour acute hypoxia exposuring. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Concentration of serum parameters between IH group and control group |  | After the 6-hour acute hypoxia exposuring. | 
| Incidence of intracranial hypertension between IH group and control group | A noninvasive cranial pressure detector will be used to monitor the intracranial pressure. | After the 6-hour acute hypoxia exposuring. | 
| Incidence of decreased reaction and executive ability between IH group and control group | Related questionnaires will be used to assess the relevant cognitive domain. | After the 6-hour acute hypoxia exposuring. |