Acute Mountain Sickness, High Altitude, Inhalation; Gas
Conditions
Keywords
Acute mountain sickness, CO2 inhalation, central sleep apnea
Brief summary
It was reported that up to 76% people who rapidly ascend to the altitude higher than 4500 m without sufficient acclimatization will have AMS which often develops 6-8 hours after reaching at high altitude. AMS could be improved if there is no continuous ascent although central sleep apnea may persist much longer. It has also been well documented that exercise capacity was impaired at high altitude. Oxygen inhalation is the most effective treatment method, but it is impractical for outdoor activities because of the large volume required. There are some drugs such as acetazolamide, and ibuprofen for relieving AMS but side effects and inconsistent treatment effect made them to be difficulty for routine use. It is noted that adding CO2 might be useful for improvement of hypoxia and exercise ability and eliminating CSA. There is no available device which can accurately supply constant CO2 and is functionally free of dead space. We innovated a portable device with a special mask for supplement of CO2 for prophylaxis and treatment of AMS.
Detailed description
Objective: To determine whether, after rapid ascent to high altitude the device could reduce the incidence and severity of AMS as defined by AMS scores, improve sleep quality and reduce central sleep apnea events. Methods: A randomized placebo-controlled study will be performed in 36 healthy adults with no history of travelling to high altitude (\>1000m) a year before the study. Subjects will be randomly and blindly given either CO2 mixed with air or air alone during daytime and sleep. Blood gases will be measured 30 minutes after inhalation of air or CO2. SaO2, heart rate, and respiratory rate will be recorded every two hours. AMS (Lake Louise Acute Mountain Sickness Score) will be recorded before and after sleep. PSG including diaphragm EMG would be recorded under CO2 or air. Exercise time, ventilation heart rate, respiratory rate, and SaO2 will be recorded and maximal load and peak ventilation will be measured during incremental cycle exercise with inhalation of CO2 or ambient air.
Interventions
DEVICEBreathing with CO2 during daytime and night at high altitude
Subjects wear the mask connecting to low dose CO2 supplied by a novel device during daytime and sleep dependent on the randomization once arriving high altitude.
DEVICESleep and doing exercise test under inhalation of air
Subjects wear the mask connecting to air supplied by the novel device during daytime and sleep dependent on the randomization once arriving high altitude.
Sponsors
State Key Laboratory of Respiratory Disease
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
18 Years to 70 Years
Healthy volunteers
Yes
Inclusion criteria
1. BMI less than 25kg/m2 2. normal lung function. 3. Healthy lowlanders (\<500m) who have no history to travel to high altitude (\>1000m) a year before the study.
Exclusion criteria
1. insomnia, 2. moderate or severe OSA based on PSG at sea level (AHI\> 15 events/hr). 3. visited to an altitude \>2500 m in the preceding year. 4. Currently using medicines for diabetes, hypertension et al.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Incidence rate of acute mountain sickness (AMS) | 72 hours | Incidence rate of AMS based on Louis's scores under inhalation of CO2 and ambient air. The maximum score is 12 points, and a score greater than 3 indicates the presence of AMS. |
| The severity of AMS | 72 hours | The severity of AMS based on Louis's scores under inhalation of CO2 and ambient air. A score of 3-5 indicates mild AMS, a score of 6-9 indicates moderate AMS and a score of 10-12 indicates severe AMS. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Central sleep apnea index based on PSG | 72 hours | Changes of central sleep apnea index under inhalation of CO2 and ambient air. |
| Sleep quality based on PSG | 72 hours | Changes of sleep quality under inhalation of CO2 and ambient air. |
| Workload in the incremental ergometer test | 72 hours | Changes of workload in the incremental ergometer test under inhalation of CO2 and ambient air. |
| Exercise duration in the incremental ergometer test | 72 hours | Changes of exercise duration in the incremental ergometer test under inhalation of CO2 and ambient air. |
Countries
China
Outcome results
None listed