HighCycle Study: Acetazolamide, High Altitude and Plasma Volume
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Acetazolamide, Placebo.
- Who it may be relevant to
- Registry conditions: High Altitude Effects, High Altitude Hypoxia, Acute Mountain Sickness (AMS), Plasma Volume. Basic parameters: 18 years — 44 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Kyrgyzstan
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
HighCycle Study: Effect of Acetazolamide on Plasma Volume During Acute Exposure to High Altitude in Women and Men
Overview
Each year, millions of people living at low altitude (\< 1,000 m) travel to high altitude (≥ 2,500 m) for work, tourism, or sports activities. These individuals are exposed to hypobaric hypoxia, which can trigger acute mountain sickness (AMS)-the most common form of altitude-related illness. Therefore, understanding the physiological responses to hypoxia that allow acclimatization, as well as the pathophysiology of acute mountain sickness, is of primary importance. The hematological response to high-altitude exposure initially includes a reduction in plasma volume (PV), leading to an early increase in hemoglobin concentration within the first 24 hours. In contrast, an increase in hemoglobin mass requires several weeks at high altitude. Recent well-controlled physiological studies conducted in hypobaric chambers have demonstrated that this hypoxia-induced PV contraction results from fluid redistribution from the intravascular to the extravascular compartment, rather than from water loss due to increased diuresis. Prophylaxis of AMS is primarily based on the administration of 250 mg/day of acetazolamide (ACZ), a carbonic anhydrase inhibitor with a mild diuretic effect. Acetazolamide induces metabolic acidosis, which stimulates ventilation and thereby improves oxygenation. The effect of prophylactic ACZ use during high-altitude exposure on PV in lowlanders remains unknown: it is unclear whether ACZ leads to a greater reduction in PV due to its diuretic effect, or to a smaller hypoxia-induced PV contraction as a result of improved oxygenation induced by increased ventilation.
Detailed description
Not provided
Interventions
- Drug Acetazolamide
Administration of 1x125mg acetazolamide in the morning, 1x125mg in the evening, starting 24 hours before departure to 3600 m. - Drug Placebo
Administration of equally looking placebo capsules in the morning and in the evening, starting 24 hours before departure to 3600 m.
Primary outcome measures
- Plasma volume [Time frame: Day 1 at 760 m then Day 2 and Day 3 at 3,600 m.]
Secondary outcome measures (4)
- Plasma volume : sex-related difference [Time frame: Day 1 at 760 m then Day 2 and Day 3 at 3600 m.]
- Plasma volume : AMS-related difference [Time frame: Day 1 at 760 m then Day 2 and Day 3 at 3600 m.]
- Hormones [Time frame: Day 2 at 760 m and Day 2 at 3600 m.]
- Arterial blood gases [Time frame: Day 2 at 760 m and Day 2 at 3600 m.]
Eligibility criteria
Inclusion criteria
- Healthy, non-smoking men and women, age 18-44 years, without any disease and need of regular medication (including oral contraceptives).
- BMI >18 kg/m2 and <30 kg/m2.
- Born, raised and currently living at altitudes <1000 m.
- Written informed consent.
- Premenopausal women with an eumenorrheic cycle.
Exclusion criteria
- Other types of contraceptvies (contraceptives (hormonal intrauterine device, vaginal ring, subcutaneous injections or implants, among others).
- Pregnancy or nursing
- Anaemic (haemoglobin concentration <10g/dl).
- Any altitude trip <4 weks before the study.
- Allergy to acetazolamide and other sulfonamides.
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Allocation
- Randomized
- Model
- Parallel assignment
- Masking
- Quadruple blind
- Primary purpose
- Basic science
Study locations
Kyrgyzstan · 1 center
- National Center for Cardiology and Internal Medicine — Bishkek
Identifiers
NCT: NCT07118462 · HighCycle_PV