Healthy Volunteers
Conditions
Brief summary
During alveolar hypoxia, for example at high altitude or in patients with respiratory disease, there is evidence to suggest that hypoxia-induced pulmonary hypertension might limit exercise performance. Intravenous iron supplementation has recently been shown to reverse pulmonary hypertension in healthy humans at high altitude, and to prevent pulmonary hypertension in volunteers exposed to hypoxia at sea level. The investigators hypothesized that intravenous iron supplementation would enhance exercise capacity during alveolar hypoxia.
Interventions
DRUGIron sucrose.
Volunteers will receive an intravenous infusion of 200 mg iron sucrose, before exposure to 8 hours of alveolar hypoxia. At the end of the exposure, pulmonary artery systolic pressure will be measured and volunteers will undertake an exercise test while breathing hypoxic gas.
DRUGNormal saline
Volunteers will receive an intravenous infusion of 100 ml normal saline, before exposure to 8 hours of alveolar hypoxia. At the end of the exposure, pulmonary artery systolic pressure will be measured and volunteers will undertake an exercise test while breathing hypoxic gas.
Sponsors
University of Oxford
Study design
Allocation
NON_RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
18 Years to 60 Years
Healthy volunteers
Yes
Inclusion criteria
* Age between 18 and 60 years * Sea level natives with no recent exposure to high altitude * Baseline iron indices within the normal range * Detectable tricuspid regurgitation on echocardiography
Exclusion criteria
* Significant cardiorespiratory disease * Known susceptibility to high altitude-related illness * Taking medications or iron supplementation * Pregnancy
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Maximal exercise capacity during hypoxia, assessed by maximal oxygen consumption. | After 8-h exposure to alveolar hypoxia. | Volunteers will receive either intravenous iron or saline placebo, before exposure to 8 hours of alveolar hypoxia. They will then undergo an exercise test while breathing an hypoxic gas mixture. The primary outcome measure will be exercise capacity as determined by maximal oxygen consumption during this test. Volunteers will receive both interventions, via a crossover design. Due to uncertainty about the duration of action of iron at a cellular level, all volunteers will receive saline infusion on the first study day, and iron sucrose infusion on a second study day, at least one week later. |
Secondary
| Measure | Time frame |
|---|---|
| Maximal exercise capacity, assessed by peak power output. | After 8-h exposure to alveolar hypoxia. |
| Pulmonary artery systolic pressure. | After 8-h exposure to alveolar hypoxia. |
| Blood levels of oxygen-regulated proteins. | After 8-h exposure to alveolar hypoxia |
Countries
United Kingdom
Outcome results
None listed