Effects of Iron on Exercise Capacity During Hypoxia

University of Oxford12 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

NON_RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Enrollment

Conditions

Healthy Volunteers

Interventions

Iron sucrose.DRUG

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.

Normal salineDRUG

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.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 60 YearsHealthy volunteers:

Medical Language ↔ Plain English

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

Locations (1)

Department of Physiology, Anatomy & Genetics, University of Oxford

Oxford, United Kingdom

Outcomes

Primary Outcomes

Maximal exercise capacity during hypoxia, assessed by maximal oxygen consumption.

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.

Time frame: After 8-h exposure to alveolar hypoxia.

Secondary Outcomes

Maximal exercise capacity, assessed by peak power output.

Time frame: After 8-h exposure to alveolar hypoxia.

Pulmonary artery systolic pressure.

Time frame: After 8-h exposure to alveolar hypoxia.

Blood levels of oxygen-regulated proteins.

Time frame: After 8-h exposure to alveolar hypoxia

Data from ClinicalTrials.gov

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