The Impact of Carbon Monoxide and Altitude on Vascular Function

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

NA

Total Enrollment

19 participants

Study Classification

INTERVENTIONAL

Study Start Date

2021-06-10

Study Completion Date

2022-05-18

Brief Summary

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The CarMA (Carbon Monoxide and Altitude) Study aims to observe the vascular effects of carbon monoxide exposure at low and high altitudes.

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Detailed Description

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Each year, millions of people make journeys from low altitude regions to high altitude for recreation, travel, and religious pilgrimage. Carbon monoxide (CO) is commonly associated with cigarette smoke, exhaust fumes, and is viewed as a life-threatening toxic gas. Exposure to CO occurs during travel to and during activities common in high-altitude travel and pilgrimage including vehicle fumes, incense, and second-hand smoke exposure. High altitude exposure and CO exposure have been observed independently to have complex and opposing effects on vascular endothelial function. Observation of these stimuli together in a controlled environment may allow for further understanding of the underlying mechanisms of vascular physiology and adaptations to both high-altitude and CO exposure. The CarMA (Carbon Monoxide and Altitude) Study aims to observe the vascular effects of carbon monoxide exposure at low and high altitudes. Recently, other studies have showed a significant improvement in flow mediated dilation (FMD) with acute exposure to low levels of CO To date, no research has been presented concerning the effect of CO on vascular function at altitude. The present study aims to observe the effect of acute carbon monoxide exposure on 1) flow mediated dilation, 2) conduit artery flow in exercise induced reactive hyperemia at sea level and at altitude, and 3) the effect of CO on vascular function in a high altitude dwelling (sherpa) population.

Conditions

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Vasodilation Vasoconstriction

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

CROSSOVER

Participants will partake in both room air and CO exposure on 2 separate visits.

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

SINGLE

Participants

Participant will not be aware of which rebreathe treatment (CO or Room Air) they are receiving.

Study Groups

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Room Air Rebreathe

Rebreathe protocol will be completed with a room air syringe rather than CO

Group Type SHAM_COMPARATOR

Sodium Nitroprusside

Intervention Type DRUG

Bolus Sodium Nitroprusside (SNP) injection for endothelium-independent vasodilation measure

Phenylephrine Hydrochloride

Intervention Type DRUG

Bolus Phenylephrine injection for observe α1-mediated vasoconstriction during mild exercise

CO Rebreathe

Rebreathe protocol will be completed with Carbon Monoxide

Group Type EXPERIMENTAL

Carbon monoxide rebreathe

Intervention Type OTHER

Carbon monoxide exposure to increase blood (Carboxyhemoglobin) COHb safely to \~10%

Sodium Nitroprusside

Intervention Type DRUG

Bolus Sodium Nitroprusside (SNP) injection for endothelium-independent vasodilation measure

Phenylephrine Hydrochloride

Intervention Type DRUG

Bolus Phenylephrine injection for observe α1-mediated vasoconstriction during mild exercise

Interventions

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Carbon monoxide rebreathe

Carbon monoxide exposure to increase blood (Carboxyhemoglobin) COHb safely to \~10%

Intervention Type OTHER

Sodium Nitroprusside

Bolus Sodium Nitroprusside (SNP) injection for endothelium-independent vasodilation measure

Intervention Type DRUG

Phenylephrine Hydrochloride

Bolus Phenylephrine injection for observe α1-mediated vasoconstriction during mild exercise

Intervention Type DRUG

Other Intervention Names

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Schmidt-Prommer blood volume test Nipride

Eligibility Criteria

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Inclusion Criteria

* Between the ages of 18-50 years
* No medical history of cardiovascular, respiratory, nervous system, or metabolic disease.
* Women must be pre-menopausal.

Exclusion Criteria

* Participants with any known cardiovascular, respiratory, nervous system, or metabolic disease.
* Having travelled above 2,000m within 1 month of testing at low and high altitude.
* Women who are pregnant, confirmed by a pregnancy test.
* Women who are post-menopausal.
* Participants that are classified as obese (body mass index \> 30 kg/m2).
* Participants who are current daily smokers.
* Participants that are currently taking monoamine (MAO) inhibitors, or tricyclic antidepressants.

Minimum Eligible Age

18 Years

Maximum Eligible Age

50 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes