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Clinical Trial Details — Status: Completed

Administrative data

NCT number NCT04928183
Other study ID # Pro00096251
Secondary ID
Status Completed
Phase N/A
First received
Last updated
Start date June 10, 2021
Est. completion date May 18, 2022

Study information

Verified date June 2021
Source University of Alberta
Contact n/a
Is FDA regulated No
Health authority
Study type Interventional

Clinical Trial Summary

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


Description:

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.


Recruitment information / eligibility

Status Completed
Enrollment 19
Est. completion date May 18, 2022
Est. primary completion date August 1, 2021
Accepts healthy volunteers Accepts Healthy Volunteers
Gender All
Age group 18 Years to 50 Years
Eligibility 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.

Study Design


Related Conditions & MeSH terms


Intervention

Other:
Carbon monoxide rebreathe
Carbon monoxide exposure to increase blood (Carboxyhemoglobin) COHb safely to ~10%
Drug:
Sodium Nitroprusside
Bolus Sodium Nitroprusside (SNP) injection for endothelium-independent vasodilation measure
Phenylephrine Hydrochloride
Bolus Phenylephrine injection for observe a1-mediated vasoconstriction during mild exercise

Locations

Country Name City State
Canada University of Alberta Edmonton Alberta

Sponsors (1)

Lead Sponsor Collaborator
University of Alberta

Country where clinical trial is conducted

Canada, 

References & Publications (5)

Basnyat B. High altitude pilgrimage medicine. High Alt Med Biol. 2014 Dec;15(4):434-9. doi: 10.1089/ham.2014.1088. Review. — View Citation

Choi BG, Lee J, Kim SW, Lee MW, Baek MJ, Ryu YG, Choi SY, Byun JK, Mashaly A, Park Y, Jang WY, Kim W, Choi JY, Park EJ, Na JO, Choi CU, Lim HE, Kim EJ, Park CG, Seo HS, Oh DJ, Rha SW. The association of chronic air pollutants with coronary artery spasm, vasospastic angina, and endothelial dysfunction. Coron Artery Dis. 2018 Jun;29(4):336-343. doi: 10.1097/MCA.0000000000000603. — View Citation

Rezk-Hanna M, Mosenifar Z, Benowitz NL, Rader F, Rashid M, Davoren K, Moy NB, Doering L, Robbins W, Sarna L, Li N, Chang LC, Elashoff RM, Victor RG. High Carbon Monoxide Levels from Charcoal Combustion Mask Acute Endothelial Dysfunction Induced by Hookah (Waterpipe) Smoking in Young Adults. Circulation. 2019 May 7;139(19):2215-2224. doi: 10.1161/CIRCULATIONAHA.118.037375. — View Citation

Tymko MM, Tremblay JC, Bailey DM, Green DJ, Ainslie PN. The impact of hypoxaemia on vascular function in lowlanders and high altitude indigenous populations. J Physiol. 2019 Dec;597(24):5759-5776. doi: 10.1113/JP277191. Epub 2019 Nov 28. Review. — View Citation

Weber LP, Al-Dissi A, Marit JS, German TN, Terletski SD. Role of carbon monoxide in impaired endothelial function mediated by acute second-hand tobacco, incense, and candle smoke exposures. Environ Toxicol Pharmacol. 2011 May;31(3):453-9. doi: 10.1016/j.etap.2011.02.008. Epub 2011 Feb 26. — View Citation

Outcome

Type Measure Description Time frame Safety issue
Primary Change in brachial artery diameter (assessed via ultrasound) following release of arterial occlusion Change in brachial artery diameter (assessed via ultrasound) following release of arterial occlusion 15 minutes
Primary Blood flow within the brachial artery during rhythmic handgrip exercise. Blood flow within the brachial artery during rhythmic handgrip exercise. 15 minutes
Primary Change in brachial artery conductance following an infusion of phenylephrine Change in brachial artery conductance following an infusion of phenylephrine 5 min
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