The Impact of Carbon Monoxide and Altitude on Vascular Function

Vasodilation Clinical Trial

— CarMA  

Official title:

The Impact of Carbon Monoxide and Altitude on Vascular Function

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT04928183
• Other study ID #: Pro00096251
• Status: Completed
• Phase: N/A
• 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
• 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.

Related Conditions & MeSH terms

• Vasoconstriction
• Vasodilation

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