VasodilationCarMANCT04928183
The Impact of Carbon Monoxide and Altitude on Vascular Function
A study testing Carbon monoxide rebreathe, Sodium Nitroprusside and Phenylephrine Hydrochloride in people with Vasodilation and Vasoconstriction, run by University of Alberta at 1 site in Canada.
Trial summary
The CarMA (Carbon Monoxide and Altitude) Study aims to observe the vascular effects of carbon monoxide exposure at low and high altitudes. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Vasodilation, Vasoconstriction
- What is being tested?
- Carbon monoxide rebreathe, Sodium Nitroprusside and Phenylephrine Hydrochloride
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 19 participants
- Where
- 1 siteCanada
- Study dates
- 10 Jun 2021to 18 May 2022
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Between the ages of 18-50 years
- No medical history of cardiovascular, respiratory, nervous system, or metabolic disease.
- Women must be pre-menopausal.
Who cannot join
- 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.
Trial locations and contacts
1 site in 1 country.
About this study
The CarMA (Carbon Monoxide and Altitude) Study aims to observe the vascular effects of carbon monoxide exposure at low and high altitudes.
Read the detailed 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.
- Conditions
- Vasodilation, Vasoconstriction
- Being tested
- Carbon monoxide rebreathe, Sodium Nitroprusside, Phenylephrine Hydrochloride
- Medical subject headings
- Aneurysm
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Carbon monoxide rebreatheOther
Also called Schmidt-Prommer blood volume test
Carbon monoxide exposure to increase blood (Carboxyhemoglobin) COHb safely to ~10%
Sodium NitroprussideDrug
Also called Nipride
Bolus Sodium Nitroprusside (SNP) injection for endothelium-independent vasodilation measure
Phenylephrine HydrochlorideDrug
Bolus Phenylephrine injection for observe α1-mediated vasoconstriction during mild exercise
| Study group | Role | What they receive |
|---|---|---|
| Room Air Rebreathe | Sham comparator | Rebreathe protocol will be completed with a room air syringe rather than CO Receives: Drug: Sodium Nitroprusside; Drug: Phenylephrine Hydrochloride |
| CO Rebreathe | Experimental | Rebreathe protocol will be completed with Carbon Monoxide Receives: Other: Carbon monoxide rebreathe; Drug: Sodium Nitroprusside; Drug: Phenylephrine Hydrochloride |
What is being measured
The primary outcome is the main question the study is designed to answer.
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
Measured: 15 minutes
Blood flow within the brachial artery during rhythmic handgrip exercise.
Blood flow within the brachial artery during rhythmic handgrip exercise.
Measured: 15 minutes
Change in brachial artery conductance following an infusion of phenylephrine
Change in brachial artery conductance following an infusion of phenylephrine
Measured: 5 min
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 Jun 2021
- Study start10 Jun 2021
- Primary completion1 Aug 2021
- Study completion18 May 2022
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for VasodilationStudies of the same condition, open and under way.
- More trials run by University of AlbertaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Participants will partake in both room air and CO exposure on 2 separate visits.
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 19 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Alberta
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Sean van Diepen, MD, MSc, Principal investigator, University of AlbertaCraig Steinback, PhD, Principal investigator, University of Alberta
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04928183
- Sponsor's protocol ID
- Pro00096251
- Acronym
- CarMA
- Status last verified
- Jun 2021
- First submitted
- 6 May 2021
- Last updated
- 25 May 2022
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Basnyat B. High altitude pilgrimage medicine. High Alt Med Biol. 2014 Dec;15(4):434-9. doi: 10.1089/ham.2014.1088.
PubMed 25330393Rezk-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.
PubMed 30764644Choi 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.
PubMed 29334505Weber 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.
PubMed 21787716Tymko 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.
PubMed 31677355
Study at a glance
From the registry record, last updated by the sponsor on 25 May 2022. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Impact of Carbon Monoxide and Altitude on Vascular Function
- ClinicalTrials.gov ID
- NCT04928183
- Acronym / sponsor ID
- CarMA / Pro00096251
- Conditions
- Vasodilation, Vasoconstriction
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 19 participants (actual)
- Lead sponsor
- University of AlbertaUniversity, hospital or other
- Study start
- 10 Jun 2021 (actual)
- Primary completion
- 1 Aug 2021 (actual)
- Study completion
- 18 May 2022 (actual)
- First posted
- 16 Jun 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The CarMA (Carbon Monoxide and Altitude) Study aims to observe the vascular effects of carbon monoxide exposure at low and high altitudes.
Detailed 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.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (participant)
- Number of arms
- 2
- Model description
- Participants will partake in both room air and CO exposure on 2 separate visits.
| Arm | Type | Receives |
|---|---|---|
| Room Air Rebreathe | Sham comparator | Drug: Sodium Nitroprusside, Drug: Phenylephrine HydrochlorideRebreathe protocol will be completed with a room air syringe rather than CO |
| CO Rebreathe | Experimental | Other: Carbon monoxide rebreathe, Drug: Sodium Nitroprusside, Drug: Phenylephrine HydrochlorideRebreathe protocol will be completed with Carbon Monoxide |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- Between the ages of 18-50 years
- No medical history of cardiovascular, respiratory, nervous system, or metabolic disease.
- Women must be pre-menopausal.
Key exclusion criteria (7 listed)
- 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).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Carbon monoxide rebreatheAlso: Schmidt-Prommer blood volume testCarbon monoxide exposure to increase blood (Carboxyhemoglobin) COHb safely to ~10% | Other | CO Rebreathe |
| Sodium NitroprussideAlso: NiprideBolus Sodium Nitroprusside (SNP) injection for endothelium-independent vasodilation measure | Drug | CO Rebreathe, Room Air Rebreathe |
| Phenylephrine HydrochlorideBolus Phenylephrine injection for observe α1-mediated vasoconstriction during mild exercise | Drug | CO Rebreathe, Room Air Rebreathe |
Primary outcome
Change in brachial artery diameter (assessed via ultrasound) following release of arterial occlusion
Time frame: 15 minutes
Change in brachial artery diameter (assessed via ultrasound) following release of arterial occlusion
Blood flow within the brachial artery during rhythmic handgrip exercise.
Time frame: 15 minutes
Blood flow within the brachial artery during rhythmic handgrip exercise.
Change in brachial artery conductance following an infusion of phenylephrine
Time frame: 5 min
Change in brachial artery conductance following an infusion of phenylephrine
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 25 May 2022.
- Background: PubMed 25330393Basnyat B. High altitude pilgrimage medicine. High Alt Med Biol. 2014 Dec;15(4):434-9. doi: 10.1089/ham.2014.1088.
- Background: PubMed 30764644Rezk-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.
- Background: PubMed 29334505Choi 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.
- Background: PubMed 21787716Weber 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.
- Background: PubMed 31677355Tymko 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.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Sean van Diepen, MD, MSc principal investigator
University of Alberta
Craig Steinback, PhD principal investigator
University of Alberta
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Carbon monoxide rebreathe, Sodium Nitroprusside and Phenylephrine Hydrochloride in people with Vasodilation and Vasoconstriction, run by University of Alberta at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 25 May 2022. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in brachial artery diameter (assessed via ultrasound) following release of arterial occlusion (time frame: 15 minutes). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04928183, which also lists 5 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 25 May 2022.