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Trial record 32 of 668 for:    CARBON DIOXIDE AND arterial

Effect of Sodium Nitroprusside on Cerebral Blood Flow

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
 
ClinicalTrials.gov Identifier: NCT03317652
Recruitment Status : Completed
First Posted : October 23, 2017
Last Update Posted : December 8, 2017
Sponsor:
Information provided by (Responsible Party):
Niels Damkjær Olesen, Rigshospitalet, Denmark

Brief Summary:

The brain has a high energy demand and requires continuous blood flow. The blood flow to the brain appears to be unaffected by small changes in blood pressure, but brain blood flow may be reduced by a large reduction in blood pressure. Large reductions in blood pressure are common during anesthesia or bleeding. It is unclear, however, how a given reduction in blood pressure affects blood flow to the brain.

In this study, medicine called sodium nitroprusside is used to dilate blood vessels and reduce blood pressure in twenty healthy young men. The study will evaluate whether blood flow to the brain is affected when sodium nitroprusside is used to induce a moderate and a large reduction in blood pressure. Blood flow to the brain is evaluated using ultrasound on the neck.

During breathing, oxygen is inhaled and carbon dioxide is exhaled. Carbon dioxide increases brain blood flow whereby changes in respiration can affect the blood flow to the brain. Sodium nitroprusside causes mild hyperventilation, whereby more carbon dioxide is exhaled, which will contribute to a reduction in brain blood flow. Thus, the study will also evaluate how brain blood flow is affected by hyperventilation and by breathing a mix of air and carbon dioxide.


Condition or disease Intervention/treatment Phase
Healthy Male Subjects Other: Hyperventilation Other: 6% CO2 breathing Drug: Infusion of sodium nitroprusside Not Applicable

  Show Detailed Description

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 20 participants
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Effect of Sodium Nitroprusside on Cerebral Blood Flow
Actual Study Start Date : November 3, 2017
Actual Primary Completion Date : December 4, 2017
Actual Study Completion Date : December 4, 2017

Resource links provided by the National Library of Medicine


Arm Intervention/treatment
Experimental: Sodium nitroprusside and CO2 reactivity

The subject rests in the supine position throughout the study that lasts for approximately three hours.

Interventions are:

  • Hyperventilation
  • 6% CO2 breathing
  • Infusion of sodium nitroprusside
Other: Hyperventilation
The subject is instructed to hyperventilate for 6 min to provoke a 0.7-1.2 kPa reduction in PaCO2, and the evaluation is repeated if the reduction in PaCO2 is not within this interval. The order of hyperventilation and 6% CO2 breathing is randomized.
Other Name: Evaluation of CO2 reactivity, hyperventilation

Other: 6% CO2 breathing
The subject breathes a mixture of 6% CO2 (with 21% O2 and 73% N2) from a bag and a face mask for 6 minutes. The order of hyperventilation and 6% CO2 breathing is randomized.
Other Name: Evaluation of CO2 reactivity, 6% CO2 breathing

Drug: Infusion of sodium nitroprusside
Using incremental intravenous infusion of sodium nitroprusside MAP is reduced by 20% (15%-25%) and then by 40% (35%-45%, MAP minimally at 50 mmHg).




Primary Outcome Measures :
  1. Change in cerebral blood flow from baseline to when MAP (mean arterial pressure) is decreased by 40% by sodium nitroprusside [ Time Frame: Values are recorded during 2-3 min at 2 time points; at baseline and when MAP is reduced by 40% by sodium nitroprusside (approximately 2 hours after the baseline evaluation) ]
    Sum of unilateral internal carotid and vertebral artery blood flow [ml/min] by duplex ultrasound corrected for changes in arterial CO2 tension (PaCO2) from baseline


Secondary Outcome Measures :
  1. Change in cerebral blood flow from baseline to when MAP is decreased by 20% by sodium nitroprusside [ Time Frame: Values are recorded during 2-3 min at 2 time points; at baseline and when MAP is reduced by 20% by sodium nitroprusside (approximately 2 hours after the baseline evaluation) ]
    Sum of unilateral internal carotid and vertebral artery blood flow [ml/min] by duplex ultrasound corrected for changes in PaCO2 from baseline

  2. Relative reduction in internal carotid artery blood flow as compared to that of the vertebral artery from baseline to when MAP is reduced by 40% by sodium nitroprusside [ Time Frame: Values are recorded during 2-3 min at 2 time points; at baseline and when MAP is reduced by 40% by sodium nitroprusside (approximately 2 hours after the baseline evaluation) ]
    Internal carotid and vertebral artery blood flow [ml/min] by duplex ultrasound corrected for changes in PaCO2 from baseline

  3. The CO2 reactivity of the internal carotid as compared to the vertebral artery [ Time Frame: Values are recorded during 2-3 min at 3 time points; at baseline, during hyperventilation for 6 min (approx 60 min after the baseline evaluation) and during 6% CO2 breathing for 6 min (approximately 60 min after the baseline evaluation) ]
    The CO2 reactivity of the internal carotid and vertebral arteries as evaluated during baseline, hyperventilation, and 6% CO2 breathing as: change in blood flow *100 / (change in PaCO2 * baseline blood flow). Internal carotid and vertebral artery blood flow [ml/min] by duplex ultrasound and PaCO2 [kilopascal] by arterial gas analysis

  4. Comparison of the slope of linear regression of MAP and cerebral blood flow for the evaluations at baseline and when MAP is reduced by 20% by sodium nitroprusside and that of the evaluations when MAP is reduced by 20% and 40% [ Time Frame: Values are recorded during 2-3 min at 3 time points; at baseline and when MAP is reduced by 20% and 40% by sodium nitroprusside (both approximately 2 hours after the baseline evaluation) ]
    Sum of unilateral internal carotid and vertebral artery blood flow [ml/min] by duplex ultrasound corrected for changes in PaCO2 from baseline and MAP [mmHg] by arterial cannulation



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Ages Eligible for Study:   18 Years to 35 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Informed consent
  • Male
  • Age 18-35 years

Exclusion Criteria:

  • Alcohol intake ≥ 420 g / week
  • Body mass index below 18 kg/m^2 and above 25 kg/m^2
  • Smoking
  • Beard on the neck
  • Chronic cardiac, lung, liver, kidney or metabolic disease that require medication
  • Vitamin B12 deficiency
  • Anemia
  • Leber's hereditary optic neuropathy
  • Tobacco-alcohol amblyopia
  • Stenosis that obstructs ≥ 16% of the internal carotid artery
  • Intake of sildenafil or vardenafil for 24 hours and tadalafil for 48 timer prior to the experiment
  • Intake of monoamine oxidase inhibitors
  • Neurologic disease considered to affect cerebral blood flow, including epilepsy and multiple sclerosis

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03317652


Locations
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Denmark
Department of Anesthesia, Rigshospitalet 2043
Copenhagen, Denmark, DK-2100
Sponsors and Collaborators
Rigshospitalet, Denmark
Investigators
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Principal Investigator: Niels D Olesen, MD Department of Anesthesia, Rigshospitalet 2043, DK-2100 Copenhagen Ø, Denmark
  Study Documents (Full-Text)

Documents provided by Niels Damkjær Olesen, Rigshospitalet, Denmark:
Study Protocol  [PDF] October 20, 2017
Statistical Analysis Plan  [PDF] October 20, 2017


Publications:

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Responsible Party: Niels Damkjær Olesen, Principal investigator, Rigshospitalet, Denmark
ClinicalTrials.gov Identifier: NCT03317652     History of Changes
Other Study ID Numbers: H-17017045
First Posted: October 23, 2017    Key Record Dates
Last Update Posted: December 8, 2017
Last Verified: December 2017
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Additional relevant MeSH terms:
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Nitroprusside
Antihypertensive Agents
Vasodilator Agents
Nitric Oxide Donors
Molecular Mechanisms of Pharmacological Action