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Influence of Variations in Systemic Blood Flow and Blood Pressure on Cerebral Oxygenation Measured by Cerebral Oximetry

This study has been completed.
Sponsor:
Information provided by (Responsible Party):
University Hospital, Ghent
ClinicalTrials.gov Identifier:
NCT01424800
First received: August 22, 2011
Last updated: March 5, 2012
Last verified: March 2012
  Purpose

This study emphasizes on the influence of changes in systemic flow and systemic mean arterial blood pressure (MAP) during cardiopulmonary bypass (CPB) on cerebral oxygenation assessed by near-infrared spectroscopy (NIRS). The aim of the study is to determine whether variations in systemic flow, in MAP, or in both variables at the same time have the greatest impact on the cerebral oxygen saturation.


Condition Intervention
Cerebral Oxygen Saturation
Device: A disposable NIRS (near-infrared spectroscopy) sensor will be applied on the patient's forehead for continuous registration of the cerebral oxygen saturation.

Study Type: Interventional
Study Design: Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Basic Science
Official Title: Influence of Variations in Systemic Blood Flow and Blood Pressure on Cerebral Oxygenation Measured by Cerebral Oximetry

Resource links provided by NLM:


Further study details as provided by University Hospital, Ghent:

Primary Outcome Measures:
  • Blood flow [ Time Frame: during the entire surgery ] [ Designated as safety issue: No ]
    Changes in blood flow during cerebral oxygen saturation measured with NIRS, during surgery when the patient is on cardiopulmonary bypass.

  • Blood pressure [ Time Frame: during the entire surgery ] [ Designated as safety issue: No ]
    Changes in blood pressure during cerebral oxygen saturation measured with NIRS, during surgery when the patient is on cardiopulmonary bypass.


Enrollment: 34
Study Start Date: July 2011
Study Completion Date: December 2011
Primary Completion Date: December 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: change in blood pressure and blood flow
34 patients will form the experimental group, in which changes of blood pressure and blood flow will be induced and monitored.
Device: A disposable NIRS (near-infrared spectroscopy) sensor will be applied on the patient's forehead for continuous registration of the cerebral oxygen saturation.
When the patient is on CPB, pressure and/or flow will be changed while continuously measuring ScO2. Temperature, CO2 , arterial oxygen content, hematocrit and anesthesia will be kept constant during the measurements. First, baseline MAP (mean arterial pressure), baseline ScO2 and baseline central venous oxygen saturation (SvO2) are determined. With the interventions, we will induce a change of 20% in MAP and/or flow. This is within the normal range during operations. Changes in blood pressure will be obtained by the use of vasoactive agents (sodiumnitroprusside for blood pressure decrease and phenylephrine for blood pressure increase). Flow is regulated by manual control of the pump flow. Values of the different variables will be obtained after a 5 min stabilisation period. Flow/pressure interventions will be randomized.

Detailed Description:

Cerebral autoregulation is defined as the whole of regulatory mechanisms that maintains a constant cerebral blood flow (CBF) during changes in cerebral perfusion pressure (CPP). Cerebrovascular resistance adjusts when CPP changes in order to keep CBF constant. In contrast with this concept of pressure-mediated autoregulation, it is suggested that cerebral autoregulation is focused on maintaining homeostasis of the cerebral metabolic rate of oxygen (CMRO2). We assume that both flow and pressure contribute to the regulation of CMRO2.

Assessment of cerebral oxygenation - Cerebral oxygen saturation will be monitored with near-infrared spectroscopy (NIRS). NIRS allows simple, continuous and non-invasive measurement of cerebral oxygen saturation (ScO2)and primarily cerebral venous saturation. Cerebral oxygen saturation will be monitored with a FDA-approved devices: INVOS 5100 (Somanetics Corporation, Troy, MI, USA).

To study the effects of changes in pressure and in flow, we need a condition where we can alter these variables separately and in a controlled manner. Therefore this study will be performed during cardiopulmonary bypass (CPB). Pressure will be varied with the administration of routinely used vasoactive substances, while flow will be varied by altering the pump flow manually. We hypothesize that if we change one parameter (pressure or flow), a compensatory mechanism will preserve the CMRO2 homeostasis, with no change in ScO2. On the other hand, if we change both pressure and flow, we expect a significant effect on cerebral oxygen saturation. With 20 % changes in pressure and/or flow, we expect a change in NIRS values of approximately 5 %. Previous studies showed that this kind of reduction is well tolerated by the brain. This means that the proposed changes are within the normal physiological range, and will have no adverse effects.

  Eligibility

Ages Eligible for Study:   21 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

  • Age 21-100 years, scheduled for elective cardiac surgery, written informed consent.

Exclusion Criteria:

  • History of cerebrovascular disease or symptomatic carotid artery stenosis.
  Contacts and Locations
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Please refer to this study by its ClinicalTrials.gov identifier: NCT01424800

Locations
Belgium
University Hospital Ghent
Ghent, Belgium, 9000
Sponsors and Collaborators
University Hospital, Ghent
Investigators
Principal Investigator: Annelies Moerman, MD University Hospital, Ghent
  More Information

No publications provided

Responsible Party: University Hospital, Ghent
ClinicalTrials.gov Identifier: NCT01424800     History of Changes
Other Study ID Numbers: 2011/208
Study First Received: August 22, 2011
Last Updated: March 5, 2012
Health Authority: Belgium: Ethics Committee

ClinicalTrials.gov processed this record on November 20, 2014