Alterations of Conjunctival Microcirculation in Brain Dead Patients

Study Overview
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Brief Summary
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Study hypothesize that ocular microcirculation is reflecting cerebral perfusion. The purpose of this study is to evaluate ocular microcirculation in brain dead patients using side dark field (SDF) videomicroscope and compare it with microcirculatory parameters of healthy volunteers.

Detailed Description
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Microcirculation videomicroscopy techniques are used to evaluate a global organ perfusion in various critical conditions using limited suitable sites available for visualisation. However, ocular microcirculation may become a window to specifically cerebral perfusion due to related blood supply, close anatomical proximity and easy accessibility for videomicroscopy. Cerebral perfusion mainly depends on cerebral flow and intracranial pressure and therefore we aim, for the first time, to demonstrate microcirculatory status of ocular conjunctiva in clinical conditions when cerebral flow is completely absent. In a single center open label observational study investigators analyzed conjunctival and sublingual microcirculation using SDF videomicroscopy in brain dead patients after reaching systemic hemodynamic targets to optimise perfusion of donor organs. All brain death diagnoses were confirmed by cerebral angiography. Microcirculatory images obtained and analyzed using standardized published recommendations by experts in this field. Microcirculation of sublingual and conjunctival areas were recorded in matching number of healthy volunteers using same techniques.

Official Title
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Alterations of Conjunctival Microcirculation in Brain Dead Patients

Conditions
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Brain Death

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Diagnosed brain dead Exclusion Criteria: Conjunctival or sublingual mucosa damage

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Brain dead patients<br>Brain dead patients certified by cerebral angiography. | |
| Healthy volunteers<br>Any person with no known cerebral pathology. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Microvascular flow index (MFI) of ocular conjunctiva. | Conjunctival convective oxygen transport presented as MFI of small vessels mostly capillaries with diameter cutoff value of 20µm. Images of microcirculation were taken from at least three different points in each ocular conjunctiva and recorded for at least 20 seconds avoiding pressure artifacts. Microcirculation images were obtained using SDF videomicroscopy (Microscan®, Microvision Medicals, Amsterdam, Netherlands). Data recorded to the hard drive of personal computer using AVA 3.0v software (Microvision Medical, Amsterdam, Netherlands). Video clips were then randomly blinded and later analyzed by 2 independent investigators. | After confirmed diagnosis of brain death of any course using cerebral angiography at any time up to 24 hours. | 
| Total vessel density (TVD) of ocular concunctiva. | Conjunctival microvascular diffusion distance presented as TVD (mm/mm²) of small vessels mostly capillaries with diameter cutoff value of 20µm. Images of microcirculation were taken from at least three different points in each ocular conjunctiva and recorded for at least 20 seconds avoiding pressure artifacts. Microcirculation images were obtained using SDF videomicroscopy (Microscan®, Microvision Medicals, Amsterdam, Netherlands). Data recorded to the hard drive of personal computer using AVA 3.0v software (Microvision Medical, Amsterdam, Netherlands). Video clips were then randomly blinded and later analyzed by 2 independent investigators. | After confirmed diagnosis of brain death of any course using cerebral angiography at any time up to 24 hours. | 
| Perfused vessel density (PVD) of ocular conjunctiva. | Conjunctival microvascular diffusion distance presented as PVD (mm/mm²) of small vessels mostly capillaries with diameter cutoff value of 20µm. Images of microcirculation were taken from at least three different points in each ocular conjunctiva and recorded for at least 20 seconds avoiding pressure artifacts. Microcirculation images were obtained using SDF videomicroscopy (Microscan®, Microvision Medicals, Amsterdam, Netherlands). Data recorded to the hard drive of personal computer using AVA 3.0v software (Microvision Medical, Amsterdam, Netherlands). Video clips were then randomly blinded and later analyzed by 2 independent investigators | After confirmed diagnosis of brain death of any course using cerebral angiography at any time up to 24 hours. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Microvascular flow index (MFI) of sublingual mucosa. | Sublingual mucosa convective oxygen transport presented as MFI of small vessels mostly capillaries with diameter cutoff value of 20µm. Images of microcirculation were taken from at least three different points in sublingual mucosa and recorded for at least 20 seconds avoiding pressure artifacts. Microcirculation images were obtained using SDF videomicroscopy (Microscan®, Microvision Medicals, Amsterdam, Netherlands). Data recorded to the hard drive of personal computer using AVA 3.0v software (Microvision Medical, Amsterdam, Netherlands). Video clips were then randomly blinded and later analyzed by 2 independent investigators. | After confirmed diagnosis of brain death of any course using cerebral angiography at any time up to 24 hours. | 
| Total vessel density (TVD) of sublingual mucosa. | Sublingual mucosa microvascular diffusion distance presented as TVD (mm/mm²) of small vessels mostly capillaries with diameter cutoff value of 20µm. Images of microcirculation were taken from at least three different points in sublingual mucosa and recorded for at least 20 seconds avoiding pressure artifacts. Microcirculation images were obtained using SDF videomicroscopy (Microscan®, Microvision Medicals, Amsterdam, Netherlands). Data recorded to the hard drive of personal computer using AVA 3.0v software (Microvision Medical, Amsterdam, Netherlands). Video clips were then randomly blinded and later analyzed by 2 independent investigators. | After confirmed diagnosis of brain death of any course using cerebral angiography at any time up to 24 hours. | 
| Perfused vessel density (PVD) of sublingual mucosa. | Sublingual mucosa microvascular diffusion distance presented as PVD (mm/mm²) of small vessels mostly capillaries with diameter cutoff value of 20µm. Images of microcirculation were taken from at least three different points in sublingual mucosa and recorded for at least 20 seconds avoiding pressure artifacts. Microcirculation images were obtained using SDF videomicroscopy (Microscan®, Microvision Medicals, Amsterdam, Netherlands). Data recorded to the hard drive of personal computer using AVA 3.0v software (Microvision Medical, Amsterdam, Netherlands). Video clips were then randomly blinded and later analyzed by 2 independent investigators. | After confirmed diagnosis of brain death of any course using cerebral angiography at any time up to 24 hours. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Conjunctival microcirculation, Sublingual microcirculation, Sidestream Dark Field (SDF) microscopy