Evaluating A Non-Invasive Tissue Perfusion Monitor

Study Overview
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Brief Summary
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The Pedra perfusion system will be used to assess changes in perfusion in response to physiological stimuli. It will be compared to other standard diagnostics.

Detailed Description
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The Pedra perfusion system measures microvascular flow through diffuse speckle contrast analysis. It will be used to assess changes in perfusion in response to a number of physiological stimuli. It will be compared to other standard diagnostics including ankle-brachial index, toe-brachial index and transcutaneous oxygen measurement. Measurements will be undertaken in non-vascular patients as well as those with chronic limb threatening ischaemia.

Official Title
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A Feasibility Study Evaluating A Non-Invasive Tissue Perfusion Monitor Utilising Diffuse Speckle Contrast Analysis

Conditions
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Circulatory; Change

Intervention / Treatment
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* Device: Pedra


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: CLTI cohort At least 40 years old Each patient will have documented arterial occlusive disease within 6 weeks of enrolment as determined by an ankle-brachial index (ABI) < 0.7 but not greater than 1.2, toe-brachial index (TBI) <0.5, skin perfusion pressure (SPP) less than 30mmHg, OR Transcutaneous oxygen measurement (TCOM) < 40mmHg in diabetics and <30mmHg in non-diabetics. The presence of skin breakdown compatible which with an underlying ischemic element (previous minor amputation for gangrene also included) that the Principle Investigator (PI) deems appropriate for the study. Subject has read, understood and signed approved consent, and is willing to participate and comply with the study procedures and requirements. Non-vascular group At least 40 years old Each patient will have documented palpable foot pulses 21 patients will be free of lower limb oedema and 6 patients will have moderate oedema present Subject has read, understood and signed approved consent, and is willing to participate and comply with the study procedures and requirements. Exclusion Criteria: CLTI Cohort Subject on an investigational drug or therapeutic device within 30 days of the study visit, which in the view of the PI may compromise the study results. Presence of a condition that PI considers will compromise the subject's ability to participate in the study. Age <40 or >90 Inability to straight leg raise to 30 degrees or tolerate calf cuff occlusion. Has smoked cigarettes/e-cigarettes on the day of testing. Has taken caffeine drinks on the day of testing In the last 3 hours the subject has exercised beyond normal daily walking. Inability to have TBI measured (e.g. absence of toe) Signs of active infection causing localised inflammation on the plantar or dorsal surfaces of the foot Pathological skin conditions that may impair the ability of the adhesive sensor pads to adhere. Non-vascular Cohort Subject on an investigational drug or therapeutic device within 30 days of the study visit, which in the view of the PI may compromise the study results. Presence of a condition that PI considers will compromise the subject's ability to participate in the study. Age <40 or >90 Inability to straight leg raise to 30 degrees or tolerate calf cuff occlusion. Has smoked cigarettes/e-cigarettes on the day of testing. Has taken caffeine drinks on the day of testing In the last 3 hours the subject has exercised beyond normal daily walking. Inability to have TBI measured (e.g. absence of toe) Signs of active infection causing localised inflammation on the plantar or dorsal surfaces of the foot Pathological skin conditions that may impair the ability of the adhesive sensor pads to adhere.

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Non vascular repeatibility<br>This cohort of patients with palpable pulses will be used to test inter- and intra- observer variability for the Pedra system | Device: Pedra<br>* Diffuse speckle contrast analysis perfusion system<br>|
| Non vascular physiology<br>This cohort of patients with palpable pulses will assess the ability of Pedra to detect perfusion changes in response to physiologic stimuli. | Device: Pedra<br>* Diffuse speckle contrast analysis perfusion system<br>|
| CLTI physiology<br>This cohort of patients with CLTI will assess the ability of Pedra to detect perfusion changes in response to physiologic stimuli. | Device: Pedra<br>* Diffuse speckle contrast analysis perfusion system<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The Blood Perfusion Index (unitless number) delta in response to reduction in arterial inflow pressure | The range of change in the Blood Perfusion Index (unitless) in response to physiologic changes in arterial perfusion, in patients with healthy circulation and those with compromised arterial circulation | Intra-procedure | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reliability of Blood Perfusion Index measurement will be assessed on repeated measures by determination of the correlation coefficient | The reliability of measurement of the Blood Perfusion Index will be measured and compared to standard diagnostics | intra-procedure | 
| Repeatability of Blood Perfusion Index measurement will be assessed on repeated measures by determination of the correlation coefficient | The repeatability of measurement of the Blood Perfusion Index will be measured and compared to standard diagnostics | intra-procedure | 
| Sensitivity of Pedra to detect differences in the Blood Perfusion Index between patient subsets | Use of a ROC curve to assess the ability of the Blood Perfusion Index to differentiate between those with healthy circulation and those with arterial disease | Intra-procedure | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Microvascular, Perfusion