Correlation Between FlowMet™ and Other Gold Standard Assessments in the Management of Critical Limb Ischemia (CLI)

The purpose of this study is to demonstrate the utility of the FlowMet™ device in the assessment of perfusion in subjects suspected of or being treated for critical limb ischemia, in comparison to other gold standard technologies, such as ankle brachial pulse index (ABI), skin perfusion pressure (SPP), toe brachial pulse index (TBI), transcutaneous oxygen tension (TcP02), and angiography currently in use in the clinic.

TRIAL OBJECTIVES

1.0

To demonstrate that the FlowMet is effective for the assessment of tissue perfusion compared to gold standard technologies in patients suspected of or being treated for CLI.

2.0 STUDY DESIGN

This is a single center, cross-sectional study of subjects who are scheduled for CLI assessment with a Rutherford score of V and VI.

The subjects will be evaluated at baseline for determination if they meet the inclusion/exclusion criteria of the protocol. If the subject is eligible to enroll in the trial and they have signed an informed consent form (ICF) and are scheduled for evaluation, they will be enrolled. Subjects will undergo FlowMet, ABI, SPP, TBI, TcPO2, and angiography measurements (if not performed previously). The correlation between the aforementioned standard clinical measurements and FlowMet measurements will be assessed.

As ABI, SPP, TBI, TcPO2, Rutherford score, time of surgical (re)admission, speed of wound healing, and angiography measurements will likely change over a period of one year following initial FlowMet measurements, future measurements up to one year post FlowMet measurement (and performed as a standard of care) may also be correlated to initial FlowMet measurements to assess the whether FlowMet data is correlated to long-term patient outcomes.

3.0 STUDY PROCEDURES

3.1 Randomization, Blinding and Subject Identification

This is a cross-sectional study of subjects being treated for CLI with a Rutherford score of V or VI. No randomization scheme is required.

3.2 Product Equipment (FlowMet)

All parts of the FlowMet were manufactured in facilities with ISO 9001:2008 certification. Instruments are constructed in an ISO 9 cleanroom. All materials intended to be in contact with the patient's skin are constructed of polydimethylsiloxane (silicone) rubber which was sterilized via autoclave prior to device construction. Polydimethylsiloxane is widely used in existing medical devices and has been shown to be safe for both short-term contact, as well as long-term implantation (The AMS Sphincter 800™ Urinary Prosthesis, PMA P000053). Between uses, all polydimethylsiloxane components, in addition to all components which can accidentally contact a patient's skin during use, can be sanitized using alcohol wipes or germicidal wipes, such as alcohoPSI Inc. Sani-Cloths, which are commonly used in hospitals and which are bactericidal, tuberculocidal, and virucidal. The FlowMet has been used on 37 patients without adverse events at the University of California, Irvine in a study of tissue optical properties approved and overseen by the University of California, Irvine IRB. The FlowMet has not been evaluated, cleared or approved for use by the FDA.

3.3 Details of FlowMet usage

Extremity perfusion measurements will be performed using the FlowMet peripheral perfusion device. All extremity blood flow measurements will be collected during room air inhalation.

3.3.1

i. The FlowMet device will be placed on the index finger of the right hand. Signal fidelity will be assured by confirming the presence of a pulse waveform if one is expected and by assuring that an appropriate amount of light is be detected by the FlowMet device. The following light intensity values are acceptable: maximum intensity greater than 25 but less than 255 and average subtracted intensity greater than 20 but less than 175.

ii. Following placement of the FlowMet device, a period of 10 seconds will be allowed to elapse to allow transient changes in perfusion due to device placement to diminish.

iii. FlowMet blood flow data will be recorded for 20 seconds using the FlowMet data acquisition software.

iv. Steps i-iii will be repeated for digits 1 and 2 on the limb with diagnosed or suspected CLI, or on both limbs if both are diagnosed or suspected of having CLI. All data sets will be saved, and blood flow in each digit will be computed as the average of the collected data over the 20 second data collection period. If alternative digits are used for data acquisition due to differences in physiology, this will be recorded. If subject is missing the aforementioned toes, the tester will choose a different set of digits and this change will be recorded.

4.0 STUDY PROCEDURES

4.1 Baseline and Assessment

The Cleveland Clinic's standard of care will be followed for all participating study subjects. The following procedures will be conducted as part of a baseline assessment:

* Informed consent
* Complete medical history
* Demographics
* Vital signs (heart rate and blood pressure), height and weight
* Record angiographic data for study (if available)

The following procedures are standard of care and will be conducted to assess perfusion:

* Ankle brachial pulse index (ABI)
* Skin Perfusion Pressure (SPP)
* Toe brachial pulse index (TBI)
* Transcutaneous oxygen tension (TcP02)
* Angiography (if not performed previously)

The following procedures are not standard of care and will be conducted to assess perfusion:

* FlowMet measurement on subject's hand and foot/feet

Eligibility Criteria:
Inclusion Criteria:

* Subject is willing and able to provide an informed consent.
* Subject is willing and able to comply with the study procedures.
* Subject is able to understand the study procedures.
* Subject is being seen at the clinic for the evaluation/treatment of CLI.
* Subject has a Rutherford score of V or VI.

Exclusion Criteria:

* Subject has any medical condition, which in the judgment of the Investigator and/or designee makes the subject a poor candidate for the investigational procedure
* Anyone with a latex allergy
* Must be over 18 years old
* Must not be pregnant during time of study