Systems and methods for revascularization assessment

Abstract

Disclosed herein are systems and methods for revascularization assessment. The methods can in some cases include one or more of the steps of measuring blood perfusion as a function of time to obtain time series data, mathematically transforming the time series data into a power spectrum, calculating at least one parameter of the power spectrum within a specific frequency range, and using the at least one calculated parameter as a discriminator for the first population and the second population.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit under 35 U.S.C. §119(e) as a nonprovisional application of U.S. Prov. App. No. 61 / 865,977 filed on Aug. 14, 2013, as well as U.S. Prov. App. No. 61 / 888,790 filed on Oct. 9, 2013. This application is also related to U.S. application Ser. No. 13 / 967,298 filed on Aug. 14, 2013. Each of the foregoing applications is hereby incorporated by reference in their entireties.BACKGROUND[0002]1. Field[0003]This disclosure relates to the measurement of blood flow in tissue, in particular measurement of blood flow in the foot or other extremities.[0004]2. Description of the Related Art[0005]The rapidly aging population in the developed world has led to an increasing prevalence of aging-associated degenerative diseases such as peripheral arterial disease and Type 2 diabetes. The manifestations of these include tissue ischemia, chronic wounds and diabetic foot ulcers, where lack of appropriate treatment may lead to infe...

AI Technical Summary

Benefits of technology

The patent describes a system that allows for remotely monitoring a patient's condition by measuring various data points on their body. This data can be obtained locally at the target site, or through a probe worn by the patient. The monitoring physician or other individual can be located anywhere in the world, and still receive the necessary information for further analysis and evaluation. The processing of the data can be done either in software or hardware, and can be performed on a local device or through a distributed network. The technical effect of this system is that it allows for efficient and accurate monitoring of patient condition with greater flexibility and accessibility.

Problems solved by technology

The manifestations of these include tissue ischemia, chronic wounds and diabetic foot ulcers, where lack of appropriate treatment may lead to infection, gangrene and, in the case of foot ischemia, partial or complete amputation of one or both feet.

PAD can if untreated result in critical limb ischemia (CLI), in which blood flow to the limb (usually the legs and feet) is compromised to such an extent that tissue damage ensues with consequent ulceration, gangrene or loss of the limb.

Patients with PAD are also at a disproportionately high risk of other cardiovascular diseases like myocardial infarction and stroke and of death as a result of these conditions.

However, clinicians currently lack the intraoperative tools to properly assess perfusion in the affected tissue, usually in the feet, in real-time to reliably guide the conduct of the interventional procedure.

Each of these techniques suffers from one or more disadvantages.

SPP only provides perfusion data at the skin dermis level, requires the skin temperature to be normalized to 44° C., is affected by skin pigmentation and is unreliable with patients with edema.

SPP also requires the use of a pressure cuff, which further limits its utility as a real-time perfusion assessment tool during peripheral vascular interventions.

TCOM requires the patient to be placed on hyperbaric oxygen, making it incompatible with the cath lab / operating room.

Furthermore, TCOM does not provide real time revascularization data as it takes about 4 to 6 weeks for the measurements to equilibrate.

Ischemia is a condition where a restriction of blood supply to tissues leads to a shortage in oxygen and glucose, resulting in irreversible damage to tissues.

If discovered too late, reperfusion of blood by various treatment options, thrombolytic or surgical, will only further increase the damage to the tissue as opposed to rescuing the tissue.

In cases where the perfusion is compromised, however, the inappropriate use of conservative wound therapy causes a time lag between the first presentment of a wound in a clinical setting to an effective therapy commensurate with the seriousness of the wound condition.

Such therapy is expensive and is not without risk; its side effects include ear and sinus barotrauma, paranasal sinuses and oxygen toxicity of the central nervous system.

Due to the lack of optimal tools to predict amputation healing, physicians have to make subjective judgments on the best site for amputation, and since the bias is to maximize limb preservation, it is not uncommon for a patient to require a subsequent amputation higher up the leg when the first amputation wound is unable to heal.

(Wounds 2009:21(11) 310-316) report that skin perfusion pressure (measured by laser Doppler) appears to be a more accurate predictor of wound healing versus TcPO2; however SPP is only able to provide data at limited depth and requires skin temperature to be normalized to 44° C., is sensitive to skin pigmentation and unreliable with edema.

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