KR20040001568A - A diagnostic method and system integration for ischemic and neuropathic food of diabetics - Google Patents

Abstract

PURPOSE: An apparatus and a method for diagnosing ischemic and neuropathic foot of a diabetic are provided to remove the pain of the diabetic by applying a noninvasive method using a PPG sensor instead of an ultrasonic device or a laser doppler device. CONSTITUTION: An apparatus for diagnosing ischemic and neuropathic foot of a diabetic includes a PPG probe(10), a temperature sensor(20), a PPG control amplifier(30), an A/D converter(40), a computer(50), and a data collection software(60). A finger is located on the PPG probe(10) is order to sense a variation of blood flow of finger artery. The variation of blood flow of finger artery is analyzed by using the temperature sensor(20), the PPG control amplifier(30), the A/D converter(40), the computer(50), and the data collection software(60).

Description

A diagnostic method and system integration for ischemic and neuropathic food of diabetics

The technical field to which the present invention pertains relates to a new diagnostic method for ischemic and neuropathic foot of a diabetic patient. And how to do it.

In order to diagnose ischemic and neuropathic diabetic patients, the patient is questioned and tested according to the symptoms. For ischemic cases, diagnosis is performed according to test results using Doppler ultrasound or laser Doppler equipment. Diagnosis is based on the results of the tests. However, these test methods require a high level of skill and suffer from pain in the patient.

Various experiments have been conducted to measure blood flow using PPG. Since the application of optical blood flow measurement was first reported in the mid-1930s, the optical blood flow measurement method was used to monitor blood flow changes in the rabbit's ears or to show blood flow changes due to exercise or cold, using a device very similar to the optical blood flow meter. Was used. Recently, PPG was used to measure the pulse waveforms of systolic and diastolic pulses caused by heartbeats in the ears, fingers, and toes.

Another method of measuring blood flow in the extremities is impedance plethysmography, which uses impedance to measure absolute blood flow, but this is measured when there is some length to which four electrodes, such as a finger, can be attached. This is possible, but it is difficult to measure at short lengths such as toes.

In order to measure the abnormality of limbs due to ischemia, many studies have been performed to measure the blood flow of limbs.

Ultrasound or a laser Doppler blood flow meter is used to measure foot blood flow, but these methods are expensive and can only measure blood flow in a small volume of 1 mm ³ . It is very different, and requires a skilled worker to make an accurate measurement.

The present invention relates to an apparatus and a diagnostic method for examining an ischemic and neuropathic disease of a subject by a small, inexpensive, non-invasive method that does not cause the subject to suffer, unlike a conventional expensive apparatus. To this end, we aim to provide an automatic analysis device and diagnostic method for the blood flow ratio at the toes of the diabetic's finger with an optical sensor, digital signal processor, computer and analysis program.

1 is a perspective photographic copy of the blood flow measuring apparatus of the present invention.

2 is a cross-sectional view of the optical blood flow measurement probe.

3 is a program for analyzing blood flow waveforms.

4 is an exemplary view illustrating calculation of a toe blood flow rate with respect to a finger.

5 is an exemplary photograph at the time of measuring the toe blood flow of the present invention.

Figure 6 shows the left and right legs of the leg conduction velocity group (NCV)

sensitivity and specificity data comparison

The present invention relates to an efficient method for diagnosing diabetic complications. Specifically, the present invention relates to the configuration and method of ischemic and neuropathic foot examination apparatuses for diabetic patients composed of an optical blood flow sensor, a digital signal processor, a computer, and an analysis program.

More specifically, the overall system configuration of the present invention is a PPG probe 1, a temperature sensor 20, a PPG control amplifier 30, an A / D converter 40, a computer 50, and data acquisition software as shown in FIG. It consists of 60.

Hereinafter, the present invention will be described in detail.

2 is a cross-sectional view of a photo blood flow measurement probe, and illustrates a process of detecting a change in blood flow. When the finger is placed on the PPG probe 10 as shown in Fig. 2 (located on the toe as shown in Fig. 5 when the toe blood flow is measured), the blood flow change caused by the finger artery 1 is reflected by the infrared LED 11 and the red LED ( 12) flashes red light and infrared light alternately and passes through the capillaries at the fingertips and passes through the fingers, the light diode 13 on the opposite side scatters along the optical shunt 2 due to optical dispersion. Amplifies the light intensity to obtain pulsating components represented by the flow of blood. At this time, since the red and infrared LEDs used may have different light intensities, they are normalized to obtain only pulsating blood flow. The normalization process was calculated by dividing the intensity of the light passing by the maximum peak signal.

3 is a screen of a PPG blood flow analysis program. The analysis program can open and analyze the signal files obtained from both fingers and toes at the same time. It is therefore possible to compare the blood flow of the left and right fingers and toes and to compare the blood flow of the toes with respect to both fingers.

The blood flow calculations for RED and IR found the highest and lowest values of each waveform from the data for 50 seconds, and then calculated the amplitudes, and then added all of them to obtain the average amplitude. The average amplitude obtained at this time was taken as the blood flow of RED and IR.

As shown in FIG. 4, IR MAX, IR MIN, RED MAX, and RED MIN are obtained from the Left Finger, Right Finger, Left Toe, and Right Toe PPG. Here, the amplitudes IR and RED are calculated by multiplying the difference between the maximum and minimum values by 10 times. The reason for the multiple of 10 is that the amplitude axis in the graph has a range of 0 to 5 V as the voltage of each signal obtained from the data acquisition (DAQ) board. If the IR and RED are calculated using the difference, the value is too small. Multiply indicated. All ratios are erased so they do not affect the overall calculation. Using the obtained IR and RED values, each flow can be calculated using the difference as in Equation (10) to remove the optical path. This is because the signal from the two-channel amplifier comes through the log amplifier, so the Left / Right Flow is simply determined by the difference.

The four flows obtained here (Left Finger Flow, Right Finger Flow, Left Toe Flow, Right Toe Flow) are respectively recalculated as the ratio of foot / hand to remove the difference in blood flow. If the blood flow of the fingers and toes is the same, the value is 1;

To evaluate this method, 54 patients diagnosed with diabetes mellitus in the right upper extremity and lower extremity in supine position, and then PPG signal was measured for 1 minute and 30 seconds in both hands and feet using PPG flowmeter. It was. Nerve conduction examination was performed using NeuroScreen (JAEGER and TOENNIES) using the median and ulnar nerves in the upper limbs, the peroneal and tibial nerves in the lower extremities and the gastrointestinal nerves. Sural nerves were examined in each compartment. The control group was comprised of 42 normal subjects with no diabetes mellitus and no specific vascular disease in the upper and lower extremities. According to the presence of abnormalities of the lower extremities, tibia motor nerves and the gastrocnemius sensory nerves, diabetic leg control group for abnormal leg nerves, diabetic leg neuropathy group for abnormal leg nerves, and normal control group Divided.

In normal subjects, the left and right PPG blood flow ratios were 0.46 ± 20 and 0.41 ± 18, respectively. In some cases, the blood flow of each of the limbs is higher than that of other normal people, or the blood flow of each of the limbs is small. In other words, the blood flow in the fingers and toes can be seen that there is a difference between people even in normal people. In the present invention, the blood flow was calculated using the foot / hand blood flow ratio based on the blood flow of the finger to eliminate the basic difference between the individuals. Figure 5 is a perspective photograph when measuring the toe blood flow using a PPG blood flow meter.

Figure 6 shows the sensitivity and specificity of left and right in the Leg NCV group to prove the validity of the analysis method of the present invention. The PPG blood flow ratio thresholds using the Bayesian method were 0.88 and 0.70 for left and right, respectively. At this time, sensitivity was 59.1% and 50.0%, respectively, and specificity was 94.4% and 90.1%, respectively. PPG blood flow ratio thresholds using the LMS method were 0.47 and 0.53 for left and right, respectively. At this time, all of the sensitivity was 72.7%, specificity was 59.2%, 71.8% (see Fig. 6).

Unlike the various clinical tests, the sensitivity and specificity of the medical device is low. In the case of the dentist's eye, the sensitivity is 20-54%, the specificity is 81-98%, and the sensitivity of the dental X-ray is 40-67. %, specificity of 81-95%, fixed frequency devices of sensitivity 77%, specificity 62%. The Xillix LIFE-Lung Fluorescence Endoscopy System, tested for FDA approval in the Food and Drug Administration (PMA) premarket approval (PMA) clinical summary, was concluded to be effective as a pretest device. And specificity were 75% and 42%, respectively, and the sensitivity and specificity were 67% and 66%, respectively. Therefore, it can be seen that the experimental results of sensitivity and specificity in the present invention are effective analytical methods.

Nerve conduction is an electrical stimulation of up to 100 mA directly to nerves, which often results in surprise or pain. In addition, the time required for the entire inspection usually takes 20 to 30 minutes, and the one-time inspection fee is never small. If you use the PPG sensor to measure the blood flow of your fingers and toes, and then use the ratio to test for ischemic and neuropathic feet, you are not invasive because you use light, so you don't have any pain at all. Because it takes only a few minutes, the test can be performed quickly without causing pain to the subject. In addition, there are symptoms such as paresthesia, and there are a lot of patients who turn out to be normal in the neuroconduction test. Cost savings and time savings can be made to help more patients get accurate tests.

In addition, vascular occlusion and neuropathy are often found after some progress. Periodic PPG blood flow examination can be used to detect vascular occlusion and neuropathy at an early stage. It can provide a preventable instrument.

Claims (2)

Method of device configuration for testing ischemic and neuropathic foot with non-invasive and non-electrical stimulation How to check ischemic and neuropathic foot using ratio of toe blood flow divided by finger blood flow amplitude by measuring blood flow of finger and toe using PPG sensor that does not cause pain