ES2288327B1 - QUANTIFICATION AND DETERMINATION OF UREA THROUGH NON INVASIVE TECHNIQUES AND ITS APPLICATION IN THE TREATMENT OF HEMODIALISIS. - Google Patents

Abstract

Urea Quantification and Determination by Non-Invasive Techniques and its Application in the Treatment of Hemodialysis. In relation to figure 1, the measurement system consists of a data acquisition module (4) and a sensor (3) itself that adapts to the arterial line (2) of any commercial hemodialysis equipment (1) a Once the signal has been obtained by means of the trigger module (5), the result of the urea concentration can be read by the user through a graphical display of alphanumeric characters (6) or through a graphic interface (7).

Description

Quantification and determination of urea by non-invasive techniques and their application in the treatment of hemodialysis.

The present invention is related to procedures for measuring urea online in those patients subject to hemodialysis treatment. The model and the Measurement method used is based on the description of the mechanisms of cellular regulation and their relationship with levels of cellular hydration, whose variability is a clear indication of the blood urea concentration level. For this they are used non-invasive techniques since the measurement system has no contact direct physicist with the patient, or with the hemodialysis team; in because the sensor only adapts to the arterial line of the blood collection cannula; what allows to obtain of form Immediate measurement of urea concentration during the process of hemofiltration

Background of the invention

Chronic renal failure (CRF) is a condition whose etiology is varied, its symptoms they are often little systematized which makes their difficult early diagnosis The most common causes of kidney failure Chronic (CRF), are diabetes mellitus and high blood pressure adding together up to 70 or 80% of cases. Of course the challenge most important for clinicians is the timely detection of IRC and prevent its progression; however there are some patients who at nevertheless they progress to a terminal stage of the disease, requiring to remain alive from the replacement of the function renal. Within the methods of substitute treatments of renal function hemodialysis is the most common worldwide, this procedure requires a clinical evaluation not only if non-biochemistry of each of the patients to be able to be in conditions to adapt the aforementioned treatment.

Recently the kinetic model has been used of urea (KTV) to determine if a treatment of this type is suitable or not; in this model the serum level of the urea at the beginning and end of treatment, involving an expense important not only in the economic aspect but also in that of resources Human and material.

The current trend in dialysis techniques, is to make use of increasingly effective measuring elements and membranes of greater surface and permeability. The techniques of On-line measurement use sensors that enter contact with blood and therefore must be disposable. He holder of the present invention M.C. Gustavo A. Martínez Chavez, has designed a prototype, whose operation is centralized in the use of photometric techniques within the range of visible light and near infrared, in order to obtain relevant information of the urea concentration during the dialysis process. Without for this, contact is made with the sterile circuit that establishes in practice this type of procedure.

Description of the invention

The invention poses the problem of creating a sufficiently descriptive model about the mechanisms of cell regulation and its relationship with hydration levels cellular (Hyperosmolarity), whose variability in those patients with kidney disorders are a clear indication of the level of blood urea concentration

This problem coupled with the conception of a measuring instrument that simply and safely in your operation allows measuring urea concentration during Hemodialysis treatment practice non-invasively as well as the technical cost is low in relation to the acquisition of its components and operation requirements.

This problem is solved according to this invention, with the definition of the model of the control mechanisms for cellular hydration, which can be presented as an expansion or compression (RVD or RVI) by the action of the change of concentration due to Hyper- phenomena. osmolarity or hypo-osmolarity. (Ref. D. Hausinger, Biochemical Journal, 1996. 313,697-710) and if we relate it to the mass index of the cell "m" and assume that these are directly proportional to its area "A" and to the difference in concentrations of the intracellular fluid C (t) and the extracellular C (s) (\ Delta C = C (s) - C (t)) contained in a constant volume "V" and inversely to a thickness "d" the thickness of the cell, It is possible to form a cell diffusion model expressed as follows:

one

That turns out to be an ordinary equation whose solution is determined by the initial conditions within a known interval and is given by:

2

Where:

C (t) = Variation of intracellular membrane concentration (moles / s.)

Cs = Extracellular membrane concentration (moles / l)

Co = Initial concentration of the intracellular membrane (moles / l)

A = Cell area (cm2)

d = Thickness of the layer intra-extracellular (cm)

t = Time (s)

K = Diffusion coefficient expressed in (cm2 / sec)

The expression that defines Absorbency (A) and Transmittance (T) and that are the simplest mathematical representation of the so-called Beer law, they are expressed as;

3

If C (t) of the expression 1 in C of formula 3 is substituted, in order to be able to estimate the change in concentration based on the variation of intensities in Absorbance we obtain that:

4

In the same way to find the relationship between the voltage and the concentration of the liquid to be measured, considering the ratio of intensities expressed as the ratio of voltages given by:

5

If 5 is substituted in the relationship formed by the expressions 3 and 3.a to estimate the change in concentration in function to the voltage variation, it is obtained that:

6

By substituting values in formulas 6 that correspond to the variation in the concentration of the urea content of a solution sample, as well as typical values in the cell dimensions of the order of microns, it is possible to obtain the graphic representation of the osmolarity balance between the intra- and extracellular layers, depending on the direction in which the change is effected in increasing concentration gradient \ Delta C plus the voltage values in the dark and lighting of a point source, so it is possible to obtain the ratio that keeps the variation of the voltage in function to the concentration of the solution.

Description of the drawings

In order to improve the understanding of how much described in this functional model proposed by this invention, the embodiment of the system is briefly described quantification and determination of urea by means of techniques not invasive, also a reason for the present invention.

In figure 1, the block diagram is shown of the operation of said system in which concepts are used photometric, in order to obtain relevant information from the solute concentration during the dialysis process.

Figure 2 is a schematic diagram of the realization of the sensing module where the photometry mechanism, which adapts to the lines of arterial extraction of hemodialysis equipment.

Figure 3 is a perspective view of the realization of the urea quantification and determination system reason for the present invention.

It is important to note that although the invention describes the performance of the procedure preferred by the subscribed, this does not imply that it is limited by these specific embodiments. Rather it is intended to cover all modifications and proposals that are within the purpose of the present invention

Preferred Description of the Invention

In relation to figure 1, the measurement system It consists of a series of electronic circuits for acquiring data by using a microcontroller (4) and a sensor opto-electronic (3) same that adapts to the lines arterial (2) of any commercial hemodialysis equipment (1), a Once the signal has been obtained by the trip switch (5) The result of urea concentration can be read by the user through a graphic character display alpha-numeric (6) or through an interface graphic (7).

Figure 2 is a sectional view. longitudinal of the urea detector body in the line for use in any hemodialysis machine, same as integrates by a point light source (9) and an arrangement photo-detector (10), which are adapted through a dark chamber (8) in the patient's arterial line (2).

Figure 3, and last, is a view in perspective of an embodiment of a monitoring system for determination and quantification of urea in line using the urea detector, as well as the application of the motive model of the present invention (11), a measured type is also illustrated of urea concentration, in the character display alpha-numeric and graphical interface (12) the which can be used in any commercial computer (13) and corresponding data can be loaded for representation graphic in any of the computer packages destined to this activity as for example; Excell, Matlab, Sigmaplot between others.

Of everything described above and from from the results obtained, the advantages that presents this invention.

First, there is scientific evidence of the existence of a correlation between urea concentration and the transmittance, that by its simplicity, its accuracy, and repeatability, offers great monitoring possibilities in the health centers that have this service.

Second, the current state of the measurement system, It has the advantage of being able to reduce the cost of this method of measure, compared to the electrochemical systems used in some hemodialysis equipment. Such is the case of the cartridges of hemodialysis for urea monitoring, which by its manufacturing features have a shelf life, being these of a single use (disposable), reason why in the majority of the cases its performance is subject to the conditions Environmental and operating mode.

Third, the state of the present invention by Its design features represents the following advantages for medical and nursing staff.

to.

Reduce subjectivity in the assessment of dialysis treatment.

b.

Make the diagnostic time in Patients be more expeditious.

C.

Be part of the new techniques in Urological treatments

d.

Contribute to the quality improvement of life and life of patients, providing true information on the most appropriate diagnostic criteria for each type of patient.

and.

Reduce costs in relation to the laboratory practice for the quantification of urea.

Finally they will be independent of the object of the present invention those electronic components and materials used in the manufacture of the measuring instrument, as well as other details and / or accessories that may arise, provided and when they do not affect the essentiality of the model and measurement method used

Claims (6)

1. The method used for the determination and quantification of urea in line by means of non-invasive techniques is characterized by establishing the direct correlation between the concentration of urea present in the arterial line of the hemodialysis equipment and the transmittance detected in the sensor, through the functional description in the mechanisms of cellular hydration and its relationship with the various metabolisms involved in uremic syndrome during hemodialysis treatment. 2. Method according to claims 1, characterized in that the measurements are made in a short period of time, which can be comparable to those obtained by laboratory equipment, by virtue of which urea itself is an unstable molecule, which is why which commercial laboratory instruments, resort to the process of hydrolyzing of urea, in order to obtain urease, producing ammonia and carbon dioxide. 3. Method according to claims 1 and 2 characterized in that the concentration of urea in dialysis fluid is measured. 4. Method according to claims 2 and 3 characterized in that the measurement is carried out by photometric techniques. 5. Method according to claims 1, 3 and 4 characterized in that the coefficients in the variability of the transmittance are related to the variations of the "clearence" that occur in the practice of hemodialysis treatment. 6. Model according to claims 1, 2, 3, 4, and 5 is characterized in that the measurement is adjusted to the variations in the concentration gradient that is present in the hemodialysis cartridge, and its direct function with the blood flow that is drawn from the patient's arterial line during the practice of this procedure.