DE10308154A1 - Apparatus for the measurement of potassium concentrations in erythrocytes, for medical laboratory diagnosis and scientific research, has a mixing chamber with distilled water and a reagent chamber as a disposable set - Google Patents

Abstract

To measure the concentrations of potassium in erythrocytes, a disposable set is used with ion selective electrodes in a few steps. The set, of a stable plastics material, has a sealed reagent chamber (3) containing distilled water and concentrated NaCl, and a blood sample chamber (6) with defined volumes. To measure the concentrations of potassium in erythrocytes, a disposable set is used with ion selective electrodes in a few steps. The set, of a stable plastics material, has a sealed reagent chamber (3) containing distilled water and concentrated NaCl, and a blood sample chamber (6) with defined volumes. Through external pressure on the sample chamber, the blood is mixed with water in a chamber (2) and the potassium from erythrocytes is released. After the addition of concentrated NaCl, by external pressure, a measurement capillary (10) pierces through a membrane (8) to be used conventionally.

Description

Current was standing

Potassium is one of the most important electrolyte ions of the human body, in various physiological and pathophysiological processes is involved.

98% of the total potassium content of the body is located intracellularly and therefore for the laboratory control is difficult to access is. The blood cells, especially erythrocytes, are the only ones for the tests easily accessible Cells that for Measurement of different cations (potassium, sodium, magnesium, etc.). can be used.

Currently known Process and its disadvantages

The for determination of potassium in Erythrocyte known method is flame photometry or atomic spectrometry (1, 2, 3, 4). The method is fairly complex and involves several work steps (erythrocyte-wash-hemolysis-dilution-photometry), and is only in special Laboratories with appropriate specialist staff and equipment.

That is why this method has been used for clinical and scientific routine is not established and remains only a few reserved for scientific laboratories. Add to that the fact that the flame photometry from laboratory practice from the ion selective Electrode technology completely has been ousted is.

So currently stands for the medical profession and scientists have no viable method for measuring potassium concentration available in erythrocytes. Accordingly, this aspect of the electrolyte balance is hardly been examined.

Fiction principle

The main idea is - the potassium concentration in Erythrocytes with the commercially available laboratory equipment to be able to measure with which every laboratory and many intensive care units are equipped as standard. All of these devices work with ion-selective electrodes, but only for the determination of electrolytes in the blood / plasma.

• 1. Die konventionelle Messung von Elektrolyten in einer arteriellen oder venösen Blutprobe. Dabei wird unter anderen Parametern für die spätere Berechnung a) Kalium und b) Hämatokrit gemessen.
• 2. Ein bestimmtes Blutvolumen aus der aktuellen Probe (0,5 ml) wird mit 5 ml destilliertes Wasser gemischt. Dabei werden die Erythrozyten in wenigen Minuten hämolysiert, das Kalium wird freigesetzt.
• 3. Nach 2–3 Min Zusatz von 0,5 ml 10% NaCl-Lösung. Dieser Schritt ist notwendig, um eine notwendige Leitfähigkeit der Lösung, für die die ionoselektive Elektroden ausgelegt sind, zu erreichen, da allein die ergebene Kaliumkonzentration (ca. 2,5–3,5 mmol/L) reicht dafür nicht aus. Dieser Zusatz ergibt eine „normale" Natrium-Konzentration in der Probe (ca. 140 mmol/L).
• 4. Messung des Kaliums in dieser Lösung (Hämolysat)
• 5. Berechnung der Kaliumkonzentration in Erythrozyten.

The procedure includes the following steps (worked out after numerous experiments)

• 1. The conventional measurement of electrolytes in an arterial or venous blood sample. Here, a) potassium and b) hematocrit are measured under other parameters for the later calculation.
• 2. A certain volume of blood from the current sample (0.5 ml) is mixed with 5 ml of distilled water. The erythrocytes are hemolyzed in a few minutes and the potassium is released.
• 3. After 2-3 minutes, add 0.5 ml of 10% NaCl solution. This step is necessary to achieve the necessary conductivity of the solution for which the ionoselective electrodes are designed, since the resulting potassium concentration (approx. 2.5–3.5 mmol / L) is not sufficient for this. This addition results in a "normal" sodium concentration in the sample (approx. 140 mmol / L).
• 4. Measurement of the potassium in this solution (hemolysate)
• 5. Calculation of the potassium concentration in erythrocytes.

Measured concentration will be accordingly the dilution and the percentage of erythrocytes in the blood converted into percent (hematocrit), percentage of plasma is subtracted from potassium.

Legend for calculation:

• Hematocrit - erytrocyte content in blood (%)
• Dilution - degree of dilution the blood test
• Potassium _hemolysate - the measured potassium value in the hemolysate
• Potassium _Sum - Total potassium in the hemolyzed blood sample
• Potassium plasma _fraction - the plasma fraction of potassium in the blood sample
• Potassium _{Erys Percentage} - Erythrocytes Percentage of potassium in the blood sample
• Potassium _{PlasmaMeasured} - conventionally measured potassium value in whole blood
• PotassiumErys - bottom line, Concentration of potassium in erythrocytes, mmol / L

Calculation:

• - Dilution = const = 0.5 ml blood + 0.5 ml NaCl + 5 ml water = 1:12 = 12
• - Potassium _Sum = Potassium _Hemolizate × 12
• - Potassium plasma _{concentration} = potassium _{plasma measured} × (100 - hematocrit) / 100
• - Potassium _{Erys content} = potassium _total - potassium _plasma
• - Potassium Erys = Potassium _{Erys portion} × 100 / hematocrit

Example:

• Potassium _{PlasmaMeasured} - 4.5 mmol / L
• Hematocrit - 38%
• Potassium _hemohsate - 3.3 mmol / L
• Potassium _sum = 3.3 × 12 = 39.6
• Potassium _{plasma content} = (4.5 × (100 - 38)) / 100 = 2.79 mmol / L
• Potassium _{Erys content} = 39.6 - 2.79 = 36.81
• Potassium Erys = 36.81 x 100/38 = 96.8 mmol / L

Those obtained with this method Normal values are completely correct with the bibliography referring to flame photometry and atomic spectrometry based (95-110 mmol / L).

In order to implement this method practically and to make it practicable for non-laboratory personnel (doctors, nursing staff, etc.) and also to enable measurements directly in intensive care units, a special device (single-use set) for the preparation of the blood sample has been developed, with which a measurement can be carried out within 3 minutes without laboratory instruments (micropipettes, reagent tubes). (S. 1 ) The set consists of a cube-shaped mixing chamber approx. 10 × 40 × 40 mm (elastic plastic with the hard lid), which is distilled with 5 ml. Water is filled. On the lid there is a U-shaped blood test chamber (volume 0.5 ml), which is equipped with an inlet for the syringe (Luer standard), with two non-return valves (inlet and outlet) and a stopper , There is also a reagent chamber with 0.5 ml 10% NaCl on the lid, also directed into the chamber. The two chambers (blood test and reagent chamber) are made of thin glass or brittle plastic.

Blood Test Preparation and measurement:

• 1. The blood test chamber is made from the syringe filled air-free (until the exit in the test exit)
• 2. The outlet of the blood test chamber is sealed with the stopper and then the blood sample chamber is passed through the elastic mixing chamber wall of Outside crushed with fingers, the blood is mixed with the water by shaking and hemolyzed.
• 3. After about 2 minutes the reagent chamber is also crushed, the Contents with the hemolysate mixed. The sample is now ready to measure.
• 4. Through a thin one A commercially available measuring capillary is inserted into the membrane in the lid Mixing chamber introduced (Drink pack principle) the measurement is carried out.
• 5. The calculation is carried out automatically by the device software.

Advantages of invention

To my knowledge, this is Invention the first attempt to be inexpensive, inexpensive and with all commercially available Feasible method, to determine the potassium concentration in erythrocytes.

The method is realized with the developed set, very practical. A measurement can be made within from 3 minutes without laboratory staff and additional instruments (also directly in intensive care units)

It becomes possible with this method intrazelluräres Electrolyte balance and the relationships with other clinical and laboratory chemical parameters more precisely and on a large scale investigate to develop new diagnostic and therapeutic approaches.

1.

cover made of sturdy plastic

Second

mixing chamber made of elastic plastic with distill. Water (5ml)

Third

Reagents chamber with 0.5ml 10% NaCl (brittle Material)

4th

Blood test - receipt for the syringe

5th

Blood sample output

6th

Blood test chamber (brittle Material)

7th

Blood test outlet plug

8th.

membrane for piercing with the measuring capillary

9th

On- and inlet check valves (to avoid blood test pendulum)

10th

Messkapillar

Claims (2)

Method and device for measuring the potassium concentration in erythrocytes in the field of medical laboratory diagnostics and scientific research, characterized in that the blood sample is prepared in a few steps for measurement with all common ion-selective electrodes. Method and device according to claim 1, characterized in that the preparation of the blood sample with the help of a closed device (disposable set) in a few Minutes. The plastic set contains all necessary for the procedure separately welded Reagents (distilled water, NaCl concentrate in exactly the specified amount) and a blood sample chamber with a precisely specified volume. By Crush the blood chamber from the outside the blood is mixed with the water, hemolyzed and the potassium out Erythrocytes are released. After adding the NaCl concentrate (also by crushing Outside) the measurement is carried out conventionally with the measuring capillary. The Potassium concentration in erythrocytes is then extrapolated.