Method for assay of blood plasma density

FIELD: medicine.

SUBSTANCE: invention relates to laboratory methods for blood analysis. Plasma is dropped in copper sulfate solution with density 1.023 g/cm3, not above, and time for drop falling on bottom of graduated cylinder with column height 243 mm is measured. The blood plasma density value is calculated by the formula:

wherein is the unknown blood plasma density (g/cm3); is copper sulfate solution density measured by areometer (g/cm3); t is average falling time of plasma drop in the copper sulfate solution (as seconds); 0.260130126 and 0.00290695 are correction coefficients. Temperature of plasma and copper sulfate solution is 20oC. Method is simple and suitable and allows carrying out analysis of small volumes of blood plasma and to reduce analysis time.

EFFECT: improved assay method.

2 ex

 

The invention relates to medicine, laboratory methods blood tests.

The density of blood plasma objectively reflect different pathophysiological changes developing in the body in many pathological conditions, such as acute intestinal infections (including cholera, Salmonella, rotavirus infection), meningitis, hemorrhagic fever with renal syndrome, diseases accompanied by the development of nephrotic syndrome. The determination of the density of blood plasma is important to assess the direction and severity hemoconcentration shifts, emerging with Hypo - or overhydration that you want to assign adequate amount of re - or dehydration therapy.

Analog is the method of determining the density of urine with the help of medical density (Laboratory research methods in the clinic /Menshikov V.V., Delektorskaya, L.N., Zolotnitskaya R.P. and others; Ed. by RIA. - M.: Medicine, 1987). The disadvantage of this method is the necessity to use for studies of sufficiently large volume of test substrate (not less than 50 ml), which is impossible in most cases in the study of blood plasma. Thus, in terms of inaccessibility for the study of a significant amount of biological fluids, characteristic of plasma, this is the manual may not be applicable, that is especially important in pediatric practice in connection with a small amount allowable exposee blood, whereas the determination of the plasma density in the rapidly developing exitosa in children is of paramount importance for the appointment of adequate rehydration therapy.

The closest analogue prototype is a method of Phillips and van slika (Cholera El tor: a guide for physicians/Burgassy PN. - M.: Medicine, 1971), which consists in sequential instillation of the investigated plasma in the working solutions of copper sulphate different specific weight. When the plasma density the density of the working solution of the droplet floats freely in the past, not floating and not plunging down. To implement this method consistently prepare a rich, Royal and working solutions of copper sulphate. Preparation of saturated solution: 720 g of copper sulphate (CuSO4·5H2O) is dissolved in water and add in a liter flask to the mark; the flask is closed and vigorously shaken for 5 minutes; the solution is quickly filtered through a large funnel, leaving the crystals in the flask. For preparation of stock solution 489 ml of saturated solution topped up with distilled water to 1 liter; specific gravity of this solution at 20° is 1,100 g/cm3. From the mother liquor prepared a series of work which their solutions with a given specific gravity (depending on the accuracy of the study the number of solutions of copper sulphate can be from 20 to 40), why the flask with the calculated amount of stock solution (16 ml to obtain a solution with a density of 1,015 g/cm3up to 51 ml to prepare a solution with a density of 1.050 g/cm3) and topped up with distilled water to 100 ml. Constant specific weight working solutions daily monitor hydrometer and, if necessary, correct by adding dropwise the mother liquor or distilled water.

The method of Phillips and van slice is essentially qualitative; quantitative expression he acquires only by the sequential use of solutions of different specific gravity. In addition, its approximate nature and complexity associated with the need to maintain the constancy of the concentration of copper sulphate in large quantities (20 to 40) working solutions, methodological difficulties in the preparation of saturated and uterine fluids limit the application of this method in practical health care. Measurement error using this method is 0,001350,000142 g/cm3(n=30). The time spent on the preparation of the described method, is 53 minutes on a daily correction unit weight working solutions - 324.8 minutes on its implementation - 3,440,26 minutes.

Object of the invention is the determination of the density of blood plasma.

The method is as follows: installed in the vertical position of the glass measuring cylinder with a capacity of 250 ml to measuring risks pour the copper sulfate solution (the height of a column of fluid 243 mm), having a density known to be lower than the measured blood plasma (less than 1,023 g/cm3). Specific gravity of the solution is determined by the hydrometer. To implement the method, you must prepare the only working solution, no need for exact dosing weight of dry powder of copper sulphate and volume of solvent, which can be used pure water. Using a micropipette (with a capacity of 200 l fixed volume) in special tip trying to enter 200 l of plasma, obtained by centrifugation of whole blood. Special tip is a glass capillary Sali (volume of 0.02 ml; 150 mm long) with a nozzle to attach to the introduction. Using this tip you need to achieve standardization of the volume of the drops of blood plasma. The tip is cut off from the micropipette and placed at a height of 1 cm above the level of the copper sulfate solution in the measuring cylinder. Under the action of gravity, the blood slowly flow out of the tip, and given the small diameter of the capillary, the error amount to the PEL minimum. Using a stopwatch, measure the time during which the drop will reach the bottom of the measuring cylinder. When touching a drop of blood plasma with a copper sulfate solution under the influence of the last plasma proteins coagulated and prevent the dissolution of the drops. Due to the fact that the density of a solution of copper sulphate is definitely lower than the density of the measured blood plasma (less than 1,023 g/cm3), the last drop will reach the bottom of the measuring cylinder, and in terms of the standard height of the column of solution of copper sulphate, the time spent by a drop of blood plasma to overcome this distance, the less the higher the density of blood plasma. To reduce measurement error, the study was conducted with six (measured by the fall in the copper sulfate solution 6 drops of blood plasma) and then finding the average time of fall of the drops. The study is carried out at an ambient temperature of 20° C. the blood Plasma and the solution of copper sulphate are the ambient temperature.

After these measurements the density of blood plasma is determined by the formula

,

where ρPLis the desired density plasma (g/cm3); ρR-RA- the density of a solution of copper sulphate, measured by hydrometer (g/cm3); t is the average time of fall of the drops p is Azmi in a solution of copper sulphate (in seconds); 0,260130126 and 0,00290695 - correction coefficients, reflecting the conditions of the study (the height of the column of solution of copper sulphate, the air temperature in the laboratory; when these conditions change, these factors must also be changed).

This formula reflects found experimentally the dependence between the average time of fall of the drops of blood plasma in a solution of copper sulphate (height of liquid column 243 mm), the density of this solution and the density of blood plasma.

In our study, 42 measuring the average deviation of the density of blood plasma is determined by the proposed method, measured by approximate method of Phillips and van slike was 0,001090.00015 grams/cm3. To prepare for the implementation of this method requires 4 minutes, and for its implementation - 3,850,27 minutes; after a single training this way daily correction is not required.

Thus, the proposed method allows to determine the density of blood plasma is reproducible and repeatable. The advantage of this method is the possibility to study small volumes of plasma (0.5-1 ml), while maintaining sufficient accuracy, there is no need to prepare and maintain a given concentration of a large number of solutions of copper sulphate that about ered leads to significant savings of this reagent and reduction of the time, spent on the preparation and conduct of the study. No need to use distilled water to prepare the solution greatly simplifies and facilitates the methodology, reducing requirements for technical equipment, which is especially important when deploying rolling infectious hospital in the conditions of admission of a large number of patients with acute intestinal infections, which always accompanies various emergency situations of natural and technogenic character.

Example 1 - extract from a case history No. 1661.

Patient R., 20 years old, was admitted to the infectious Department of the MUSES city Hospital No. 10 of Khabarovsk 05.10.2003 with complaints of abdominal pain, frequent diarrhea. Sick for three days, acutely ill, disturbed body temperature to 38.5° C, abdominal pain, loose stools up to 15 times per day with greens. Were outpatients adsorbents, enzymes and copious drinking. On the eve of the disease ate raw chicken eggs. When inspecting a state of moderate severity, body temperature 36,6° C, normal skin color, turgor of tissues is saved. Blood pressure 130/80 mmHg, heart rate 70 beats per minute, satisfactory filling and voltage. Tongue moist, coated whitish bloom. The belly of the correct form, not swollen, participates in the act of breathing, soft, painful and purring at ileocecal Inoi region, symptoms of peritoneal irritation no.

Liquid stools, green. Symptom tapping on the lumbar region is negative on both sides. Meningeal symptoms are not present.

Diagnosed with salmonellosis, gastrointestinal option.

The density of blood plasma, determined by the method of Phillips and van slice and proposed method, respectively 1,025 and 1,02508 g/cm3.

This example shows that the results in both cases are comparable and consistent with clinical symptoms, identifying (I) the extent of dehydration.

Example 2 - extract from a case history No. 1476.

Patient S., 17 years old, was admitted to the infectious Department of the MUSES city Hospital No. 10, Khabarovsk 09.09.2003 with complaints of weakness, dizziness, chills, abdominal pain, loose stools. Sick for days, acutely ill, suffered from chills, weakness, abdominal pain, loose stools up to 4-5 times. On the eve of the disease was in close contact with patients who had fever and diarrhea. When inspecting a state of moderate severity, body temperature 39,3° C, normal skin color, tissue turgor reduced somewhat. Blood pressure 105/60 mm Hg, pulse 98 beats per minute, weak filling and voltage. Tongue dry, the root of white furred. The belly of the correct form, not swollen, participates in the act of breathing, soft, painful and purring in EP is gastria and right iliac region and in the course of the large intestine, symptoms of peritoneal irritation no. Chair liquid, rich. Symptom tapping on the lumbar region is negative on both sides. Meningeal symptoms are not present.

Diagnosed with shigellosis, acute, enterocolitis option. The diagnosis was confirmed bacteriologically allocation coproculture Sh.flexneri 2a.

In General, the analysis of blood revealed erythrocytosis (5,3· 1012/l), the increase in hemoglobin (179 g/l), leukocytosis (13,2· 109/l) with a left shift (plasmic order has been revealed - 3%, metamyelocytes - 7%, stab neutrophils - 23%, segmented - 54%), which speaks not only about acute bacterial inflammation, and thickening of the blood.

The density of blood plasma, determined by the method of Phillips and van slice and proposed method, respectively 1,028 and 1,02814 g/cm3.

This example shows that the results in both cases are comparable and consistent with clinical data, revealing II the degree of dehydration.

The method of determining the density of blood plasma, consisting in the study of free fall drops of plasma in a solution of copper sulphate, characterized in that the plasma is infused into the copper sulfate solution with a density of not more than 1,023 g/cm3and measure the time of fall of the drops to the bottom of the measuring cylinder with the height of the liquid column 243 mm, while platnost the plasma is calculated by the formula:

where ρPLis the desired density of blood plasma, g/cm3;

ρR-RA- the density of a solution of copper sulphate, measured by the hydrometer, g/cm3;

t - average time of fall of the drops of plasma in a solution of copper sulphate, C;

0,260130126 and 0,00290695 - correction coefficients,

when this temperature plasma, solution of copper sulphate and the environment equal to 20°C.



 

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FIELD: medicine.

SUBSTANCE: invention relates to laboratory methods for blood analysis. Plasma is dropped in copper sulfate solution with density 1.023 g/cm3, not above, and time for drop falling on bottom of graduated cylinder with column height 243 mm is measured. The blood plasma density value is calculated by the formula:

wherein is the unknown blood plasma density (g/cm3); is copper sulfate solution density measured by areometer (g/cm3); t is average falling time of plasma drop in the copper sulfate solution (as seconds); 0.260130126 and 0.00290695 are correction coefficients. Temperature of plasma and copper sulfate solution is 20oC. Method is simple and suitable and allows carrying out analysis of small volumes of blood plasma and to reduce analysis time.

EFFECT: improved assay method.

2 ex

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