BLOOD CLOTTING TIME

From Big Medical Encyclopedia

BLOOD CLOTTING TIME — indicator of the general coagulating activity of blood. Covers time from the moment of contact of blood with an alien surface of in vitro before formation of a clot. This test characterizes the slowed-down phase of a blood coagulation.

There are many methods of definition of V. of page to., each of to-rykh has the standards. For V.'s definition by the village to. use a capillary or venous blood. At a research of capillary blood the puncture of a finger is always done about one depth, and the first drop which acted from a puncture is deleted surely (impurity of an intercellular lymph can distort result). At use of any method strictly meet reference conditions and use needles and test tubes of a certain diameter, watch a temperature schedule etc.

Fonio's method (A. Fonio, 1928) it is eurysynusic in clinical practice. Prepare a moist chamber: in a Petri dish put the gauze moistened with water. Blood is taken from a vein in number of 10 drops on clock glass, a cut placed in a moist chamber. Carefully carry out by the end of the soldered pasterovsky pipette on the surface of blood. Emergence of the first threads of fibrin is considered the beginning of coagulation, formation of a clot — the end of coagulation. The beginning of a blood coagulation is normal observed in 5 — 8 min., the end — in 15 — 18 min.

Li's method — Whyte (R. I. Lee, P. D. White, 1913) is more sensitive, than Fonio's method. Blood is removed from a vein a needle by means of the dry waxed or silikonirovanny syringe and spilled on 1 ml in four absolutely pure dry test tubes which are in the water bath at t ° 37 °. Test tubes carefully turn each 30 sec. until blood does not cease to separate from walls. The stop watch is included at receipt in the syringe of the first drops of blood and stopped after its full coagulation. Century of page to. measure in each test tube separately, and then calculate average result. Norm — 6 — 10 min.

Modification of a method of Li — Whyte (known in literature as Jacques's method — Fidlera — Mac-Donelda). For a research use silikonirovanny test tubes that allows to reveal small defects of coagulation; it is normal of V. of page to. in silikonirovanny test tubes makes 18 — 25 min. At a big difference in the results received in simple and silikonirovanny test tubes it is possible to assume deficit of a factor of XII — Hageman's factor (I eat. Hemorrhagic diathesis).

Byurker's method (1910). The drop of blood taken after a puncture of a finger without pressing mixes up on clock glass with a drop of a distilled water; stir slowly with a glass rod with the delayed end before emergence of the first threads of fibrin. Normal coagulation comes in 5 — 5 1/2 min.

Mas-and-Magro method (Mas-Margo) (F. Mas at Magro, 1915). On the waxed clock glass Sali's pipette pour a drop of a liquid paraffin. The same pipette from a finger nasasyvat 20 mkl blood and carefully blow it on a liquid paraffin. At the same time include a stop watch. Every 2 min. blood is involved in a pipette. The stop watch is stopped at the moment when blood is not involved in a pipette any more. Normal fibrillation occurs in 8 — 12 min.

Sitkovsky's method — Egorova (1913). The research is conducted in Sitkovsky's device: in the special capillary placed in water at t ° 37 ° blood is moved, forcing pressure. The beginning of coagulation is determined by emergence of the first clot. Then in 20 sec. each 5 sec. increases pressure again to the moment when blood remains motionless (with a pressure in system in 60 mm of mercury.). It corresponds to the end of coagulation (norm — 3 — 4 min.).

Value of definition of a blood clotting time

V. of page to. does not characterize a condition of a hemostasis completely. E.g., at an afibrinogenemiya and a hyperheparinemia of a blood coagulation practically does not occur, and hemorrhages can be expressed moderately. On the contrary, at heavy thrombocytopenia of V. of page to. usually it is not increased, and bleeding can be expressed. V. of page is the most frequent to. it is extended at hemophilia, however it is also not always adequate to disease severity.

See also Blood , methods of a laboratory research, Coagulant system of blood .


Bibliography: The guide to clinical laboratory trials, under the editorship of E. A. Kost and L. G. Smirnova, page 76, M., 1964; The Reference book on clinical laboratory methods of a research, under the editorship of E. A. Kost, page 90, M., 1975; The Reference book on functional diagnosis, under the editorship of I. A. Kassirsky, page 434, M., 1970; Lee R. I. a. White P. D. A clinical study of the coagulation time of blood, Amer. J. med. Sci., v. 145, p. 495, 1913.

L. D. Orlova.

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