BLEEDING TIME

From Big Medical Encyclopedia

BLEEDING TIME — one of the indicators characterizing fiziol, the mechanism of a stop of bleeding from the smallest blood vessels (so-called primary or microcirculator hemostasis). Is defined by duration of bleeding from the superficial puncture or a cut of skin made the same at each research.

Dyyuk's test (W. Duke, 1910) — a classical method of definition of V. to.: in the lower outer edge of a lobe of an ear a needle or a feather scarificator give an injection depth apprx. 4 mm; in 15 — 30 sec. filter paper, without concerning a wound, absorb the appearing drops of blood. Count of time is kept from the moment of emergence of the first drop of blood to a stop of bleeding. Norm — 1 — 4 min. Results of modification of test (a puncture of skin of fingers) are less exact because of big individual differences of thickness and density of a corneous layer of skin.

Ivy's test (A. S. Ivy, 1937) — on skin of an inner surface of a forearm do three punctures, 3 mm in depth. Normal duration of bleeding no more than 4 min.

Borkhgrevink's test (S. of Borchgrevink, 1958) is carried out against the background of the venous hyperemia caused by squeezing of a shoulder a cuff of the sphygmomanometer (40 mm of mercury.). Blood is received from cross notches of 1 mm in depth and 12 — 14 mm long on skin of an inner surface of a forearm. The norm — up to 10 min. Borkhgrevink recommends to define in addition secondary V. to.: in 24 hours after conducting usual test from notches delete with a stupid way the formed crusts of blood and determine duration of the renewed bleeding, the edge is not exceeded normal by 2 min.

«The test of tolerance to aspirin at» (acetilsalicylic to - that), offered by Kvik (A. Quick, 1967), can be used for identification of the hidden disturbances of a hemostasis at the persons predisposed to development of bleeding at reception of salicylates. Century to. define in 2 hours after intake up to 1,0 g acetilsalicylic to - you. At faces with the hidden bleeding V. to. at a one-stage prothrombin time test it is much extended while at an ordinary research this indicator was not changed.

Importance at a research B. to. it is given to volume lost a shelter and, for definition to-rogo the last it is eluated from filter paper and it kolorimetrirutsya or at once it nasasyvatsya in special measured micropipets.

Century to. is defined generally by ability of thrombocytes to form in the damaged microvessels platelet traffic jams (adhesion, aggregation, viscous metamorphoses of thrombocytes) and to emit at the same time the substances strengthening a spasm of the bleeding vessels — serotonin (see), catecholamines (see). Between V. to. and blood clotting time (see) usually there is no compliance. So, at hemophilias And, In and With, deficit of the XII factor time of coagulation is considerably extended at almost normal V. to.; at small number or inferiority of thrombocytes of V. to. increases, and the blood clotting time changes a little. At the expressed afibrinogenemiya (concentration of fibrinogen less than 15 — 20 mg of %), disturbance of the external mechanism of formation of «ignition» doses of thrombin because of sharp deficit of factors of VII, X and V, and also at the expressed trombo-hemorrhagic syndrome with an afibrinogenemiya and activation of a fibrinolysis of V. to. it can be considerable or unsharply increased that is explained by the fact that small doses of fibrinogen and thrombin are necessary for preservation of haemo static function of thrombocytes, and products of a fibrinolysis suppress it (see. Hemorrhagic diathesis , table).

V. is most increased to. at all types of thrombocytopenia (less than 50 000 in 1 mkl blood), angiogemophilias (see), trombotsitasteniya (see. Trombotsitopatii ). At other trombotsitopatiya, both inborn, and symptomatic (at acute leukoses, a radial illness, a hepatic unsufficiency and kidneys, overdose of anticoagulants), V. to. it is extended only in the most hard cases.

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


Bibliography: Barkagan 3. S. O principles of recognition and classification of trombotsitopatiya, Probl, gematol. and modulation. blood, t. 29, No. 5, page 3, 1974, bibliogr.; Kassirsky I. A. and Alekseev G. A. Clinical hematology, M., 1970; The Guide to clinical laboratory trials, under the editorship of E. A. Kost and L. G. Smirnova, page 91, M., 1964; Borchgrevink of Page F. Studies on hemostatic mechanism, Oslo, 1961; Duke W. W. The relation of blood platelets to hemorrhagic disease, J. Amer. med. Ass., v. 55, p. 1185, 1910; Ivy A. C., Shapiro P. F. a. Melnick P. The bleeding tendency in jaundice, Surg. Gynec. Obstet., v. 60, p. 781, 1935; Thomson J. M. A practical guide to blood coagulation and haemostasis, L., 1970.

3. S. Barkagan.

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