Materials for auditory self-work
4.1. List of study practical tasks necessary to perform at the practical class.
Materials and methods: thromboelastograph, saliva, thromboelastogram, water bath, seconds-meter, plasma, 0,27% solution of CaCl2, 5% solution of CaCl2, capillaries, filter paper, centrifuge, thromboplastin, plasma.
Task 1. To study thromboelastogram.
Main thromboelastogram’s indexes are the following:
· Reaction time (R) – is measured on direct line from record beginning till thromboelastogram curves dilation in 1 mm. Given segment corresponds to blood coagulation invisible phase, i.e. prothrombinase formation. Norma: 9-14 min.
· K-segment from R end till thromboelastogram dilation in 20 mm. It is blood coagulation visible phase, clot formation time; it depends on forming thrombin concentration and fibrinogen amount. Norma: 5-8 min.
· mA – thromboelastogram branches divergence maximal amplitude is linked mainly with fibrinogen concentration, thrombocytes amount and functional activity.
It’s necessary to take into account for thromboelastogram analysis that diagram band velocity is 10 mm per 1 minute. Norma: 48-52 mm.
FIGURE 13. Thromboelastogram.
Task 2. Express-coagulogram
It is laboratory tests set providing preliminarily but quite exactly to determine blood coagulation and fibrinolysis disorders. Doctor can prescribe differentiated coagulogram after its assessment in patient on its concrete nosologic form.
Express-coagulogram (normal values):
1. Coagulation time (by Li-White) 4-8 min
2. Thromboelastogram: R 9-14 minutes
K 5-8 minutes
mA 48-52 mm
3. Thrombocytes 180-400 x 109/l
4. Thrombocytic aggregation: spontaneous absent
on ADP present
5. Recalcification time 180-400 sec
6. Prothrombin time by Quick 11-15 sec
|
|
|
7. Thrombin time 12-17 sec
8. Fibrinogen 2-4 g/l
9. Ethanol test negative
10. Prothamine-sulphate test negative
11. Fibrinogen “B” negative
12. Activated partial thromboplastin time (APTP) 25-35 sec (35-50 sec)
13. Fibrin or fibrinogen degrading products less than 0,5 mg/ml or 7,3-3,9
(FDP) or D-dimeres mg%
14. Fibrinolysis (probe on accelerated reaction) 120-240 min (10 min)
Blood coagulation time by Li-White – coagulation time of venous blood in the test-tube (up to clot formation). This method is not sensitive, it can only tell about general direction of coagulation (if it is less than 4 min one can tell about hypercoagulation because blood coagulates faster under such conditions; more than 8 min – hypocoagulation because blood coagulates slower than under norm).
Thromboelastogram is registered as blood coagulation process objective index. Platelets amount and their aggregation give us the information about microcirculative hemostasis.
Recalcification time – general coagulation test which reveals the rudest disorders in blood coagulation system. The method essence: calcium ions activating blood coagulation under physiological conditions are neutralized by sodium citrate corresponding amount. It defines blood liquid state in organism (one mechanism). Prefix re- means repeated process. They add calcium for clot formation and measure clotting time. Factors deficiency participating in prothrombinase formation internal way influence in the biggest extent on test values. If it is more than 140 sec than it can testify to blood coagulation deep deficiency, thrombocytopeny, heparinization (anticoagulant heparin taking). This state is named as hypocoagulation. Index value less than 80 sec (hypercoagulation) is observed at thromboses, disseminated intravascular syndrome (see below), hyperviscosity, erythrocytosis.
|
|
|
Prothrombin time – this time prolongation at normal fibrinogen content and normal thrombin time testifies to deficiency of one or some prothrombin complex factors (II, VII, IX and X). One should think about hypo- or dysfibrinogenemia or anticoagulants excess (heparin, fibrinolysis products et al.) into blood at simultaneous thrombin time prolongation.
Thrombin time – characterizes antithrombin, fibrinogen, heparin content. It is prolonged at antithrombin excess into blood, hypofibrinogenemia, hypoheparinemia, fibrin and fibrinogen degrading products excess in plasma (these FDP possess anticoagulant action). These states can be at disseminated intravascular syndrome (see below), massive thromboembolism. The index prolonging at fibrinogen normal values takes place at some fibrinogen molecular anomalies. Thrombin time maximal prolonging is possible at expressed hyperfibrinogenemy as well as at highly-molecular proteins or paraproteins presence in blood that can absorb procoagulants from plasma (for instance paraprotein as lg hard chain at hard chains disease, Bens-Jons' protein at myelomic disease). Plasma complete non-coagulation under thrombin influence is observed at significant hyperheparinemy and during the third hypocoagulation phase of hard disseminated intravascular coagulation syndrome.
Activated partial thromboplastin time (APTP) or kaolin-kephalin time represents highly-standartized coagulative probe sensitive only to plasmic coagulation factors deficiency especially to the XII, XI, IX and VIII factors as well as to anticoagulants excess in blood. This time prolonging (hypocoagulation) takes place at anticoagulants increasing. Also it will be bigger than normal values if there will be deficiency of mentioned procoagulants. According to some data, this test represents one of basic tests for disseminated intravascular syndrome (see below) determining testifying about hyper-, normo- and hypocoagulation. APTP is applied at control for performed therapy effectiveness. The time shortening is observed at DIC-syndrome hypercoagulation stage as well as some thrombophilies. Positive moments: this test excludes platelet hemostasis disorders while making sensitive only to coagulation hemostasis disorders. It reflects blood coagulation intrinsic way disturbances. It is considered to be the most sensitive coagulation test.
|
|
|
Ethanole, prothamine-sulfate and beta-naphthole tests and probe to fibrinogen “B” allow to determine “paracoagulation” products – fibrin-monomeric complexes. They are formed as a result of fibrinogen or fibrin decomposition at fibrinolysis activation. Positive probes testify to blood disseminated intravascular coagulation (DIC). These tests receive the name “paracoagulative” because other substances except them do not coagulate at their adding to fibrinogen and fibrinogen degrading products but they do. These substances adding to PDP results in euglobulins transfer from zole to gel. The degree of this sediment is designated from one till four pluses (++++). Mentioned paracoagulative tests interadd each other and they are better to be applied together. They can be negative at significant hypofibrinogenemy.
D-dimeres or fibrin (fibrinogen) degrading products (FDP) appear at fibrinolysis (plasmin action to fibrin or fibrinogen). Test essence: antifibrinogen antibodies binding with FDP in test-serum with latex loaded with fibrinogen. Level increasing is observed at DIC-syndrome (at the first hypercoagulation phase), thromboses, thrombophilies (tendency to thrombosis) treatment.
Probe to accelerated fibrinolysis gives the possibility to evaluate blood (plasma) lythic features.
Some express-coagulogram tests:
· Plasma recalcification time (it is not estimated in English-speaking countries but is still assessed in some Ukrainian clinics) – 0,1 ml of plasma + 0,1 ml of physiological solution, to stay test tube into water bath at 37°C; after 30 sec to add 0,2 ml of 0,277% CaCl2. To determine plasma coagulation time by means of second arrow.
|
|
|
· Thrombin time – 0,1 ml of healthy person plasma + 0,1 ml of physiological solution and in 60 sec after test tube heating in water bath to add 0,1 ml of thrombin standard solution. To determine clot time formation time on stop-watch.
· Prothrombin time – 0,1 plasma of a healthy person + (after heating on water bath in course of 60 sec) 0,2 ml of thromboplastin-calcium mixture and to determine clot formation time on stop-watch.
· Activated partial thromboplastin time course determining. 0,1 ml of platelet-weakened plasma (it takes after blood centrifuging at centrifuge velocity during 30 min at 30000 rotations per 1 min) + 0,1 ml of kaolin; to shake the mixture; to put on watery bath for 2 min; the mixture should be shaken in every 10 min for maximal contact activation; after 2 min 0,2 ml of kephalin and 0,2 ml of calcium chloride is added to the mixture.
· Fibrinogen content determining – 0,5 ml of plasma + 0,1 ml of 5% CaCl2. To wait for solid clot appearance, to carry it to paper filter and to dry till dry-air state, to weight it on torsion weight, to divide the result received into 2. We receive fibrinogen concentration in g/l.
· Reaction on ethanol (ethanol test) – 0,4 ml of plasma + 0,15 ml of 50% ethanol solution, to shake up the test tube and to switch on stop-watch. To determine in 10 min at room temperature whether gel clot occurred in plasma. Probe is considered positive at clot existence.
· Fibrinogen “B” determining. To add 2 drops of beta-naphthol to 0,5 ml of investigated plasma. To shake up test tube and to leave it at room temperature for 10 minutes. Stock-taking is performed by the following way: plasma sediment (+), small granulose flakes falling (++), rude flakes falling (+++), clot formation (++++).
5. Literature recommended:
1. Lecture course.
2. Mistchenko V.P., Tkachenko E.V. Methodical instructions for dental students (short lecture course).-Poltava, 2005.-P.43-44.
3. Mistchenko V.P., Tkachenko E.V. Methodical instructions for medical students (short lecture course).-Poltava, 2005.-P. 73-74.
4. Mistchenko V.P., Tkachenko E.V. Blood system Physiology //Methodical recommendations to practical classes for students of medical and dental departments.-Poltava, 2005.-20p.
5. Kapit W., Macey R.I., Meisami E. The Physiology Colouring Book: Harpers Collins Publishers, 1987.-P. 138.
6.Guyton – Ganong – Chatterjee. Concise Physiology /Ed. By Dr Raja Shahzad Gull: M.B.B.S., F.C.P.S., King Edward Medical College.-Lahore, 1998 (1st Edition).-P.198-202, 209-210.
7. Stuart Ira Fox. Human Physiology.-8th Ed.-McGrawHill, 2004.-P.374-375.
8. Seeley R.R., Stephens T.D., Tate P. Essentials of Anatomy and Physiology.-The 3rd Ed.-McGraw Hill, 1999.-P.294-295, 300-303.
6. Materials for self-control:
Control questions
1. Coagulational factors.
2. Coagulation mechanism.
3. Fibrin and fibrinogen degradation products and their role in hemostasis.
4. Oral cavity role in coagulational hemostasis support.
5. Positive paracoagulational probes at dental diseases.
LESSON 37
Дата добавления: 2018-09-22; просмотров: 441; Мы поможем в написании вашей работы! |
Мы поможем в написании ваших работ!