DR NILESH KATE

MBBS,MD ASSOCIATE PROF

DEPT. OF PHYSIOLOGY

HAEMOSTASIS IIANTIHAEMOSTATIC

MECHANISMS

OBJECTIVES. Anti-haemostatic

mechanism.

Bleeding disorders.

Laboratory tests

Monday, May 1, 2023

ANTIHAEMOSTATIC MECHANISM

The factors which balance the tendency of blood to

clot in VIVO forms Anti-Haemostatic Factors.

Factors preventing platelet aggregation

Factors preventing coagulation

Factors causing fibrinolysis.

Monday, May 1, 2023

FACTORS PREVENTING PLATELET AGGREGATION

PROSTACYCLIN – Endogenous factor inhibit Thromboxane A2( Promote Platelet Aggregation).

Normally balance between

Prostacyclin

Thromboxane A2 Prevents Intravascular spread of

plug.

Monday, May 1, 2023

FACTORS PREVENTING COAGULATION

Circulating Anticoagulant Heparin Anti-thrombin III or heparin Co-factor II Protein C.

Monday, May 1, 2023

HEPARIN Powerful Natural Anti-

coagulant. First isolated from Liver. Its Polysaccharides

containing sulphate groups Mol wt – 15000-18000

dalton. Secreted by Basophils &

mast cells. Destroyed by Heparinase.

Monday, May 1, 2023

HEPARIN MECHANISM OF ACTION

Prevents activation of Prothrombin to Thrombin.

Inhibits action of thrombin on fibrinogen.

Facilitate action of Antithrombin –III & inhibits factor IX,X,XII & XII

Monday, May 1, 2023

ANTI-THROMBIN III OR HEPARIN CO-FACTOR II

Present in plasma & vascular endothelium.

Inactivates Coagulation factors including thrombin.

Monday, May 1, 2023

PROTEIN C. Plasma protein from

liver. Along with

Thrombomodulin & protein S forms Negative feedback for Coagulatory process under control.

Monday, May 1, 2023

PROTEIN C PATHWAY INHIBITING COAGULATION & PROMOTING

FIBRINOLYSIN.

Monday, May 1, 2023

THROMBOMODULIN Thrombin binding

protein produced by endothelial cells except cerebral microcirculation.

Converts thrombin into protein C activator.

Monday, May 1, 2023

FIBRINOLYTIC MECHANISM FIBRINOLYSIS –

dissolution of Fibrin. Important component

is Plasmin or fibrinolysin present in inactive form called plasminogen or Profibrinolysin.

Monday, May 1, 2023

FACTORS CAUSING FIBRINOLYSIS Plasminogen plasmin. Extrinsic plasminogen

activator system Intrinsic plasminogen

activator system

Monday, May 1, 2023

PLASMINOGEN Beta globulin produced

by liver. It is associated with

fibrinogen molecule. Plasminogen is

activated by plasminogen activator system to produce PLASMIN.

Monday, May 1, 2023

PLASMIN. Powerful protease formed

from plasminogen. Lysis fibrin & fibrinogen into

fragments known as fibrin degradation products that inhibit thrombin.

2 plasminogen activator system. Extrinsic Intrinsic

Monday, May 1, 2023

EXTRINSIC PLASMINOGEN ACTIVATOR SYSTEM

Predominant mechanism

In its absence extensive fibrin deposition occurs.

Its absence causes delayed wound healing Defect in growth &

fertility.

Monday, May 1, 2023

FIBRINOLYTIC MECHANISM OPERATING THROUGH EXTRINSIC PLASMINOGEN

ACTIVATOR SYSTEM.

PLASMINOGEN

TPA

THROMBIN

UPA

PLASMIN

Fibrin Fibrin degradation product (FDP)

Monday, May 1, 2023

TISSUE PLASMINOGEN ACTIVATOR

Also called Vascular Plasminogen Activator released from vascular endothelium.

Its release depend upon release of Serotonin from platelets & release of adrenaline.

E.g – In soldier in battlefield there is massive fibrinolysis due to release of adrenaline.

TPA is now produced by Recombinant DNA technology & used clinically.

Monday, May 1, 2023

UROKINASE TYPE PLASMINOGEN ACTIVATOR

Found in endothelial cells, renal cells & Tumor cells.

E.g. – STREPTOKINASE & STAPHYLOKINASE are bacterial enzymes causes activation of Plasmin like TPA & UPA.

Monday, May 1, 2023

INTRINSIC PLASMINOGEN ACTIVATOR SYSTEM

Contact factor XIIa & Kallikrein intiate

clotting mechanism also stimulate

dissolution of clot by activating plasminogen

& form intrinsic plasminogen activator

system.

Monday, May 1, 2023

FIBRINOLYTIC MECHANISM OPERATING THROUGH INTRINSIC PLASMINOGEN

ACTIVATOR SYSTEM.

Prekallikrein XII XIIa

Kallikrein

Thrombin

Plasminogen Plasmin

Fibrin Fibrin Degradation Product (FDP)

Monday, May 1, 2023

FIBRINOLYSIS INHIBITORS Rate of fibrinolysis is influenced by

promoters & inhibitors. Various INHIBITOR s are

ANTIPLASMIN – alpha2 antiplasmin Drugs – aprotinin & Epsilon amino caproic acid

(EACA) Inhibitors are present in plasma, blood cells,

tissues & extracellular matrix.

Monday, May 1, 2023

PHYSIOLOGICAL ROLE OF FIBRINOLYSIS SYSTEM

Cleaning the minute clots of tiny vessels Promote normal healing process. Liquefaction of menstural clot. Liquefaction of sperms in the epididymis. Role in inflammatory response

Monday, May 1, 2023

ANTICOAGULANTS Substances which delay or prevent process of

coagulation of blood. In vitro – done by substances which sequester

calcium – sodium citrate or oxalate, sodium edetate(EDTA)

In vivo –done by Antagonizing clotting factors – heparin Destruction of fibrinogen By inhibiting synthesis of factors – II,VII,IX & X

Monday, May 1, 2023

ANTICOAGULANTS Endogenous Anticoagulants – inside body

naturally – Heparin, antithrombin III & protein C

Exogenous anticoagulants or decalcifying agents. Heparin Calcium sequesters Vitamin K antagonists Defibrination substances.

Monday, May 1, 2023

CALCIUM SEQUESTERS By removing Ca from the blood.

Two types of agent

One which form insoluble salts with Ca – Na citrate

& Na oxalate

Calcium Chelators – which binds with Ca – EDTA.

Monday, May 1, 2023

VITAMIN K ANTAGONISTS Used orally. MOA – occupy Vit K active site & prevent Vit K to

function – inhibit synthesis of Vit K dependent factors as VII,IX & X Eg- Coumarin derivatives Warfarin Phenindione Nicoumalone

Monday, May 1, 2023

DEFIBRINATION SUBSTANCES. Which causes destruction of fibrinogen. Malaysian pit viper venom Arvin or ancord – preparation of snake

venom.

Monday, May 1, 2023

BLEEDING DISORDERS Spontaneous escape of blood from blood

vessels or Persistent or excessive bleeding following

minor injuries like tooth extraction etc.

Monday, May 1, 2023

BLEEDING DISORDERS Classification of bleeding disorders.

Platelet disorders Deficiency of platelets Functional disorders of platelets

Coagulation disorders or defective coagulation mechanisms

Deficiency of clotting factors Vit K deficiency. Anticoagulant overdose. DIC

Monday, May 1, 2023

BLEEDING DISORDERS Classification of bleeding disorders.

Vascular disorders. Damage of capillary endothelium(Non-thrombocytopenic Purpura)

Infection by bacteria & toxins,Toxic effects of drugs & chemicals

Avitaminosis , alergic purpura, connective tissue diseases.

Monday, May 1, 2023

PURPURA Group of bleeding

disorders due to various causes.

PURPURA – purple coloured petechial hemorrhages & bruises in the skin.

Monday, May 1, 2023

CAUSES AND TYPES OF PURPURA

Platelet disorders. Deficiency of platelets. (thrombocytopenic Purpura) Normal count – 1.5 l- 4 lac/mm3

Below 1.5lac – thrombocytopenia Causes –

Primary – cause not known Secondary –

Bone marrow depression. Leukemia. Acute septicemia, toxemia & uremia Hypersplenism.

Monday, May 1, 2023

CAUSES AND TYPES OF PURPURA

Functional disorders of platelets.(Thrombosthenic purpura) Drug induced defects –aspirin Von-willebrand’s disease. Vascular disorders (Non-

thrombocytopenic Purpura)

Monday, May 1, 2023

CAUSES OF NON-THROMBOCYTOPENIC PURPURA.

Drug induced damage to capillary wall. Deficiency of vitamin-C Allergic purpura. Infections Senile purpura Connective tissue diseases.

Monday, May 1, 2023

HAEMOPHILIA Group of disorders

due to hereditary deficiency of coagulation.

Characterized by Bleeding tendencies with Increased clotting time.

Monday, May 1, 2023

HAEMOPHILIA Haemophilia-A Haemophilia-B Haemophilia-C

Monday, May 1, 2023

HAEMOPHILIA-A Classical haemophilia

due to Deficiency of factor VIII.

Sex linked recessive disease affects males and females carrier.

Clinical features not apparent since birth but start early in life.

Monday, May 1, 2023

HAEMOPHILIA-A c/f – tendency to bleed into soft tissues, muscle, joints , GI

tracts, urinary tracts & from nose

Severely damaged joints.

Hemorrhage into soft tissue of mouth cause respiratory

obstruction & death by suffocation.

Normal bleeding time, platelet count & PT but prolonged CT &

PTT.

T/t – repeated small fresh blood, fresh plasma, factor VIII

conc.

Monday, May 1, 2023

HAEMOPHILIA-B Known as Christmas

Disease due to Deficiency of factor IX.

Reccessive X-Linked disease occurs in males, transmitted by females.

T/t – Fresh blood transfusion.

Monday, May 1, 2023

HAEMOPHILIA-C Deficiency of

PTA(Factor X) Inherited as Mendelian

dominant affects both males & females.

Without bleeding tendencies.

CT may be prolonged or normal.

Monday, May 1, 2023

DISSEMINATED INTRAVASCULAR COAGULATION.

Condition when clotting mechanism is activated in widespread circulation.

Due to wide spread coagulation plugging of small vessels leads to decreased O2 & nutrient supply- organ damage.

Monday, May 1, 2023

DISSEMINATED INTRAVASCULAR COAGULATION.

Most of the coagulation factors & platelets used up leads to its deficiency causing bleeding tendencies. So called consumption coagulopathy.

Fibrin degradation product formed due to fibrinolysis of clot have anti-haemostatic effect further aggravate bleeding tendency.

Monday, May 1, 2023

LABORATORY TESTS IN BLEEDING DISORDERS

Bleeding time(BT) Definition – time interval between

skin prick and the arrest of bleeding. Procedure.

Duke’s method – take a prick at finger skin , blood is wiped at 15 sec interval till it stops

Normal time :- 1-6 min. Ivy’s method – apply 40 mm Hg at upper

arm with BP cuff & take deep prick on ant surface of skin of forearm

Normal time – 3-6min.

Monday, May 1, 2023

LABORATORY TESTS IN BLEEDING DISORDERS

Prolonged BT – occurs in purpura & normal in Haemophilia.

Capillary fragility tests of Hess or Tourniquet test – To assess

the mechanical fragility of capillary by raising pressure.

Procedure – A circle of 1 inch diameter is marked on forearm &

pressure midway between systolic & diastolic is applied on upper

arm for 15min using cuff. any purple spot is marked with blue ink.

Monday, May 1, 2023

PLATELET COUNT Normal Platelet Count – 1.5 – 4 lac/mm3 Procedure

Direct method – using Reese-E-Kar fluid counted in Haemocytometer.

Indirect method – from RBC count & RBC:platelet ratio. 1platelet :16-18 RBC.

Monday, May 1, 2023

COAGULATION TIME. Def – Time taken by the fresh

blood to get coagulated by formation of fibrin threads.

Procedure. Capillary tube method – 3-6 min Modified Lee & white test tube

method (whole blood coagulation time) – blood is collected by venepuncture & kept in a test tube & time is noted to form a clot.

Normal time – 8-12 min.

Monday, May 1, 2023

IMPORTANCE OF CLOTTING TIME

Physiologically – CT prolonged during mensturation & before & during Parturition.

Pathologically – Prolonged in Haemophilia, liver diseases, Afibrinogenemia, Christmas disease, vit K deficiency DIC

Monday, May 1, 2023

PROTHROMBIN TIME Procedure – Quick’s one stage

method Oxalated or citrated plasma of

patient are added to tissue thromboplastin & Ca chloride solution & mixture incubated at 37oc – result is conversion of fluid plasma to gel.

NT – 11-16 sec Importance – used to monitor pt

receiving anticoagulant therapy.

Increase in Pts on oral

anticoagulants, liver failure, vit K deficiency, deficiency of factor II,V,VII,X

Normal in Haemophilia &

Christmas disease

Monday, May 1, 2023

PARTIAL THROMBOPLASTIN TIME

Procedure – To oxalated & citrated plasma of patients kaolin & ca chloride are added & mixture is incubated at 370 C, Result is formation of plasma gel

Importance – used to monitor Heparin therapy Prolonged in – haemophilia, Von-willebrand disease,

liver failure, deficiency of XII, anticoagulant therapy & intravascular clotting.

Monday, May 1, 2023

THROMBOPLASTIN GENERATION TESTS.

Normal value – 12 sec or less Prolonged Value Indicates – Deficiency of

factors needed to form prothrombin activator by intrinsic mechanism i.e factor V, VIII,IX & X

In Haemophilia – PT is normal but TGT prolonged.

Monday, May 1, 2023

THROMBIN TIME Measures final step in coagulation i.e functional

fibrinogen available. Thrombin is added to plasma which covert

fibrinogen to fibrin End Point – Formation of clot NT – 10 sec Prolonged in Hyperfibrinogenemia,

dysfibrinogenemia, DIC & heparin treatment.

Monday, May 1, 2023

CLOT RETRACTION TEST. It measures time needed for contraction of

clot. Indicate function & number of platelets NT – 2-24 hrs. Increased in – thrombocytopenia. Clot is soft & small in – Thrombosthenia

( Functional disorder of platelet)

Monday, May 1, 2023

Thank You