Thrombosis, Embolism & Shock Flashcards
What is blood clotting an example of?
Haemostatis
What is haemostatis?
The balance between maintaining blood clotting function and the loss of blood. it requires anti-coagulant factors and pro-coagulant factors
What is the process of blood clotting?
1) Damage to the endothelium
2) Vasodilation
3) Platelets adhere, active and aggregation
4) Primary platelet plug is formed
5) Clotting factors are activated due to collagen exposure
5) The final stage of the clotting factor cascade causes the stable fibrin clot
Why would you want to limit coagulation at the site of injury?
Prolonged clotting will cause thrombosis
What factors limit coagulation?
1) Clotting factors are only activated once collagen is exposed
2) Anti-thrombin factors
3) Protein C and S will inactive some clotting factors
4) Plasmin performs fibrinolysis
How is blood clotting measured?
INR (international normalised ratio)/ Prothrombin time
What is the normal INR/Prothrombin time?
1 - 1.5
What causes an increase in INR/Prothrombin time (longer for blood to clot)?
1) Vitamin K deficiency
2) Malabsorption
3) Liver disease
4) Warfarin Therapy
5) Increased consumption of clotting factors
Definition of thrombosis?
The process of the inappropriate activation of blood clotting resulting in a thrombus
Definition of thrombus?
A semi-solid or solid mass containing blood constituents (at the primary site)
Definition of emboli?
Any detached intravascular solid, liquid or gas travelling in a vessel to a secondary site distant from the primary site
Definition of a Thromboemboli?
A fragment of the thrombus which causes an emboli in a distant site to its primary site
What 3 factors increase the likelihood of a thrombus?
VIRCHOW’S TRIAD:
1) Abnormalities in the endothelial wall
2) Abnormalities in the blood flow
3) Abnormalities in the blood constituents
How can a thrombus be detected?
Using an echocardiogram
What are the 2 types of thrombus?
Mural and Ball thombus
What causes a mural thrombus?
Rheumatic endocarditis = Inflammatory condition of the heart
What causes a ball thrombus?
Atrial fibrillation = No loner getting the normal sequential contractions to cause the normal flow of blood from the atria into the ventricles
How can a thrombus in the aorta be detected?
Using an arteriogram
Name a problem that a thrombus in the aorta would cause?
Ischaemia in the legs
Describe an aneurysm:
An aneurysm is a dilation of the heart muscle wall and it occurs after myocardial infarction. This is because a the heart cells die the walls become thinner and they dilate in order to cope with the pressure
What does the Virchow’s triad explain?
3 factors that increase the likelihood of a thrombus formation
Describe the abnormalities of the blood vessel wall that can increase the likelihood of thrombus formation?
1) Atheroma = fatty deposits
2) Inflammation of the vessel walls (e.g. Rheumatic endocarditis which results in a mural thrombus)
Describe the abnormalities of the blood flow that can increase the likelihood of thrombus formation?
Anything that stops the blood from travelling in a laminar flow formation:
1) Plaques
2) Aneurysms (dilation)
3) Spasms
How can a post-morterm image of a thrombus tell us if the thrombus developed over time or after death?
If the thrombus shows a layered structure (lines of Zahn) then this shows the thrombus developed over time in the persons life and not after death.
What do the lines of Zahn in a post-morterm thrombus image show?
Alternating lines of erythrocytes and platelets
What can a thrombus in the vein lead to?
Deep vein thrombosis
What 3 factors cause a venous thrombus?
1) Stasis
2) Inactivity / immobility
3) Direct compression on the vein
What is the most likely cause for a venous thrombus and an arterial thrombus?
Venous thrombus - Stasis
Arterial thrombus - Injury/foreign bodies
What 3 things can happen once a thrombus has formed?
1) Resolve - by fibrinolysis
2) Organisation - scar tissue formation by fibroblasts and macrophages
3) Detachment - causing an emboli
What are the 7 main types of emboli and expand on each?
1) Thromboemboli (e.g. pulmonary thromboemboli caused by CVT –> lungs)
2) Fat (secondary to traumas and commonly occurs in those with multiple bone fractures)
3) Trauma material (if the material penetrates into the BV)
4) Infectious agents (e.g. infective endocarditits)
5) Atheroma (from atheromatous plaques)
6) Amniotic fluid (common cause of maternal death and is caused when uterine contractions are strong and the amniotic fluid travels from the baby into the mother uterine veins)
7) Foreign bodies (common with IV drug users)
Definition of shock:
A state of the body in which the tissues and the organs are not receiving adequate blood flow
What are the resulting factors of shock?
1) Inadequate O2 supply
2) Build up of waste products as they are not being removed
3) Serious damage and death
What are the 3 different stages of shock?
1) Compensated: Blood loss is under 25% and the patient can recover
2) Non-compensated: Blood loss is over 25% and the patient needs help
3) Irreversible: Normal blood flow can not be restored and causes critical organ damage
What would you expect the EWS to be in a patient in shock?
1) Low systolic BP
2) Tachycardia
3) Low urine output
4) Metabolic acidosis
5) Hypoxia
6) Anxiety, agitated, lethargic
What are the 6 different types of shock? (think: NACHOS)
1) Neurogenic shock
2) Anaphylactic shock
3) Cardiogenic shock
4) Hypovolemic shock
5) Obstructive shock
6) Septic shock
What is the cause of a neurogenic shock?
Traumas to the spinal cord
What is the cause of a anaphylactic shock?
Severe allergic response
What is the cause of a cardiogenic shock?
Failure of the heart muscle
What is the cause of a hypovolemic shock?
When there isn’t enough blood volume to supply the tissues and organs
What is the cause of a obstructive shock and 3 examples?
Obstruction to an organ:
1) Massive pulmonary embolism
2) Tension Pneumothorax (when air in the thoratic cavity outside of the lungs causes tension on the lungs)
3) Cardiac tamponarde: Blood around the heart is built up
What is the cause of a septic shock?
Systemic response to a systemic infection.
If it is endotoxic - related to a gram -ve bacteria
If it is exotoxic - related to a gram +ve bacteria
