Bleeding and Shock Flashcards
What three factors can be classified as shock
Decreased blood perfusion of tissue
Increased oxygen demand from tissues
Inadequate blood oxygen
How can shock be recognised
lactate
urine output
Biochemical markers
Describe distributive shock
Failure of vasoregulation (vasodilation relaxes blood vessels and organs dont get enough blood). Can be caused by sepsis, anaphylaxis or be neurogenic
Describe hypovolaemic shock
Loss of intravascular blood volume (due to bleeding? sickness?). Includes haemorrhage (trauma) or non haemorrhage (burns)
Describe obstructive shock
Barrier to cardiac flow
eg PE or tension pneumothorax
Treatment for distributive shock
Fluid
antibiotics
Treatment for hypovolaemic shock
Fluid
blood
stop losses
Treatment for Cardiogenic shock
inotropes
Vasopressors
fluids
a cardiologist
Treatment for obstructive shock
Relieve obstruction (needle for unctured lung burst clots)
How are HR and RR BP and OF affected by shock
HR and RR increase
BP and OF decrease
4 types of wounds
laceration
incised
degloving
bites
Describe laceration wounds
Blunt force trauma resulting in skin splitting or tearing
describe incised wounds
Sharp or penetrating trauma stab/slash type
clean edges/uniform shape
Describe degloving wound
Skin and its blood supply are torn off limbs/digits
major trauma
Describe bite wounds
Small entry wound
possibly deep
foreign body contamnination
Describe components of blood
RBCs
WBCs
platelets
Plasma (mainly water)
carries coagulation factors
electrolytes
nutrients
hormones and waste products.
Describe red blood cells
Biconcave discoid shape
large surface area
no nuclei or organelles
packed with haemoglobin (gives blood its red colour)
Describe white blood cells
“leucocytes”
lymphocytes: b, t and NK (shapes vary from spherical to pleomorphic)
nuclei are large
round, densely staining and eccentrical
granulocytes
basophils
monocytes
structure of platelets
biconvex discoid shape maintained by circumferential bundle of microtubules
fucntion of RBCs
gas exchange
transport oxygen from the lungs to peripheral tissues and carbon dioxide in reverse. they carry haemoglobin which has high affinity for oxygen in lungs and low in tissues allowing it to be displaced.
fucntion of wbcs
defence against infection. Neutrophils,
monocytes, basophils and eosinophils are phagocytes that engulf and destroy pathogens. B-Ls produce antibodies against a specific antigen and T-Ls specifically recognise foreign/infected antigens and bind to the cell to release proteins that induce apoptosis
describe role of platelets
involved in blood clot formation. they form an occlusive plug to stop blood flow by binding to the vessel (adhesion) and each other (aggregation)
They are also ‘antibody factories’
function of tranexamic acid
can help control bleeding as it prevents clot lysis by inhibiting activation of plasminogen into plasmin
what causes haemophilia A
deficiency of factor VIII (intrinsic pathway)
what causes haemophilia B
deficiency of factor IX (intrinsic pathway)
explain production of blood cells
haematopoiesis. haematopoietic stem cells can develop into myeloid or lymphoid progenitor.
M: further differentiates into RBC, platelet and the phagocytes
L: further differentiates into B-Ls, T-Ls and NKCs
three steps in blood clot formation
vasoconstriction
platelet plug formation
coagulation cascade
importance of von Willebrand Factor
vWF acts as an anchor for platelets to bind to the vessel wall in platelet plug formation
describe the extrinsic pathway
Damaged tissue triggers tissue factor which activates factor VII. this stimulates the final common pathway
describe the intrinsic pathway
Sub-endothelial contact activates platelets. This activates factors XII, XI and IX in a cascade. Then activated VIII stimulates the final common pathway.
describe the final common pathway
Activated of factor X converts prothrombin into thrombin. This activates conversion of fibrinogen into fibrin forming a stable fibrin clot.
what are the tests for haemophilia
APTT (intrinsic)
PT (extrinsic)
Describe the process of fibrinolysis
process by which a clot is removed.
1. plasmiogen is synthesised in the liver and circulates in the plasma.
2. plasminogen gets trapped in a clot as it forms
3: plasminogen is activated by a serine protease called tissue plasminogen activator (tPA)
4. tPA converts plasminogen into plasmin which breaks down the fibrin mesh.
What is EPO and where is it primarily synthesised
Erythropoietin is a peptide growth hormone that stimulates the production of red blood cells
mainly produced in the kidneys
What does a fucntional haemoglobin molecule contain
four haem groups and four polypeptide chains
Why is sodium citrate added to blood donation samples
It is a chelating agent
chelates calcium and inhibits clot formation
What surfaces does the Phospholipid/kaolin suspension mimick in vitro?
negatively charged surfaces of activated platelets when they change from spherical to finger-like projections
What is the major protein missing from serum compared to plasma
Fibrinogen
this means clots cannot form with just serum
is calcium required for clotting?
Yes
but it is not required for thrombin action
what is TXA
Tranexamic Acid
Antifibrinolytic - reversibly binds to 4 or 5 Lysin receptor sites on plasminogen
Prevents conversion into plasmin thus preventing vlot lysis/breakdown of fibrin matrix
What is vitamin K a cofactor for
the activation of factors II, VII, IX and X
