[A] 1.19 Hemostasis, shock Flashcards
Haemostasis
Arrest of bleeding
- Finely regulated physiological response
Purpose of physiological haemostasis
- Respond to vascular damage → Prevent blood loss
- Without affecting fluidity and flow of blood in normal, undamaged vasculature
Disruption of the balance of:
- Endothelium
- Platelets
- Coagulation factors
- Haemorrhage
- Thrombosis
Give the steps of haemostasis
- Primary stage
- Secondary stage
- Thrombus dissolution
- Tissue repair at the damaged site
Haemostasis: Primary stage
- Transient vasoconstriction
- Platelet aggregation to form platelet plug
Haemostasis: Secondary stage
- Coagulation to form a meshwork of fibrin
- Intrinsic (XII activation)
- Extrinsic (TF - VII activation)
- Common pathway activation of X
- Fibrin activation
Haemostasis: Thrombus dissolution
- Thrombus retraction by plasmin
- Fibrinolysis
List the disturbances of microcirculation
- Prehaemostasis
- Haemostasis
- Posthaemostasis
- Peristasis
Praehaemostasis
Blood flow slows down
Haemostasis of microcirculation
- In terminal bed
- Leakage
- Reversible
Posthemostasis
Start of the blood flow
Peristasis
Slow bloodflow
What can induce haemostasis?
- Cellular changes
- Viscosity
- Chemical factor
- Rheological factors
Cellular changes inducing haemostasis
- Stabile suspension - labile suspension
- Thrombocytes, RBCs, WBCs
Viscosity changes inducing haemostasis
- Plasma leakage
- Higher density
Chemical factors inducing haemostasis
- Intercellular bridges
- Hypercoagulability
Shock
- General circulatory disturbance
- Peripheral circulatory failure
- Clinical term
- Blood is in the terminal circulatory bed
Mild shock
Can lead to collapse
- Mild disorder for a short time
Define shock
Cardiovascular collapse
- The syndrome resulting from a disproportion between blood volume and volume of the circulatory system (1:6)
- Profound circulatory failure resulting in life-threatening hypoperfusion of vital organs
Give the types of shock
- Cardiogenic
- Hypovolaemic
- Blood maldistribution
Cardiogenic shock
Acute/chronic heart failure
Hypovolaemic shock
- Blood loss
- Reduced circulating blood volume
- Fluid loss
- Secondary to vomiting, diarrhoea, burn
Blood maldistribution shock
- Neurogenic
- Vasodilation - paralysis of the vasomotor centre
- Anaphylactic - Type I hypersensitivity reaction
- Septic (endotoxin)
Septic shock: Causes
- Gr- lipopolysaccharide
- Gr+ fungi
- Cytokines
- Vasoactive mediators
Give the steps of septic shock cause
- LPS blocks production of anticoagulant substances
- Activation of the complement cascade
- Activation of the intrinsic coagulation
- TNFα & IL-1 production by activated macrophages
- Promotion of extrinsic coagulation by TF expression
- PAF - Thrombocyte aggregation
Give the phases of shock
- Non-progressive
- Progressive
- Irreversible
Non-progressive phase of shock
- Compensation
- Baroreceptors
- Sympathetic effect, epinephrine
- ↑ Cardiac output, ↑ peripheral resistance (vasoconstriction)
- ADH
- Renin-angiotensin-aldosterone system
- ACE-blockers
- Sympathetic effect, epinephrine
Progressive phase of shock
- Inadequate compensation
- Anaerobic glycolysis in the cells (lack of O2)
- Lactate, local hypoxia, ↑ CO2 → Arteriolar relaxation & dilation
Irreversible phase of shock
- Severe metabolic acidosis
- Insufficient blood supply of the vital organs, DIC
Shock: Pathological signs
- Haemorrhages:
- Under the serosal membranes
- On mucous membranes
- In some organs
- Congestion in the abdominal organs
- Acute dilation of the heart
- Ischemia in the kidney
