Haemorrhage Flashcards
Define circulatory shock.
An acute failure of the cardiovascular system to adequately perfuse the tissues of the body
What are the 4 types of circulatory shock?
Hypovolaemic
Cardiogenic
Distributive
Obstructive
What are some signs and symptoms of shock?
Rapid breathing
Decreased MAP
Impaired urine output
Weak and rapid pulse
Weakened muscle function
What is a class I haemorrhage?
10-15% blood loss - no shock, MAP unaffected
What is a class II haemorrhage?
Rapid 15-30% blood loss - shock, decreased MAP
What is a class III haemorrhage?
Rapid +30% loss - severe shock, major decrease in MAP
What happens when blood coagulability is increased?
Production of micro-thrombi
WBC adhesion
Inflammatory response exaggerated
How does blood coagulability affect perfusion?
Reduced tissue perfusion and organ failure
What happens after hypovolaemia?
Decrease in central venous pressure -> decrease in end diastolic volume -> decrease in stroke volume -> decrease in pulse pressure and MAP -> decrease in baroreceptor activity
What do chemoreceptors detect?
Reduction in blood perfusion
Acidosis - low pH
What are the three reflex responses?
Increased sympathetic outflow
Vasoconstrictor hormones
Increased renin secretion
What does cardiac sympathetic activity, vasopressin and adrenaline cause?
Dilation of coronary arteries and cerebral arteries
What are 2 features of the compensated (non-hypotensive) phase?
Loss of up to 15% of blood volume
MAP maintained
What are 2 features of the decompensated (hypotensive) phase?
Loss of over 30% of blood volume
MAP falls rapidly
What is the immediate cardiac response?
Increased sympathetic outflow
Decreased parasympathetic outflow
Adrenaline secretion
CO increased
What is the immediate vascular response?
Increased sympathetic outflow and vasoconstrictor hormones _> TPR and venoconstriction increases
Adrenaline and glucagon stimulate glycogenolysis
What are the two intermediate term responses?
Reduced capillary pressure
Stimulation of glycogenolysis
What does reduced capillary pressure encourage?
Fluid reabsorption from interstitial fluid
What does stimulation of glycogenolysis raise?
Osmolarity of plasma and interstitial fluid
Draws fluid from ICF
Reduced hematocrit
What are the 3 long-term responses?
Restoration of water and electrolyte balance
Restoration of plasma proteins
Restoration of haematocrit
How is the restoration of water and electrolyte balance achieved?
Increased salt and water reabsorption by aldosterone levels
Increased thirst from angiotensin II levels
How is the restoration of plasma proteins achieved?
By the liver
How is the restoration of hematocrits achieved?
Kidneys secrete erythropoietin -> triggers RBC production in bone marrow
What happens in the decompensated phase (loss of >30%)?
Cardiac failure
CNS depression
Metabolic acidosis of tissues
Death
What is a disease associated with haemorrhage?
Cerebral ischemia
