Shock and haemorrhage Flashcards
What is shock?
A state of inadequate perfusion of the body
Give examples of high output shock
Anaphylactic shock
Sepsis
Give examples of low output shock
Cardiogenic
Hypovolaemic
What is cardiogenic shock?
Due to any form of pup failure or myocardial infarction
Arterial blood pressure and the effective circulating volume fall
Central venous pressure rises
Widespread vasoconstriction
Sympathetic innervation of kidneys activates the renin-angiotensin system
What is hypovolaemia?
Commonly caused by haemorrhage, diarrhoea, vomiting, burns or dehydration
Fall in central venous pressure
Kidneys trigger renin-angiotensin system
What percentage of blood is lost to induce mild, moderately severe, severe and fatal shock?
20%
30%
40%
50%
What are other changes with an effect on the kidney?
Switch to anaerobic respiration
Tissue damage
Cardiac hypoxia
Renal hypoxia
What does prolonged hypotension lead to?
Acute renal failure
What is the renal response to shock?
Fall in venous pressure activates ADH release
Hyponatraemia triggers aldosterone release
Renin angiotensin system helps retain both Na+ and water
What is present in fluids given to treat haemorrhage?
Colloids
Crystalloids
When is blood given in haemorrhage?
Only when haemoglobin is low
What two systems auto regulate renal blood flow?
Myogenic response
Tubuloglomerular response
What is the myogenic response?
When afferent arterioles are stretched, they contract increasing perfusion pressure, narrowing the vessels, reducing flow rate
What is tubuloglomerular feedback?
Each nephron regulates its GFR
High Na+ triggers ATP release by macula densa
Converted to adenosine
Causes vasoconstriction of afferent arterioles
What also controls renal flow?
Innervation
Hormones
