Flashcards in P9- Shock and atheroma (atherosclerosis) Deck (59)
what do all causes of shock result in?
acute circulatory failure with hypotension and inadequate tissue perfusion
what is a large component of the syndrome, regardless of aetiology?
failure of microcirculation
what happens if shock is not reversed quickly?
leads to multiorgan failure and death
Name the 5 major types of shock.
What are other causes of shock?
Include ‘Chemical’ shock eg
acute pancreatitis, acute peritonitis from perforated gastric ulcer
What is hypovolaemic shock due to?
- Due to reduced blood volume
eg haemorrhage,vomiting, diarrhoea,
- Inadequate circulating volume
what is susceptibility to hypovolaemic influenced by?
age and prior health if patients
Who tolerate blood loss less well?
elderly and hypertensive patients
How much blood can be lost that is still asymptomatic?
10% in healthy adult
what does rapid loss of half blood volume lead to?
coma and death
What causes septic shock?
- Severe infection, often Gram-negative bacilli that produce endotoxins
- LPS, liopolysaccahride, from the outer cell wall of the bacilli binds to and activates macrophages and endothelial cells
- TNF-α---IL-1- cytokine cascade
What does septic shock lead to?
Peripheral vasodilation, tissues underperfused, endothelial injury, fluid leakage, oedema, activated coagulation, DIC (disseminated intravascular coagulation)
Describe cariogenic shock.
- Severe acute reduction in cardiac output due to pump failure
- Massive myocardial infarct, arrhythmia, cardiac tamponade, pulmonary embolism, valve dysfunction
- Failure to maintain perfusion pressure and flow
what type of reaction is anaphylactic shock?
Systemic Type I Hypersensitivity
What happens in anaphylactic shock?
Massive mast cell degranulation causes release of vasodilators and permeability factors
Name 2 types of neurogenic shock.
• Acute brain injury
• Spinal cord injury
What role do compensatory mechanisms play?
In the early stages, compensatory mechanisms maintain blood flow to vital organs- CNS, heart, Kidneys- reduced perfusion to other tissues
Give examples of compensatory mechanisms.
- Increased sympathetic activity
- CNS, heart and kidney autoregulate their own perfusion
What happens if tissue perfusion is not restored urgently after shock?
ischaemia causes multiorgan failure and death
what is the shock consequence to the lungs?
Diffuse alveolar injury (ARDS Adult Respiratory Distress Syndrome)
what is the shock consequence to the heart?
ischaemia and failure
what is the shock consequence to the gut?
ischaemia and endotoxaemia
what is the shock consequence to the adrenal?
initially stimulated then failing
what is the shock consequence to the brain and kidneys?
-initially auto regulated blood supply
-later loss of consciousness and acute renal failure
How do shocked patients present?
-Rapid weak pulse
-Increased rate and depth of respiration
-Eventually drowsy then comatose
Give the layers of a normal artery from the inside out.
what are artery structural adapted to?
pressure and flow of blood within them
What does the aorta do?
multiple layers of elastic tissue to absorb impulse of cardiac systole and maintain blood flow in diastole
what do the medium-sized arteries do?
Medium-sized arteries regulate distribution of blood to various organs by constriction and dilatation, so possess thick medial wall with less elastic tissue