Ischaemia, infarction and shock Flashcards
Limitations of therapeutic reperfusion
Only works in reversible ischaemia
Risk of reperfusion injury due to the generation of reactive O2 species
Causes of infarction
Thrombus Embolus Vasospasm Atheroma expansion Tumour Volvulus Rupture
This type of infarction has a single blood supply
White infarction
This type of infarction has a dual blood supply
Red infarction
Difference between thrombus and embolus
Thrombus: solid mass of blood constituents formed in vascular system in life
Emboli: derived from thrombi. Can be exogenous
Neurone death vs cardiac myocyte death time?
3 minutes for neurone in absence of oxygen
20-30 minutes for myocytes
Reduced O2 in blood increases chances of what?
Infarction
What occurs at the point of anastomosis of two vessels?
Watershed region
Arteries occluded which lead to ischaemic bowel disease?
Superior / inferior mesenteric
Types of gangrene and explanation
Dry - ischaemic coagulative necrosis
Wet - superimposed infection
Gas - Superimposed infection with gas producing organisms
Define shock
Physiological state characterised by significant reduction of systemic tissue reperfusion resulting in decreased oxygen delivery to the tissues
Critical imbalance between oxygen delivery and oxygen consumption
Effect of shock
Systemic effects of shock
Changes to serum pH
Vascular leakage
Stimulation of inflammatory and anti-inflammatory cascades
End organ damage
Cellular effects of shock
Membrane ion pump dysfunction
Intracellular swelling
Anaerobic respiration
Types of shock
Hypovalaemic Cardiogenic Distributive Anaphylactic Neurogenic
Characteristics of hypovalaemic shock
Intravascular fluid loss
Leads to decreased preload
Decreased SV=Decreased CO
Counteracted by increased systemic vascular resistance
Characteristics of cariogenic shock
Cardiac pump failure
Decreased CO
Counteracted by increasing systemic vascular resistance
Causes of cariogenic shock
Myopathic
Arrhythmia related
Mechanical
External cardiac
Characteristics of distributive shock
Severe vasodilation leading to decrease in systemic vascular resistance
Compensated for by increasing CO
Subcategories of septic shock
Septic
Anaphylactic
Neurogenic
Causative agents of septic shock
S. aureus
S. pyogenes
Mechanism in toxic shock syndrome
SA and SP release exotoxins which do not require processing by APCs
Non specific binding of C2MHC to TCRs
Widespread release of massive amounts of cytokines
Decreased systemic vascular resistance
