Shock Flashcards
Name the four types of shock.
Hypovolaemic
Cardiogenic
Maldistributive
Obstructive
What is the cause of hypovolaemic shock?
Loss of 20% or more of circulating volume
What is the cause of cardiogenic shock?
Failure of the heart to act as an effective pump
What is the cause of obstructive shock?
Mechanical impediments to forward flow, e.g. blocked circulation
What is the cause of maldistributive shock?
Abnormalities of the peripheral circulation, e.g. dilated arteries
What is shock?
Describes acute circulatory failure with inadequate or inappropriately distributed tissue perfusion
Which type of shock is associated with sepsis?
Maldistributive shock
What is a good biomechanics marker for the severity of shock?
Lactic acid
What are the three stages of shock?
Non-progressive
Progressive
Irreversible
What is the sympathetic response to shock?
Hypotension causes increased sympathetic activity with noradrenaline release
Results in vasoconstriction, increased myocardial contractility and heart rate
What does the adrenal medulla produce in response to shock?
Catecholamines, specifically adrenaline
What is the renal response to hypotension?
renal-angiotensin-aldosterone pathway
What is the renin-angiotensin-aldosterone pathway?
Reduction in perfusion in renal cortex stimulates release of renin.
Renin converts angiotensinogen to angiotensin I, which in the lungs is converted to angiotensin II.
Angiotensin II stimulates secretion of aldosterone from adrenal cortex.
In the long-term, what occurs in non-progressive shock?
Internal transfusion
More glucose produced
What is internal transfusion?
Body tries to move fluid from interstitial to vasculature by decreasing BP, which decreases capillary hydrostatic pressure
What happens when fluid loss exceeds 30%?
It becomes progressive shock
What happens in progressive shock?
Increased vascular permeability
Further decrease in blood volume
Further tissue damage
Impaired tissue perfusion and gas exchange
What is the golden hour?
The hour after the start of rapid blood/fluid loss where rapid treatment will be most effective
What is irreversible shock caused by?
Prolonged fluid loss causing irreversible damage to the heart
What is SIRS?
Systemic inflammatory response syndrome - an inflammatory state affecting the whole body, usually in response to infection
What is SIRS usually related to?
Sepsis
How is SIRS defined?
Having two or more of the following features:
Temp >38 or 90)
Tachypnoea (>20 RR)
High white cells (>12 x10l)
What does DIC stand for?
Disseminated intravascular coagulation
What is DIC?
Widespread activation of blood coagulation, due to release of procoagulants into the circulation
What is sepsis?
Systemic inflammatory response to infection, marked by characteristic haemodynamic disturbance or organ dysfunction
Why is there refractory hypotension in septic shock?
Low systemic vascular resistance
Low central venous pressure
Pulmonary artery occlusion pressure
How is sepsis diagnosed?
Clinical recognition
What are the clinical manifestations of sepsis?
Fever Confusion Tachycardia Tachypnoea Hypotension
Why is there ‘warm shock’ in septic shock?
Decreased BP is due to increased cardiac output and decreased peripheral resistance
Also there is normal stroke volume
What is ARDS?
Acute respiratory distress syndrome
Decreased compliance of vessels and decreased oxygen exchange
What should be given urgently in sepsis to increase chance of survival?
Antimicrobial agent
What does haemodynamic support involve?
Maintaining cardiac output
Ensure sufficient arterial blood pressure to perfuse organs
