Shock and hypertensive emergencies Flashcards
define shock
serious and life threatening conditions resulting in tissue hypoperfusion
what can shock lead to?
hypotension which if prolonged an result in organ failure
what are the two signs in BP indicating shock?
low BP -90/60
or any drop of 30mmHg
what will a patients body do to maintain BP in shock?
increase cardiac output - not sustainable hence large drop
how do you calculate shock index?
Hr divided by systolic BP
why is shock index more accurate than BP itself?
- More accurate sign of shock than BP
- Should be 0.5-0.8
- 0.8< - suspicion of shock
what types of shock affect stroke vol?
- Anaphylactic shock
- Neurogenic shock
- Septic shock
- Vasodilator shock
- Induced shock
what are general signs of shock?
- Tachycardia
- Increased resp rate
- Signs of tissue hypoperfusion – delayed capillary refill time (2 sec< ), may have bounding pulses/ warm peripheries
- Weak pulse
- Decreased urine output – keep fluids in to maintain BP
- Confusion – by-products of everything
how is shock a vicious cycle?
inflammatory mediators are released
blood diverted - more hypoxia etc
what can cause hypovolaemic shock?
haemorrhage
fluid loss/ dehydration
how can DKA contribute to hypovolaemic shock?
blood glucose so high, excreted with urine - more water follows - more dehydration
what is the mechanism of hypovolaemic shock?
reduced cardiac output due to reduced fluid volume
how does body respond in hypovolaemia to increase fluid?
shift interstitial fluid
ADH secreted
splenic discharge
what occurs to the heart during hypovolaemic shock?
heart increased contractibility due to more noradrenaline
how do you treat hypovolaemic shock
more fluids
need to find initial cause
what is cardiogenic shock
failure of heart to pump effectively
what can occur as a result of cardiogenic shock?
large MI
arrhythmia
heart failure - congestive, cardiomyopathy/ myocarditis
pulmonary oedema
what is the mechanism responsible for cardiogenic shock
poor myocardial contractility
- high venous pressure leads to fluid extravasation and oedema (build up of fluid in the body which causes affected tissues to be swollen)
what is distributive shock?
inappropriate peripheral vasodilation causing pool of blood/ fluid in tissues
what types of shock can cause distributive shock?
septic shock
anaphylactic shock
neurogenic shock
what is the mechanism responsible for distributive shock?
- pooling of blood by peripheral vasodilation
- capillary leak worsens hypovolaemia and causes odema (inc pulmonary)
- changes above lead to reduction in BP and organ perfusion
- vessels dilate causing relative hypovolaemia and reduction in SVR
which type of shock is the biggest emergency?
obstructive
what is obstructive shock?
obstruction of blood flow
what can cause obstructive shock?
cardiac tamponade
pulmonary embolus
aortic stenosis
what is cardiac tamponade?
collection of fluid in pericardial space and prevents effective contraction of heart
what is a PE?
pulmonary embolus - blockage of major pulmonary artery
what is afterload?
amount of work the heart has to do to pump blood to the rest of the body
what are the stages of shock?
initial compensation
decompensated/ refractory
what occurs during initial compensation?
hypoperfusion causing anaerobic resp
acidosis - increasing resp rate
increased hr and increased systemic vascular resistance
what builds up during anaerobic respiration and part of initial compensation of shock?
lactic acid
what happens during decompensated/ refractory period- shock
- cell injury results in loss of function
- worsening acidosis and inflammatory mediators released – peripheral vasodilation, leaky capillaries
- blood and fluid pool – sludging of microcirculation, reduced intravascular volume and worsening hypotension
- vital organs fail and cell damage cannot be reversed
- death
how do you treat shock?
- give 100% oxygen
- IV normal saline (1l in adult, 500ml – if small, frail, cardiogenic shock)
- Keep warm
- Seek senior
- Try identify cause
what is a hypertensive emergency in terms of BP?
Sudden increase in BP ≥ 180/110 but usually 220/120
what is hypertensive urgency?
no signs of acute end stage organ damage – only 10% survival after 1 yr if untreated. Want slow and steady reduction to 160/100 over 24hrs. For discharge should be 140/90
