Hypovolaemia Flashcards
define hypovolaemia
loss of 20% of blood volume (~1L)
what is “shock”
acute failure of cardiovascular system to perfuse the tissues of the body adequately
list 4 types of shock
- Hypovolaemic
- Cardiogenic (HF)
- Maldistributive (sepsis/anaphylaxis)
- Obstructive (PE)
What is non-progressive shock
systolic BP w/in 20% of normal
can recover as compensatory mechanisms
what is progressive shock
more than 30% loss, can trigger positive feedback loop
describe a FAST response to progressive shock
nervous system (baro and chemo Rs) can stabilise unto 50% loss
describe an INTERMEDIATE response to progressive shock
microvascular fluid resorption
can last unto 1 hour
describe HUMORAL/DELAYED responses to progressive shock
ADH
RAAS
increased renal retention
What is irreversible shock
fading of the sympathetic nervous system
what are the clinical features of shock
inadequate perfusion
increased sympathetic tone
metabolic acidosis
what are the treatments of hypovolaemic shock
- maximise O2 delivery
- control further blood loss
- fluid resus
- monitoring (HR,BP, SaO2,RR, urine <20ml/hr, GCS)
what is initial fluid resuscitation
20ml/kg isotonic crystalloid
what are the consequences of haemorrhage
significant loss –> baroreceptors and fluid shifts from tissue to blood (dilution upsets fluid balance)
huge loss:
- > prolonged intense vasoconstriciton
- > shock
- > tissue damage > vasodilator products > expansion of venous tree > decreased CO and VR
- > fluid loss from plasma to tissues > increased viscosity > intravascular coagulation
what might cause hyper osmotic expansion
oral rehydration therapy
what might cause hyposomotic expansion
water retention
