Cardiovascular responses to shock Flashcards
Define shock
Abnormal state resulting in inadequate tissue perfusion and oxygenation.
What is the end result in the process of shock?
Cellular failure, as a result of inadequate perfusion
Two factors that Tissue perfusion depends on?
- MAP
2. CO
What happens in hypovolemic shock?
Lower blood volume–> lower venous return–> lower EDV + SV–> Lower CO + BP–> Inadequate tissue perfusion
Frank Starling law?
Higher EDV= Higher SV
What is the main cause of cardiogenic shock?
Sustained hypotension
What happens in cardiogenic shock?
Reduced contractility–> lower SV–> Lower CO + BP–> Inadequate tissue perfusion
What happens in tension pnuemothorax induced shock?
Increased intrathoracic pressure–> lower venous return–> lower EDV + SV–> Lower CO + BP–> Inadequate tissue perfusion
What happens in neurogenic shock?
Loss of sympathetic tone-> Venous and arteriolar dilatation–> lower venous return–> lower EDV + SV–> Lower CO + TPR–> Inadequate tissue perfusion
What happens in vasoactive shock?
Release of vasoactive mediators-> Venous and arteriolar dilatation–> lower venous return–> lower EDV + SV–> Lower CO + TPR–> Inadequate tissue perfusion
Steps for treatment for shock?
- ABCDE
- High flow Oxygen
- Volume replacement
- Immediate chest drain if tension pnemothorax
- Cardiogenic shock- Inotropes
- anaphylactic shock- adrenaline
- Septic shock - vasopressers
What are the common causes of hypovolemic shock?
- Haemorrhage
- diarrhoea, vomiting
What % of haemorrhagic blood loss can the body cope with?
upto 30%, not more.
Two clinical signs in haemorrhage?
- Cool peripheries- increased systemic vascular resistance
- small vol pulse- lower CO
- tachycardia- increased HR, baroreceptor reflex.
