Shock Flashcards
what is heamodynamic shock ?
Acute condition of inadequate blood flow throughout the body
A catastrophic fall in arterial blood pressure leads to
circulatory shock
MABP = CO * TPR
draw a diagram to outline the causes of shock
check against lec
outline cardiogenic shock
Potential causes:
• following myocardial infarction – damage to left ventricle
• due to serious arrhythmias
• acute worsening of heart failure
• Heart fills, but fails to pump effectively
- Dramatic drop in arterial BP
- Tissues poorly perfused
outline mechanical shock
• Cardiac tamponade
– blood or fluid build up in pericardial space
– restricts filling of the heart – limits end diastolic volume
– affects left and right sides of heart
pulmonary embolism
• Embolus occludes a large pulmonary artery – Pulmonary artery pressure is high – Right ventricle cannot empty – Central venous pressure high – Reduced return of blood to left heart – Limits filling of left heart – Left atrial pressure is low – Arterial blood pressure low – Shock – Also chest pain, dyspnoea
How might an embolus reach the lungs? - DVT
outline hypovolaemic shiick
Hypovolaemic shock
• Reduced blood volume
• haemorrhage
• 30-40% substantial decrease in mean aBP and serious shock response
• Haemorrhage – venous pressure falls – cardiac output falls (Starling’s Law) – arterial pressure falls – detected by baroreceptors
• Compensatory response – increased sympathetic stimulation – tachycardia – increased force of contraction – peripheral vasoconstriction – venoconstriction
• In hypovolaemic shock blood flow reverses – get some ‘internal transfusion’ • Net movement of fluid into capillaries
Hypovolaemic shock • Patient has: – Tachycardia – Weak pulse – Pale skin – Cold, clammy extremities – Low CVP
– Tissue damage due to hypoxia – Release of chemical mediators – vasodilators – TPR falls – Blood pressure falls dramatically – Vital organs can no longer be perfused
outline septic shock
• Sepsis - Can lead to septic shock
• Endotoxins released by circulating bacteria – Profound inflammatory response (excessive) – Causes profound vasodilation – Dramatic fall in TPR – Fall in arterial pressure – Impaired perfusion of vital organs – also - capillaries become leaky • reduced blood volume
outline anaphylatic shock
severe allergic reaction (anaphylaxis) – release of histamine from mast cells • other mediators – powerful vasodilator effect – fall in TPR – dramatic drop in arterial pressure • increased sympathetic response - CO, but can’t overcome vasodilation – impaired perfusion of vital organs
Anaphylactic shock • Patient will have – Difficulty breathing – Collapsed – Rapid heart rate – Red, warm extremities • Acutely life threatening
gice • Adrenaline
– Vasoconstriction via action at α1 adrenoceptors
