Session 11 - Haemodynamic Shock Flashcards
What is haemodynamic shock?
Acute condition of inadequate blood flow leading to catastrophic fall in arterial blood pressure leading to circulatory shock
What are 2 factors that can lead to shock?
Fall in cardiac output
Fall in peripheral resistance
What are 3 possible causes of fall in cardiac output?
Mechanical - Pump cannot fill
Pump failure
Loss of blood volume
What is a cause of fall in peripheral resistance?
Excessive vasodilation
What are 3 types of shock due to fall in cardiac output?
Cardiogenic shock
Mechanical shock
Hypovolaemic shock
What is cardiogenic shock?
Acute failure of the heart to maintain cardiac output = pump failure
What are 3 potential causes of cardiogenic shock?
MI
Arrythmias
Acute worsening of heart failure
How does cardiogenic shock occur?
Heart fills but fails to pump effectively, increasing central venous pressure and decreasing cardiac output, leading to dramatic drop in arterial blood pressure
What is cardiac arrest?
Unresponsivenesas associated with lack of pulse as heart has stopped or is not pumping effectively
What are 3 forms of cardiac arrest?
Asystole - no electrical or mechanical activity
Pulseless electrical activity
Ventricular fibrillation
What are 3 ways to treat cardiac arrest?
Basic life support
Advanced life support
Adrenaline
What are 2 factors of basic life support?
Chest compressions
External validation
What is advanced life support?
Defibrillation - delivering electric current to heart, depolarizing all cells and putting them into refractory period and allowing uncoordinated electrical activity to restart
How does adrenaline treat cardiac arrest?
Enhances myocardial function and increases peripheral resistance
What is mechanical shock / cardiac tamponade?
Blood or fluid build up in pericardial space, restricting filling of heart and limiting end diastolic volume, resulting in high central venous pressure but low arterial blood pressure
How does pulmonary embolism lead to mechanical shock?
Occlude pulmonary artery, right ventricle cannot empty so central venous pressure is very high, reducing return of blood to left heart, left heart cannot fill, so low arterial blood pressure leading to shock
How can an embolus reach the lungs?
Deep vein thrombosis, part of thrombus breaks off, travels in venous system to right heart, pumped out via pulmonary artery to lungs,
What is hypovolaemic shock?
Reduced blood volume commonly due to haemorrhage
How does the body compensate during hypovolaemic shock?
Drop in arterial pressure detected by baroreceptors, increases sympathetic stimulation, tachycardia + increased force of contraction, peripheral vasoconstriction
What are 2 longer term responses to restore blood volume?
Renin-angiotensin-aldosterone syste,
Anti diuretic hormone
What is distributive shock?
Low resistance shock - profound peripheral vasodilation reduces total peripheral resistance
What are 2 types of distributive shock?
Toxic shock
Anaphylactic shock
What is toxic shock?
Endotoxins released by circulating bacteria causes profound inflammatory response, profound vasodilation, dramatic fall in TPR, fall in arterial pressure, impairing perfusion of vital organs, capillaries become leaky hence reduces blood volume
What are 5 signs or symptoms of hypovolaemic shock?
Tachycardia Weak pulse Pale skin Cold clammy extremities Decreased CVP
What are 2 symptoms or signs of septic shock?
Tachycardia
Warm red extremities
P
What is anaphylactic shock?
Shock caused by severe allergic reaction
How does anaphylaxis cause anaphylactic shock?
Release of histamine from mast cells causes fall in TPR, causing dramatic drop in arterial sure, impaired perfusion of vital organs
What are 4 signs or symptoms of anaphylactic shock?
Difficulty breathing
Collapsed
Rapid heart rate
Red warm extremities
How to treat anaphylactic shock?
Adrenaline causes vasoconstriction via action at alpha1 adrenoceptors
