Classifying shock Flashcards
What is shock?
circulatory failure and inadequate tissue perfusion and oxygen delivery
Hypovolemic shock
Cardiac output is inadequate as quantity of fluids inside the vessels is unable to fill them appropriately
Inadequate fluid intake, loss of fluid and loss of blood can cause it
Characteristics of hypovolemic shock
- Lower venous return to cardiac chambers - reduced preload
- Reduced EDV
- Reduced stroke volume (EDV-ESV)
- Reduced cardiac output (CO=SV x HR)
- Hypotension
- Increased SVR
- Reduced o2 sats
- Increased HR
- Decreased blood to kidney stimulates RAAS - Na+ is retained and therefore water is too
- ADH released from hypothalamus - causes further retention of water and causes vasoconstriction
- Decreased in aerobic respiration and increase in anaerobic respiration - causes build up of lactic acid
Treatment hypovolemic shock
- Stop bleeding
- Replace fluid - normally crystalloids
- Blood transfusion
- Coagulation correction
What is cardiogenic shock
Volume inside vessels is normal but the pump of the heart (ventricular muscle) isn’t working well
Causes include myocardial infarction (reduction in stroke volume and BP), myocarditis, arrythmias, septal/ventricular rupture, severe acidosis
Characteristics of cardiogenic shock
- Pump doesn’t work properly - BP drops
- Activation of sympathetic system
- RAAS and ADH activated
- In hypovolemic shock, you have a reduced preload but in cardiogenic the preload is increased
- Failure of o2 delivery to tissues
- Reduced stroke volume
- Reduced cardiac output
- Increased SVR
Treatment cardiogenic shock
- PCI or stent
- Thrombolysis
What is obstructive shock?
Cardiac output is inadequate as a result of obstructed blood flow to lungs or heart
Intracardiac obstruction: pulmonary embolism, valve obstruction etc
Extracardiac obstruction: tamponade, tension pneumothorax, pericarditis
Tamponade: fluid build up in pericardial space, compression of veins feeding heart reduces preload
Tension pneumothorax: pressure in pleural space is normally negative. When pleural space is breached, it is not negative anymore which squeezes lungs and mediastinum (deviation) - veins are compressed and no blood reaches lungs
Characteristics of obstructive shock
- Variable preload
- Reduced SV
- Reduced CO
- Hypotension
- Increased SVR
treatment obstructive shock
- Pulmonary embolism: anticoagulants, thrombolysis
- Tension pneumothorax: needle decompression, thoracostomy
- Tamponade: pericardiocentesis
What is distributive shock
Cardiac output is relatively inadequate because the size of the vascular system is increased by vasodilation even though blood volume is normal
Characteristics of distributive shock
- Reduction in SVR and afterload
- Decreased preload and afterload
- Decreased SVR
- Hypotension
septic shock
- Caused by gram -ve, gram +ve and fungi
- Gram -ve produce endotoxins - cellular damage, inflammation and activation of the cytokine cascade
- Initially, skin seems warm and well-perfused but after a while, the patient becomes cold
- Impairment of o2 delivery - increase in anaerobic respiration and lactic acid - lactic acid is a negative ionotrope so decreases contractility
- Diagnosed by lactate higher than two and persistent hypotension requiring a vasopressor
Anaphylactic shock
- Caused by mast cells
- Hyper-reaction to food allergens/insect stings/drugs
- First exposure you are okay but second exposure there are IgE on mast cell surface - allergen links to mast cell and causes release of histamine
- Histamine is vasodilator and increases permeability
- Decreased preload and filling of cardiac chambers
- Hypotension
Treatment for anaphylactic shock
Adrenaline - vasoconstriction
