Shock

Definition Failure of circulation, that leads to inadequate tissue perfusion. Despite the compensatory mechanisms tissue hypoxia is developed. Tissue hypoxia leads to functional and morfological changes in organs. The result of untreated shock is irreversible organ failure and death.

Pathomechanisms different mechanisms all leads to: decrease in return of blood to the heart decrease in cardiac minute output hypotension hypoperfusion of peripheral tissues

Stages of shock 1. stage – reversible, compensated response of compensatory mechanisms activation of SAS – peripheral vasoconstriction (skin, kidneys), vasodilatation in „central“ organs (brain, heart) RAAS activation increased ADH secretion

Stages of shock 2. stage – developed, decompensated failure of compensatory mechanisms microcirculation failure increased blood viscosity, higher platelets agregation, thrombosis higher concentration of vasoactive mediators (histamine, bradykinin...) – higher permeability metabolic (lactate) acidosis

Stages of shock 3. stage - irreversible cell damage MODS (multiple organ dysfunction syndrome) ARDS – „shock“ lungs acute kidney failure acute liver failure loss of consciousness, coma, DIC ulcers, bleeding in GIT ...

Types of shock hypovolemic shock haemorrhagic - bleeding nonhaemorrhagic – GIT – diarhea, vomiting; kidneys – treatment with diuretics, DM; skin - burns cardiogenic shock inadequate contractility – acute MI, myocarditis, cardiomyopathies arrhythmias mechanical obstruction – acute valves dysfunction, rupture of ventricular septum, cardiac tamponade distributive shock septic – toxic anaphylactic neurogenic – CNS, spinal cord damage

Clinical signs low minute cardiac output SAS activation hypotension SAS activation tachycardia sweating piloerection cold, pale skin inadequate peripheral perfusion cyanosis oliguria unconsciousness muscle weakness

Hypovolemic shock deficiency in volume of extracelular fluid most frequent – haemorrhagic shock bleeding traumatic shock – bleeding + pain other – nonhaemorhagic shock GIT – diarhea, vomiting kidneys – treatment with diuretics, patient with diabetes mellitus skin – burns (burn shock)

Cardiogenic shock heart failure reduced cardiac output inadequate contractility – acute MI, myocarditis, cardiomyopathies arrhythmias – ventricular tachycardia, supraventricular tachycardia, atrial fibrilation, AV block - bradycardia, WPW syndrome mechanical obstruction – acute valves dysfunction, acute rupture of ventricular septum in MI, cardiac tamponade...

Anaphylactic shock accelerated allergic reaction increase of vasoactive mediators – histamine – marked vasodilatation 8 – 10% - lethal signs itching, nausea, erythema, dyspnoe larynx oedema, bronchospasm circulation failure, unconsciousness, cramps

Septic shock Neurogenic shock bakterial, virus infection release of vasoactive mediators – permeability, vasodilatation platelets adhesion and agregation acute damage of brain or spinal cord inflammation, trauma, bleeding, anaesthesia loss of vasomotoric regulation  marked vasodilatation irritation of n. vagus  bradycardia, damage of respiratory centre  hypoventilation Neurogenic shock