Shock
description
Transcript of Shock
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
leading to:
Decrease in return of blood to the heart (!) Decrease in cardiac output Hypotension Hypoperfusion of peripheral tissues General activation of different neural, humoral
response at systemic, organ, tissue and cellular level
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 And pro- and antiinflammatory cytokines as
procalcitonin and many others
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, the cytokines as a double-edged sword
Metabolic (lactate) acidosis
Stages of shock
3. stage - irreversible
Cell damage, necrosis or apoptosis 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 (obstructive shock)
distributive shock– septic – toxic– anaphylactic– neurogenic – CNS, spinal cord damage
Clinical signs
low minute cardiac output– 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 form – haemorrhagic shock
– bleeding
– traumatic shock – bleeding + pain
other – nonhaemorhagic shock
– GIT – diarhea, vomiting
– kidneys – treatment with diuretics, patient with diabetes mellitus
– 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 bacterial, viral 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