Shock Flashcards
What is shock?
Clinical syndrome of tissue hypoperfusion due to circulatory failure
How does the body keep organs perfused?
Global perfusion (MAP) leads to adequate perfusion of organs with oxygen-carrying nutrient rich borth and enables function of cells
What is the pathological mechanism leading to hypoperfusion?
MAP falls below 50-60mmHg leading to slow flow, thrombus formation and inadequate perfusion
List some consequences of tissue hypoperfusion
Systemic acidosis and lactic acid formation
Thrombosis
Necrosis
What clinical sign is a very poor prognostic indicator and sign of circulatory failure?
Skin mottling
What are the immediate signs of tissue hypoperfusion?
SKIN: Mottled, clammy skin
BRAIN: Acute confusional state (low GCS)
KIDNEYS: Reduced urine output (oliguria)
What biochemical result is diagnostic of shock?
Blood lactate level at ABG >2mmol/l
Why does hypotension not always lead to shock?
Physiological compensation of mean arterial pressure
List the two cardiac mechanisms affecting mean arterial pressure
Cardiac output
Systemic vascular resistance
What is the mechanism behind cardiogenic shock?
PUMP NOT WORKING
Reduced stroke volume + force of contraction, thus reduced cardiac output and mean arterial blood pressure
How does the body try to compensate for cardiogenic shock?
Increase vascular resistance (vasoconstriction), resulting in cool clammy peripheries
What is the mechanism behind obstructive shock?
OBSTRUCTION TO PUMP WORKING
Obstruction to cardiac outflow (otherwise similar to cardiogenic shock) leads to venous back pressure
What clinical signs might be seen in obstructive shock?
Raised JVP
Distended neck veins
List some causes of obstructive shock
Aneurysm
Pulmonary embolism
Tension pneumothorax
Cardiac tamponade
What is the mechanism behind hypovolaemic shock?
Reduced blood volume/lower venous return to heart, causing decreased cardiac output and reduced force of contraction (Frank-Starling law)
How is hypovolaemic shock differentiated from distributive shock?
Cool peripheries due to reduced cardiac output
List some causes of hypovolaemic shock
Haemorrhage/bleeding Dehydration Trauma Burns Diabetic ketoacidosis
What is the mechanism behind distributive shock?
BOUNDING CIRCULATION
Reduced systemic vascular resistance due to vasodilation, causing reduced mean arterial blood pressure
How does the body try to compensate for distributive shock?
Increase in cardiac output
Vasodilation causes warm, red peripheries
List some causes of distributive shock
Inflammation (infection, sepsis)
Anaphylaxis
Spinal cord injury
What is the most common type of shock?
Distributive shock caused by sepsis
Define massive haemorrhage in terms of clinical situation
Bleeding which leads to a heart rate ?110bpm +/- systolic BP <90 mmHg
Bleeding which has prompted use of emergency RhD- cells
What is the initial management for massive haemorrhage?
ABCDE (IV access)
Stop bleeding
Call blood bank
Send blood samples (FBC,coag,crossmatch,U+E,Ca)
What blood component support is given in massive haemorrhage?
Transfuse red cells (tissue oxygenation)
FFP (replace coagulation factors)
Platelets
Cryoprecipitate (replace fibrinogen)