Shock Flashcards
What is a definition of shock?
An acute clinical syndrome initiated by ineffective perfusion and cellular hypoxia resulting in severe dysfunction of organs vital to survival
What are the key features of shock, physiologically?
Acute hypoperfusion to tissues/organs Impaired O2 delivery Cellular hypoxia Anaerobic respiration Haemodynamic abnormalities Oxygen utilisation may be abnormal, not just impaired
Where in the blood is the oxygen?
Bound to haemoglobin as oxyhaemoglobin, small amount dissolved in plasma
How are pressure, CO and vascular tone related?
Pressure = COxvascular tone
What affects CO?
CO = SV x HR
What can affect the stroke volume?
Preload
Contractility
Afterload
What are the four types of shock?
Hypovolaemic
Cardiogenic
Distributive
Obstructive
Whatever is the mechanism for the different types of shock?
Hypovolaemic - reduced intravascular tone
Distribution - vasodilatation and malperfusion
Cardiogenic - intrinsic cardiac failure
Obstructive - impairment of circulatory flow
What are some clinical examples of hypovolaemic shock?
Haemorrhage
Burns
GI blood losses (D/V, fistulat)
Dehydration (heat exposure, polyuria)
What are some clinical examples of distributive shock?
SIRS related -sepsis, pancreatitis, trauma, burns
Neurogenic - spinal cord injury
Anaphylaxis
What are some clinical examples of cardiogenic shock?
MI/ischaemia
Arrhythmia
Acute valve pathology
What are some clinical examples of obstructive shock?
Tension pneumothorax
Pericardial tamponade
PE
How does hypovolaemia cause shock?
Reduction of venous return Fall in SV and CO Hypotension Hypoperfusion of organs Organ dysfunction
What is starling’s law?
Contraction of the heart is directly related to stroke volume and preload
What are the physiological responses of hypovolaemia?
SNS activation Adrenal catecholamine release NA and H2O retention due to renin-angiotensin system Coagulation system activation Cortisol release
What does the SNS system activate to compensate for CO?
Tachycardia
Vascular tone increase
Contractility of heart increases (>SV)
What are the signs of organ hypoperfusion?
Oliguria Cognitive changes Metabolic acidosis Skin changes (blue and cool >CRT)
What are the management principles of shock?
Restore tissue perfusion and O2 delivery to cells
Administer O2
Increase BP with IV fluids
Treat the cause
Which size cannulas would you insert?
14G/16G
Which bloods do you take in shock?
Cross match
Haemotology - FBC, cloting
Biochemistry - UE, glucose, liver, bone, lactate
ABG
Which investigations can you do super quickly?
ECG
US abdo
ALL OBS
How does hypothermia affect blood loss?
It has adverse affects on clotting so BEWARE
What must you do if the patient isn’t responding to fluids as you had expected?
THINK AGAIN
Is the bleeding too rapid?
Are we missing something important? e.g. MI, sepsis, PE
Is there something specific they need urgently?
Which conditions need a specific therapy and therefore must be ruled out?
How do you rule them out?
Tension pneumothorax
Pericardial tamponade
Pulmonary embolism
Acute MI
ECG
CXR
What suggests other types of shock to hypovolaemic?
Cardiogenic:
History of CV
Signs of CCF
ECG evidence
Obstructive:
Impaired cardiac filling (cardiac tamponade/tension pneumo)
Obstructive forward flow
Specific symptoms and signs
Distributive (can masquerade as
What is further management of shock post-stabilisation?
Surgery to control bleeding Drugs (inotropes to increase contractility) Invasive lines Monitoring ICU
What are the mortality rates of shock?
Septic: 30-50%
Cardiogenic: 60-80%
What are the consequences of shock?
Death
Cellular injury and death
Multiple organ dysfunction and failure
Which is the best marker for improved tissue perfusion?
Urine output increase
What does lactate returning to less than 2 indicate?
Indicates that the tissues are aerobically respiring and that the risk of cardiac arrest is reducing
