Shock Flashcards
Define shock
Term to describe acute circulatory failure with inadequate or inappropriately distributed tissue perfusion, resulting in generalised hypoxia and/or an inability of the cells to utilise oxygen
What is meant by ‘inadequate or inappropriately distributed tissue perfusion’
Inadequate substrate (glucose and oxygen) for aerobic cellular respiration
How would you recognise shock
Skin is pale, cold, sweaty and vaso-constricted
Pulse is weak and rapid
Pulse pressure is reduced (not arterial as this is maintained until large blood loss)
Reduced urine output
Confusion, weakness, collapse, coma
Is venous or mean arterial pressure (MAP) a better indicator of shock
Venous
Pulse pressure reduced from shock but MAP may be maintained (only decreases if v large amount of blood loss)
Effects of shock
Prolonged hypotension which can lead to life threatening organ failure after recovery from the acute event (possibly linked with inflammatory response)
Long capillary refill time (CRT)
Describe Capillary Refill Time as a measure of Shock
If takes >3 seconds to turn pink after 5 seconds of compression = early/accurate sign of shock
Types of shock
Hypovolaemic shock
Cardiogenic shock
Distributive shock (3 types)
Haemorrhagic shock Heat exposure (heat exhaustion)
Unsure:
Anaemic shock
Cytotoxic shock
What are 3 types of distributive shock
Septic shock
Anaphylactic shock
Neurogenic shock
Cause of hypovolaemic shock
Low blood volume, as a result of loss of blood or loss of fluid
Can be secondary to haemorrhagic shock
Hypovolaemic shock: What can cause loss of blood?
Acute GI bleeding
Trauma
Peri-post-operative
Splenic rupture
Hypovolaemic shock: What can cause loss of fluid?
Dehydration - diarrhoea and vomitting
Burns - heat damage increase capillary permeability so plasma leaks
Pancreatitis
Causes of cardiogenic shock
Heart doesn’t pump due to:
- Cardiac tamponade - blood in pericardial sack placing pressure on heart thereby limiting cardiac output
- Pulmonary embolism - flow of blood to lungs is blocked
- Acute MI
- Fluid overload
- Myocarditis - inflammation of the muscle itself
Why does cardiac tamponade prevent heart from pumping
Blood in pericardial sack places pressure on heart thereby limiting cardiac output
When do you get sepsis
When a systemic inflammatory response is associated with an infection
When do you get septic shock
When sepsis is complicated by persistent hypotension that is unresponsive to fluid resuscitation
What causes anaphylactic shock
- Release of IgE due to allergic response
- Massive release of histamine and other vasoactive mediators causing haemodynamic collapse
- Accompanied by breathlessness and wheeze (due to bronchospasm)
What are the different groups of Haemorrhagic Shock classification
(Tennis score)
Class I, II and III
Haemorrhagic Shock classification: Describe class I
15% blood loss Pulse <100bpm BP normal Resp rate 14-20 Urine output greater than 30ml/hr Slightly anxious
Haemorrhagic Shock classification: Describe class II
15-30% blood loss Pulse >100bpm BP normal (due to ANS/ increased sympathetic activity) Pulse pressure decreased Resp rate 20-30 Urine output 20-30ml/hr Mental status: mildly anxious
Haemorrhagic Shock classification: What is earliest sign of class II
Tachycardia
Haemorrhagic Shock classification: Describe class III
30-40% blood loss Pulse >120bpm BP decreased Pulse pressure decreased Resp rate 30-40 Urine output 5-15ml/hr Mental status: confused
What haemorrhagic shock class would someone be is had a resp rate of 21, decreased pulse pressure but normal BP
Class II
therefore blood loss around 15-30%
What haemorrhagic shock class would someone be is had a urine output of 15ml/hr and pulse of 125bpm
Class III
therefore blood loss around 30-40%
What signs would show someone to have 15% blood loss
Class I Haemorrhagic shock Pulse <100bpm BP normal Resp rate 14-20 Urine output greater than 30ml/hr Slightly anxious
How does blood loss lead to release of adrenaline
- Reduction in ventricular filling
- Fall in BP and SV
- Results in hypotension
- Reduced stimulation of baroreceptors in aortic arch and carotid sinuses
- Increased sympathetic activity with release of noradrenaline and adrenaline
What is effect of adrenaline and nor-adrenaline on vascular system
Vasoconstriction
Increased myocardial contractility and heart rate, helps restore BP and CO
What is autotransfusion
Reduced capillary BP leads to greater level of net movement of fluid into the vascular compartment from the tissues
What hormones counter hypotension
ADH/Vasopressin Angiotensin II Aldosterone Cortisol Glucagon
How does ADH/Vasopressin counter hypotension
Vasopressin is released in response to decreased Blood Volume which which binds to V2 receptor resulting in insertion of Aquaporin 2 into the lumen of the collecting duct, resulting in increased water reabsorption
How does RAAS counter hypotension
Reduction in the perfusion of renal cortex stimulates Juxtaglomerular appartus to release RENIN.
Renin converts Angiotensinogen (from liver) to Angiotensin I.
Angiotensin I is converted to Angiotensin II by ACE (in lungs).
Angiotensin II causes thirst, is a potent vasoconstrictor and stimulates secretion of Aldosterone by the adrenal cortex. Both cause Na+ and therefore water retention - to help restore circulating volume and blood pressure.
How does Cortisol counter hypotension
Increases fluid retention
How does Glucagon counter hypotension
Raises blood sugar levels
Fluid also moves into blood then due to osmotic effect
Clinical presentation of hypovolaemic shock
Inadequate tissue perfusion
Increased sympathetic tone
Tachycardia - narrow pulse pressure and weak pulse
Sweating
BP may be maintained initially but later hypotension
Bradycardia
Describe how you would differentially diagnose inadequate tissue perfusion (for someone with hypovolaemic shock) - Not capillary test
Skin = cold, pale, clammy, slate-grey Brain = drowsiness and confusion
Clinical presentation of cardiogenic shock
Signs of myocardial failure
Raised jugular venous pressure (JVP)
Gallop rhythm
Basal crackles and pulmonary oedema
Clinical presentation of septic shock
Pyrexia and rigors
Nausea and vomiting
Vasodilation with warm peripheries
Bounding pulse
Clinical presentation of anaphylactic shock
Signs of profound vasodilation Warm peripheries Low BP Tachycardia Bronchospasm Pulmonary oedema
What organs are most at risk of shock
Kidneys
Lungs
Heart
Brain
What could result from shock affecting kidneys
Acute tubular necrosis
What could result from shock affecting the lungs
Acute Respiratory Distress Syndrome (ARDS)
What could result from shock affecting the heart
Myocardial ischaemia and infarction
What could result from shock affecting the brain
confusion
irritability
coma
Treatment of shock
ABC
Airway Breathing Circulation
Treatment of shock - B (of ABC)
Breathing Give 100% O2 Correct any immediately life threatening problems such as: Congestive HF Bronchospasm Tension pneumothorax
Treatment of shock - C (of ABC)
Circulation
Establish secure IV access
Give fluid quickly and blood if acute blood loss
Ensure haemostasis i.e. stop bleeding
What is acute respiratory distress syndrome
Type of resp failure characterised by rapid onset of widespread inflammation in the lungs
Which of these is true in ARDS:
High Pulmonary Arterial pressure (PAOP)
No cardiac failure
No cardiac failure is true
Pulmonary Arterial Pressure is NORMAL
Extrapulmonary causes of ARDS
Shock of any cause
Head injury
Drug reaction
Sepsis
Pulmonary causes of ARDS
Pneumonia
Chemical pneumonitis
Smoke inhalation
Near drowning
Pathophysiology of ARDS
Injury to alveolar capillary membrane results in leakage of fluid into alveolar spaces
There is resulting neutrophil invasion which attracts more neutrophils (exudative phase)
Eventually fibroblasts come in and initiate healing (proliferative phase)
Forms Scar tissue (fibrotic phase)
Results in severely stuff lungs and thus Severe difficultly in ventilation and thus O2 blood perfusion
*Clinical presentation of ARDS
Cyanosis
Tachypnoea (quick breathing)
Tachycardia
Peripheral vasodilation
Investigations and management of sepsis
BUFALO Blood cultures Urine output (measure) iv Fluid (administer) Administer broad spectrum Antibiotics serum Lactate (measure) administer high flow Oxygen
What is septic shock
Life-threatening condition that is characterised by low blood pressure despite adequate fluid replacement, and organ dysfunction or failure
Symptoms of septic shock
feeling dizzy or faint a change in mental state – such as confusion or disorientation diarrhoea nausea and vomiting slurred speech severe muscle pain severe breathlessness less urine production than normal – for example, not urinating for a day cold, clammy and pale or mottled skin loss of consciousness
Define neurogenic shock
Distributive type of shock resulting in low blood pressure, occasionally with a slowed heart rate, that is attributed to the disruption of the autonomic pathways within the spinal cord.
It can occur after damage to the central nervous system, such as spinal cord injury and traumatic brain injury.
Management of Hypovolaemic shock
pg.790 (also do management of other shocks)
