EM - Shock Flashcards
Define shock
Global tissue hypoperfusion resulting in inadequate oxygen delivery to meet metabolic demands and metabolic acidosis
Describe the autonomic response to maintain oxygen delivery and cardiac output during shock/ inadequate systemic oxygen delivery
- Vasoconstriction to cutaneous, muscle and visceral circulation protects the heart, kidneys and brain
- Pre-load is increased by venous vasoconstriction, this utilises starlings law to increase stroke volume
- Increased HR, water and sodium retention and increases in blood volume and pressure
What happens to pulse pressure and BP?
Pulse pressure will initially decrease due to this autonomic activation increasing peripheral vascular resistance
Hypotension will follow when the compensatory mechanisms begin to fail
What happens at the cellular level during shock?
ATP depletion (when oxygen supply is removed) which leads to a loss of ion pump activity and resultant cellular oedema that can lead to hydrolysis
The endothelial inflammation and disruption from hypoxia results in lactic acidosis, cardiovascular insufficiency and increased metabolic demands
What is the common physiological progression in shock?
Cardiac depression, respiratory distress, renal failure, DIC and organ failure
What are they types of shock?
Inadequate cardiac output:
- Hypovolaemia (through blood or fluid loss)
- Cardiogenic shock (pump failure or obstruction)
Peripheral circulation failure (leading to loss of systemic vascular resistance):
- Sepsis
- Anaphylaxis
- Neurogenic
Can you multiple causes of shock co-exist in the same patient?
Yes
What should be asked in the history in a case of shock?
- Recent illness or fever
- CP, abdo pain, SOB
- Comorbidities and medications
- Ingestion of any toxins
- Recent hospitalisation or surgery
What would BP and urine output be in shock?
Hypotension (less than 90 systolic or less than 65 MAP in severe cases)
Reduced urine output (to less than 0.5ml/kg/hr)
At what level of systolic BP does the post tibial pulse disappear?
less than 90
At what level of systolic BP does the radial pulse disappear?
less than 80
At what level of systolic BP does the femoral pulse disappear?
less than 70
At what level of systolic BP does the carotid pulse disappear?
less than 60
What does low diastolic pressure suggest the cause of shock is?
It suggests arterial vasodilation e.g. septic or anaphylactic shock
What does narrowed pulse pressure suggest the cause of shock is?
It suggests arterial vasoconstriction e.g. cardiogenic or hypovolaemic
How would you manage A and B (of an A to E assessment) in shock?
Ensure the airway is patent
shocked patients will be SOB
- give O2 through non- rebreathe
- Monitor SpO2
- Perform breathing assessment as normal, correcting as required e.g. tension pneumothorax causing cardiogenic shock
- Perform ABG (lactate will usually be more than 2)
How would you manage C (of an A to E assessment) in shock?
- Assess HR, CRT and BP
- Lie patient flat and elevate their legs
- Gain IV access using two large bore cannulae
Take bloods: FBC, U&Es, LFTs, coagulation studies, G&S, crossmatch, cultures
Give IV fluids (500ml bolus then high rate infusion when BP improves)
- ECG
- Catheter to monitor urine output
When BP improves after initial IV boluses how do you give fluid?
Switch from boluses to a high rate infusion
titrated to keep HR more than 100, SBP more than 90
If 2 fluid boluses fail to improve BP what do you do?
Refer to ITU
What do you specifically look for in shock during D (of an A to E assessment)?
That the patient is sufficiently able to maintain their airway
Spinal shock
What do you specifically look for in shock during E (of an A to E assessment)?
Look for further signs of infection and haemorrhage
Assess fluid balance
Name the type of shock:
Patient is warm and well perfused with a bounding pulse
Septic shock
Name the type of shock:
Patient has a raised JVP, pulmonary and peripheral oedema
Cardiogenic shock
Name the type of shock:
Patient is flushed and warm, with additional signs including urticaria, stridor, wheeze and swelling
Anaphylactic shock
Name the type of shock:
Patient is pale and cool to touch
Hypovolaemic shock
What may be required before ventilation in a patient with shock?
Volume resuscitation
As propofol will further decrease BP
What other treatments can you give to help with oxygen consumption?
Analgesia and anxiolytics
to relax muscles and avoid shivering
What should central venous pressure (CVP) be?
5-10mmHg
What could a CVP of more than 10 indicate?
Cardiogenic shock and fluid overload
What could a CVP of less than 5 indicate?
Hypovolaemic shock or loss of systemic vascular resistance
What factors can affect how patients present with hypovolaemic shock?
- Younger, fitter patients have better compensatory mechanisms
- CNS injury can lead to disruption of cardiovascular reflexes and auto-regulatory systems
- Medications e.g. B-blockers, antihypertensives
- Pregnancy tends to lead to later presentation with shock due to higher circulating volumes
What are the most common causes of internal bleeding causing hypovolaemic shock?
Ruptured AAA
GI bleed
How is haemorrhagic shock classified?
Classification is 1 to 4 based on % blood volume lost, HR, BP, pulse pressure, RR, CRT, UO and mental status
1 = less than 15% blood volume lost, HR over 100, normal BP, RR, CRT etc.
4 = more than 40% blood volume lost, unrecordable BP, lethargic etc.
What interventions can be used to gain control of a haemorrhage?
External Bleeding:
- Direct pressure (+/- elevation where possible)
- Indirect pressure where a wound is too large for direct
- Tourniquets where pressure is ineffective
Internal Bleeding:
- Traction and re-alignment of fractures
- Apply pelvic binder
- Emergency surgery or interventional radiology
How do you apply indirect pressure to a wound?
Apply pressure over the supplying artery against underlying bone, cutting off blood supply to the wound
How do you apply a tourniquet?
Apply to a single bone above the wound as close to the wound as possible
What medication can be given for Haemorrhagic shock?
Tranexamic acid (1g bolus then infusion)
What are the 3 groups patients can be divided into depending on their physiological response to shock?
- Rapid responders
- Transient responders
- Non responders
What are the vital signs of rapid responders?
Normal
How do you manage rapid responders?
They have a low need for fluids and blood products so:
- G&S and cross-match
so that units of appropriate blood are available if later required
What are the vital signs of transient responders?
Initially normal but then will fall
How do you manage transient responders?
The need for fluids is high and there may be a need for blood products so:
- G&S and cross-match
How long does full cross-match take?
Around 45 mins
How long does it take to order group specific blood?
15 mins
What are the vital signs of non responders?
Abnormal
How do you manage non responders?
They have a very high need for fluids and blood products so:
Activate the major haemorrhage protocol
as they may need urgent O neg blood
Also give tranexamic acid
What is a massive haemorrhage?
- More than 150ml/min of blood loss
- Loss of more than 50% of blood volume in 3 hours
- Haemorrhage causing a more than 25% reduction in SBP
How many units of FFP should be transfused per unit of packed red cells?
1 unit of FFP to 1 unit of packed red cells
How many units of packed red cells are given per unit of platelets?
1 unit of platelets should be given for every 4 units of packed red cells
At what level of Hb should we consider transfusing the patient?
Less than 8
What should we aim to keep a patients Hb level at if we are transfusing them?
Above 10
How much should 1 unit of packed red cells increase a patient’s Hb by? and if this doesn’t occur what may be the cause?
1g
they may still be bleeding
How many samples of blood must be sent for cross-match?
at least 2 samples
so in any new patient snd both G&S and cross-match
What are the three main causes of shock due to fluid loss?
- Inadequate fluid intake
- Salt and fluid loss: vomiting, diarrhoea, burns, polyuria
- Third space losses: bowel obstruction, post op ileus, pancreatitis, ascites
How should shock due to fluid loss be managed?
A to E
Treat the cause and correct fluid deficit
What is anaphylaxis?
Anaphylaxis is a type 1-IgE mediated hypersensitivity reaction. It causes histamine release which causes widespread vasodilation and shock.
What are the causes of anaphylaxis?
Causes:
- Food triggers - peanuts, eggs, shellfish and milk
- Drug triggers - Abx, opioids, NSAIDs, IV contrast agents, anaesthetic agents, blood transfusions
What are the clinical features of anaphylaxis?
- Widespread vasodilation and shock
- Bronchospasm and wheeze
- Urticaria, angioedema (particularly of eyes, lips, tongue and larynx)
- Diarrhoea, vomiting, abdo pain
How is anaphylaxis managed?
A to E
A
- stridor should give Dx
- Secure airway and give 100% O2
- Remove offending cause
- Give adrenaline 0.5mg IM (0.5ml of 1:1000) repeating every 5 mins as needed
- Contact resuscitation team (2222)
B
- Assess breathing (attach Sp02 monitoring)
- ABG
- Salbutamol nebs for wheeze
C
- IV access
- 0.9% NaCl at a rate of 2L/hr
- 10mg Chlorphenamine
- 200mg Hydrocortisone
Continue to reassess
continuous ECG recording
Serum mast cell tryptase should be measured as soon as possible to confirm Dx
What is the dose of adrenaline in adults?
0.5mg IM (0.5ml of 1:1000)
How often should adrenaline be given if patient isn’t responding?
every 5 mins
What is the dose of adrenaline in under 6 year olds?
0.15mg IM (0.15ml of 1:1000)
What is the dose of adrenaline in 6-12 year olds?
0.3mg IM (0.3ml of 1:1000)
What are the causes of cardiogenic shock?
Pump failure:
- MI, arrhythmia, myocarditis, acute valve failure, aortic dissection
Obstruction:
- PE, tamponade, tension pneumothorax
How is cardiogenic shock managed?
A to E
(attempting to identify the underlying cause and treat them)
carefully assess fluid balance - if hypotensive it is better to give fluid and correct later unless pulmonary oedema is present
What are the two main causes of spinal (neurogenic) shock?
- Cervical and upper thoracic spine (above T6) injury leading to loss of sympathetic tone
- Iatrogenesis from spinal anaesthesia
What are the signs of Neurogenic shock?
- Hypotension
- May have focal neorology
- No narrowing of pulse pressure
- No tachycardia (may be bradycardic)
- No cutaneous vasoconstriction
How should neurogenic shock be managed?
A to E
If iatrogenic - stop the epidural infusion immediately and contact anaesthetist urgently