Shock Flashcards
Define shock
Clinical syndrome caused by inadequate tissue perfusion and oxygenation leading to abnormal metabolic function
Name the 4 different types of shock
Cardiogenic
Hypovolaemic
Obstructive
Distributive
Give examples of causes of cardiogenic shock
Post-MI - most common
Myocarditis
Dysrhythmia
Give examples of causes of hypovolaemic shock
Haemorrhage e.g. trauma, GI bleed, ruptured AAA
Fluid loss e.g. burns, dehydration, pancreatitis
Give examples of causes of obstructive shock
Cardiac tamponade
Tension pneumothorax
PE
Give examples of causes of distributive shock
Sepsis
Anaphylaxis
Neurogenic shock - spinal cord injury, traumatic brain injury
What clinical features often define shock?
Systolic BP < 90 mmHg
MAP < 65 mmHg
AND
Evidence of tissue hypoperfusion
- Mottled skin
- Urine output <0.5ml/kg/h
- Lactate > 2mmol/L
How do you calculate MAP?
MAP = CO x SVR
therefore, shock can result from inadequate cardiac output or a loss of systemic vascular resistance or both
OR
MAP = (systolic + 2xdiastolic)/3
How do you calculate cardiac output?
CO = stroke volume x HR
Which types of shock cause inadequate cardiac output?
Hypovolaemic shock
Cardiogenic shock
Obstructive shock
Which types of shock cause peripheral circulatory failure i.e. loss of systemic vascular resistance?
Distributive shock
- Sepsis
- Anaphylaxis
- Neurogenic shock
Dissociative shock
- carbon monoxide poisoning
- cyanide poisoning
What happens in sepsis caused by gram negatives?
Gram negatives produce endotoxin
This causes sudden and severe shock without signs of infection
Which type of shock causes a decreased HR?
Neurogenic shock
What is the pathophysiology behind anaphylactic shock?
A type 1 IgE-mediated hypersensitivity reaction leading to histamine release
What is an anaphylactoid reaction?
Direct (i.e. not immune-mediated) release of mediators from mast cells
Usually in response to a drug
What are the signs and symptoms of anaphylaxis?
Respiratory
- Lower airway: dyspnoea, wheeze, chest
tightness, bronchospasm
- Upper airway obstruction (swelling of lips,
tongue, pharynx, epiglottis), laryngeal oedema - stridor
- Type 2 respiratory failure
Skin
- Itchy, urticarial rash
- Angioedema
CVS
- Oedema
- Tachycardia, hypotension
GI
- D&V
- Abdominal cramps
What are some differential diagnoses of anaphylaxis?
Carcinoid crisis from carcinoid tumour
Phaeochromocytoma
Systemic mastocytosis
Hereditary angioedema
What is the management of anaphylaxis?
- Airway
- Secure airway
- If serious upper airway oedema call anaesthetist
- 15L O2 via NRBM - Call for help, lie patient flat, raise patient’s legs
- Give IM adrenaline 0.5mL of 1:1000 - repeat every 5 min if no response
- Breathing
- If wheeze, give salbutamol 5mg NEB B2B - Circulation
- IV 0.9% sodium chloride
- IV chlorphenamine 10mg
- IV hydrocortisone 200mg
- Monitor ECG - Admit to ward/ICU and observe for 4-6hr after symptoms have stopped
What investigation helps you to differentiate hypovolaemic shock from cardiogenic shock?
Echocardiogram
How do you manage haemorrhagic shock?
Stop bleeding if possible 2L IV 0.9% sodium chloride Crossmatch blood and request O Rh negative blood in emergency Give FFP with red cells Consider IV tranexamic acid 2g
What is SIRS?
Systemic Inflammatory Response Syndrome
Defined as 2 or more of:
- Temp >38 or <36
- HR >90
- RR >20 or PaO2 <4.3
- WCC >12 or <4
Define sepsis (in relation to SIRS), severe sepsis and septic shock
Sepsis = SIRS + source of infection
Severe sepsis = sepsis + organ disorder
Septic shock = sepsis + hypotension despite adequate fluid resuscitation
What is the management of sepsis?
BUFALO
Blood cultures (before starting Abx) & bloods (FBC, U&Es, glucose, clotting, LFTs)
Urine output
Fluids - 500ml IV 0.9% sodium chloride over 15 min
Antibiotics - IV broad spectrum stat
Lactate - ABG/VBG
Oxygen - 15L NRBM
What should you consider giving to a septic patient that is non-responsive to fluids?
Systemic vasopressor e.g. noradrenaline or phenylephrine
