Reviewed and revised 31 August 2016
OVERVIEW
Shock is a state of circulatory failure characterised by globally impaired tissue perfusion that is insufficient for needs of the body.
CLASSIFICATION
Classification (shock can be classified as PROVED?)
- cardiogenic (Pump)
- Rhythm abnormalities (some purists exclude dysrhythmia as a cause of cardiogenic shock)
- Obstructive
- hypovolemia (Volume)
- Endocrine causes (often mixed classification, but a useful subheading to make sure endocrine causes aren’t missed!)
- Distributive (due to vasodilation)
- ? = is it real? (check the BP measurement, is the arterial line in an artery, is the transducer at the correct height?)
Remember that drugs and toxic exposures can contribute to cardiogenic, rhythm, or distributive causes of shock.
CARDIOGENIC SHOCK
Impaired contractility
- Myocardial ischemia and compliations
- Infarction — anterior MI, reinfarction, right ventricular infarction, myocardial stunning
- Acute mitral regurgitation due to papillary muscle rupture
- Ventricular septal rupture
- Left ventricular free wall rupture and tamponade
- Myocarditis
- Myocardial contusion
- Takotsubo Cardiomyopathy
- Septic shock
- Poisoning or toxic exposure including calcium channel blockers, beta-blockers and digoxin
- End stage cardiomyopathy
Dysrhythmia
- Tachycardias
- Bradycardias
Valvular dysfunction
- Severe aortic regurgitation
- Severe aortic or mitral stenosis
Left ventricular outflow tract obstruction
- Hypertrophic cardiomyopathy
- Left atrial myxoma
OBSTRUCTIVE SHOCK
Within the circulatory system
- Massive pulmonary embolus
- atrial thrombus or myxoma
- occulsive valvular lesion
- other emboli (e.g. air, amniotic fluid)
External to the circulatory system
- Cardiac tamponade
- abdominal compartment syndrome
- Tension pneumothorax
- Dynamic hyperinflation (e.g. severe asthma)
- Tension pneumomedistinum
- caval compression (e.g. supine hypotension syndrome in the pregnant female)
HYPOVOLAEMIC SHOCK
Hemorrhage
- Traumatic
- Major vessel injury
- Pelvic vessel disruption
- Massive hemothorax
- Intra-abdominal hemorrhage
- Retroperitoneal hemorrhage
- Long bone fracture
- External blood loss
- Non traumatic
- Gastrointestinal bleeding
- Epistaxis
- Hemorrhagic pancreatitis
- Aneurysm rupture
- Ectopic pregnancy
- Postpartum
- Coagulopathy
Fluid loss
- GI losses (vomiting, diarrhoea, short gut, etc)
- Excessive diuresis (diabetes insipidus, diuretics)
- Excessive diaphoresis (heat-related illness)
- Diabetic ketoacidosis
- Burns
- “Third spacing” (pancreatitis, severe sepsis, anaphylaxis)
- Iatrogenic (post-dialysis)
DISTRIBUTIVE SHOCK
- neurogenic shock
- liver failure
- adrenal insufficiency
- anaphylaxis
- septic shock
- post-bypass vasoplegia
- drugs and toxic exposures, e.g. calcium channel blockers, epidural anaesthesia
ENDOCRINE AND METABOLIC CAUSES OF SHOCK
- Adrenal insufficiency
- Hypothyroidism
- Hyperthyroidism
- Diabetic ketoacidosis
- Severe acidosis/ alkalosis and electrolyte disturbances (e.g. hypocalcemia)
? (ERRORS AND ARTEFACTS)
- non-invasive blood pressure measurement error
- arterial line inadvertently sited in a vein
- arterial line transducer position higher than the right atrium
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of two amazing children.
On Twitter, he is @precordialthump.
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