Cardiac arrest (A&E) Flashcards
Define cardiac arrest.
Sudden state of circulatory failure due to loss of cardiac systolic function
Which four specific cardiac rhythm disturbances lead to cardiac arrest?
- ventricular fibrillation (VF): shockable rhythm
- pulseless ventricular tachycardia (VT): shockable rhythm; absence of carotid pulse in the presence of sinus tachycardia
- pulseless electrical activity (PEA): non-shockable rhythm; absence of carotid pulse in the presence of sinus rhythm
- asystole: non-shockable rhythm
What are the most common causes of ventricular tachycardia and fibrillation? (2)
IHD and acute MI
What is Torsades de pointes (cardiac arrest)?
Subgroup of polymorphic VT in patients with underlying prolonged QT interval, sometimes related to hypomagnesaemia
List the reversible causes of cardiac arrest. (4+4)
4 H’s:
- Hypoxia - give O2
- Hypothermia
- Hyperkalaemia/Hypokalaemia
- Hypovolaemia - IV fluids
4 T’s:
- Thrombosis
- Tension pneumothorax - may cause PEA (pulseless electrical activity)
- Tamponade - especially in Trauma
- Toxins
What are the most common underlying causes of cardiac arrest? (3)
- ischaemic heart disease
- MI
- in some cases: respiratory arrest triggered by opioid toxicity
What are the clinical features of cardiac arrest? (5)
- symptoms preceded by fatigue, fainting, blackout, dizziness
- patient unresponsive and unconscious
- not breathing
- absence of circulation - no carotid pulses
- cardiac rhythm disturbance
What are some risk factors for cardiac arrest? (9)
- coronary artery disease (CAD)
- LV dysfunction
- age
- hypertrophic cardiomyopathy (HCM)
- arrhythmogenic RV dysplasia (ARVD)
- long QT syndrome (LQTS)
- medications prolonging QT/causing electrolyte disturbances
- acute medical or surgical emergency
- poisoning/illicit substances (opioids)
What are the first-line investigations for cardiac arrest? (3)
- continuous cardiac monitoring
- bloods - FBC, serum electrolytes, ABG, cardiac biomarkers
- point of care ultrasound (POCUS)
Why is continuous cardiac monitoring important in cardiac arrest?
To identify if the rhythm is shockable or non-shockable
List shockable rhythms in cardiac arrest. (2)
- pulseless VT
- VF
List non-shockable rhythms in cardiac arrest. (2)
- PEA (pulseless electrical activity)
- asystole
When should you do ECG in cardiac arrest?
Immediately after return of spontaneous circulation
What might ECG show in cardiac arrest?
Monomorphic VT
Why would you do FBC in cardiac arrest?
Cardiac arrest may be due to hypovolaemia –> low Hct
Why would you do serum electrolytes in cardiac arrest?
Arrest may be due to electrolyte abnormalities, especially hyperkalaemia and hypokalaemia
Describe the American College of Cardiology/American Heart Association/Heart Rhythm Society classification of ventricular arrhythmias (cardiac arrest). (5)
- VT: 3+ consecutive complexes originating in the ventricles at >100bpm
- sustained VT lasts >30s or results in haemodynamic compromise
- monomorphic VT: VT with a stable single QRS morphology from beat to beat
- polymorphic VT: VT with a changing QRS morphology from beat to beat
- Torsades de pointes: polymorphic VT in setting of a prolonged QT interval, with waxing and waning of QRS amplitude
- VF: rapid, grossly irregular electrical activity with marked variability in waveform; ventricular rate usually >300bpm (cycle length <200ms)
What are the two shockable rhythms in cardiac arrest?
- pulseless VT
- VF
What is the management for an unwitnessed event of cardiac arrest with a shockable rhythm (VT/VF)?
- defibrillate (shock)
- CPR for 2 mins, then assess rhythm (shock again if still VT/VF)
- IV adrenaline 1mg after 3rd shock, and then every 3-5min
- if persisting after 3rd shock, give IV amiodarone 300mg (or lidocaine)
- a further dose of amiodarone 150mg should be given if VT/VF after 5 shocks
How does the management of shockable cardiac arrest change if it was a witnessed attack in a monitored patient?
Administer up to 3 quick successive (stacked) shocks, rather than 1 shock followed by CPR (like in unwitnessed event)
What if IV access cannot be achieved in cardiac arrest (e.g. for adrenaline/amiodarone)?
The drugs should be given via the intraosseous (IO) access in the proximal tibia
What can be given for cardiac arrest if Torsades de pointes is the cause?
Magnesium sulfate
What are the two non-shockable rhythms in cardiac arrest?
- PEA (pulseless electrical activity)
- asystole
What is the management for non-shockable cardiac arrest?
- CPR for 2 mins, then reassess
- IV adrenaline 1mg ASAP (after first cycle), then every 3-5 mins
