Cardiac Arrest Flashcards
What is cardiac arrest?
Sudden cardiac arrest is a sudden state of circulatory failure due to a loss of cardiac systolic function.
It is the result of 4 specific cardiac rhythm disturbances: ventricular fibrillation, pulseless ventricular tachycardia (VT), pulseless electrical activity, and asystole.
What are the causes of cardiac arrest?
The main underlying causes are ischaemic heart disease, unspecified cardiovascular disease, and cardiomyopathy/dysrhythmias.
Other causes include hypoxia, hypovolaemia, hyperkalaemia, hydrogen ion excess (acidosis), hypothermia, hypo- or hyperglycaemia, trauma, tension pneumothorax, obstructive shock (pulmonary embolism, myocardial infarction), toxins, and cardiac tamponade.
What are the 4 conditions included in sudden cardiac arrest?
Sudden cardiac arrest is the term used to describe the ultimate result of 4 different cardiac arrhythmias:
- Ventricular tachycardia (VT)
- Ventricular fibrillation (VF)
- Pulseless electrical activity (PEA)
- Asystole
What is ventricular tachycardia (VT)?
Ventricular tachycardia (VT): ≥3 consecutive complexes originating in the ventricles at a rate >100 bpm. Sustained VT lasts >30 seconds or results in haemodynamic compromise.
What is ventricular fibrillation (VF)?
Ventricular fibrillation: rapid, grossly irregular electrical activity with marked variability in waveform; ventricular rate usually >300 bpm (cycle length <200 milliseconds).
What are the risk factors for cardiac arrest?
- Coronary artery disease
- Left ventricular dysfunction
- Hypertrophic cardiomyopathy (HCM)
- Long QT syndrome
- Medications that prolong QT interval or cause electrolyte disturbances
- Acute medical or surgical emergency
- Illicit substances
What are the signs of cardiac arrest?
- Absence of normal breathing
- Absence of circulation
- Cardiac rhythm disturbance (including ventricular fibrillation, pulseless ventricular tachycardia, pulseless electrical activity or asystole)
What are the symptoms of cardiac arrest?
- Absence of normal breathing
- Absence of circulation
- Cardiac rhythm disturbance
What investigations should be ordered for cardiac arrest?
- Continous cardiac monitoring
- FBC
- Serum electrolytes
- ABG
- Cardiac biomarkers
- Echocardiogram
Why is continuous cardiac monitoring important?
Identifying the cardiac rhythm is a key step in determining which cardiac arrest treatment algorithm to use.
Identifies shockable rhythm (ventricular fibrillation/pulseless ventricular tachycardia) or non-shockable rhythm (asystole/pulseless electrical activity).
Why investigate using FBC?
Haemorrhage may cause hypovolaemia and should be evaluated for.
Low haematocrit can be seen in haemorrhage.
Why investigate using serum electrolytes? And what may this show?
Electrolyte abnormalities occur as a result of sudden cardiac arrest and contribute to cardiac arrest.
May show electrolyte abnormalities, particularly hyperkalaemia or hypokalaemia.
Why investigate using ABG?
Respiratory and metabolic parameters should be optimised as necessary to normalise acid-base status. Abnormal results may be a result of sudden cardiac arrest and not necessarily the cause. May indicate an underlying respiratory aetiology of pulseless electrical activity/asystole.
May show respiratory acidosis, metabolic acidosis, respiratory acidosis with renal compensation, metabolic acidosis with respiratory compensation, mixed metabolic and respiratory acidosis or can also reveal hyperkalaemia.
Why investigate using cardiac biomarkers?
Elevations in markers of myocardial infarction (MI) may be a result of sudden cardiac arrest and do not necessarily indicate that an MI is the cause.
Positive or elevated.
Why investigate using echocardiogram?
Cardiac activity may be assessed acutely during resuscitation.
Assesses cardiac activity and left ventricular function; may show valvular abnormalities, myocardial scarring, cardiomyopathy, pericardial effusion.
