Cardiac Arrest

Question 1

Define cardiac arrest.

Answer 1

Sudden loss of cardiac systolic function. It is the result of 4 specific cardiac rhythm disturbances: ventricular fibrillation (VF), pulseless ventricular tachycardia (VT), pulseless electrical activity, and asystole. Each of these rhythms may present in different clinical scenarios, though VT and VF are the most common causes of sudden cardiac arrest.

Question 2

Explain the aetiology/risk factors of cardiac arrest.

Answer 2

Myocardial ischaemia/infarction

Hypovolaemia

Hypoxia

Pulmonary embolism.

Other potential causes of cardiac arrest, all of which require emergent treatment, including hyperkalaemia, hydrogen ion excess (acidosis), hypothermia, hypo- or hyperglycaemia, trauma, tension pneumothorax, toxins, and cardiac tamponade.

Question 3

Summarise the epidemiology of cardiac arrest.

Answer 3

In Europe, out-of-hospital cardiac arrest incidence for patients considered for resuscitation by emergency medical services has been reported as 84 per 100,000 population per year.
Survival is estimated at <20% for patients presenting out-of-hospital with VF, and <10% overall for patients presenting with out-of-hospital cardiac arrest. In contrast, 36% of patients with VF/ventricular tachycardia (VT) and 11% of patients with pulseless electrical activity/asystole, presenting in-hospital, survive to discharge.

Question 4

Recognise the presenting symptoms of cardiac arrest. Recognise the signs of cardiac arrest on physical examination.

Answer 4

Family history of sudden cardiac arrest
Pulmonary disease
Chest pain
Palpitations- possibility of pre-existing arrhythmias
Syncope
Tachycardia
Unusual heart sounds

Question 5

Identify appropriate investigations for cardiac arrest and interpret the results.

Answer 5

ECG
FBC
Serum electrolytes
ABG
Cardiac biomarkers
Toxicology screen
CXR
Echocardiogram
Coronary angiography

Question 6

Generate a management plan for cardiac arrest.

Answer 6

INITIAL
CPR

ACUTE
Shockable rhythms (pulseless ventricular tachycardia or ventricular fibrillation)
CPR and defibrillation
Adrenaline (epinephrine)
Adjunct
Magnesium
Anti-arrhythmic

Non-shockable rhythms (pulseless electrical activity or asystole)
CPR and adrenaline (epinephrine)

ONGOING
Return of spontaneous circulation
Post-resuscitation care
No return of spontaneous circulation
Continue or consider termination of resuscitation

Question 7

Identify the possible complications of cardiac arrest and its management.

Answer 7

Death

Rib and sternal fractures

Anoxic brain injury

Ischaemic liver injury (“shock liver”)

Renal acute tubular necrosis (ATN)

Recurrent cardiac arrest

Question 8

Summarise the prognosis for patients with cardiac arrest.

Answer 8

The outcome of sudden cardiac arrest is generally poor. Early provision of CPR, including compression-only CPR by bystanders in out-of-hospital arrest increases the rate of survival from sudden cardiac arrest. The strongest predictor of survival is bystander CPR.
Even those who do survive to hospital admission do not always survive to hospital discharge. Furthermore, those who do survive to hospital discharge often have neurological, pulmonary, cardiac, hepatic, renal, or musculoskeletal complications.
Most important, the neurological outcome of the comatose survivors of sudden cardiac arrest must be carefully assessed. The following characteristics portend death or a poor neurological outcome:
At 24 hours - loss of corneal reflex, lack of motor response, lack of withdrawal to pain, and loss of pupillary response.
At 72 hours - lack of motor response.