Cardiac arrest

Question 1

Define cardiac arrest and summarise its aetiology and epidemiology.

Answer 1

Definition: 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 (VF)
- Pulseless ventricular tachycardia (VT)
- Pulseless electrical activity
- Asystole.
- Torsades de pointes is a sub-group of polymorphic VT in patients with an underlying prolonged QT interval, sometimes related to hypomagnesaemia.

Aetiology: 
The reversible causes of cardiac arrest can be summarized as the 4Hs and 4Ts
- Four Hs
     • Hypothermia 
     • Hypoxia
     • Hypovolaemia 
     • Hypokalaemia/ Hyperkalaemia 

- Four Ts
     • Toxins
     • Thromboembolic
     • Tamponade
     • Tension pneumothorax 

Epidemiology: None available

Question 2

Describe the history/presenting symptoms of cardiac arrest

Answer 2

• Family history of sudden cardiac arrest
• Pulmonary disease
• Chest pain
• Palpitations
• Syncope
• Presence of other risk factors

Question 3

What are the signs of cardiac arrest upon physical examination?

Answer 3

• Unconscious
• Not breathing
• Absent carotid pulses
  elevated jugular venous pulse
• Heart murmur
• Abnormalities on auscultation of lungs
• Tracheal deviation
• Neurological deficits
• History of eating disorders

Question 4

What investigations are used to identify cardiac arrest?

Answer 4

1st investigations to order:

• ECG and cardiac monitor
• FBC
• serum electrolytes
• ABG

Other investigations:

• X-match
• Clotting
• Toxicology screen
• Blood screen

Question 5

How is cardiac arrest managed? TO EDIT

Answer 5

• Safety is important
  • Approach any arrest with caution
  • The cause of the arrest may pose a threat
  • Defibrillators and oxygen are hazards
• Basic Life support
  • If unwitnessed immediately move on to CPR
  • If witnessed consider giving a precordial thump with on the sternum with the ulnar aspect of the wrist
  • Clear and maintain the airway with head tilt, jaw thrust and chin lift
  • Assess breathing by look, listen and feel- if they are not breathing, give to rescue breaths
  • Reassess for circulation at carotid pulse if absent continue chest compressions at about 100 per minute if present continue chest compressions as normal.
  • Proceed to Advanced life support ASAP
• Advanced life support:
  ACUTE
  • Shockable rhythms (pulseless ventricular tachycardia or ventricular fibrillation)
  - 1st line: CPR and defibrillation
  - Plus: adrenaline (epinephrine)
  - Adjunct: magnesium
  - Adjunct: anti-arrhythmic

  • Non-shockable rhythms (pulseless electrical activity or asystole) 
       - 1st line: CPR and adrenaline (epinephrine)

  ONGOING
  • Return of spontaneous circulation
  - 1st line: post-resuscitation care
  • No return of spontaneous circulation
  - 1st line: continue or consider termination of resuscitation

Question 6

What are the complications of cardiac arrest?

Answer 6

• Irreversible hypoxic brain damage

- Death

Question 7

Summarise the prognosis for patients with cardiac arrest

Answer 7

• Resuscitation is less successful of cardiac arrest happens outside the hospital
• Increased duration of inadequate effective cardiac output - poor prognosis