Cardiac Arrest

Question 1

Definition

Answer 1

Acute cessation of cardiac function

Question 2

Aetiology/Risk factors

Answer 2

The REVERSIBLE causes of cardiac arrest can be summarised as the 4 Hs and 4 Ts

· FOUR Hs
o Hypothermia
o Hypoxia
o Hypovolaemia
o Hypokalaemia/Hyperkalaemia

· FOUR Ts
o Toxins (and other metabolic disorders (drugs, therapeutic agents, sepsis))
o Thromboembolic
o Tamponade
o Tension pneumothorax

Question 3

Presenting symptoms

Answer 3

· Management precedes or is concurrent to history

· Cardiac arrest is usually sudden but some symptoms that may preceded by fatigue, fainting, blackouts, dizziness

Question 4

Signs on physical examination

Answer 4

· Unconscious

· Not breathing

· Absent carotid pulses

Question 5

Investigations

Answer 5

· Cardiac Monitor
o Allows classification of the rhythm

· Bloods
o ABG
o U&E
o FBC
o X-match
o Clotting
o Toxicology screen
o Blood glucose

Question 6

Management plan (basic life support)

Answer 6

o If the arrest is witnessed and monitored, consider giving a precordial thump (thump the sternum of the patient with the ulnar aspect of your fist)

o Clear and maintain the airway with head tilt, jaw thrust and chin lift

o Assess breathing by look, listen and feel
· If they are not breathing, give two rescue breaths

o Assess circulation at carotid pulse for 10 seconds
· If absent - give 30 chest compressions at around 100/min
· Continue cycle of 30 chest compressions for every 2 rescue breaths

o Proceed to advanced life support as soon as possible

Question 7

Management plan (advanced life support)

Answer 7

o Attach cardiac monitor and defibrillator

o Assess rhythm
· If pulseless ventricular tachycardia or ventricular fibrillation (shockable rhythms)

§ Defibrillate once (150-360 J biphasic, 360 J monophasic)
· Make sure no one is touching the patient or the bed
§ Resume CPR immediately for 2 minutes and then reassess rhythm, and shock again if still in pulseless VT or VF
§ Administer adrenaline (1 mg IV) after second defibrillation and again ever 3-5 mins]
§ If shockable rhythm persists after 3rd shock - administer amiodarone 300 mg IV bolus (or lidocaine)

· If pulseless electrical activity (PEA) or asystole (non-shockable rhythms)
§ CPR for 2, and then reassess rhythm
§ Administer adrenaline (1 mg IV) every 3-5 mins
§ Atropine (3 mg IV, once only) if asystole or PEA with rate < 60 bpm

o During CPR:
· Check electrodes, paddle positions and contacts
· Secure airway
(Once secure, give continuous compressions and breaths)
· Consider magnesium, bicarbonate and external pacing
· Stop CPR and check pulse only if change in rhythm or signs of life

Question 8

Management plan (treating the reversible causes)

Answer 8

o Hypothermia - warm slowly
o Hypokalaemia and Hyperkalaemia - correction of electrolyte levels
o Hypovolaemia - IV colloids, crystalloids and blood products
o Tamponade - pericardiocentesis
o Tension Pneumothorax - aspiration or chest drain
o Thromboembolism - treat as PE or MI
o Toxins - use antidote for given toxin

Question 9

Possible complications

Answer 9

· Irreversible hypoxic brain damage

· Death

Question 10

Prognosis

Answer 10

· Resuscitation is less successful if cardiac arrest happens outside the hospital

· Increased duration of inadequate effective cardiac output –> poor prognosis