Reversible causes of cardiac arrest

Four Hs

• Hypoxia
• Hypovolaemia
• Hypoglycaemia, hypo/hyperkalaemia, metabolic
• Hypothermia

Four Ts

• Thrombosis - coronary or pulmonary
• Tamponade - cardiac
• Toxins
• Tension pneumothorax

Shockable and non-shockable rhythms

How does CPR work?

• CPR involves cyclical changes in intrathoracic pressure serving to create a gradient for forward blood flow and organ perfusion as well as filling of the cardiac chambers by artificially augmenting venous return
• Explains importance of allowing recoil between compressions

Shockable rhythms - ventricular fibrillation and pulseless ventricular tachycardia

• Ventricular tachycardia presents as a regular broad complex tachycardia on cardiac monitoring
• Ventricular fibrillation presents as as chaotic irregular deflections of varying amplitude

Management