Which expresses the standard adult chest compression-to-ventilation ratio?

• A. 15:2
• B. 30:2
• C. 30:1
• D. 3:2

Answer: (B)

In adult CPR, the priority is to maximize blood flow to vital organs while still delivering enough oxygen. The standard chest compression-to-ventilation ratio is 30 compressions followed by 2 breaths. This 30:2 rhythm keeps coronary and cerebral perfusion high by providing quick, strong compressions and then a brief ventilation pause that isn’t excessive. The cycle is performed at about 100–120 compressions per minute, with compressions about 2 inches (5 cm) deep and allowing complete chest recoil.

Other ratios would disrupt this balance: more frequent breaths would interrupt compressions too often, lowering perfusion, while fewer compressions would reduce blood flow. This is why 30:2 is the established standard for adult CPR.