During adult cardiopulmonary resuscitation, the recommended compression-to-ventilation ratio is:

Current basic life support guidelines specify 30:2 compressions-to-ventilations for adults, at a rate of 100 to 120 per minute and a depth of at least 2 inches, allowing full chest recoil (equal compression and relaxation time).Other options: 15:2 applies to two-rescuer child/infant CPR; 5:1 and 30:5 are outdated or incorrect.Key exam takeaway: Adult CPR = 30:2, rate 100-120/min, depth at least 2 inches, full recoil.