When performing CPR on an adult, how many hands should be used for compressions?

Using two hands for compressions when performing CPR on an adult is essential for several reasons. Firstly, the adult chest is typically large and requires more force to ensure that the compressions are effective in promoting blood circulation. Using both hands allows for greater power and better control, enabling the rescuer to compress the chest adequately to the recommended depth, which is about 2 to 2.4 inches (5 to 6 cm) in adults.

Additionally, the proper technique involves interlocking the fingers of one hand on top of the other, positioning the heel of the hands on the lower half of the breastbone. This positioning not only distributes the force more evenly but also allows the rescuer to maintain a more stable and consistent rhythm during the compressions. It is crucial to keep the elbows straight and use body weight to maximize the efficiency of the compressions.

The other choices do not provide the necessary force or coverage of the chest area needed for effective adult CPR. One hand would not provide sufficient compression depth, and two fingers or three fingers would be inappropriate, as these methods are only applicable in infant CPR. Therefore, using two hands is the correct approach to ensure effective and life-saving compressions during adult CPR.