Cardiopulmonary Resuscitation (CPR) is an emergency procedure that temporarily keeps blood flowing to the brain and other vital organs when a person’s heart has stopped. The effectiveness of this intervention depends significantly on the quality of chest compressions delivered. Achieving high-quality compressions starts with knowing the precise location for hand placement on the chest. Mastering this technique is the single most important action a bystander can take to increase the chances of survival during a cardiac arrest event.
Locating the Center of the Chest
For an adult, the correct location for chest compressions is the center of the chest, specifically the lower half of the breastbone, known as the sternum. Rescuers often visualize this location by drawing an imaginary line between the person’s nipples and placing the heel of one hand directly on the sternum just below this line. This placement ensures the force of the compressions is directed over the heart, which lies beneath this bony structure.
The breastbone is a flat, strong bone that provides a stable surface for the chest compressions. It is important to avoid placing the hands too low, near the tip of the sternum (the xiphoid process), because applying pressure here can damage internal organs like the liver. Placing the hands too high, near the collarbones, will not effectively compress the heart, rendering the effort ineffective. Proper positioning over the lower half of the sternum maximizes blood flow while minimizing the potential for internal injury.
Physical Mechanics of Hand Stacking
Once the correct spot is located, the physical mechanics of hand stacking are crucial for delivering sufficient force with control. The rescuer should place the heel of one hand directly on the lower half of the sternum. The heel of the second hand is then placed directly on top of the first hand, creating a stacked position.
The fingers of the top hand should be interlocked with the fingers of the bottom hand, or simply held up and off the chest wall. This specific action ensures that pressure is exerted only through the heel of the bottom hand onto the sternum, preventing force from being applied to the more fragile ribs.
The rescuer should then position their shoulders directly over their hands, keeping their arms straight. This alignment allows the rescuer to use their upper body weight to push straight down, which helps achieve the recommended compression depth of at least two inches for an adult without tiring the arm muscles too quickly.
Hand Placement for Children and Infants
The technique for hand placement is modified for pediatric patients. For a child, generally defined as one year old to the onset of puberty, the hand placement remains in the center of the chest over the lower half of the sternum. Depending on the child’s size, the rescuer may use the heel of only one hand to perform compressions instead of the two-hand stacked technique used for adults.
For infants, defined as less than one year old, the technique shifts to using two fingers instead of the heel of the hand. The index and middle fingers are placed in the center of the infant’s chest, just below the nipple line. This two-finger placement is appropriate for the smaller body size, aiming for a compression depth of about 1.5 inches, or approximately one-third the depth of the infant’s chest. An alternative, especially if two rescuers are present, is the two-thumb encircling technique, where both thumbs are placed side-by-side on the center of the chest while the hands wrap around the infant’s back.
Why Accuracy in Placement Matters
Precise hand placement is a direct factor in the effectiveness and safety of chest compressions. When the hands are correctly positioned over the lower half of the sternum, compressions are most efficient at squeezing the heart between the sternum and the spine. This action generates the pressure necessary to circulate oxygenated blood to the brain and vital organs.
Incorrect placement, such as positioning the hands too far to the side or too low on the abdomen, drastically reduces blood flow. Misplaced hands significantly increase the risk of harm. Applying force to the ribs instead of the breastbone makes rib fractures more likely, and pressing too low can damage abdominal organs such as the liver or spleen. Accurate positioning is necessary to maximize the chance of survival while mitigating preventable complications.