Cardiopulmonary Resuscitation (CPR) is an emergency procedure performed when a person’s heart stops beating, a condition known as cardiac arrest. The immediate goal of CPR is to temporarily circulate oxygenated blood to the brain and other vital organs until professional medical help can take over. The difference between life and death often hinges on the quality of the CPR provided by bystanders. Delivering high-quality CPR involves several precise characteristics that maximize the chance of survival, requiring specific attention to mechanics, timing, and consistency.
Achieving Optimal Compression Rate and Depth
The mechanical force and speed of chest compressions are fundamental to creating artificial blood circulation. Compressing the chest at the correct rate ensures that blood is moved frequently enough to keep the brain and heart supplied with oxygen. The recommended compression rate for adults, children, and infants is consistently between 100 and 120 compressions per minute.
Proper compression depth is equally significant, as insufficient force will not generate enough pressure to circulate blood effectively. For an adult, the chest must be compressed at least 2 inches (5 centimeters), but not more than 2.4 inches (6 centimeters).
For children, the depth should be approximately 2 inches (5 centimeters), and for infants, about 1.5 inches (4 centimeters), or roughly one-third of the chest’s front-to-back diameter. Maintaining this specific depth range is necessary because shallower compressions fail to move blood, while overly deep compressions may increase the risk of injury.
Ensuring Full Chest Recoil
While the downward push of a compression moves blood out of the heart, the release phase is equally important for allowing the heart to refill. Full chest recoil refers to the chest wall returning completely to its normal, uncompressed position after each push. This action creates a negative pressure within the chest cavity, which effectively draws blood back into the heart chambers.
If the rescuer leans on the chest between compressions, this prevents the chest from fully expanding, diminishing the heart’s ability to refill with blood. Incomplete recoil reduces the amount of blood available for the next compression, significantly lowering the overall circulation provided by the CPR.
To ensure proper recoil, the rescuer must remove all weight and pressure from the chest after each compression while keeping their hands in contact with the chest to maintain correct positioning.
Maximizing Hands-On Time
The effectiveness of CPR is directly tied to the amount of time compressions are actually being performed, a metric known as the “chest compression fraction.” This fraction is the percentage of total resuscitation time spent delivering compressions, and guidelines recommend aiming for a value of 80% or higher.
When compressions pause, blood flow to the brain and heart immediately stops, meaning every second of interruption negatively impacts the patient’s outcome. Interruptions commonly occur when switching rescuers, analyzing the heart rhythm with a defibrillator, or delivering rescue breaths.
To maximize hands-on time, pauses for any reason should be limited to less than 10 seconds. For instance, a rescuer should charge a defibrillator while compressions are still in progress to minimize the “pre-shock pause.” Alternating the person performing compressions every two minutes should be done quickly during a brief, planned pause to combat rescuer fatigue.
Delivering Effective Rescue Breaths
For cardiac arrests that are not purely heart-related, such as those caused by drowning or respiratory failure, the addition of ventilation is necessary to supply oxygen. The standard sequence for combined CPR is 30 chest compressions followed by two rescue breaths, known as the 30:2 ratio.
Each of the two breaths must be delivered over approximately one second. This timing prevents the air from being forced into the stomach, a complication known as gastric insufflation, which can lead to vomiting and aspiration.
The volume of air delivered should only be enough to cause the patient’s chest to visibly rise. Excessive force or volume during rescue breaths is counterproductive, as it can increase pressure within the chest and reduce the blood flow generated by the compressions. After delivering the two breaths, the rescuer must immediately return to chest compressions to minimize the pause in circulation.