Cardiopulmonary Resuscitation (CPR) is a life-saving technique used when a person’s heart has stopped beating to circulate blood and oxygen to the brain and other vital organs. The goal is to maintain minimal function until the heart can be restarted or advanced medical care arrives. Simply performing compressions is not enough; the effectiveness of the intervention hinges on adhering to specific, measurable metrics collectively known as High-Quality CPR. Adherence to these metrics is directly linked to the patient’s chances of survival and recovery.
Compression Rate and Depth Standards
The mechanical force applied during CPR must fall within a narrow range, involving both the speed and depth of each push. Compressions must be delivered at a rate between 100 and 120 pushes per minute to maximize blood flow. If the rate is too slow, the resulting blood flow is insufficient to meet the organs’ oxygen needs. Rates exceeding 120 per minute can lead to shallower compressions, reducing the volume of blood pushed with each beat.
The depth of each compression is also critical, with a standard requirement of at least 2 inches (5 cm) but not more than 2.4 inches (6 cm) for adults. Compressing the chest forces the heart, situated between the sternum and the spine, to squeeze blood into the circulatory system. If compressions are too shallow, they fail to generate the necessary pressure to circulate blood to the coronary arteries and the brain. Pushing too deeply carries the risk of causing injury to internal organs like the liver or lungs.
Maximizing Blood Flow Through Recoil and Continuity
The effectiveness of compressions relies on how the chest is managed between each push and how consistently compressions are maintained. Full chest wall recoil is required after every compression, meaning the rescuer must completely lift their weight off the chest. This allows the chest to return to its normal position, creating negative pressure inside the chest cavity so the heart can refill with blood before the next compression.
Failure to allow full recoil, often called “leaning” on the chest, prevents the heart from adequately refilling. This significantly reduces the amount of blood that can be pumped out, lowering the overall blood circulation created by the CPR effort. Minimizing interruptions to compressions is also a primary component of maximizing blood flow.
The time spent actively performing compressions, known as the Chest Compression Fraction (CCF), should be as high as possible, ideally 60% or greater. Every pause, whether for ventilation, checking a pulse, or switching rescuers, causes a rapid drop in coronary and cerebral blood flow. It takes several compressions to re-establish adequate blood pressure after even a short interruption, making the continuity of flow paramount.
Controlling Ventilation and Avoiding Excessive Breaths
Properly managing rescue breaths balances the need for oxygen delivery with the potential for negative consequences. For a single rescuer performing CPR, the standard ratio is 30 compressions followed by two breaths. When an advanced airway is in place, the ventilation rate is one breath every six seconds, or 10 breaths per minute, with continuous compressions.
A frequent error is hyperventilation, which involves providing too many breaths or delivering breaths that are too forceful. Excessive ventilation increases intrathoracic pressure, which squeezes the large veins and makes it harder for blood to return to the heart. This reduction in venous return decreases the blood available for the heart to pump, lowering the effectiveness of chest compressions and reducing cardiac output. Hyperventilation can also cause air to enter the stomach, increasing the risk of regurgitation and aspiration. Breaths should only be given just enough to cause the chest to visibly rise.