Cardiopulmonary Resuscitation (CPR) is an immediate intervention performed when a person’s heart or breathing stops, serving as a substitute for natural circulation. This technique involves rhythmic chest compressions and often rescue breaths, manually forcing blood and oxygen to the body’s most sensitive organs. The duration of this life-saving effort directly influences the outcome, making the question of “how long” a matter of survival and neurological function.
The Physiological Urgency of Oxygen Deprivation
The need for continuous CPR is fundamentally driven by the brain’s intolerance to a lack of oxygenated blood. When the heart stops, “clinical death” begins, which is the immediate cessation of breathing and circulation. Brain cells are highly sensitive to this deprivation, and irreversible damage can begin within approximately four to six minutes under normal conditions.
This period is often referred to as the “window of survival,” where CPR plays its most significant role. Chest compressions artificially generate a minimal amount of blood flow, typically 15% to 25% of normal output, which is just enough to keep the brain and heart supplied with oxygen. The objective of this artificial circulation is to delay the onset of “biological death,” the irreversible death of cells throughout the body.
Practical Criteria for Continuing or Stopping CPR
For a lay rescuer, the core answer to how long to perform CPR is to continue indefinitely until specific, clear stopping criteria are met. CPR should not be voluntarily stopped simply because a certain amount of time has passed. The primary goal is to maintain oxygenation and circulation until the person’s own body can take over or until trained professionals arrive to provide advanced life support.
A rescuer should cease compressions immediately if the person shows definitive signs of life, such as purposeful movement, coughing, or beginning to breathe normally. The arrival of trained medical professionals, like paramedics or emergency medical technicians, also marks an appropriate time to stop, as they will assume responsibility for the resuscitation.
The safety of the rescuer is another legitimate reason to stop, and CPR should be discontinued if the scene becomes physically hazardous. Finally, if the rescuer is alone and becomes physically exhausted to the point of being unable to maintain high-quality compressions, they can stop. This fatigue-related stoppage is recognized as a necessary limitation of single-rescuer CPR.
Maintaining Effective Compression Quality
The effectiveness of CPR is directly tied to the physical quality of the compressions, not just the duration of the effort. High-quality CPR requires maintaining a compression rate of 100 to 120 compressions per minute and a consistent depth of at least two inches in an adult. Unfortunately, the physical strain of performing chest compressions at this intensity is considerable, leading to rapid rescuer fatigue.
Studies have shown that the physical quality of compressions can begin to decline significantly as early as 90 seconds, with compression depth notably decreasing within two to three minutes. The rate of compressions tends to be maintained longer than the depth, but the loss of adequate depth reduces the amount of blood flow to the organs.
If multiple rescuers are present, it is strongly recommended that they switch the person performing chest compressions every two minutes. This planned rotation minimizes the impact of fatigue and helps ensure that the compressions remain at the necessary depth and rate. The use of an Automated External Defibrillator (AED) can assist by providing verbal cues and delivering an electrical shock.