Cardiopulmonary Resuscitation (CPR) involves chest compressions and artificial ventilation meant to preserve brain function until medical services arrive. For decades, the standard approach included both compressions and rescue breathing. Modern guidelines recognize that rescue breaths are not always necessary for an adult who suddenly collapses. This shift is rooted in the body’s existing oxygen reserves and the primary cause of many sudden cardiac arrests. Hands-Only CPR simplifies the procedure for bystanders and minimizes delays in starting the most critical intervention.
The Physiological Rationale for Compression-Only CPR
The body has a built-in oxygen supply that supports the brain and other organs for a short time after the heart stops. Sudden cardiac arrest is typically an electrical problem in the heart, not an immediate lack of oxygen in the blood. The immediate problem is a failure of circulation, meaning the oxygen already present in the bloodstream is not being delivered to the tissues.
Effective chest compressions manually push blood out of the heart and into the circulation. This action mimics the heart’s pumping function, albeit at a much lower efficiency, circulating the existing oxygen to the brain and heart. Researchers have found that this supply of oxygenated blood can be sufficient for the first several minutes following a sudden collapse.
The priority during this initial period is maintaining continuous blood flow with minimal interruptions. Pausing compressions to deliver two rescue breaths stops the already inefficient circulation, causing blood pressure to drop significantly. Since compressions achieve less than 25% of normal cardiac output, minimizing any pause is paramount. Focusing solely on high-quality compressions maximizes the delivery of the body’s existing oxygen to the vital organs until advanced care arrives.
Hands-Only CPR: Recommended Protocols for Bystanders
Hands-Only CPR is defined as providing continuous, high-quality chest compressions without pausing to administer rescue breaths. Health organizations recommend this simplified approach primarily for untrained bystanders who witness an adult suddenly collapse. The ease of the technique helps eliminate hesitation and encourages more people to act immediately in an emergency.
Bystanders are instructed to push hard and fast in the center of the chest at a rate of 100 to 120 compressions per minute, often likened to the rhythm of the song “Stayin’ Alive.” The compressions should be delivered to a depth of at least two inches, but no more than 2.4 inches, on an adult.
For an adult victim of a witnessed, out-of-hospital cardiac arrest, Hands-Only CPR has shown similar survival outcomes to conventional CPR. The goal is to provide uninterrupted circulation, which is often compromised when untrained rescuers attempt the compression-to-breath ratio. This protocol does not apply to all situations and is specifically tailored for cases where the cause is presumed to be cardiac.
When Rescue Breaths Remain Essential
The preference for Hands-Only CPR changes in situations where the cardiac arrest is the result of a breathing problem. Rescue breaths remain a necessity where the victim’s oxygen reserves are likely depleted before the collapse. These are known as asphyxial or respiratory arrests, and they require immediate external ventilation to replenish the blood’s oxygen content.
Examples of respiratory-caused arrests include drowning, drug overdose, choking, and severe respiratory failure. In these scenarios, the heart has stopped because the body ran out of oxygen, making the delivery of air more urgent than the circulation of already deoxygenated blood. For these victims, conventional CPR, using a ratio of 30 compressions to two breaths, is the recommended standard.
Rescue breaths are mandatory for all pediatric cases, including infants and children. Cardiac arrest in children is overwhelmingly caused by respiratory compromise, such as severe asthma or choking, rather than an underlying heart problem. Because their bodies have smaller oxygen reserves, ventilation must be provided to increase the likelihood of survival.