Mouth-to-mouth rescue breaths provide oxygen to an individual who is not breathing or is breathing inadequately. This intervention, sometimes called rescue breathing, manually forces air into the victim’s lungs, serving as artificial ventilation. Understanding the specific circumstances where this technique is required is paramount for effective care. Rescue breaths are a life-saving measure when the root cause of the collapse is a lack of oxygen rather than an immediate failure of the heart.
Understanding Respiratory vs. Cardiac Arrest
The primary indication for mouth-to-mouth rescue breaths is primary respiratory arrest, where a person stops breathing but still has a detectable pulse. The heart is still circulating blood, but the lack of air intake quickly depletes oxygen in the bloodstream. If this oxygen deprivation is not corrected, the body’s tissues will sustain damage, and the condition will rapidly progress to cardiac arrest.
This differs from primary cardiac arrest, which is often caused by an electrical problem, causing the heart to stop pumping effectively. When the heart stops in an adult, a reserve of oxygenated blood remains in circulation for the first few minutes. Chest compressions alone can circulate this remaining oxygen, delaying the need for immediate breaths. The decision to incorporate rescue breaths is based on whether the primary problem is a failure to oxygenate the blood or a failure to circulate it.
Critical Scenarios Where Breaths Are Essential
Rescue breaths are necessary when the collapse is directly caused by a lack of oxygen, resulting in profound hypoxia. In these emergencies, the body’s oxygen stores are depleted from the outset, making chest compressions alone less effective. Providing immediate ventilation is the most direct way to reverse the underlying issue and prevent subsequent cardiac arrest.
Common examples include drowning, where asphyxia due to water inhalation leads to rapid oxygen loss. Opioid overdose also causes severe respiratory depression, slowing and eventually stopping breathing while the heart may continue to beat. For victims of drowning or overdose, the immediate delivery of rescue breaths is the most important action a rescuer can take.
Breaths are also particularly important for pediatric victims, including infants and children. Unlike adults, a child’s heart usually stops due to a prolonged lack of oxygen from a respiratory cause, such as severe asthma or choking. Because oxygen deprivation is the initial trigger, conventional cardiopulmonary resuscitation (CPR) that includes rescue breaths provides significantly better outcomes for this age group.
Current Guidelines for Rescuer Action
Current emergency guidelines translate the physiological indication for rescue breaths into actionable protocols for rescuers. For an untrained bystander who witnesses an adult suddenly collapse, Hands-Only CPR—performing only chest compressions—is recommended. This simplified approach ensures immediate, uninterrupted circulation of residual oxygenated blood, which is often sufficient for the first few minutes of a primary cardiac arrest.
For a trained rescuer, or when the collapse is clearly due to a respiratory cause like drowning or overdose, conventional CPR combining compressions and breaths remains the standard of care. This approach uses a compression-to-ventilation ratio of 30 chest compressions followed by two rescue breaths (30:2). The two-breath pause should be brief, lasting no more than 5 to 10 seconds, to minimize interruptions in blood flow provided by the compressions.
The 30:2 ratio is applied to adults and children in most single-rescuer situations. However, protocols for pediatric victims often include a modification: rescuers are advised to begin with five initial rescue breaths before starting compressions. This acknowledges the high likelihood of a respiratory cause in children, ensuring that rescue breaths remain a targeted, necessary intervention based on the cause of the emergency.