The frequency of delivering ventilations, or rescue breaths, during cardiopulmonary resuscitation (CPR) varies based on the patient’s age and clinical status. Rescue ventilation manually supplies oxygen to a person who is not breathing adequately. This process is necessary because chest compressions alone cannot sustain life indefinitely without oxygen replenishment. The rate and timing of breaths must balance oxygen delivery with minimizing interruptions to chest compressions. The correct approach depends on whether the patient has a pulse, if compressions are being performed, and whether an advanced airway has been placed.
Ventilation Rates During Standard CPR
Standard CPR protocols use a ratio-based approach, alternating chest compressions with ventilations. For an adult patient who is pulseless and not breathing, the standard ratio is 30 compressions followed by 2 ventilations, regardless of the number of rescuers. This 30:2 cycle maximizes time spent on compressions, which is vital for maintaining blood flow.
The two ventilations must be delivered quickly, each lasting about one second, to keep the interruption under ten seconds. The ratio changes for children and infants depending on the number of rescuers. A single rescuer uses the 30:2 ratio, but when two or more rescuers are present, the ratio shifts to 15 compressions followed by 2 ventilations.
This shift to 15:2 for pediatric patients in a two-rescuer scenario reflects that cardiac arrest in children is often caused by a respiratory problem. The increased frequency of ventilations provides more oxygen per minute to the younger patient. This ensures the body receives the necessary oxygenation that may have been lacking before the arrest.
Rescue Breathing (Pulse Present)
When a patient has a pulse but is not breathing adequately (respiratory arrest), a different approach is used. Chest compressions are not performed because the heart is still circulating blood. The ventilation rate is time-based and aims to mimic a normal respiratory rate. For adults, the rate is one ventilation every 5 to 6 seconds (10 to 12 breaths per minute). This steady rate delivers sufficient oxygen while preventing hyperventilation.
The rescuer must check the patient’s heart rate every two minutes to ensure the pulse is maintained. For children and infants, the recommended rate is faster: one breath every 3 to 5 seconds (12 to 20 breaths per minute). This higher frequency acknowledges the naturally faster metabolism and respiratory rates of younger individuals.
Ventilating with an Advanced Airway
When an advanced airway, such as an endotracheal tube or a laryngeal mask airway, has been placed, the procedure changes significantly. Securing the airway eliminates the need to pause chest compressions for ventilation, improving resuscitation quality. Compressions become continuous, maintaining a steady rate of 100 to 120 per minute without interruption.
Ventilations are delivered asynchronously, meaning they are no longer coupled to the compressions in a ratio. For adults, the recommended rate is one ventilation every 6 seconds (10 breaths per minute). For infants and children, the rate is higher: one breath every 2 to 3 seconds (20 to 30 breaths per minute).
The advanced airway isolates the trachea, preventing air from entering the stomach and allowing continuous chest compressions. This continuous compression maintains better coronary perfusion pressure, which is vital for the heart’s recovery. The ventilator can focus solely on the correct timing of the breaths.
Assessing and Maintaining Ventilation Quality
The quality of each delivered ventilation is a primary concern, regardless of the specific rate or ratio used. The most important indicator of an effective breath is the visible rise and fall of the patient’s chest. Each ventilation should be delivered over approximately one second, providing just enough volume to cause this gentle chest rise. Rescuers must actively avoid excessive ventilation (hyperventilation), which means giving breaths too quickly or too forcefully.
Hyperventilation is detrimental because it increases pressure inside the chest cavity, reducing the vacuum effect that helps draw blood back to the heart (venous return). This decrease in blood return lowers the effectiveness of chest compressions and can reduce coronary and cerebral perfusion. The physiological disruption caused by excessive ventilation can also lead to a drop in blood pressure and an imbalance in blood chemistry. Focusing on the recommended rate and delivering only the necessary volume to achieve visible chest rise is a core principle of high-quality resuscitation.