Cardiopulmonary resuscitation (CPR) is a technique designed to maintain blood flow and oxygen to the brain and other organs when an infant’s heart or breathing has stopped. Understanding the specific guidelines for infants, such as a 4-month-old, is necessary for effective intervention. Because an infant’s anatomy and common causes of cardiac arrest differ significantly from those of an adult, the procedure requires modifications in rate, depth, and technique. Following established protocols gives the infant the best possible chance of survival until professional medical help arrives.
The Critical Compression Rate for Infants
For an infant in cardiac arrest, the speed at which chest compressions are performed is a defining factor in generating adequate circulation. The primary goal of compressions is to pump oxygenated blood from the heart to the rest of the body. This mechanical action temporarily takes over the heart’s function.
The standard minimum number of compressions recommended for a 4-month-old is 100 per minute. The upper range of this recommendation extends to 120 compressions per minute, providing a target zone for rescuers. This rate is necessary to maintain a continuous, albeit artificial, blood flow.
Maintaining this consistent rhythm is important because the infant’s body needs constant pressure to sustain the flow of oxygenated blood to the brain and vital organs. Pausing or delivering compressions too slowly allows the blood pressure to drop significantly, which reduces the overall effectiveness of the CPR.
A simple way to monitor and maintain the correct pace is to compress the chest to the rhythm of a song with 100 to 120 beats per minute. This method helps the rescuer focus on a steady, uninterrupted tempo. Consistent delivery ensures that the infant receives the full benefit of the circulatory support provided by the compressions.
Technique and Depth for Effective Infant Compressions
The physical act of performing compressions on a 4-month-old is modified to account for the infant’s small size and delicate rib cage. For a single rescuer, the recommended technique involves using two fingers—the index and middle fingers—placed on the center of the infant’s breastbone. The correct location is just below an imaginary line drawn between the infant’s nipples.
The depth of each compression must be approximately 1.5 inches, which is roughly one-third the front-to-back depth of the infant’s chest. Pressing too lightly will not circulate blood effectively, while pressing too deeply risks causing internal injury.
The rescuer must ensure they allow the chest to fully recoil after each compression, meaning they must completely lift their fingers off the chest without losing contact. Full recoil is necessary to allow the heart to properly refill with blood before the next compression. Incomplete recoil decreases the amount of blood pumped with the subsequent compression, reducing the overall efficacy of the procedure.
If two trained rescuers are present, the preferred method is the two-thumb encircling technique. Rescuers wrap their hands around the infant’s chest, placing both thumbs side-by-side on the breastbone just below the nipple line. The fingers support the infant’s back while the thumbs deliver the compressions. This technique is generally more effective at achieving the proper depth and generating higher blood pressure. Regardless of the technique used, the rate of 100 to 120 compressions per minute must be strictly maintained.
Integrating Compressions into the Full CPR Cycle
Chest compressions are performed as part of a cycle that also includes rescue breaths, a sequence that addresses the common respiratory causes of cardiac arrest in infants. For a single rescuer performing CPR on a 4-month-old, the correct ratio is 30 compressions followed by 2 rescue breaths. This cycle must be repeated continuously.
The two rescue breaths should be delivered gently, lasting about one second each, and should be just enough to cause the infant’s chest to visibly rise. It is important to avoid forceful breaths, which could cause injury to the infant’s lungs. The rescuer must quickly transition from the 30th compression to the first breath to minimize interruptions.
If two rescuers are available, the ratio changes to 15 compressions followed by 2 rescue breaths. This altered ratio of 15:2 allows for more frequent ventilation, which is beneficial since an infant’s cardiac arrest is often precipitated by a respiratory problem. The two rescuers should switch roles approximately every two minutes to prevent fatigue without interrupting the cycle. Minimizing the time spent between the final compression and the first breath significantly improves the outcome of CPR.
Recognizing the Need for Infant CPR and Next Steps
The proper response to an unresponsive infant begins with immediate assessment and activation of the emergency response system. The first step is to gently check for responsiveness, which involves carefully tapping the infant’s feet. Shaking an infant is never recommended.
If the infant is unresponsive and not breathing or only gasping, the rescuer should immediately activate emergency medical services by calling 911 or sending someone else to do so. This is followed by quickly checking for a pulse for no more than 10 seconds. The absence of a pulse, or a heart rate below 60 beats per minute with signs of poor circulation, indicates the need for CPR.
The procedure follows the C-A-B protocol, which prioritizes Compressions first, then opening the Airway, and finally providing Breathing. This sequence ensures that the most time-sensitive action—circulating blood—is started without delay. This protocol replaced the former sequence to ensure that compressions begin as quickly as possible.
If a rescuer is alone and does not have a phone, they should perform about two minutes of CPR before pausing to call for help. The procedure should continue without interruption until professional help arrives, an automated external defibrillator (AED) is ready to use, or the infant shows obvious signs of life, such as purposeful movement or breathing.