A phrase commonly heard in the Neonatal Intensive Care Unit (NICU), A’s and B’s refer to a baby’s irregular breathing and heart rate. One usually accompanies the other, and they can be quite worrisome for parents of NICU babies. Rest assured, the experts in the NICU know how to manage A’s and B’s. Here is a brief overview for new parents to better understand these conditions and what to expect when the baby stops breathing.
Apnea is when a baby stops breathing for more than 20 seconds or more than 10 seconds but is also accompanied by a decrease in heart rate and oxygenation.
Bradycardia is when the heart rate falls by 30 beats per minute below its normal baseline, and in the NICU, 80 beats per minute or less is considered bradycardia.
There are three types of apnea: central, obstructive, and mixed apnea.
There are several treatment options available for apnea and bradycardia, and the majority of babies will outgrow them.
Apnea of prematurity
The word apnea refers to the absence of breathing. Apnea of prematurity (AOP) is the cessation of breathing in a premature baby (born before 37 weeks gestation) that lasts more than 20 seconds. Or it can be when a baby stops breathing for more than 10 seconds but is also accompanied by a decrease in heart rate and oxygenation.
The NICU specializes in caring for ill or premature newborn babies, and one of the most common diagnoses in the NICU is AOP. There are three types of apnea:
Central Apnea - caused by immaturity of the central nervous system and the respiratory control system located in the medulla oblongata of the brain.
Obstructive Apnea - caused by the blockage of airflow into the lungs due to neck positioning, occlusion of the nasal passageways, or laryngospasms (muscular contraction of the vocal cords).
Mixed Apnea - caused by a mix of both central and obstructive apnea
Following an episode of apnea, desaturation can occur, which refers to low oxygen levels in the blood (hypoxemia). Due to the lower blood oxygen levels, the heart rate may slow, resulting in bradycardia.
When a baby’s heart rate falls by 30 beats per minute below its normal baseline, it is considered bradycardia. The Neonatal Resuscitation Program (NRP) recommends intervention when a baby’s heart rate drops under 100, and in the NICU, a heart rate less than 80 is considered bradycardia. Bradycardia is often preceded by apnea but can also be caused by other factors.
Monitoring A’s and B’s in the NICU
Babies in the NICU will be connected to continuous monitors that display their heart rate and rhythm, respiratory rate, oxygen saturation, and blood pressure. These monitors will alarm if a baby’s levels go below or above the parameter settings. The monitor uses waveforms that can show when a baby has shallow or paused breathing.
The majority of premature/ill babies will outgrow their episodes of apnea and bradycardia. However, some babies may need to be discharged home with an apnea monitor because they still experience A’s and B’s long after admission to the NICU.
There are various treatment options available for A’s and B’s and are often used in conjunction with one another. Some of the treatments include:
Nasal Continuous Positive Airway Pressure (NCPAP) - a non-invasive breathing support system that provides continuous positive airflow into the nose, preventing complete airway collapse.
Caffeine Citrate - a medication that can either be given orally or intravenously and is one of the leading pharmacological treatments for AOP. It acts as a smooth muscle relaxant in the lung and is a central nervous system and cardiac stimulant.
Tactile Stimulation - gently and briefly touching or rubbing the baby during an episode of apnea/bradycardia will activate sensory neurons and stimulate the brain, which triggers respiratory drive. This method can disrupt sleep patterns and cause overstimulation in neonates, so it should only be used when necessary.
Prone Positioning - placing NICU babies in the prone position (lying on their stomach) has been shown to improve the disbursement of air throughout the lungs and reduce AOP. Prone positioning is ONLY suggested while the baby is in the hospital. After discharge, babies should be placed on their backs to sleep to reduce the risk of Sudden Infant Death Syndrome (SIDS).
Having a baby in the NICU can be very stressful and scary, but the staff in the NICU work 24 hours a day to ensure that these fragile babies receive the best possible care. They are extensively and specially trained experts who know what to do for a baby experiencing A’s and B’s. Most babies will outgrow this condition, so it is generally only a temporary issue.