Apnea of prematurity

Apnea is breathing that slows down or stops from any cause. Apnea is more common in premature babies than in full-term babies. Apnea of prematurity refers to short episodes of stopped breathing in premature or preterm babies who were born before 37 weeks of pregnancy (premature birth):

• pauses breathing for more than 15 to 20 seconds
  or
• pauses breathing for less than 15 seconds, but has a slow heart rate or low oxygen level

The most common cause of apnoea is apnea of prematurity; the incidence depends on the neonate’s gestational age:

• >60% when born at 28 weeks or below.
• 50% when born between 30-31 weeks.
• 14% when born between 32-33 weeks.
• 10% when born at 34-35 weeks or above.

Apnea appears to be more common during sleep, especially during active sleep — a period when your baby has rapid eye movement (REM) while sleeping.

Apnea may be followed by bradycardia (decreased heart rate). With bradycardia, when your baby’s breathing slows, the heart rate also slows.

After they’re born, babies must breathe continuously to get oxygen. Most premature babies or preemies have some degree of apnea. In a premature baby, the part of the central nervous system (brain and spinal cord) that controls breathing is not yet mature enough for nonstop breathing. This causes large bursts of breath followed by periods of shallow breathing or stopped breathing.

Doctors usually diagnose apnea of prematurity before the mother and baby are discharged from the hospital, and the apnea usually goes away on its own as the infant matures.

Generally, babies who are born at less than 35 weeks’ gestation have periods when they stop breathing or their heart rates drop. The medical name for a slowed heart rate is bradycardia. These breathing abnormalities may begin after 2 days of life and last for up to 2 to 3 months after the birth. Smaller and more premature infants are more likely to have apnea of prematurity.

Although it’s normal for all infants to have pauses in breathing and heart rates, those with apnea of prematurity have drops in heart rate below 80 beats per minute. This causes them to become pale or bluish. They may also look limp and their breathing might be noisy. They’ll either start breathing again by themselves or need help to do so.

Apnea of prematurity is different from periodic breathing, which is also common in premature newborns. Periodic breathing is a pause in breathing that lasts just a few seconds and is followed by several fast and shallow breaths. Periodic breathing doesn’t cause a change in facial color (such as blueness around the mouth) or a drop in heart rate. A baby who has periodic breathing starts regular breathing again on his or her own. Although it can be frightening, periodic breathing usually causes no other problems.

Apnea of prematurity usually ends on its own after a few weeks. Once it goes away, it usually doesn’t come back.

When your baby has apnea, stimulating her by patting or rubbing her skin can help her to begin breathing again. Your baby’s treatment plan for apnea of prematurity may also include:

• monitoring of her breathing and heart rates
• medications
• caffeine or theophylline to stimulate the central nervous system
• continuous positive airway pressure (CPAP) – a mechanical breathing machine that pushes a continuous flow of air or oxygen to the airways to help keep tiny air passages in your baby’s lungs open

Many premature babies will “outgrow” apnea of prematurity by the time they are 36 weeks. If the apnea is not due to prematurity, your baby may require other treatments.

Types of apnea

• Central apnea (40%): Caused by decreased central nervous system stimuli to respiratory muscles. Both the respiratory effort and airflow cease simultaneously (absence of chest wall movement and airflow).
• Obstructive apnea (10%): Caused by pharyngeal instability / collapse, neck flexion or nasal obstruction. Absence of airflow in presence of inspiratory efforts (There is presence of chest wall movement but no airflow).
• Mixed apnea (50%): Has a mixed cause. Central apnea is either preceded (usually) or followed by obstructed respiratory effort

Short episodes of apnea are usually central whereas prolonged ones are often mixed.

Periodic breathing may be mistaken for apnea. Apnea may be a symptom of seizure activity.

How can I help my baby?

Apnea of prematurity usually ends on its own with time. Healthy infants who have had apnea of prematurity usually do not go on to have more health or developmental problems than other babies. apnea of prematurity does not cause brain damage, and a healthy baby who is apnea free for a week will probably never have apnea of prematurity again.

Aside from apnea of prematurity, other complications with your premature baby may limit the time and interaction that you can have with your little one. But you can still bond with your baby in the neonatal intensive care unit (NICU). Talk to the NICU (neonatal intensive care unit) staff about what would be best for your baby, whether it’s holding, feeding, caressing, or just speaking softly. The NICU staff is not only trained to care for premature babies, but also to reassure and support their parents.

If your baby comes home with a monitor, it can be a stressful time. Some parents find themselves constantly watching the monitor, afraid to take a break even to shower. This usually gets easier with time. If you’re feeling this way, the NICU staff can reassure you and perhaps put you in touch with other parents of preemies who went through the same thing.

Causes of apnea of prematurity

Apnea of prematurity may have several causes, resulting in two main kinds of apnea:

• Central apnea: This kind of apnea is due to a disturbance in a child’s brain’s breathing control center. Problems in her organs might also affect this breathing control center.
• Obstructive apnea: With this kind of apnea, a child’s breathing stops because something is blocking the child’s airway.

There are several reasons why newborns, in particular those who were born early, may have apnea, including:

• If their brain is not fully developed
• If the muscles that keep the airway open are weak

Other stresses in a sick or premature baby may worsen apnea, including:

• Anemia
• Feeding problems
• Heart or lung problems
• Infections: Sepsis, necrotising enterocolitis, meningitis.
• Low oxygen levels
• Temperature problems
• Bleeding or tissue damage in your baby’s brain
• Respiratory disease
• Gastrointestinal problems such as reflux (your baby’s stomach contents move back up into the esophagus)
• Your baby’s levels of chemicals such as glucose or calcium are too high or too low
• Heart or blood vessel problems
• The stimulation of reflexes that can trigger apnea such as with feeding tubes or suctioning, or when your baby’s neck is very flexed
• Unstable temperature
• Airway obstruction: Assess position of head and neck to ensure neutral alignment.
• Cardiovascular: Anemia, hypotension, hypertension, patent ductus arteriosus, cardiac failure, hypovolemia.
• Pain: Acute and chronic pain.
• Central nervous system: Intraventricular hemorrhage, seizures, hypoxic injury, neuromuscular disorders, brainstem infarction or anomalies, birth trauma, congenital malformations.
• Respiratory: Pneumonia, intrinsic / extrinsic mass or lesions causing airway obstruction, upper airway collapse, atelectasis, phrenic nerve paralysis, respiratory distress syndrome, pneumothorax, hypoxia, malformations of chest, pulmonary hemorrhage, aspiration.
• Gastrointestinal: Oral feeding, bowel movement, esophagitis, intestinal perforation, gastroesophageal reflux, abdominal distension.
• Metabolic: Hypoglycemia, hypocalcemia, hyponatremia, hypernatremia, hyperammonemia, low organic acids, high ambient temperature, hypothermia, hyperthermia.
• Drugs: Maternal drugs (consider neonatal abstinence syndrome), opiates, prostin, high levels of phenobarbitone, chloral hydrate or other sedatives, general anesthetic.

What are the symptoms of apnea of prematurity?

The breathing pattern of newborns is not always regular and may be called “periodic breathing.” This pattern is even more likely in newborns born early (preemies).

This irregular pattern is felt to be normal, but also thought of as immature.

It consists of short episodes (about 3 seconds) of either shallow breathing or stopped breathing (apnea). These episodes are followed by periods of regular breathing lasting 10 to 18 seconds.

Apnea episodes that last longer than 20 seconds are considered serious. The baby may also have a:

• Drop in heart rate. This heart rate drop is called bradycardia or, sometimes, a “brady.”
• Drop in oxygen level (oxygen saturation). This is called desaturation or, sometimes a “desat.”

While each baby may experience apnea of prematurity differently, some of the most common symptoms include:

• periods of absent breathing for 20 seconds or more
• symptoms begin during in the first week of life or later

Signs of the more serious forms of apnea of prematurity may include:

• longer periods of absent breathing
• blue coloring
• bradycardia
• symptoms begin right after birth or after the second week

Apnea of prematurity may be confused with another breathing pattern called periodic breathing. Periodic breathing:

• is a pattern of short pauses followed by a burst of faster breaths
• may affect both premature and full-term babies
• is a normal type of breathing in babies

Unlike periodic breathing, apnea of prematurity can be a symptom of a more serious condition. The symptoms of apnea of prematurity may resemble other conditions or medical problems.

Apnea of prematurity diagnosis

It is important to find out if your baby’s apnea is due primarily to prematurity or if it is caused by another problem. Your baby’s physician will check many of her body systems to find out what might be causing the apnea. Diagnostic procedures may include:

• physical examination
• blood tests to check for blood counts, oxygen level, electrolyte levels and infection
• x-ray to check for problems in the lungs, heart or gastrointestinal system
• apnea study to monitor breathing effort, heart rate and oxygenation

These babies will be placed on monitors in the hospital.

• The monitors keep track of their breathing, heart rate, and oxygen levels.
• Apnea, drop in heart rate, or drop in oxygen level can set off the alarms on these monitors.

Drops in heart rate and oxygen levels may occur for other reasons than apnea such as passing stool or moving around, so the monitor tracings are most often reviewed by the health care team.

Apnea of prematurity treatment

How apnea is treated depends on:

• The cause
• How often it occurs
• Severity of episodes

Premature babies who are otherwise healthy and sometimes have few minor episodes are simply watched. In these cases, the episodes go away when the babies are gently touched or “stimulated” during periods when breathing stops. Most premature infants (especially those less than 34 weeks’ gestation at birth) will get medical care for apnea of prematurity in the hospital’s neonatal intensive care unit (NICU). Right after they’re born, many of these premature infants must get help breathing because their lungs are too immature to let them breathe on their own.

Apnea of prematurity can happen once a day or many times a day. Doctors will closely watch an infant to make sure the apnea isn’t due to another condition, such as infection.

Babies who are well, but who are very premature and/or have many apnea episodes, may be given caffeine. This will help make their breathing pattern more regular. Sometimes, the nurse will change a baby’s position, use suction to remove fluid or mucus from the mouth or nose, or use a bag and mask to help with breathing.

Breathing can be assisted by:

• Proper positioning
• Slower feeding time
• Oxygen
• Continuous positive airway pressure (CPAP)
• Breathing machine (ventilator) in extreme cases

Some infants who continue to have apnea but are otherwise mature and healthy will be discharged from the hospital on a home apnea monitor, with or without caffeine, until they have outgrown their immature breathing pattern.

Medicines

Many babies with apnea of prematurity are given oral or intravenous (IV) caffeine medicine to stimulate their breathing. A low dose of caffeine helps keep them alert and breathing regularly.

Monitoring breathing

Babies are watched continuously for any sign of apnea. The cardiorespiratory monitor (also known as an apnea and bradycardia, or A/B, monitor) also tracks the infant’s heart rate. An alarm sounds if there’s no breath for a set number of seconds, and a nurse will immediately check the baby for signs of distress.

If the baby doesn’t begin to breathe again within 15 seconds, the nurse will rub the baby’s back, arms, or legs to stimulate breathing. Most of the time, babies will begin breathing again on their own with this kind of stimulation.

A baby who still isn’t breathing after being stimulated and is pale or bluish might get oxygen through a handheld bag and mask. The nurse or doctor will place the mask over the infant’s face and use the bag to slowly pump a few breaths into the lungs. Usually only a few breaths are needed before the baby begins to breathe again on his or her own.

If your baby is on a home apnea monitor

Although apnea spells usually end by the time most preemies go home, a few will continue to have them. In these cases, if the doctor thinks it’s necessary, the baby will be discharged from the neonatal intensive care unit (NICU) with an apnea monitor.

An apnea monitor has two main parts:

1. a belt with sensory wires that the baby wears around the chest
2. a monitoring unit with an alarm

The sensors measure the baby’s chest movement and breathing rate and the monitor continuously records these rates.

Before your baby leaves the hospital, the NICU staff will review the monitor with you and give you detailed instructions on how and when to use it, and how to respond to an alarm. Parents and caregivers also will be trained in infant CPR, even though it’s unlikely they’ll ever have to use it.

If your baby isn’t breathing or his or her face seems pale or bluish, follow the instructions from the NICU staff. Usually, your response will involve some gentle stimulation, like stroking your baby’s back, arms, or legs. If it doesn’t work, start CPR and call your local emergency number. Remember, never shake your baby to wake him or her.

Your doctor will let you know how long your baby wears the monitor, so be sure to ask if you have any questions or concerns.

Apnea of prematurity prognosis

Apnea is common in premature babies. Most babies have normal outcomes. Mild apnea does not appear to have long-term effects. However, preventing multiple or severe episodes is better for the baby over the long-term.

Apnea of prematurity most often goes away as the baby approaches their “due date.” In some cases, this may last as long as the 44th week, such as in infants who were born very prematurely.

In 1985, Perlman and Volpe described a decrease in the cerebral blood flow velocity that accompanies severe bradycardia (heart rate < 80 beats per minute) ¹. Infants with clinically significant apnea of prematurity do not perform as well as prematurely born infants without recurrent apneas during neurodevelopmental follow-up testing ².

Butcher-Puech and coworkers found that infants in whom obstructive apnea exceeded 20 seconds had an increased incidence of intraventricular hemorrhage, hydrocephalus, prolonged mechanical ventilation, and abnormal neurologic development after their first year of life ³.

References

1. Perlman JM, Volpe JJ. Episodes of apnea and bradycardia in the preterm newborn: impact on cerebral circulation. Pediatrics. 1985 Sep. 76(3):333-8.
2. Emancipator JL, Storfer-Isser A, Taylor HG, et al. Variation of cognition and achievement with sleep-disordered breathing in full-term and preterm children. Arch Pediatr Adolesc Med. 2006 Feb. 160(2):203-10.
3. Butcher-Puech MC, Henderson-Smart DJ, Holley D, et al. Relation between apnoea duration and type and neurological status of preterm infants. Arch Dis Child. 1985 Oct. 60(10):953-8.