Apnea of Prematurity
Apnea episodes may occur in premature newborns if the part of their brain that controls breathing (respiratory center) has not matured fully.
Apnea may lower the amount of oxygen in the blood, resulting in a slow heart rate and bluish lips and/or skin.
This disorder is diagnosed by observation or by the alarm of a monitor attached to the newborn.
As the respiratory center of the brain matures, apnea episodes become less frequent and then stop altogether.
If gentle prodding does not cause the newborn to resume breathing, artificial respiration may be needed.
Newborns with significant apnea are given caffeine, along with other treatments, to stimulate breathing.
(See also Overview of General Problems in Newborns.)
Apnea of prematurity commonly occurs in about 25% of infants who are born prematurely (delivered before 37 weeks of gestation). Apnea of prematurity is often more frequent and more severe the more premature a baby is. This disorder usually begins 2 to 3 days after birth and only rarely on the first day. In apnea of prematurity, newborns may have repeated episodes of normal breathing alternating with brief pauses in breathing. In some premature babies, the pause in breathing may not last 20 seconds but does cause a decrease in the heart rate or in the amount of oxygen in the blood. Shorter pauses in breathing that cause decreases in heart rate or blood oxygen levels are still considered apnea of prematurity.
There are three types of apnea:
Central apnea occurs when the part of the brain that controls breathing (respiratory center) is not functioning properly because it has not matured fully. This is the most common type of apnea of prematurity.
Obstructive apnea is caused by temporary blockage of the throat (pharynx) due to low muscle tone or a bending forward of the neck. This type may occur in full-term babies as well as those born prematurely.
Mixed apnea is a combination of central apnea and obstructive apnea.
In all types of apnea, the heart rate can become slow and levels of oxygen can decrease.
Not all pauses in breathing are problems. Periodic breathing is 5 to 20 seconds of normal breathing followed by periods of apnea that last less than 20 seconds. Periodic breathing is common among premature newborns and is not considered apnea of prematurity. Full-term newborns can also have periodic breathing. It does not cause the heart rate or oxygen levels to drop and usually does not cause other problems.
In the hospital, premature newborns are routinely attached to a monitor that sounds an alarm if they stop breathing for 20 seconds or more or if their heart rate slows. Depending on the length of the episodes, pauses in breathing may decrease the oxygen levels in the blood, which results in a bluish discoloration of the skin and/or lips (cyanosis) or pale skin (pallor). Low levels of oxygen in the blood may then slow the heart rate (bradycardia).
The diagnosis of apnea is usually made by observing the newborn breathe or by hearing the alarm of a monitor attached to the newborn and noting no breathing movements when the newborn is checked.
Apnea can sometimes be a sign of a disorder, such as infection in the blood (sepsis), low blood sugar (hypoglycemia), or a low body temperature (hypothermia). Therefore, doctors evaluate the newborn to rule out these causes when apnea begins suddenly or unexpectedly or the frequency of apnea episodes increases. Doctors may take samples of blood, urine, and cerebrospinal fluid to test for serious infections and test blood samples to determine whether the level of blood sugar is too low.
Over time, as the respiratory center matures, episodes of apnea become less frequent, and by the time the newborn approaches 37 weeks of gestation, the episodes usually no longer occur. Apnea may continue for weeks in infants who were born extremely prematurely (such as at 23 to 27 weeks). Apnea of prematurity rarely causes death.
Although premature birth is a risk factor for sudden infant death syndrome (SIDS), an association between apnea of prematurity and a later risk of SIDS has not been proved. Likewise, there is no proof that discharging a premature newborn from the hospital with an apnea monitor decreases the risk of SIDS.
When apnea is noticed, either by observation or monitor alarm, newborns are touched or prodded gently to stimulate breathing, which may be all that is required.
Further treatment of apnea depends on the cause. Doctors treat known causes such as infections.
If episodes of apnea become frequent, and especially if newborns have cyanosis, they remain in the neonatal intensive care unit (NICU). They may be treated with a drug that stimulates the respiratory center, such as caffeine. If this treatment does not prevent frequent and severe episodes of apnea, newborns may need treatment with continuous positive airway pressure (CPAP). This technique allows newborns to breathe on their own while receiving slightly pressurized oxygen or air given through prongs placed in the nostrils. Newborns who have apnea spells that are difficult to treat may need a ventilator (a machine that helps air get in and out of the lungs) to help them breathe.
Newborns should always be placed on their back to sleep. Safe sleeping practices should be followed for all infants whether they are premature or not.
Because all premature newborns, especially those with apnea of prematurity, are at risk of apnea, low levels of oxygen in the blood, and a slow heart rate while in a car seat, they should have a car seat challenge test before leaving the hospital. This test determines whether the newborn is able to safely ride home in the semi-reclined position of a car seat.
Most newborns are able to go home from the hospital without a monitor, whereas some newborns are sent home with an apnea monitor and may also need caffeine. Parents should be taught how to properly use the monitor and any other equipment, what to do when the alarm sounds, how to do cardiopulmonary resuscitation (CPR) in case it is needed, and how to keep a record of events. Most monitors electronically store information about events that occur. Parents should consult a doctor about when to stop using the monitor.