The respiratory control systems of the newborn may be immature, resulting in instability of ventilation and pauses in respiration. Hypoxia and hypercarbia, impaired ventilatory response, and inhibitory reflexes are exaggerated. Even normal term newborns may exhibit occasional respiratory pauses of 30 seconds or more (1, 2). Premature infants may be even more unstable, with more frequent and longer respiratory pauses (2) often associated with bradycardia, hypoxemia, and/or hypercarbia. These are accentuated by the newborns’ rapid respiratory rate and smaller oxygen capacities.

Apnea of prematurity (AOP) is often seen in infants less than 33 weeks’ gestation. These events may be noted in the preterm nursery. AOP is usually central in nature, although obstructive and mixed events can also occur. By the time premature babies have reached term, the prevalence and severity of events is similar to that of healthy term babies (2), although very premature babies (24 to 28 weeks’ gestation) may have persisting apnea beyond full term (3).

If the events are clearly documented in the neonatal intensive care unit, treatment is often initiated without a sleep study. Full polysomnography (PSG) is needed if obstructive events are being considered, but a pneumogram measuring chest wall movement by impedance, airflow by thermistor, heart rate, oximetry, and perhaps esophageal pH may be requested to document central apneas and establish their relationship, if any, to gastroesophageal reflux (GER).

AOP is usually treated with methylxanthine therapy (caffeine or theophylline). Caffeine can significantly reduce apneas within the first week of treatment (4). Theophylline significantly improves periodic breathing and central apneas in premature infants in both active (rapid eye movement [REM]) and quiet (non-REM) sleep but does not affect bradycardia or obstructive events (5). If the patient continues to have significant obstructive events, positive airway pressure, either CPAP or BPAP, can be used. CPAP can reduce obstructive events and the severity of apnea-related desaturations (6). Caffeine in combination with CPAP therapy may reduce
the number of days for which respiratory support is required. The combination of these treatments may also have neurodevelopmental benefits (7). Long-term effects of caffeine use in newborns have not been shown to increase obstructive sleep apnea (OSA) but may increase periodic limb movements in sleep (8).

Sleeping position may affect the frequency and severity of cardiorespiratory events. Healthy preterm infants sleeping supine have a higher respiratory rate, lower oxyhemoglobin saturation, and reduced ventilatory response to hypercapnia compared with those in the prone position (9). Although the total number of events remained low, infants sleeping supine had nearly twice the number of obstructive events than the ones sleeping prone (10).

However, infants sleeping prone have deeper, quiet sleep and fewer arousals with increased central apnea (10, 11). The risk of sudden infant death syndrome (SIDS) is increased in the prone position. Therefore, it is recommended that healthy term newborns sleep in the supine position (12).

Brief resolved unexplained event (BRUE) is “an event occurring in an infant younger than 1 year when the observer reports a sudden, brief, and now resolved episode of one or more of the following: (1) cyanosis or pallor; (2) absent, decreased, or irregular breathing; (3) marked change in tone (hyper- or hypotonia); and (4) altered level of responsiveness” (13). Patients are classified on the basis of history and physical examination. Suggested care of low-risk patients may include a 12-lead electrocardiogram, pulse oximetry monitoring, child abuse evaluation, and pertussis testing. The family should receive education about BRUEs and where cardiopulmonary resuscitation training is offered. There are no specific treatment recommendations for high-risk BRUEs.

Some of these events have been classified as an apparent life-threatening event (ALTE). ALTE is defined as “An episode that is frightening to the observer and is characterized by some combination of apnea (central or occasionally obstructive), color change (usually cyanotic or pallid but occasionally erythematous or plethoric), marked change in muscle tone (usually marked limpness), choking, or gagging” (12). The cause of an ALTE is identified in only about half of the patients. Possible diagnoses include seizures, cardiac arrhythmias, laryngomalacia, tracheomalacia, and child abuse. A patient presenting with an ALTE is usually hospitalized to ascertain a cause for the event. Laboratory tests may include a blood count, metabolic panel, chest roentgenogram, electrocardiogram, and physiologic monitoring during sleep. An overnight PSG is needed if obstructive events are suspected. A pneumogram, measuring chest wall movement by impedance, airflow by thermistor, heart rate, oximetry, and perhaps esophageal pH, may be requested to document central apneas and establish their relationship, if any, to GER. Visual cues such as work of breathing, positioning, and type of bedding are important and should be documented during an infant’s overnight study. Episodes of cyanosis or pallor should be documented and warrant a call to the physician covering the lab. If esophageal pH or impedance monitoring is performed, the technologist should document feeding times, volume, and type. Apple juice feedings are preferred because milk may act as a buffer, limiting the ability of the pH probe to detect reflux. If a cause of the event is found, it should be treated, but in many cases no cause is found (14, 15). When no specific cause of the event is found in an infant greater than 37 weeks’ gestational age, the patient is considered to have “apnea of infancy.” These patients are often sent home on cardiorespiratory monitors (16).

A relationship between ALTE and SIDS has not been proven. SIDS is defined as “The sudden death of any infant under 1 year of age, which remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and review of the clinical history” (17). The prevalence of SIDS in the United States is about 0.6 per 1,000 infants, with a peak incidence at about 2 months of age (18).

Several studies have noted an increased risk of SIDS in patients sleeping in the prone position, leading to international public health campaigns encouraging families to put their infants to sleep in the supine position (19). Since the 1992 “Back to Sleep” (20) campaign in the United States, the prevalence of supine sleeping has increased, and the incidence of SIDS has decreased dramatically (21). The number of ALTE cases has increased during this time, however, with an increased prevalence of GER, possibly because more babies are sleeping in the supine position (22, 23).

The majority of children studied in a sleep center will have been referred for suspected obstructive SDB, which in children can range from primary snoring to OSA. Nearly 12% of children snore “on most nights,” with obstructive sleep apnea syndrome (OSAS) occurring in 1% to 4% of school-age children (24). OSAS in children is characterized by prolonged partial upper airway obstruction (obstructive hypopnea) and/or intermittent complete obstruction (obstructive apnea) that disrupts normal ventilation and sleep patterns (25). Risk factors for snoring and OSAS include anything that affects the size or compliance of the pharynx, such as adenotonsillar hypertrophy, obesity, disorders affecting
tone, and craniofacial and neuromuscular disorders (25, 26). Parents usually report nighttime snoring, snorting, gasping, nighttime awakenings, enuresis, diaphoresis, and/or apnea. Reported daytime symptoms such as irritability, hyperactivity, poor school performance, mouth breathing, headaches, and sleepiness are common. Even primary snoring, in the face of a normal polysomnogram, has been associated with neurocognitive impairments, resulting in poor school performance for math, science, and spelling (27). Newborn infants may initially present with what seems to be severe apnea on a PSG. This may, in part, be due to their higher respiratory rate, resulting in more events being scored. However, their breathing typically improves as they grow older (28).