Apnea

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Chapter 7 Apnea

Andrew D. DePiero, MD

1 What defines apnea?

Apnea is a respiratory pause of greater than 15 seconds or any pause that is associated with cyanosis, pallor, or bradycardia.

2 What is the difference between obstructive apnea and central apnea?

Obstructive apnea is related to an obstruction of the upper airway. Respiratory movements continue during attempts to relieve the obstruction. Adenotonsillar hypertrophy is a common cause. Central apnea is a dysfunction of the neurologic centers that regulate breathing. During central apnea, all respiratory efforts cease. Occasionally, both central and obstructive components are present. This is classified as mixed apnea.

3 What is periodic breathing?

Periodic breathing describes a pattern of a short respiratory pause followed by an increase in respiratory rate. This occurs in cycles and is a normal pattern in infants.

4 What are some of the pathophysiologic factors contributing to apnea in young infants?

image Hypoxic drive: In the neonate, hypoxia results in a brief increase in respiratory rate followed by depressed respiratory drive and apnea. Mild hypoxemia during sleep can cause periodic breathing or apnea, and hypoxemia during sleep may not cause arousal.

image Effects of feeding: Difficulty with coordination of sucking and breathing can result in hypoxemia. The presence of an accentuated laryngeal chemoreflex can cause apnea and bradycardia if regurgitation occurs while the infant is hypoxic.

image Metabolic abnormalities: Apnea can develop in newborns and young infants as the result of hypoglycemia or anemia.

image Mechanical factors: Because of the pliable thoracic cage and fatigability of the diaphragmatic muscle, attempts to increase minute ventilation by increasing tidal volume can increase the work of breathing. Thus, the infant in respiratory distress is more susceptible to respiratory failure and apnea.

5 What are some of the underlying causes of apnea?

image Central nervous system: Seizure activity, breath-holding

image Infection: Meningitis, bronchiolitis (in premature infants or infants with lung or heart disease), sepsis, croup, infant botulism, pertussis

image Cardiac: Dysrhythmia

image Gastrointestinal: Gastroesophageal reflux

image Metabolic: Hypoglycemia, inborn errors of metabolism, toxin (ingestion)

image Trauma: Accidental or inflicted head or blunt abdominal injury

image Prematurity

Arens R, Gozal D, Williams JC, et al: Recurrent apparent life-threatening events during infancy: A manifestation of inborn errors of metabolism. J Pediatr 123:415–418, 1993.

Southall DP, Plunkett CB, Banks MW, et al: Covert video recordings of life-threatening child abuse: Lessons for child protection. Pediatrics 100:735–760, 1997.

KEY POINTS: APPROACH TO THE INFANT WITH APNEA

1 Determine the clinical significance of the episode.

2 Stabilize the infant if necessary.

3 Obtain detailed history from observer, emergency medical services personnel.

4 The history and physical examination should guide any diagnostic testing.

5 A period of observation and/or admission is necessary.

6 What is sudden infant death syndrome (SIDS)? How is it diagnosed?

SIDS is defined as “the sudden death of an infant under 1 year of age that remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and review of the clinical history.”

Willinger M, James LS, Catz C: Defining the sudden infant death syndrome (SIDS): Deliberations of an expert panel convened by the National Institute of Child Health and Human Development. Pediatr Pathol 11:677–684, 1991.

7 What is an “apparent life-threatening event” (ALTE)? Is it related to SIDS?

An apparent life-threatening event is a severe, apneic episode that is frightening to the observer and is characterized by change in color, muscle tone, and mental status, which may include choking. Although the cause of an apparent life-threatening event is frequently elusive, most infants who die from SIDS have not previously had such an event.

8 What are the risk factors for SIDS? Are they the same as the risk factors for an apparent life-threatening event?

The risk factors for SIDS include male sex, prematurity, low birthweight, maternal smoking, lower socioeconomic status, poor prenatal care, young maternal age, higher parity, multiple gestation, and unsafe sleeping conditions. SIDS tends to peak in the winter months. These factors have not been shown to correlate well for a life-threatening event. However, there may be some association of a life-threatening event with maternal smoking. Upper respiratory tract infections are known to prolong apneic episodes during sleep.

Kiechl-Kohlendorfer U, Hof D, Peglow UP, et al: Epidemiology of apparent life-threatening events. Arch Dis Child 90:297–300, 2005.

9 Has the decline in the incidence of SIDS resulted in a similar decrease of apparent life-threatening events?

While the recommendation of prone sleeping position for babies has correlated with a significant decrease in the number of SIDS cases, the same cannot be said for life-threatening events. Several studies have concluded that the incidence of these events remains unchanged.

Gershan WM, Besch NS, Franciosi RA: A comparison of apparent life-threatening events before and after the back to sleep campaign. West Med J 101:39–45, 2002.

Kiechl-Kohlendorfer U, Hof D, Peglow UP, et al: Epidemiology of apparent life threatening events. Arch Dis Child 90:297–300, 2005.

10 How should the evaluation of an infant with apnea begin?

The infant who requires resuscitation and stabilization must be immediately identified. Most children who have had an apneic episode do not require aggressive initial treatment. They are generally awake, alert, and breathing spontaneously by the time they arrive in the emergency department. Nevertheless, a thorough and appropriate evaluation is essential to the identification of underlying life-threatening conditions. This process must answer two key questions:

1 Did a clinically significant episode occur?

2 What is the risk of recurrence?

11 How should the history be obtained?

It is essential to question firsthand observers of the apneic event as objectively as possible. This can be challenging considering the stressful nature of the event. Questions such as, “What did the baby look like?” “What color was she?” “Was he awake?” “Did he appear frightened?” and “Then what did you do?” may help the historian relate his or her observations to you more objectively. Information from prehospital personnel is useful as well.

12 Are there specific details that must be included in the history?

Ask these questions to ensure a thorough history:

image Where did the event take place: in the infant’s crib, in another bed, in a car seat?

image How long did the episode last?

image Was the infant awake or asleep?

image Was there a change in the baby’s color?

image Was there a change in tone or posture, or were there abnormal movements?

image Did the child require resuscitation, and, if so, how did he respond?

image When was the infant last fed?

13 Are there other questions that should be asked in the history?

image History of present illness: Prior to the event, was the child well? Are there symptoms of other illnesses, specifically changes in behavior, activity, and/or appetite? Does the baby have gastroesophageal reflux? Has there been a recent illness, fever, cough, or cold? Has the infant recently received an immunization?

image Past medical history: Have there been similar episodes in the past? Were there problems with pregnancy, labor, or delivery? What was the child’s birthweight?

image Family history: Is there any family history of seizures, infant deaths, or serious illnesses in young family members?

image Social history: Who was watching the child at the time of the episode? Are there medications or other toxins accessible to the child?

14 Can a child with a normal physical examination have had a significant apneic episode?

Yes. After careful examination, the infant’s heart rate, respiratory rate, blood pressure, pulse oximetry, and rectal temperature can be entirely normal—even though the baby “looked dead” at the time of the episode. The remaining physical examination may also be unremarkable. Therefore, you must obtain a careful history to guide further evaluation.

15 Are there physical findings that can indicate specific etiologies for an apneic episode?

Fever or hypothermia suggests the possibility of infection. Tachypnea may be the result of respiratory disease or metabolic acidosis. A young infant with cough or wheezing may have bronchiolitis. A child in shock may have sepsis or hypovolemia from an occult injury. Depressed mental status, bulging fontanelle, or papilledema are consistent with central nervous system infection or injury. An infant with dysmorphic features may have an underlying congenital abnormality as the cause of apnea.

16 What laboratory tests should be ordered?

The laboratory evaluation must be guided by the history and physical examination. An infant who has had a short choking episode and now appears entirely well may require only a careful examination with routine vital signs and a short period of observation including feeding. In contrast, a hypothermic, lethargic baby should have a full sepsis evaluation, including a lumbar puncture and possibly metabolic studies and computed tomography of the head. An arterial blood gas in an infant who required resuscitation at the scene but now appears well will undoubtedly be normal.

17 When should an infant who has had an apneic episode be admitted to the hospital?

If you are convinced by the history that a significant episode of apnea has occurred, admit the child for observation and further diagnostic evaluation even if no specific cause is identified. Generally, if the caretaker reports that the baby was cyanotic, hospital admission is advised. Any underlying cause of significant apnea that becomes evident will also require admission to be adequately treated.

Claudius I, Keens T: Do all infants with apparent life-threatening events need to be admitted? Pediatrics 119:679–683, 2007.

18 When can the baby with a history of apnea be discharged from the emergency department?

If a careful history and physical examination with appropriate laboratory studies lead you to conclude that a significant apneic episode has not occurred, the baby can often be discharged home. A period of observation, including watching the infant feed, is prudent. The seriousness of the event may not become obvious until you observe some of the features that the caretakers have described. For example, an infant with pertussis may appear well until she coughs. Arrange follow-up with the primary care provider for the next day.

19 Should a home cardiorespiratory monitor be recommended for patients after an apparent life-threatening event?

Home cardiorespiratory monitoring has never been proven to prevent SIDS, nor has the practice of home monitoring changed the incidence of SIDS. The Committee on Fetus and Newborn from the American Academy of Pediatrics recommends that monitoring should not be prescribed to prevent SIDS. Monitoring may be indicated for a select group of premature infants until 43 weeks after conception or until the extreme apneic and bradycardic episodes have ceased, whichever comes last.

American Academy of Pediatrics: Policy statement. Apnea, sudden infant death syndrome and home monitoring. Committee on Fetus and Newborn. Pediatrics 111:914–917, 2003. Available at http://aappolicy.aappublications.org/cgi/content/full/pediatrics;111/4/914.

Acknowledgment

The author wishes to acknowledge Dr. Susan B. Torrey, who authored this chapter in the first edition of Pediatric Emergency Medicine Secrets.

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