Chapter 7 Apnea
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?
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.
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.
Metabolic abnormalities: Apnea can develop in newborns and young infants as the result of hypoglycemia or anemia.
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?
Central nervous system: Seizure activity, breath-holding
Infection: Meningitis, bronchiolitis (in premature infants or infants with lung or heart disease), sepsis, croup, infant botulism, pertussis
Gastrointestinal: Gastroesophageal reflux
Metabolic: Hypoglycemia, inborn errors of metabolism, toxin (ingestion)
Trauma: Accidental or inflicted head or blunt abdominal injury
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.
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.
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