A variety of unproven mechanisms have been proposed to explain SIDS. SIDS is associated with prone position during sleep, especially on soft bedding. The widely advocated supine sleeping position explains, in part, the decreased incidence of SIDS during the past two decades. Current theories for a predisposition to SIDS include cellular brainstem abnormalities and maturational delay related to neural or cardiorespiratory control. A portion of SIDS deaths may be due to prolongation of the Q-T interval, abnormal CNS control of respiration, and CO2 rebreathing from sleeping face down (especially in softbedding).
See Table 134-1 for the differential diagnosis of SIDS.
There has been a significant decline in SIDS with the backto-sleep program and avoiding soft bedding. Thus, all parents should be instructed to place their infants in the supine position unless there are medical contraindications. All soft
Fulminant infection*,† Infant botulism*
Seizure disorder† Brain tumor* Intracranial hemorrhage due to accidental or non-accidental trauma*,‡
Hypoglycemia† Medium-chain acyl-coenzyme A dehydrogenase deficiency‡ Carnitine deficiency*,‡
Gastroesophageal reflux*,‡ Midgut volvulus/shock* *Obvious or suspected at autopsy.
†Relatively common.
‡Diagnostic test required.
Chapter 134 u Control of Breathing 463 bedding should be avoided, and parents who share beds with their infants should be counseled on the risks. Decreasing maternal cigarette smoking, both during and after pregnancy, is recommended.
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Apnea is defined as the cessation of airflow due to either lack of respiratory effort (central apnea) or upper airway obstruction (obstructive apnea). Central apnea lasting less than 10 seconds is common in healthy infants and can be present in normal children during sleep, especially after a sigh breath. Central pauses lasting longer than 15 to 20 seconds are considered abnormal. Central apnea is more common in infants, and obstructive apnea, especially during sleep, is more common in older children.
Premature infants can have apnea of prematurity, which consists of recurrent apneic episodes that are often of central origin, though they can be mixed central/obstructive. Apnea of prematurity should resolve by 44 weeks postconceptional age. Older infants and children with apnea warrant thorough investigation (Table 134-2).
Central apnea outside of infancy is a rare occurrence and may be primary or secondary. Secondary causes of central hypoventilation, which are more common, include medications impairing central respiratory drive (narcotics), increased intracranial pressure, CNS tumors, myelomeningocele and/or Arnold-Chiari malformation, and mitochondrial/metabolic disorders. Genetic syndromes associated with abnormal central respiratory control and developmental delays include Rett, Joubert, and Prader-Willi syndromes and tuberous sclerosis.
Congenital central hypoventilation syndrome (CCHS) is a rare genetic disorder in which there is profound loss of respiratory control during sleep leading to central apnea, hypercarbia, and hypoxemia. Most patients with CCHS have a defect in the PHOX2B gene, which is necessary for autonomic nervous system development. Most infants with CCHS have respiratory difficulties within the first several weeks of life, although it can also present later in childhood. CCHS is associated with an increased risk of Hirschsprung disease and neural crest tumors (neuroblastoma).