Figure 134-1 Schematic representation of the respiratory control system. The respiratory neurons in the brainstem receive information from the chemoreceptors, peripheral sensory receptors, and cerebral cortex. This information is integrated, and the resulting neural output is transmitted to the diaphragms and lungs. The sign denotes stimulation of the receptor. (From Andreoli TE, Bennett JC, Carpenter CJ, et al, editors: Cecil Essentials of Medicine, ed 4, Philadelphia, 1997, WB Saunders, p 171.) apnea, color change (usually blue or pale), sudden limpness, choking, or gagging. The incidence of such events is 0.05% to 1%. Specific causes can be identified in more than 50% of the cases. Gastroesophageal reflux and laryngospasm are the most common causes of ALTE, and they are associated with emesis, choking, or gagging. Central nervous system (CNS) causes (e.g., seizures, breath-holding spells, intracranial bleeding from accidental or nonaccidental trauma) account for approximately 15% of cases, and cardiovascular events and metabolic derangements account for smaller percentages. Acute infection with respiratory viruses (respiratory syncytial virus [RSV] and others), pertussis, and serious bacterial infections (sepsis, meningitis) can also cause apnea in infants.
In most cases, a careful history can lead to a correct diagnosis. Questions should include history of premature birth, prior apnea, level of consciousness at the time of the event, presence or absence of respiratory effort, limpness or stiffness, jerking movements (seizure), feeding history, intercurrent illnesses, any trauma, and the social situation of the family. The physical examination should focus on bruising and injury, the general and neurologic condition of the infant, nutritional status, respiratory pattern, and cardiac status. The laboratory evaluation may include serum electrolytes, serum glucose, blood urea nitrogen, creatinine, hemoglobin, hematocrit, white blood cell count, a chest radiograph, and blood gas analysis. Testing for respiratory viruses and pertussis in patients with evidence of respiratory infection should occur. If gastroesophageal reflux is suspected, a barium swallow or pH probe study may be useful. Cardiorespiratory monitoring for 12 to 24 hours in the hospital can provide information on respiratory and cardiac patterns and feeding difficulties (choking, gagging, emesis); provide time to get more history and assess the home situation; and alleviate parental anxiety. Useful tests to determine CNS causes include a head computed tomography (CT) scan, magnetic resonance imaging of the brain, and an electroencephalogram (EEG) (for seizures).
There are no standard recommendations for when home monitoring should be prescribed. Polysomnography is not useful in predicting which children with ALTEs are likely to progress to sudden infant death syndrome (SIDS). The key to prevention of future events is to identify the underlying cause and treat it. Teaching parents infant cardiopulmonary resuscitation (CPR) and attempting to alleviate anxiety surrounding the event are recommended.
SIDS is defined as the unexpected death of an infant younger than 1 year of age in which the cause remains unexplained after an autopsy, death scene investigation, and review of clinical history. The risk of SIDS is higher in premature and low birth weight infants, infants of young impoverished mothers who smoke cigarettes, African American and Native American infants, and in infants whose mothers have abused drugs. The risk of SIDS is increased threeto fivefold in siblings of infants who have died of SIDS and is highest during the winter. SIDS is rare before 4 weeks or after 6 months of age and is most common between 2 and 4 months of age. The incidence of SIDS has decreased dramatically since the 1980s.