This term refers to the sudden, unexpected death of an apparently healthy infant, usually 2–3 months of age, who had been put to the bed without any suspicion of such an occurrence. A conventional autopsy fails to reveal the cause of death.
When an apparently healthy infant suffers from an episode in which his breathing ceases, cyanosis or pallor develops, and he becomes unresponsive but is successfully revived (resuscitated), the term, apparent life-threatening event (ALTE), is employed. This state is also called near- miss or aborted sudden infant death syndrome (SIDS). In this state, there is a considerable risk of SIDS subsequently. In the event of a SIDS in a family, risk for the next or subsequent infant is five times higher than the usual risk.
Etiopathogenesis
Etiology remains obscure. Allergy to cow milk, enlargement of thymus, suffocation, deficiency of parathyroids or adrenals, hypernatremia, and fulminant respiratory infection causing laryngeal obstruction and/ or spasm figure among the large number of conditions/ factors that are incriminated in its etiology. Such states as prolonged sleep, apnea, [associated with central nervous system (CNS) disorders], vascular rings, familial prolongation of QT interval (Romano-Ward and Jervell and Lange-Nielsen syndrome), accidental suffocation, and child abuse and neglect (CAN) at times camouflage as SIDS. An abnormality of cardiorespiratory control, in which state of consciousness or CNS activity plays a modulating role, appears to be shared by all cases of true SIDS. Prone sleeping position is an important risk factor for SIDS.
Though the pathologic findings, taken in totality, suggest occurrence of hypoxia preceding the tragic event, autopsy shows no hyperplasia of the carotid bodies.
Diagnosis
In case of infants at risk [low birth weight (LBW), near-miss, or ALTE, siblings of SIDS cases], history should include information on physiologic handicaps before birth such as low Apgar score, abnormality in control of respiration, heart rate and temperature, and postnatal growth retardation. The parents must be questioned about the infant’s feeding, medications, etc.
Physical examination should concentrate on infant’s nutritional status, hydration, evidence of infection, CAN, and neurologic handicaps. Respiratory system should be particularly evaluated. The infant needs to be observed while he is being fed. Investigations include:
- Blood analysis for glucose, sodium, potassium, calcium, phosphorus, magnesium, blood urea nitrogen (BUN), pH, and blood-gas analysis
- Urinalysis
- Microbiologic tests
- ECG monitoring
- Electroencephalogram (EEC)
- Radiology—barium swallow, chest X-ray, skeletal survey
- Esophageal pH studies
- 4–8 hours sleep studies.
Currently, home monitoring technologies utilizing event recordings (respiratory pattern, heart rate, ECG, oxygen- ation) are being evaluated for prospective identification of risk of SIDS.
Treatment
The parents distressed with guilt feeling need to be assured that they were not the cause of the sudden death of the infant. They also need to be counseled on anticipatory guidance. Use of caffeine and theophylline in apnea of prematurity and infancy may indirectly cut down the incidence of SIDS by improving respiratory pattern in these subjects.
