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At a glance

The sudden death of an apparently healthy infant, who is younger than 1 year of age, which is unexpected by history and which remains unexplained after a thorough postmortem investigation (autopsy), and where examination of the death scene failed to demonstrate an adequate cause for death.


SIDS; Crib Death Syndrome.


Variable from 0.09/1000 (Japan) to 0.8/1000 (New Zealand). Two to seven times more likely among Native Americans and blacks. Third leading cause of infant mortality.


Uncertain; probably multifactorial, involving subtle cardiac, respiratory, and neurological abnormalities and precipitating environmental factors. Current theories include mild trivial infections as well as mild tracheobronchial inflammation and altered serum immunoglobulin or cytokine levels. Prone sleep positioning triples the risk of SIDS. Infanticide thought to be responsible in less than 5%.


Diagnosed by exclusion only where cause of death remains unexplained and should be considered after an adequate postmortem examination that includes (a) an autopsy, (b) investigation of the scene and circumstance of the death, and (c) exploration of the medical history of the infant and the family.

Clinical aspects

A common scenario is that of a previously well infant being put into a crib for a nap and then found dead some time later by the parents. Cause of death remains unexplained after investigation. From epidemiological studies, risk of SIDS is found to be increased with a variety of factors. Demographic factors include the age of the infant (2-4 months), male predominance, high birth order, lower socioeconomic status, and younger maternal age. Antenatal factors include low birth weight, low gestational age, multiple pregnancies, maternal smoking, and substance-abusing mother. Postnatal factors include parental smoking, prone sleeping position, overheating of bedroom, soft mattress with excessive wrappings, and recent respiratory tract infections. Beast-feeding appears to have a protective effect from SIDS. By far, the most significant factor in the last few years has been the avoidance of a prone sleeping position and bed sharing, which has led to the reduction in the incidence of SIDS in many countries.

Precautions before anesthesia

Obtain full perinatal medical history of “apneic spells” in near-SIDS or SIDS siblings.

Anesthetic considerations

In case of near-SIDS or SIDS siblings (particularly a SIDS twin), the risk of SIDS is unknown but presumed to be increased after anesthesia. Therefore, the patient should have cardiorespiratory monitoring for a 24-hour postoperative period or longer, particularly if an opioid-based analgesia regimen is further utilized. It is uncertain whether regional anesthesia techniques may lessen the risk of SIDS postoperatively. There is the potential for an increased risk of apnea during spontaneously breathing techniques, but this increase has not been ...

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