The correlation between serotonergic neurons in the brainstem and sleep apnea in SIDS victims

Sudden Unexpected Death and the Mammalian Dive Response: Catastrophic Failure of a Complex Tightly Coupled System

In tightly coupled complex systems, when two or more factors or events interact in unanticipated ways, catastrophic failures of high-risk technical systems happen rarely, but quickly. Safety features are commonly built into complex systems to avoid disasters but are often part of the problem. The human body may be considered as a complex tightly coupled system at risk of rare catastrophic failure (sudden unexpected death, SUD) when certain factors or events interact. The mammalian dive response (MDR) is a built-in safety feature of the body that normally conserves oxygen during acute hypoxia. Activation of the MDR is the final pathway to sudden cardiac (SCD) in some cases of sudden infant death syndrome (SIDS), sudden unexpected death in epilepsy (SUDEP), and sudden cardiac death in water (SCDIW, fatal drowning). There is no single cause in any of these death scenarios, but an array of, unanticipated, often unknown, factors or events that activate or interact with the mammalian dive reflex. In any particular case, the relevant risk factors or events might include a combination of genetic, developmental, metabolic, disease, environmental, or operational influences. Determination of a single cause in any of these death scenarios is unlikely. The common thread among these seemingly different death scenarios is activation of the mammalian dive response. The human body is a complex tightly coupled system at risk of rare catastrophic failure when that "safety feature" is activated.

Current controversies in the pathophysiology and prevention of sudden infant death syndrome

PURPOSE OF REVIEW

To examine recent research relevant to sudden infant death syndrome (SIDS) to determine whether there is a place for home monitoring in the care of children believed to be at risk.

RECENT FINDINGS

Current SIDS research has focused on the genetics of SIDS, brainstem abnormalities and arousal failures, the effects of tobacco smoke and other environmental agents, the role of infectious diseases, and prenatal factors that may contribute to SIDS. Investigations have suggested that there are infants who appear to respond less effectively when challenged by certain environmental or infectious agents. These infants have blunted responses to stress and diminished arousal to hypoxemia, in part because of failures in genetically determined brainstem function. It is unclear at this time whether home monitoring would offer protection in all circumstances, but it may be helpful in certain patients.

SUMMARY

There appears to be progress in understanding the causes of SIDS. As additional studies emerge, the optimal approaches to care will become more apparent, with home monitoring one of the possible interventions.