Infant asphyxia, soft mattresses, and the "trough" effect.

Although unexpected infant death in a cot has traditionally been attributed to sudden infant death syndrome, careful evaluation of death scenes and sleeping environments has increasingly identified deaths due to accidental asphyxia from so-called sleeping accidents. The case of a 5-month-old infant boy who was found facedown and unresponsive in a wooden portable cot with a sagging canvas base is reported to illustrate another potentially lethal situation. Although the autopsy revealed no specific findings, examination of the cot showed a significant depression caused by the sagging canvas base that was exacerbated by a soft-foam mattress and layers of bedding. Once in the trough, the infant would not have been able to extricate himself. Death was therefore attributed to accidental suffocation due to the infant's position resulting in contact of the mouth and face with soft bedding. In addition to again demonstrating the potential dangers of using old second-hand cots, this case clearly shows the problems that may exist when soft and sagging bedding forms a central trough that may entrap an infant. Death scene investigators should specifically comment on the presence of such troughs and measure of depth of the trough and/or cot base to provide some quantification of the degree of concavity present.