What is SIDS?
What SIDS is Not
Suffocation and Positional Asphyxia
Much confusion and concern has also arisen in recent years about the potential relationship between SIDS and suffocation. Some parents whose infant has died sometimes struggle with the question of whether their infant actually suffocated. The answer is not always easy to determine and often depends on circumstantial evidence found at the time of death.89
Suffocation causes death from a restriction of oxygen flow to the blood vessels. When this happens, the cells of the body can no longer function properly and vital organs fail. Suffocation is generally divided into four categories: smothering, choking, mechanical suffocation and environmental suffocation. Smothering is defined as physical obstruction of the nose and mouth while choking is characterized by an obstruction within the airway. Mechanical suffocation occurs when external pressure is applied to the body, preventing chest movement and respiration. Environmental suffocation occurs when oxygen is displaced from the atmosphere an individual is breathing.
In some instances, these types of suffocation leave subtle signs after death, but a SIDS death may be difficult to distinguish from death by accidental or intentional suffocation.90 Many SIDS infants will have had a resuscitation attempt which will often leave clinical markings similar to suffocation. Experienced forensic pathologists can usually discern the signs of resuscitation from those of suffocation.
Asphyxia refers to a breathing insufficiency that leads to an inadequate intake of oxygen and exhalation of carbon dioxide It can be caused by a variety of factors, some of which may be related to sleep position or bedding materials.
“Positional asphyxia” is a term that was created by some pathologists and used when a SIDS infant was found in the prone sleep position. Its use has been strongly discouraged. If a pathologist cannot distinguish SIDS from suffocation, accidental or non-accidental, the case should be diagnosed as “undetermined.”
A scientific study reported that similar unsafe sleeping practices were occurring in a majority of cases diagnosed as SIDS, accidental suffocation and cause undetermined. This is the first study to scrutinize these diagnoses together in terms of sleep practices common to all three postmortem diagnoses. Most notably, these practices included bedsharing and placing infants to sleep on surfaces other than cribs.91