Gas dispersal potential of bedding as a cause for sudden infant death

We assessed the gas dispersal potential of bedding articles used by 14 infants diagnosed with sudden unexpected infant death at autopsy. Of these cases, eight exhibited FiCO₂ values greater than 10% within 2.5 min, six of which were found prone and two supine. The results demonstrated that these eight beddings had a high rebreathing potential if they covered the babies’ faces. We did not, however, take into account in our model the large tissue stores of CO₂. As some bicarbonate pools will delay or suppress the increase of FiCO₂, the time–FiCO₂ graphs of this study are not true for living infants. This model, however, demonstrated the potential gas dispersal ability of bedding. The higher the FiCO₂ values, the more dangerous the situation for rebreathing infants. In addition, FiO₂ in the potential space around the model's face can be estimated mathematically using FiCO₂ values. The FiO₂ graph pattern for each bedding item corresponded roughly to the inverse of the FiCO₂ time course. The FiO₂ of the above eight cases decreased by 8.5% within 2.5 min. Recent studies using living infants placed prone to sleep reported that some babies exhibited larger decreases in FiO₂ than increases observed in FiCO₂. While the decrease of FiO₂ in our model is still theoretical, CO₂ accumulation and O₂ deprivation are closely related. If a striking O₂ deficiency occurs in a short period, babies can lose consciousness before an arousal response is evoked and all infants could be influenced by the poor gas dispersal of bedding; the main cause of sudden death in infancy would thus be asphyxia. When the bedding is soft, the potential for trapping CO₂ seems to be high; however, it is impossible to assess it by appearance alone. We sought to provide some objective indices for the assessment of respiratory compromise in relation to bedding using our model. When a baby is found unresponsive with his/her face covered with poor gas dispersal bedding, we should consider the possibility of asphyxia.