Evaluation of rebreathing potential on bedding for infant use

Background: Rebreathing is thought to be associated with sudden infant death syndrome (SIDS). The aim of the present study was to evaluate the rebreathing potential of different types of Japanese infant bedding. Methods: The rebreathing potential of various combinations of infant bedding was measured using a mechanically simulated breathing model. The types of bedding included five types of mattresses, four types of o-nesyo sheets (waterproof sheets) and a towel. The half-life of the expiratory CO2 concentration, t(1/2)-value was calculated as the index of the rebreathing potential. The softness of the bedding was also measured. Results: There was a moderate proportional correlation between the t(1/2) -value and the softness (correlation coefficient = 0.509). When a new hard infant mattress was used, the t(1/2) -values were 13.6-14.1 s, and when o-nesyo sheet was added, the values were 14.1-16.2 s. When other mattresses were used with the o-nesyo sheet, the values were 14.1-19.2 s. Adding a towel onto the bedding, the t(1/2) -value (18.5-22.3 s) was prolonged without exception. Conclusion: It is difficult to estimate the rebreathing potential of the bedding on the basis its appearance or its softness. All infants should be placed on appropriate bedding in case they turn to a prone-sleeping position. Our recommendations to avoid rebreathing are as follows: (i) a new hard mattress specifically designed for babies should be used; (ii) a towel should not be used; (iii) an o-nesyo sheet may be used with a new hard infant mattress if necessary.