Inhaled Air Trapping Effect of Japanese Bedding as a Risk of Sudden Unexpected Death in Infancy

Abstract

We assessed some Japanese bedding on the assumption of the effects of air trapping using an infant mannequin. The change of CO₂ concentration in the airway of a mannequin head placed on bedding was continuously monitored using a CO₂ analyzer during simulated breathing. To compare the level of CO₂ dispersal among different items of bedding, CO₂ half time (t_1/2) values were used. The t_1/2 values were calculated by measuring the time required for the expired percent CO₂ to reach 1/2 the initial percent end-tidal P_CO2. We also measured softness and resistance to airflow (R) of the same items. As for the bedding, 4 types of futon and several types of bottom sheets/towels were combined. The t_1/2 value in supine position was 9.8 seconds. When the model was placed prone on futon, the t_1/2 values increased to 14.1 seconds (hard mattress type) −17.2 seconds (soft cotton-like futon). With respect to present Japanese baby futon (hard mattress type), there may be a relatively low potential for rebreathing to occur, compared with soft futon. In every case, the t_1/2 value was prolonged by the use of a towel spread on the futon. CO₂ dispersal may depend not only on the softness of the futon, but also on the combination of bottom sheet/towel and mattress. There was no relationship between R values and t_1/2 values. The potential of rebreathing increased in face down position among all bedding, and supine position was the best CO₂ dispersal position.