Problems on the diagnosis of sudden infant death syndrome

Sleep position and bed-sharing in sudden infant deaths: an examination of autopsy findings

OBJECTIVE

To determine the effect of sleep position, sleep location, and bed-sharing on the incidence of sudden unexpected death in infancy and the frequency of significant autopsy findings.

METHODS

We evaluated the cause of death in infants <1 year of age who died during sleep from January 1, 1986, through September 30, 1999. This retrospective series was compiled from log books and files of the Medical Examiner Office, Palm Beach County, Florida.

RESULTS

The incidence of sudden unexpected infant death decreased 50% over the study period (P <.01). Of the 217 infants that fit the study criteria, 62.7% were sleeping prone (on the stomach), 9.7% were supine (on the back), 5.5% were on their side, 22.1% were in an unknown position, and 40.1% were bed-sharing. Significant autopsy findings that could explain death were documented by autopsy in 37.5% of all supine and side sleeping infants and only 14.0% of all prone sleeping infants (P <.001). Deaths of supine and side sleeping infants were more likely to be classified as a natural disease process other than sudden infant death syndrome (P <.01). Significant autopsy findings that could explain death were found in 47.6% of the infants sleeping alone in the supine or side position (P <.01), 18.2% of infants bed-sharing in the supine or side position, 16.5% of infants sleeping alone while prone, and 9.3% of infants bed-sharing while prone.

CONCLUSIONS

Infant deaths associated with the prone position were less frequently explained by illness or disease than infant deaths associated with non-prone sleeping positions. Bed-sharing appears to increase the proportion of unexplained deaths, regardless of the position of the infant. The "Back to Sleep" campaign appears to be effective in reducing the incidence of unexpected sleeping infant deaths regardless of the certified cause of death.

Inhaled air trapping effect of Japanese bedding as a risk of sudden unexpected death in infancy

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 (t1/2) values were used. The t1/2 values were calculated by measuring the time required for the expired percent CO2 to reach 1/2 the initial percent end-tidal PCO2. 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 t1/2 value in supine position was 9.8 seconds. When the model was placed prone on futon, the t1/2 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 t1/2 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 t1/2 values. The potential of rebreathing increased in face down position among all bedding, and supine position was the best CO2 dispersal position.