ARE BEDDING AND REBREATHING SUFFOCATION A CAUSE OF SIDS

Suffocation by bedclothes became a popular diagnosis in the 1940s but gradually became replaced with the diagnostic label of Sudden Infant D eath Syndrome (SIDS). In 1991 a paper purported that, instead of SIDS, pillows filled with polystyrene beads had caused death by rebreathing suffocation this conclusion was reached on the basis of experiments w ith anesthetized rabbits breathing through a doll's head that was plac ed face down on the pillow. Because of the anesthesia, rabbits could n ot change their face down position. The doll's nares could not collaps e, which would have resulted in rapid death due to conventional suffoc ation. The rabbits required up to 3 hours or more to die of hypercarbi a and hypoxia. Studies in normal infants revealed that they turned fro m the face-down position after only 2 minutes. (The only infant who re tained CO2 soon died of a fatal neurologic disorder, with central hypo ventilation). Using the rabbit/doll's head and mechanical models, a wi de range of bedding was indicted, including cushions, sheepskins, pill ows, comforters, foam mattresses, and even simple blankets and sheets as potentially causing fatal rebreathing. Except for the use of pillow s in general, as well as mattresses filled with kapok and bark, there has been no epidemiologic support for these indictments. Although norm al infants are unlikely to succumb to rebreathing suffocation, infants with blunted ventilatory responsiveness and delayed arousal due to pr ior hypoxia were hypothesized to be at increased risk. Support for thi s concept was found in the pathology of the brain stem in Victims of S IDS that was attributed to prior hypoxic injury. In infants who surviv ed prolonged apnea, less than 20% have demonstrated a diminished venti latory responsiveness to hypercarbia, but, more significantly, none ha d an absent response. Arousal to hypercarbia, an abnormality which is crucial to the hypothesis of rebreathing suffocation, is regularly pre sent in normal subjects, but the threshold is higher in near-SIDS infa nts; however, no instances of failure to arouse have been reported in near-SIDS. If the infant is placed on his or her back or side, the iss ue of bedding could become moot; unfortunately, a sizable percentage o f infants are still being placed prone for sleep. Instead of confusing parents with an ever-expanding list of ''dangerous bedding,'' the mes sage ''Back to Sleep'' should be emphasized. (C) 1996 Wiley-Liss, Inc.