ABSTRACT. Objective. To study the consequences of getting the head covered by bedding (fiber quilt) on carbon dioxide (CO 2 ) accumulation around the face, behavior, and physiologic responses during prone and supine sleep in infants to add understanding to why victims of sudden infant death syndrome are often found under the bedding.Methodology. Of 33 healthy term, usually nonprone sleeping infants, behavior and computerized polysomnography were successfully recorded for 30 during prone and supine sleep at 2 1 ⁄2 months and for 23 prone and 25 supine at 5 months.Results. For both ages and body positions, covering the head resulted in significant CO 2 accumulation around the face, fewer apneas (3 to 10 seconds), shorter duration of apneas after sighs, higher heart and respiratory rates, and peripheral skin temperature. Differences were generally greater at 2 1 ⁄2 than at 5 months. While covered, the prone position was associated with higher CO 2 levels close to the face, slightly higher transcutaneous PCO 2 , and higher heart rates and peripheral skin temperatures than the supine position. In the supine position 23% were able to remove the cover from the head at 2 1 ⁄2 and 60% at 5 months, whereas only 1 infant of 5 months managed to remove the cover when prone.Conclusions. The observed responses are consistent with a potential for distress when the head is covered, particularly when placed prone. Probably most important with respect to sudden infant death syndrome is the infants' inability to remove the bedding from the head upon awakening from prone sleep. Pediatrics 1997;100(2). URL: http://www.pediatrics.org/cgi/content/ full/100/2/e6; behavior, CO 2 rebreathing, hyperthermia, SIDS, sleeping position. 3 Although the concentration of carbon dioxide (CO 2 ) in the atmosphere is .03% to .04%, the exhaled air of infants contains 4% to 5% CO 2 , 4 and it has been speculated that under certain conditions, such as sleeping face down on soft bedding, extensive CO 2 accumulation around the infant's face may result in rebreathing, asphyxia, and suffocation. 3,5,6 The possibility of CO 2 rebreathing has mainly been studied in experimental in vitro and animal models, 3,5-10 whereas studies in infants are limited.
11-13We have previously shown that a significant number of SIDS victims are found with their head covered by bedding and usually in the prone position.14 The purpose of the present investigation was to study the effect of getting the head covered by bedding on CO 2 accumulation around the face, behavior, and physiologic responses in sleeping infants, and to compare outcome measures for the prone and supine sleeping positions.
SUBJECTS AND METHODS
SubjectsThirty-three infants (17 girls and 16 boys) were recruited for an overnight sleep study both at 2 1 ⁄2 (mean, 74 days; range, 71 to 79 days) and 5 (mean, 152 days; range, 147 to 158 days) months of age. The ages were chosen to correspond with the age of highest risk for SIDS (2 1 ⁄2 months) and a period of significantly lower risk (5 months) in Norway. 15 Only t...