DYNAMICS OF RESPIRATORY PATTERNING IN NORMAL INFANTS AND INFANTS WHO SUBSEQUENTLY DIED OF THE SUDDEN-INFANT-DEATH-SYNDROME

Despite evidence that respiratory control mechanisms may be altered in infants who succumb to the sudden infant death syndrome (SIDS), overa ll respiratory variability in SIDS victims is comparable to that of co ntrol infants. We assessed dynamic characteristics of breathing in 16 recordings of apparently healthy infants who subsequently died of SIDS , and 35 recordings of age-matched control infants. Each breath-to-bre ath interval in 10-min epochs of quiet sleep and rapid eye movement sl eep was plotted against the previous interval. Dispersion of next-inte rvals was determined after short, intermediate, and long interbreath i ntervals. In SIDS victims, dispersion after long intervals (slow respi ratory rates) was significantly restricted relative to control infants . Moreover, after long breath-to-breath intervals, SIDS victims showed smaller mean breath-to-breath changes in respiratory rate than did co ntrols. The findings indicate that breath-to-breath respiratory patter ns differ in infants who succumb to SIDS, and the differences occur pr eferentially at low respiratory rates.