Abstract Mkid 115

The study was designed to evaluate the presence of sighs during sleep in 15 infants who became victims of SIDS. There were 11 boys and 4 girls, born at term, and with a median age of 12 weeks at the time of polysomnographic recording. They were 34 week old at the time of death. The recordings of the SIDS victims were age- and sex-matched with those of healthy control subjects. Sighs were defined as a brisk and isolated increase in thoracoabdominal excursion with an amplitude at least twice superior to that measured during the 10 seconds that preceded the event. Sighs were classified in four categories depending on their association with apneas: isolated, pre-apneic, post-apneic, and intraapneic. No significant difference was found between the two groups of infants for total sleep time, types, number or duration of apneas. A total of 218 sighs were scored during sleep (135 in the future SIDS victims, 83 in the control infants). In the two groups, the types of sighs were seen with decreased order of frequency as: pre-apneic, isolated, postapneic, and intra-apneic. Sighs were found in all sleep states, but were more frequently found in NREM sleep. The distribution of the sighs in the various sleep stages was not different between the two groups. Pre-apneic sighs were significantly more common in the future SIDS victims (p= .035). No significant difference was found between the two groups of infants for the frequency of the other types of sighs. Transient increases in EEG frequencies following the sighs were observed significantly more frequently in the future SIDS victims. Oxygen blood saturation preceding the sighs was lower in the SIDS victims. The mechanisms responsible for a greater frequency of sighs preceding central apneas in future SIDS infants remain unclear.