Similarities between lethal asphyxia in postneonatal rats and the terminal episode in SIDS

The age-related decrease in asphyxia tolerance was examined in young rats under conditions that mimic prolonged apnea. A precise end point of asphyxia tolerance was determined by calculation of LD50 values for exposed groups. Daily exposure to episodes of sublethal asphyxia did not alter the age-related decrease in asphyxia tolerance. These results permitted further studies in which groups of 10-day-old rats were exposed to 10 min of asphyxia resulting in partial mortality of the group. The postmortem findings in these animals were compared to figures for unexposed littermates. The age-related changes in response to asphyxia and the postmortem findings in asphyxiated animals were compared to the age distribution of sudden infant death syndrome (SIDS) and the postmortem findings in these infants. The comparison showed that the terminal event in SIDS shares many features with lethal asphyxia.