Anoxic cardiopulmonary arrest in a pediatric animal model: clinical and laboratory correlates of duration.

We studied the response to anoxia in young dogs in order to provide some clinical and laboratory guidelines with which to gauge duration of respiratory and cardiorespiratory arrest in children. Immediately following the onset of anoxia, the animals developed hypertension. After a mean period of 279.5 seconds (range, 224 to 325 sec), they became asystolic. Following an observation period of five minutes after the onset of asystole, pH declined to a mean of 7.01 and PO2 declined to 7.1 torr, while PCO2 rose to 92.1 torr. We concluded that asystole occurs after a relatively brief period of anoxia during a time interval when the brain retains the potential for full recovery. While no single factor clearly indicates a very prolonged arrest, a pH below 6.9 which does not rise with the institution of adequate ventilation suggests anoxia of greater than five minutes' duration.