Effects of naloxone on apnoea duration during sleep in infants at risk for SIDS.

The effects of intravenous injections of the opiate antagonist naloxone (0.005-0.4 mg/kg body weight) on respiratory pattern, apnoea duration and frequency were investigated in six infants with severe sleep apnoea syndrome. Since several authors found elevated plasma- and CSF-levels of endogenous opioids (endorphines) in infants with sleep apnoea syndrome, we wanted to determine whether the impairment of the control mechanisms of respiration during sleep is due to an effect of endogenous opioids. Independent of the dose, naloxone did not exert any effect on respiratory pattern and occurrence of periodic apnoea. We were unable to prove that endorphines play a major role in pathogenesis of sleep apnoea syndrome in infancy and possibly in sudden infant death syndrome (SIDS). We speculate that elevated levels of endorphines reported by some investigators rather seem to be a consequence of hypoxic stress than a cause for sleep apnoeas.