Caffeine is widely used for the treatment of
apnea in premature neonates. However, the localization of
caffeine's target site (central nervous system and/or peripheral chemoreceptors) is not well defined, especially for sleeping neonates whose sleep stages interact with respiratory control. The aim of this study was to assess the activity of the peripheral chemoreceptors in relation to sleep stages in premature neonates treated (or not) with
caffeine for idiopathic
apnea. Peripheral chemoreceptor activity was assessed in 22 neonates (postconceptional age of 36 +/- 1 wk with
birth weights ranging from 790 to 1,910 g) by performing a 30-s hyperoxic test during active and quiet sleep. Eleven neonates received
caffeine treatment (4.0 +/- 0.5 mg.kg(-1).day(-1)) and 11 served as controls. For all neonates, the decrease in minute ventilation observed during
hyperoxia was greater during active than during quiet sleep. Neonates receiving
caffeine showed a significantly greater decrease in ventilation during
hyperoxia in both sleep stages, compared with controls (
caffeine; -29.7 +/- 12.8% vs. control; -22.0 +/- 7.4%; F(1,15) = 4.6, P = 0.04). We conclude that
caffeine administration increases the effectiveness of chemoreceptor activity. Because sleep stage durations were not affected by the treatment, it is likely that the decrease in apneic episodes typically observed with
caffeine therapy is only related to respiratory processes and is independent of the sleep stage organization.