Response of premature infants with periodic breathing to ventilatory stimuli.

Abstract

Nineteen rebreathing CO2 response curves were obtained on 13 premature infants with and without periodic breathing. The slopes of the curves (1/min. per kg per mm Hg arterial CO2 pressure for the periodic and regular groups were not significantly different, averaging .048 [plus or minus] .024 and .060[plus or minus].027, respectively. Therefore, increased sensitivity to CO2 does not appear to be a factor in the etiology of periodic breathing of premature infants. Premature infants resembled term infants in having rebreathing response curves shifted far to the left of steady-state curves and the adult rebreathing curve, presumably on the basis of an additive ventilatory stimulus. The effect on the end-tidal CO2 pressure of facial s timulation alone was tested in 66 trials on periodic and regular premature infants. The regular group hypoventilated slightly while the periodic group had no significant change in ventilation to facial stimulation. A similar increase in ventilatory oscillation to this nonchemical stimulus occurred in both groups. Underdamping of the respiratory control mechanism disappears with maturation of the premature infant since regular breathing becomes established around a postconceptual age of 38-40 wks.