Doxapram is used to stimulate respiration. For a given dose, the fluctuations in concentrations observed in infants' blood may be wide, leading to a risk of lack of efficacy or of toxic effects. Two factors are linked to these fluctuations: age and gender. The aim of this study is to compare a dosage regimen based only on patient's weight, to another one using a dosing chart taking into account weight, age and gender.