In this controlled trial with intra-subject design infants will be studied using multichannel intraluminal impedance pH (pH-MII) monitoring , during which they receive one 20 min session of 'Expiration Lente Prolongée (ELPr)' . The number of reflux episodes (RE) is the outcome measure. The results obtained during and 20 min after the intervention will be compared to a period of 20 min before treatment ( control ).

l'Expiration Lente Prolongée (ELPr) is a passive technique to enhance the expiration used in infants, obtained by a slow and increasing manual thoraco-abdominal pression applied at the end of a spontaneous expiration till the residual volume. The aim is to obtain a bigger expired volume compared to a normal expiration and drain the mucus out of the airways (Postiaux 2003). This technique has been invented by Guy Postiaux and is used in the Chest Physiotherapy (CPT).