Prematurity is the main cause for respiratory distress syndrome (RDS) in neonates. The goal in the treatment of RDS is to maintain respiration with adequate oxygenation. ETS needs to be performed to remove lung secretions in the ventilated premature infants with RDS. Oxygen saturation(SpO$_2$) and heart rate(HR) were compared in 22 premature infants with RDS using two types of ETS : open ETS versus close ETS. The results showed there was no significant difference in the SpO$_2$ and HR responses between open ETS and close ETS. The SpO$_2$ and HR returned to the baseline within 1 minute after suctioning. But in some case, there was a significantly greater incidence in the decrease of SpO$_2$ below 90% occured in the open ETS than in the close ETS. It implies that closed ETS may be beneficial to the premature infants who tend to develop desaturation easily.