Thirty four infants were enrolled in this study based on the following inclusion criteria : age between @ to @ weeks of gestational age , birth weight @ grams or more , having an endotracheal tube , no congenital anomalies , no seizures diagnosis , no chest tubes , no intracranial hemorrhage higher than degree II , not receiving opiates and sedatives four hours before intervention and not receiving any painful procedure at least half an hour before the intervention .