The aim of this study is comparing the effect of open and close endotracheal suctioning on hemodynamic status of patient with head trauma under mechanical ventilation. Design: 88 patients who needed endotracheal suctioning in SICU of Shahid Beheshti hospital on Babol University of medical science who were randomly allocated to undergo either closed (n=44) or open (n=44) suctioning. After getting oxygenated with 100% O2 for one minute, the patients are suctioned with either method for 15 seconds. They will also receive 100% oxygen for one minute after suctioning and then hemodynamic indices (Heart rate, Respiratory rate, Mean Arterial Pressure, Cardiac Dysrhythmia, Central venous pressure, Positive end expiratory pressure, Arterial Blood Oxygen Saturation) are compared after suctioning every five minutes up to fifteen minutes between two groups. This study is single-blind, parallel clinical trial. Inclusion criteria: Patients without lung problems, Age more than 12 years old, Head trauma, Level of consciousness between 4-8, Patients with Endotracheal tube, Hemodynamic stability, lack of dysrhythmia. Exclusion criteria: Patients require frequent suctioning, any serious adverse effects during study (increasing of intracranial pressure, severe impairment in hemodynamic status). Intervention: In one group closed suction method and in another one, open suction method will perform. Main outcome measures: evaluating changes in hemodynamic indices with two methods in head trauma patients.