The effect of endotracheal tube on pneumonia in ICU patients

INTERVENTION: Control group: patients will be intubated with routin endotracheasl tubes Intervention 1: Intervention group: patient will be intubated with EVAC endotracheal tubes. Intervention 2: Control group: patients will be intubated with routin endotracheasl tubes. Intervention group: patient will be intubated with EVAC endotracheal tubes CONDITION: Influenza and pneumonia J09, J10, Pneumonia. ; Influenza and pneumonia PRIMARY OUTCOME: Ventilatory associated pneumonia. Timepoint: During ICU stay. Method of measurement: CIPS (Clinicaly infectious pulmonary score). SECONDARY OUTCOME: Length of ICU stay. Timepoint: During ICU stay. Method of measurement: days of ICU stay. Mortality. Timepoint: During ICU stay. Method of measurement: being alive or death. INCLUSION CRITERIA: INCLUSION CRITERIA: ICU patients with age more than 18 y. old who will be intubted for more than 72 hours. Exclusion criteria: Previous history of HIV, pregnancy, mechanical ventilation, malignancy, immunosuppresion or leucopenia with leukocyte count less than 1000/mm3.