This research is clinical trial study to determine the effect of rib cage compression on hemodynamic changes in patients under mechanical ventilation in intensive care units.The samples included of 58 mechanically ventilated patients .The patients will be selected gradually according to inclusion criteria .Inclusion criteria includes:age 18 to 65 years, having endotracheal tube for 24 hour, stable hemodynamic status (mean arterial pressure between 110 to 60 mm Hg, heart rate of less than 110 beats per minute ), lack of a chest tube, no chest surgery or injuries, no rib fractures,, no skin grafts and reconstructive surgery of the chest,no pregnancy, obesity (body mass index (BMI)> 30).The procedure is that patients randomly are divided into two groups.In intervention group,patients receive expiratory rib cage compression before suctioning three times a day and control group receive routine suction without rib cage compression. Then 5 min before and 15,25 min after intervention, blood pressure, heart rate and O2saturaion measured.