Chest trauma is the most common injury in the emergency trauma and rib fractures is the most common trauma in chest trauma. Severe rib fractures can cause paradoxical respiration and mediastinal swing, which has large effects on respiratory and circulatory system, result in acute respiratory distress syndrome. Mechanical ventilation can significantly improve the hypoxemia of the patients, correct paradoxical respiration, and treat the pulmonary atelectasis

To compare between Biphasic Intermittent Positive Airway Pressure (BIPAP) ventilation and Airway Pressure Release Ventilation (APRV) mode in patients with multiple fracture ribs as regard:

• Resting Energy Expenditure
• Oxygenation
• Stability of Physiological Status as cardiovascular activity
• cardiac output
• arterial blood gas measurement including [ blood PH, arterial oxygen tension, arterial carbon dioxide tension, bicarbonate level and base deficit]
• lung and chest compliance
• Length of intensive care unit stay.
• The ICU mortality rate.
• The development of major complications as nosocomial infection (hospital acquired pneumonia and ventilator associated pneumonia), major atelectasis and pneumothorax.

Inclusion Criteria:

• Isolated chest trauma patient with Multiple fracture ribs patients [ >3 ribs] who will be admitted to the surgical ICU for ventilatory support and will be expected to continue for 2 days or longer

Exclusion Criteria:

• Age < 18 years old.
• Pregnant patient.
• Patient who will require fraction of inspired oxygen more than 0.6.
• Air leak from the chest tube.
• Patient with body temperature > 39 Celsius.
• Acute hepatitis or severe liver disease (Child-Pugh class C).
• Left ventricular ejection fraction less than 30%.
• Heart rate less than 50 beats/min.
• Second or third-degree heart block.
• Systolic pressure < 90 mmHg despite of infusion of 2 vasopressors.
• Patients with known endocrine dysfunction.
• Patient with hypothermia
• Patient on Positive end expiratory pressure more than 14 cmH2o