This study evaluates whether sustaining inspiratory pressure for 10 seconds at a time can open collapsed lung areas in non-dependant regions of the lung in mechanically ventilated patients.

Collapse of lung volume, atelectasis, is a common complication in sedated and mechanically ventilated patients. In adults the atelectasis occur mainly in the dependant areas of the lung. In this study the investigators examine whether these atelectasis can be opened by repeatedly sustaining the inspiratory pressure for 10 seconds when the patient has been positioned so that the atelectasis is located in a non-dependant position. Furthermore, the investigators examine how many times the inspiratory pressure needs to be sustained before the atelectasis is opened and at what pressure.

Inclusion Criteria:

• Continuously or intermittently mechanically ventilated with artificial airway (endotracheal tube or tracheostomy tube)
• Pressure controlled or pressure supported ventilator mode
• PEEP ≤ 12 cm H2O, registered peak pressure ≤ 32 cm H2O
• Non-ventilated lung regions according to E.I.T. measurements
• Richmond Agitation Score 0 -(-5)
• Circulatory stable or stabilized

Exclusion Criteria:

• Pregnancy
• BMI > 50
• Pacemaker or other electrically active implants
• Skin lesions, wounds or bandages on chest area where E.I.T. belt needs to be placed
• Undrained pneumothorax
• Pulsating air-mattress
• Unstable skeletal injury to spinal column
• Recent brain injury or spinal chord injury
• Recent injury to heart, to major blood vessels in chest, to major airways or to the oesophagus.