This study wil examine the effect of altered intrathoracic pressure on lymphatic function, by investigating the lymphatic vessels in the lower limb during mechanical ventilation.

The lymphatic function will be examined using Near-Infrared Fluorescence Imaging.

This study wil examine the effect of altered intrathoracic pressure on lymphatic function. This will be done by investigating peripheral lymphatic vessels on patients undergoing surgery for malformations of the jaw who are being mechanically ventilated.

Subjects will be examined on two occasions. One to establish baseline function, and one during surgery following a ventilation protocol with altered PIP and PEEP.

Inclusion Criteria:

• Patients undergoing surgery for jaw malformations
• Age > 18 years
• Informed consent
• Cardiopulmonary healthy

Exclusion Criteria:

• History of Cardiac disease
• History of pulmonary disease
• History of lymphatic disease
• Peripheral edema
• Chronic infectious disease
• Age > 30 years
• BMI > 30