Functional Residual Capacity Measured by Capnography in Ventilated Patients

Effect of Positive End-expiratory Pressure on Functional Residual Capacity Measured by Volumetric Capnography in Mechanically Ventilated Patients

Changes in body position during anesthesia can alter functional residual capacity and gas exchange. The monitoring of such changes in functional residual capacity is difficult at the bedside. The present study was designed to determine if volumetric capnography can detect changes in the functional residual capacity during surgery.

This is a prospective and observational study designed to test the reliability of the capnodynamic equation to determine changes in functional residual capacity measured during anesthesia. The investigators will studied 40 mechanically ventilated patients undergoing general anesthesia. Functional residual capacity will be continuously measured in a non invasive way using expired carbon dioxide. Changes in functional residual capacity with standard modification in body positioning (Trendelenburg or anti-Trendelenburg position) and ventilatory settings wiil be tested.

Inclusion Criteria:

• Written Inform Consent
• Programmed surgery
• Laparoscopic surgery
• Supine position

Exclusion Criteria:

• Emergency surgery
• Chronic respiratory disease
• Active smoking