The aim of this study is to examine chest wall volume changes monitored by opto-electronic plethysmography during recovery from anesthesia and early postoperative period.

This is prospective, randomized clinical trial in subjects undergoing elective surgery requiring general anesthesia.

Opto-electronic plethysmography (OEP) has been developed as a non-invasive method for the analysis of chest wall motion, allowing highly accurate measurements of chest wall volume changes of different respiratory compartments in various conditions.

The investigators set out to use this technology to study chest wall volume changes during recovery from total intravenous anesthesia (from discontinuing the anesthetic agent till extubation) and early postoperative period.

The study protocol compares two different approaches:

1. The group receiving recruitment maneuver (RM) immediately after intubation and positive end expiratory pressure (PEEP) 7 cm H20 until extubation. Inspiratory oxygen concentration 40% during recovery from anesthesia.
2. The group not receiving RM, PEEP 0 cm H2O and inspiratory oxygen concentration 100% during recovery from anesthesia.

The volume changes of the chest wall is monitored continuously by OEP, functional residual capacity (FRC) and arterial oxygenation are measured at the defined points in the protocol.

Inclusion Criteria:

• age > 18 years
• ASA classification I-II, scheduled for elective surgery requiring general anesthesia
• signed informed consent

Exclusion Criteria:

• BMI > 35
• co-existing respiratory disease (COPD, asthma )
• patient refusal
• pregnancy
• deformities of the thorax