Intraoperative positive end-expiratory pressure evaluation using the intratidal compliance-volume profile

Area of Science:

• Anesthesiology
• Respiratory Physiology
• Critical Care Medicine

Background:

• Lung-protective mechanical ventilation with PEEP can reduce postoperative pulmonary complications.
• Intraoperative mechanical ventilation settings are often chosen empirically.
• Previous studies suggest PEEP can improve lung function during surgery.

Purpose of the Study:

• To evaluate volume-dependent respiratory system compliance during intraoperative mechanical ventilation.
• To assess the effectiveness of PEEP levels in preventing intratidal recruitment/derecruitment.
• To determine if individualized PEEP titration is beneficial.

Main Methods:

• Prospective observational study of 40 adult patients undergoing ear-nose-throat surgery.
• Measurement of respiratory variables during mechanical ventilation in 5-minute intervals.
• Calculation and classification of dynamic compliance (CRS) and intratidal CRS curves into specific profiles.

Main Results:

• The initial PEEP level was set to 5 cm H2O in 83% of patients.
• Mean CRS decreased continuously during the procedure.
• Intratidal recruitment/derecruitment occurred more frequently at PEEP of 5 cm H2O (18.6%) compared to higher PEEP levels (5.5%, P<0.01).
• Overdistension was rarely observed.

Conclusions:

• A PEEP of 5 cm H2O is generally too low to prevent intratidal recruitment/derecruitment during intraoperative mechanical ventilation.
• Analysis of intratidal compliance profiles can guide individualized PEEP titration.
• Optimizing PEEP stabilizes alveolar recruitment during surgery.