Optimal PEEP during one-lung ventilation with capnothorax: An experimental study.

Area of Science:

• Anesthesiology
• Respiratory Physiology
• Thoracic Surgery

Background:

• One-lung ventilation (OLV) with induced capnothorax presents significant risks for ventilation and circulation.
• Positive end-expiratory pressure (PEEP) may help mitigate these physiological challenges.

Purpose of the Study:

• To determine the optimal PEEP level during right-sided OLV with capnothorax in piglets.
• To investigate the effects of varying PEEP on ventilation, perfusion, and hemodynamics.

Main Methods:

• Right-sided OLV with capnothorax was induced in piglets.
• A recruitment maneuver followed by decremental PEEP titration from 20 cm H2O to zero end-expiratory pressure (ZEEP).
• Regional ventilation and perfusion were assessed using electrical impedance tomography and CT scans; hemodynamics and lung volumes were recorded.

Main Results:

• PaO2 peaked at PEEP 12 cm H2O, decreasing significantly at ZEEP.
• PaCO2 increased markedly at PEEP levels below 12 cm H2O.
• Ventilatory driving pressure was lowest at PEEP 14 cm H2O.
• Reducing PEEP below 12-14 cm H2O led to ventilation shifting to nondependent regions and perfusion to the nonventilated lung.

Conclusions:

• Optimal PEEP for OLV with capnothorax in this model was 12-18 cm H2O.
• Suboptimal PEEP (<12 cm H2O) resulted in ventilation/perfusion mismatch and blood flow redistribution to the nonventilated lung.