Effects of non-dependent lung oxygen insuffation on oxygenation and respiratory mechanics during one-lung ventilation in patients with stage II COPD

Introduction: The aim of this study was to investigate the changes on oxygenation, shunt ratio and respiratory mechanics of 6 L/min oxygen insuffation to the non-dependent lung, while extrinsic PEEP (PEEPe, equivalent to the patient's PEEPi) was being applied to the dependent lung in patients undergoing lung surgery. Material and Methods: Patients with stage II COPD undergoing elective lung surgery (n=22) were intubated with a doublelumen endobronchial tube and performed a PA catheterization. One lung ventilation settings were: tidal volume 6 ml/kg, 12 breaths/min, and I: E ratio 1: 2. Procedure was performed in four sequential periods (each period continued for 15 minutes): After frst stabilization period (PEEP0-1), PEEPe (at the level of intrinsic PEEP, PEEPi) was applied in the dependent lung while the non-dependent lung was exposed to air. After second stabilization period (PEEP0-2), the non-dependent lung received 6 L/min oxygen (O2) through a catheter placed into the tube while PEEPe (at the level of PEEPi) was applied in the dependent lung (PEEPe+O2). At the end of each 15 minute period, haemodynamic data, lung compliance (C), airway resistance (R), and PEEPi were recorded and blood gas samples were obtained. Results: PaO2 was signifcantly higher during the PEEPe+O2 period (p2 period when compared with the PEEPe period (p<0.0001). Compliance increased signifcantly during PEEPe compared to PEEP0-1 (p