Effects of Non-Dependent Lung Oxygen Insufflation on Oxygenation and Respiratory Mechanics During One-Lung Ventilation in Patients with Stage II COPD

SUMMARY Introduction: The aim of this study was to investigate the changes on oxygenation, shunt ratio and respiratory mechan- ics of 6 L/min oxygen insufflation 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 undergo- ing elective lung surgery (n=22) were intubated with a double- lumen endobronchial tube and performed a PA catheteriza- tion. 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 min- utes): After first stabilization period (PEEP0-1), PEEPe (at the level of intrinsic PEEP,PEEPi) was applied in the depen- dent lung while the non-dependent lung was exposed to air. Af- ter second stabilization period (PEEP0-2), the non-dependent lung received 6 L/min oxygen (O 2 ) through a catheter placed into the tube while PEEPe (at the level of PEEPi)was applied in the dependent lung (PEEPe+O 2 ). At the end of each 15 min- ute period, haemodynamic data, lung compliance (C), airway resistance (R), and PEEPi were recorded and blood gas sam- ples were obtained. Results: PaO2 was significantly higher during the PEEPe+O 2 period (p<0.001), while Qs/Qt was significantly lower in the PEEPe+O2 period when compared with the PEEPe period (p<0.0001). Compliance increased significantly during PEEPe compared to PEEP0-1 (p<0.05). Discussion and Conclusion: The insufflation of oxygen to the non-dependent lung with application of PEEPe- equivalent to the patient's PEEPi -to the dependent lung increased oxygen- ation and decreased Qs/Qt in patients with moderate COPD. We recommend this simple and useful method which does not need extra equipment.