Volume of Tidal Gas Movement in Nonventilated Lung During One-lung Ventilation and its Relevant Factors
Abstract BACKGROUND: Effective collapse of the nonventilated lung is important for exposure of critical structures during thoracoscopic surgery. The passive ventilation of nonventilated lung results in tidal gas movement (TGM) and thus affects the lung collapse. The present study aimed to measure the volume of TGM and to establish a mathematical model to predict the volume of TGM.METHODS: One hundred and sixty-five patients scheduled for elective thoracoscopic surgeries were enrolled. Lung isolation was achieved with a double-lumen endobronchial tube (DLT). The pediatric spirometry sensor was connected to the double-lumen connector of the non-ventilated lung to measure the volume of the TGM during one-lung ventilation (OLV) in lateral position. Other variables were also recorded: 1) age, gender, height, the deviation between actual body weight and ideal body weight (ABW-IBW); 2) forced vital capacity (FVC), FEV 1 /FVC, minute ventilation volume (MVV); 3) dynamic lung compliance (Cdyn) and airway resistance (Raw) during dual lung ventilation; 4) the side of OLV; 5) whether lung puncture for localization of pulmonary nodule was performed on the surgery day. RESULTS: The volume of tidal gas movement in the nonventilated lung during one-lung ventilation was 78 ± 26 mL. Gender, side of OLV, FVC and Cdyn independently correlated with the volume of TGM (P<0.05). The linear regression model for the volume of TGM was deduced: TGM (mL)=C+16.452×a-8.371×b+14.017×c+0.206×d. C: Constant=26.915 mL; a: male=1, female=-1; b: right OLV=1, left OLV=-1; c: FVC (L); d: Cdyn (mL/cmH 2 O). CONCLUSIONS: The tidal gas movement of the nonventilated lung during one-lung ventilation does exist. Gender, FVC, side of OLV and Cdyn independently correlate with the volume of TGM. Trial registration: This clinical research was registered at the Chinese Clinical Trial Registry ( www.chictr.org.cn , ChiCTR1900024220, date of registration: July 1 st , 2019). Key Words: tidal gas movement, one-lung ventilation, lung collapse, double-lumen endobronchial tube, dynamic lung compliance, thoracoscopy