Effects Of Volume Controlled Mechanical Ventilation Assisted With Auto Flow On Respiratory Mechanics And Oxygenation In Patients During One Lung Ventilation

Objective:To observe the effects of volume controlled mechanical ventilation with auto flow on respiratory mechanics and oxygenation in patients during one lung ventilation（OLV）,and to explore the clinical safety and efficacy of the new ventilation mode.Methods:Sixty American Society of Anesthesiologists physical（ASA）class I～II patients with body mass index of 18～25kg/m²,aged 40～65yr,regardless of gender,scheduled for elective pulmonary lobectomy via video-assisted thoracoscope,were randomly divided into 2 groups（n=30each）:control group（group C）and volume controlled ventilation（VCV）assisted with auto flow group（group A）.VCV+auto flow（group A）:VCV+const flow ventilation mode was used before OLV and was converted to VCV+auto flow ventilation mode after OLV till the end of surgery.VCV+const flow（group C）:VCV+const flow ventilation mode was used till the end of surgery.Mean arterial pressure（MAP）,heart rate（HR）,pulse oxygen saturation（Sp O₂）,platform pressure（Pplat）,peak airway pressure（Ppeak）and pulmonary dynamic compliance（Cdyn）were recorded at 5 minutes before OLV（T₀）,at 30 minutes（T₁）,90 minutes（T₂）after OLV and the end of surgery（T₃）.Blood samples were taken from the radial artery and internal jugular vein at the above time points for blood gas analysis,and shunt rate（Qs/Qt）and oxygenation index（OI）were calculated according to blood gas indexes.Results:（1）Comparison of hemodynamic parameters during operation:from T₀to T₃,there were no significant differences in the MAP、HR and Sp O₂in the two groups（P>0.05）.（2）Comparison of respiratory mechanical indicators during operation:there were no significant differences in the Pplat、Ppeak and Cdyn between the two groups at T₀（P>0.05）.Compared with group C,the Ppeak and Pplat of group A were decreased and the Cdyn of group A was increased from T₁to T_3.There is a statistical significance（P<0.05）.Compared with T₀,from T₁to T₂,the Ppeak and Pplat of both groups were higher and the Cdyn of both groups were lower than those at T₀.The Ppeak and Pplat of group A at T₃were lower than those at T₀,and the Cdyn of group A at T₃was higher than that at T₀.There is a statistical significance（P<0.05）.（3）Comparison of intraoperative oxygenation indexes:there were no significant differences in the OI and Qs/Qt between the two groups at T₀（P>0.05）.Compared with Group C,Qs/Qt in Group A was significantly different,at T₁-T₂has a significantly decreased（P<0.05）.Compared with T₀,Qs/Qt of both groups were statistically different,have significantly increased from T₁to T₂（P<0.05）.Compared with T₀,OI of both groups were statistically different,have significantly decreased from T₁to T₂（P<0.05）.Conclusion:It is helpful in improving the intraoperative respiratory mechanic and oxygenation,when volume controlled mechanical ventilation assisted with auto flow is used during OLV.Therefore,the ventilation mode has higher safety and effectiveness.