Controlled Low Central Venous Pressure Under Goal-directed Fluid Therapy On Effect Of Bleeding And Tissue Perfusion In Spinal Surgery

Objective:This study is designed to explore the optimal fluid therapy for blood loss and tissue perfusion in patients undergoing spinal surgery by using different fluid therapies（goal-directed fluid therapy,controlled low central venous pressure,and a combination of both）.Methods:In this study,59 ASA classification I-II patients who underwent posterior lumbar decompression graft fusion（involving 1 lumbar segment）under general anesthesia were selected.They were randomly divided into 3 groups:19 cases in the goal-directed fluid therapy group（Group G）,20 cases in the controlled low central venous pressure group（Group L）,and 20 cases in the controlled low central venous pressure group under goal-directed fluid therapy（Group LG）.All three groups used the same Intravenous-Inhalation Combined Anesthesia methods.group G used goal-directed fluid therapy（GDFT）throughout the surgery,and intraoperative fluid infusion was guided by the target of variability per beat volume（SVV）,cardiac index（CI）,and mean arterial pressure（MAP）;group L maintained central venous pressure（CVP）<5 cm H₂O in the pre-decompression phase,and gradually adjusted the dose of vasoactive drugs according to CVP.In the LG group,goal-directed fluid therapy was adopted throughout,with controlled low central venous pressure only in the pre-decompression phase and rapid infusion of crystalloid and colloid fluid after decompression of the spinal canal to restore CVP to normal.HR,MAP,CI,CVP were recorded after induction（supine position）（T1）,before lumbar canal decompression（prone position）（T2）,completion of canal decompression（T3）,end of surgery（T4）,and when leaving PACU（T5）;total fluid intake,crystalloid fluid intake,colloid fluid intake,and bleeding volume were recorded.Central venous blood and radial arterial blood gas were collected at each time point,and S_cvO₂ and central venous carbon dioxide partial pressure,arterial carbon dioxide partial pressure and lactate（Lac）were measured,and the corresponding arteriovenous carbon dioxide partial pressure difference(P_cv-aCO₂)was calculated.Results:（1）Changes in intake and output volume:the total fluid intake in the LG group was reduced compared with that in the G group,and the bleeding volume in the LG and L groups was significantly reduced compared with that in the G group（P<0.05）;（2）Changes in perfusion indexes:P_cv-aCO₂ was reduced and blood lactate was significantly reduced in the G and LG groups compared with the L group at T4 and T5 time points（P<0.05）,and there was no significant change in S_cvO₂.（3）Changes in circulatory indexes:PP,MAP,and CI were higher in LG and G groups compared with L group at T2 and T3 time points.Conclusion:（1）Controlled low central venous pressure performed in spinal surgery along with goal-directed fluid therapy resulted in less blood loss and better tissue perfusion than low central venous pressure or goal-directed fluid therapy alone.（2）The results of the study suggest that the low central venous pressure technique reduces patient bleeding more than the goal-directed fluid therapy technique,but that goal-directed fluid therapy is more advantageous in improving perfusion.