Effects Of Different Body Positions And Foot Pump Pressure On Deep Venous Blood Flow In Lower Extremities In ICU Patients

Background: DVT(deep venous thrombosis)is commonly occurred in clinic,and its incidence is 88～112/100,000 people per year.In ICU(Intensive Care Unit),DVT incidence and DVT complications is higher than that of general ward patients due to their long-term bed rest,central venous catheter placement or other invasive operations,as well as positive pressure ventilation,sedation,blood hypercoagulability and other factors.The most serious DVT complications is PE(pulmonary embolism),which strongly affect the prognosis,or even death,of patients.Therefore,the guidelines of various countries have made the prevention of DVT one of the priorities in clinical work.Studies have shown that the application of mechanical equipments can improve blood flow in the lower extremities,reduce the risk of DVT,and improve the survival of patients.VFP(venous foot pump)(referred to as "foot pump")is a convenient,cheap,easy tolerated,universally applicable mechanical equipment to prevent DVT;but at present,clinical efficacy are different due to the fact that different manufacturers of foot pump device pressure file settings are distinct,and foot pump pressure mode settings are not standardized in clinical application.In addition,clinically,it is often used to improve venous return by elevating the lower limbs,thereby preventing the occurrence of DVT.However,one of the reason for the difference in the effect of foot pump in preventing DVT is the strong position variation of the lower limbs of patients when foot pump therapy is implemented in the ICU.Therefore,to achieve the purpose of more effective prevention of DVT,we would like to explore the effect of different foot pump pressures combined with different positions of patients’ lower limbs on the deep vein blood flow of the lower extremities in this study.Objective: Explore the effects of different lower limb positions and foot pump pressure on deep venous blood flow in ICU patients.Methods: From July 2022 to September 2022,167 patients were selected in this study from the Department of Critical Care Medicine of the Affiliated Hospital of Yangzhou University,and 40 were enrolled after inclusion criteria.Color Doppler ultrasound was used to measure the femoral venous blood flow parameters(peak flow rate,volume flow)of different positions of the lower limbs(lower limb flat,lower limb elevation 18°,lower limb elevation 30°)combined with different foot pump pressure usage(no pump resting state,foot pump pressure 80 mm Hg,foot pump pressure 130 mm Hg,foot pump pressure level 180 mm Hg)under the condition of 30° elevation of the head of the bed.Using SPSS26.0 software,ANOVA and repeated measurement to analyze and compare the effects of different positions of lower limbs and different pressures of foot pump on femoral venous blood flow.Results: The peak flow rate of femoral venous blood flow gradually increased along with the foot pump pressure in all three lower extremity positions(lower limb flat,lower extremity elevation 18°,lower extremity elevation 30°).When foot pump was not used,the peak flow rate of femoral venous blood flow tended to increase,but not significant,as the angle of lower extremity elevation increased.Interestingly,upon all three foot pump pressures(80 mm Hg,130 mm Hg,180 mm Hg),the peak flow rate of femoral venous blood flow gradually decreased as the angle of lower extremity elevation increased,but was still higher than the condition without foot pump.In all three lower limb positions,the volume flow of the femoral vein gradually increased as the foot pump pressure increased.However,under the pressure of no pump or three types of foot pump,there was no significant alternations in femoral vein volume flow with the increase of lower limb elevation angle.Moreover,there were interaction effects on the peak flow rate of femoral vein blood flow,but no significant interaction effects on the volume flow of femoral veins,between different lower limb positions and foot pump pressure.Conclusions: Different pressures of foot pump have a significant impact on femoral venous blood flow;and the higher of the foot pump pressure,the greater of the peak flow rate and volume flow of femoral venous blood flow.Lying flat on the lower limbs can remarkably increase the venous return rate during foot pump treatment,which can play better roles in preventing DVT.