Effects Of Different Body Positions On Lower Extremity Venous Blood Flow Rates During Limb Pneumatic Pump Therapy In ICU

Background:Deep vein thrombosis（DVT）with high incidence,which affects about 1.5 million people in Europe and 1 million in the United States as reported in 2019.Due to long-term bed rest,immobilization,vascular injury and blood hypercoagulability,patients in ICU sustain high risk of DVT.In 2018,the prevention rate of deep vein thrombosis in ICU in China reached 83.27%,and mechanical prevention is much common because anticoagulant contraindications.However,in 2018,a study noted that the incidence rates of DVT in ICU were around 31%-44%,even after adequate prevention.Purposes:Differences in mean velocity of blood flow in deep veins of the lower extremity in ICU patients treated with limb pump under different positions.Methods:A total of 44 patients were enrolled in this study.A number of 12 positions were included in the study,including supine position,head raised 30°,lateral position,and leg raised 30° with slope,trapezoidal and triangular posture respectively.The average blood flow velocity were measured under each position of 4 sampling points（central popliteal vein,edge of popliteal vein,central femoral vein and edge of femoral vein）.Results:1.The mean blood flow velocity in the three sampling points（central popliteal vein,edge of popliteal vein and edge of femoral vein）with supine position was significantly higher than the the head raised 30° posture,with statistical difference（P<0.05）,while there was no significant differences at one sampling point（central femoral vein）（P=0.919）.2.Average blood flow velocity at the four sampling points（central popliteal vein,edge of popliteal vein,central femoral vein and edge of femoral vein）was significantly higher than the level position of lower limbs when the lower limb raised 30°as slope or trapezoidal,with statistical difference（P<0.05）.3.The lateral position has 5 sample points（edge of bilateral popliteal vein,bilateral femoral vein central department and pressure side femoral vein edges）average blood flow velocity are reduced significantly（P<0.05）,2 sampling points（both central popliteal vein）speed increased（P<0.05）,bilateral popliteal vein central,one sample point（no-pressure side femoral vein edges）doesn’t show significant statistical difference（P=0.856）.Conclusions:Body positions influence the velocity of deep venous blood flow strikingly during limb pneumatic pump working.In this study,the venous blood flow rate was reduced significantly when the lower limb raised 30° as triangular or the lateral position.The venous blood flow velocity of deep vein of lower extremity increased when the head raised 30° as slope and trapezoid.However,the preventive effect of body position on DVT after pneumatic pump treatment as well as its mechanisms remain to be further investigated.