通过监测中心血容量评估血液透析干体重的新方法-超声稀释

目的观察血液透析过程中患者血压变化的影响因素，并用超声稀释的方法测定中心血容量（CentralBloodVolumeCBV）变化对预防透析过程中低血压，及对调整透析患者干体重的作用。方法将60名患者按照以往的透析记录分为高血压组（HighbloodpressureHBP）、低血压组（Low blood pressureLBP）、正常血压组（Normal blood pressure NBP）。所有患者分别在透析治疗1h和透析3h时采用超声稀释的方法检测中心血容量（CBV），心输出量（c0），心脏指数（cI），外周血管阻力（PVR）。结果对整体分析，C0、CI、CBV下降，平均下降（-12．3±15．8）％、（-18．2±21．0）％、（-0．12±0．16）％，变化有统计学意义，而血压变化和外周阻力变化无统计学意义，以低血压组下降较为明显；透析过程中CBV变化与CO变化呈正相关（，值为0．648，P值〈0．001），与外周阻力变化、超滤速度呈负相关（r值分别为-0．487，和-0．524；P〈0．001和〈0．005）；根据CBV变化对20例血压未达标患者101次透析例次中予以逐步评估干体重后，透析过程中及透析结束后患者血压能够维持正常。结论CBV是反应中心血容量的有效指标，透析过程中CBV下降，说明患者在透析治疗期间细胞外液逐渐减少；透析过程中CBV变化与C0变化呈正相关，与PVR变化、超滤速度呈负相关；血压变化与心率变化呈负相关；不同分组PVR变化的影响因素不确定。我们可以根据患者超声稀释的方法测定透析前后CO、CI、CBV，来指导超滤量，设置合适的干体重，并对于防治血液透析中血压波动过大具有积极的意义。

Ultrasound dilution: A new method to evaluate dry body weight by monitoring central blood volume in hemodialysis pafients

Objective To investigate the related factors for blood pressure changes in hemodialysis patients,and to measure central blood volume （CBV） by ultrasound dilution method for the prevention of hypotension and the adjustment of dry body weight during dialysis. Methods Sixty patients were assigned in 3 groups based on their previous blood pressure in patients＇ dialysis records： high blood pressure （HBP） group, low blood pressure （LBP） group and normal blood pressure （NBP） group. CBV, cardiac output （CO）, cardiac index （CI）, and peripheral vascu- lar resistance （PVR） were examined by ultrasound dilution method during the dialysis at one hour and 3 hours. Results In the 60 patients, CO （- 12.3 ＋ 15.8）%, CI （- 18.2 ＋ 21.0）% and CBV （-0.12 _ 0.16）% were significantly decreased （P〈0.01）, but without significant changes in blood pressure and PVR. However, the decreases of CO, CI and CBV were only detected in LBP group but not in HBP and NBP groups. In a dialysis session, change of CBV was positively correlated with that of CO （r=0.648, P 〈 0.001）, and was negatively correlated with changes ofPVR （r =-0.487, P 〈 0.001） and ultrafiltration volume （r = -0.524, P 〈 0.005）. By using CBV to monitor patient＇s dry body weight in 101 dialysis sessions for 10 hypertension patients and 10 hypotension patients, we observed normal blood pressure during and after dialysis sessions. Conclusions CBV is a useful marker for circulating blood volume. During a dialysis session, the decrease of CBV reflects the decrease of extracellular fluid, and is also related to hypotension. CBV correlates positively with CO, and negatively with PVR and ultrafiltration volume. Blood pressure change positively correlates with the change of heart rate. In the 3 groups, factors relating to PVR change are uncertain. By measuring CBV, CO and CI using ultrasound dilution method before and after a dialysis session, we can estimate the appropriate ultrafiltration volume and dry body weight, and perform the dialysis under a normal and stable blood pressure condition.