手术病人对急性等容血液稀释的耐受程度

The acceptable limitation of acute normovolemic hemodilution in surgical procedures

目的:观察非心脏外科手术病人应用急性等容血液稀释(ANHD)的组织缺氧界限及机体对ANHD的代偿机制。方法:随机选择非心脏外科手术病人40例,ASA Ⅰ～Ⅱ级,麻醉平稳后正常体温下行ANHD,待Hct降至约28％时(HD_1)停止ANHD,进行手术。手术失血使血液进一步稀释,造成不同的血液稀释水平(HD_2,HD_3),于HD前、HD_1、HD_2、HD_3及回输自家血后测定动脉及混合静脉血气及动脉血乳酸,用温度稀释法测血流动力学参数,并计算氧供(DO_2)、氧耗(VVO_2),摄氧率(DRO_2)等。结果:(1)HD_1(Hct29.1％±1.3％),HD_2(Hct25.3％+1.58％)时,DO_2分别降低4％和20％,ERO_2升高14％和25％,心脏指数(CI)升高9.9％和24％(P<0.05),血乳酸(LA)及VO_2均未显著改变;(2)HD_3(Hct23.02％+1.93％)时,DO_2降低42.3％(P<0.01),ERO_2升高34.9％,CI降至基础水平,VO_2降低24.9％,明显低于HD前(P<0.05).LA明显升高(P<0.01);(3)回输自家血后,DO_2升高HD前水平,VO_2高于HD前水平。结论:成年非心脏外科手术病人,术中应用ANHD,Hct以不低于23％为宜,机体对ANHD的代偿主要来自心输出量和摄氧率的升高。

Objective: To study the acceptable limitation of acute normovolemic hemodilution(ANHD) and its compensatory mechanisms in non-cardiac surgery. Method: In forty adults ASA classⅠ-Ⅱpatients undergoing non-cardiac surgery under general,anesthetic at normal body temperature ANHD was accomplished by exchanging whole blood for 4％ Gelofusine,The Hemotocrit (Hct) were hemodiluted approximately to 28％ (HD_1) preoperatively. Further hemodilution(HD_2,HD_3) was achieved due to intraoperative blood loss which was replaced by 4％ Gelofusine,Arterial and mixed venous blood gases,Plasma lactic acid(LA) were measured, Hemodynamic variables were determined using the thermodilution technique, Oxygen delivery/consumption (DO_2/VO_2) and oxygen extraction ratio (ERO_2)were calculated using standard formula. Results: (1)During the HD_1 (Hct29.16±1.31％ ),and HD_2 (Hct25.34％±1.58％), DO_2 decreased by 14％ and 20％, ERO_2 increased by 14％ and 25％, cardiac index (CI) increased by 9.9％ and 24％ ,respectively,(P<0.05),LA and VO_2 did not change. (2)Duning the HD_3 (Hct23.02+1.95％),DO_2 decreased by 42.3％ (P<0.01),ERO_2 increased by 34.90％ ,CI decrease to baseline,VO_2 decreased by 24.90％ (P<0.05), LA increased significantly (P<0.01).(3)After reinfusion, DO_2 rose approximately to the baseline VO_2 was higher than the baseline. Conclusion:ANHD can be tolerated until Hct decreases to 23％. The trimary compensatory mechanisms of ANHD are mainly through increases in cardiac output and oxygen extraction ratio.