摘要目的 探讨容量状态改变对犬脉搏轮廓持续心排血量(PCCO)监测准确性的影响.方法 对20只杂种犬制备失血性休克模型,并进行容量复苏.每一个模型同时放置两根脉搏轮廓心排血量(PiCCO)导管进行心排血量(CO)监测,1根用于经肺热稀释法问断监测心排血量(COTp)(定标组),另1根用于PCCO监测(非定标组).失血相血容量每下降5％定标组监测一次,直至失血量达40％血容量,非定标组持续监测.随后两根导管均采用经肺热稀释进行定标并进入容量复苏相,复苏容量每增加5％当量的血容量,定标组监测一次,非定标组持续监测,直至补回100％血容量.各时间点均记录COTp、PCCO、平均动脉压(MAP)、体循环阻力(SVR)、全心舒张末期容积(GEDV).结果 (1)在基线,定标组COTP与非定标组PCCO的差异无统计学意义(P＞0.05).(2)在失血相,定标组COTp与GEDV均逐渐下降,TH8时分别降至最低值(1.06±0.57) L/min和(238±93) ml,SVR逐渐上升,TH6时升至最高值(5 074 ±2 342)dyn·s·cm-5,而非定标组PCCO、SVR下降,TH8时分别降至最低值(2.42±1.37) L/min和(2 285 ±1 033)dyn·s·cm-5;定标组COTp与非定标组PCCO在各时间点的差异均有统计学意义(TH1～TH8的t值分别为-5.218、-5.495、-4.639、-6.588、-6.029、-5.510、-5.763、-5.755,P值均＜0.01),且从TH1至TH8两组差值百分比逐渐增大,两组SVR的差异有统计学意义(TH1、TH4的t值分别为2.866、2.429,P值均＜0.05,TH2～ TH3、TH5～ TH8的t值分别为3.073、3.590、6.847、8.425、6.910、8.799,P值均＜0.01),两组MAP的差异无统计学意义(P＞0.05).(3)在容量复苏相,定标组COTp与GEDV均逐渐上升,TR7时GEDV升至最高值[(394±133) ml],TR8时COTp升至最高值[(3.15±1.42) L/min],SVR逐渐下降,TR8时降至最低值[(3 284±1 271)dyn·s· cm-5],而非定标组PCCO、SVR波动上升,TR7时SVR升至最高值[(8 589±4771)dyn·s·cm-5],TR8时PCCO升至最高值[(1.35±0.70) L/min];定标组COTP与非定标组PCCO在各时间点的差异均有统计学意义(TR1～ TR8的t值分别为8.195、8.703、7.903、8.266、9.600、8.340、8.938、8.332,P值均＜0.01),从TR1至TR8两组差值百分比逐渐增大,两组SVR的差异有统计学意义(TR1的t值为-2.810,P＜0.05,TR2～ TR8的t值分别为-6.026、-6.026、-5.375、-6.008、-5.406、-5.613、-5.609,P值均＜0.01),两组MAP的差异无统计学意义(P＞0.05).结论 容量快速改变时,PCCO不能反映真实CO,此时应通过提高定标的频率来保持PCCO的准确性.

abstractsObjective To study the accuracy of pulse contour cardiac output(PCCO) during blood volume change.Methods Hemorrhagic shock model was made in twenty dogs followed by volume resuscitation.Two PiCCO catheters were placed into each model to monitor the cardiac output (CO).One of catheters was used to calibrate CO by transpulmonary thermodilution technique (COTp) (calibration group),and the other one was used to calibrate PCCO (none-calibration group).In the hemorrhage phase,calibration was carried out each time when the blood volume dropped by 5 percents in the calibration group until the hemorrhage volume reached to 40 percent of the basic blood volume.Continuous monitor was done in the none-calibration group.Volume resuscitation phase started after re-calibration in the two groups.Calibration was carried out each time when the blood equivalent rose by 5 percents in calibration group until the percentage of blood equivalent volume returned back to 100.Continuous monitor was done in none-calibration group.COTP,PCCO,mean arterial pressure (MAP),systemic circulation resistance (SVR),global enddiastolic volume(GEDV) were recorded respectively in each time point.Results (1)At the baseline,COTP in calibration group showed no statistic difference compared with PCCO in none-calibration group (P ＞ 0.05).(2) In the hemorrhage phase,COTP and GEDV in calibration group decreased gradually,and reached to the minimum value (1.06 ± 0.57) L/min,(238 ± 93) ml respectively at TH8.SVR in calibration group increased gradually,and reached to the maximum value (5 074 ± 2 342)dyn · s · cm-5 at TH6.However,PCCO and SVR in none-calibration group decreased in a fluctuating manner,and reached to the minimum value (2.42 ± 1.37)L/min,(2 285 ± 1 033)dyn · s · cm-5 respectively at TH8.COTP in the calibration group showed a significant statistic difference compared with PCCO in the none-calibration group at each time point (At TH1-8,t values were respectively-5.218,-5.495,-4.639,-6.588,-6.029,-5.510,-5.763and-5.755,all P ＜ 0.01).From TH1 to TH8,the difference in percentage increased gradually.There were statistic differences in SVR at each time point between the two groups (At TH1 and TH4,t values were respectively 2.866 and 2.429,both P ＜ 0.05,at TH2-TH3 and TH5-TH8,t values were respectively 3.073,3.590,6.847,8.425,6.910 and 8.799,all P ＜0.01).There was no statistic difference in MAP between the two groups (P ＞ 0.05).(3) In the volume resuscitation phase,COTP and GEDV in the calibration group increased gradually.GEDV reached to the maximum value ((394 ± 133)ml) at TR7,and COTP reached to the maximum value (3.15 ± 1.42)L/min at TR8.SVR in the calibration group decreased gradually,and reached to the minimum value (3 284 ± 1 271) dyn · s · cm-5 at TR8.However,PCCO and SVR in the none-calibration group increased in a fluctuating manner.SVR reached to the maximum value (8 589 ± 4 771) dyn · s · cm-5 at TR7,and PCCO reached to the maximum value (1.35 ±0.70) L/min at TR8.COTP in the calibration group showed a significant statistic difference compared with PCCO in the none-calibration group at each time point (At TR1-8,t values were respectively 8.195,8.703,7.903,8.266,9.600,8.340,8.938,8.332,all P ＜ 0.01).From TR1 to TR8,the difference in percentage increased gradually.There were statistic differences in SVR at each time point between the two groups (At TR1,t value was-2.810,P ＜ 0.05,at TR2-8,t values were respectively-6.026,-6.026,-5.375,-6.008,-5.406,-5.613 and -5.609,all P ＜ 0.05).There was no statistic difference in MAP between the two groups (P ＞ 0.05).Conclusion PCCO could not reflect the real CO in case of rapid blood volume change,which resulting in the misjudgment of patient's condition.In clinical practice,more frequent calibrations should be done to maintain the accuracy of PCCO in rapid blood volume change cases.