CT肺动脉造影对肺栓塞诊断和严重程度的评估价值及其与动脉血气的相关性

The role of CT pulmonary angiography in the diagnosis and prognosis of pulmonary embolism and correlation with blood gas values

目的探讨cT肺动脉造影（CTPA）对肺栓塞的诊断及严重程度的评估价值，并分析其与动脉血气问的相关性。方法收集安徽医科大学第一附属医院2007年1月至2010年10月经CTPA确诊的肺栓塞患者44例，其中男27例，女17例，分为严重组19例和非严重组25例；另纳入经CTPA确诊为非肺栓塞的患者37例作为对照组。比较3组间左心室短轴最大径（IJV），右心室短轴最大径（RV），右／左心室短轴最大径比（RV／LV），上腔静脉和肺动脉直径，计算栓塞指数，判定室间隔是否左移及造影剂是否反流入下腔静脉。进一步分析栓塞指数和RV／LV与动脉血氧分压（PaO2）、肺泡．动脉血氧分压差[P（A-a）、O2]的相关性。以栓塞指数60％、70％和80％为分界点，分别比较不同分界点PaO2和P（A-a、O2的差异。结果严重组RV，LV，RV／LV[（53±8）mm，（35±6）mm，1．56±0．50]与非严重组[（45±7）mm，（43±9）mm，1．09±0．31]比较，差异均有统计学意义（t值分别为3．44，3．08，4．62，均P〈0．05）；严重组与对照组[（40±7）mm，（43±9）mm，0．96±0．23]比较，差异亦有统计学意义（t值分别为5．76，3．40，6．33，均P〈0．05）。严重组上腔静脉直径及肺动脉直径分别为（24±4）mm和（33±4）mm，与对照组[（21±4）mm，（29±4）mm]比较，差异均有统计学意义（t值分别为2．80，3．98，均P〈0．05）；非严重组肺动脉直径[（31±5）mm]高于对照组（t=2．59，P〈0．05）。室间隔左移在3组间比较差异均有统计学意义（均P〈0．05）。造影剂反流入下腔静脉严重组高于对照组（Xz=5．54，P〈0．05）。严重组栓塞指数为（76±24）％，高于非严重组（52±34）％（t=-2．75，P〈0．05）。栓塞指数、R、yLV均与PaO2呈负相关（r值分别为-0．525，-0．502），与P（A-a、O2呈正相关（r值分别为0．753，0．630）。不同分界点的PaO2和P（A-a）O2，差异均有统计学意义（均P〈0．05）。结论上腔静脉及肺动脉直径，造影剂反流入下腔静脉可作为CTPA诊断肺栓塞的间接征象；栓塞指数，RV．LV．RV／LV及搴间隔左移可作为评估肺栓寒严重程度的指标．目与动脉向与佰有相关件。

Objective To analyze the value of CT pulmonary angiography （CTPA） in assessing the severity of pulmonary embolism （PE） , and to investigate the correlations of the parameters from CTPA with blood gas values. Methods Forty-four PE patients were classified into 19 critical and 25 non-critical patients, and 37 subjects without PE were defined as control group. Right ventricular （RV） and left ventricular （LV） maximal short axis, RV to LV （RV/LV）, superior vena cava and pulmonary artery diameter, obstruction index, leftward bowing of interventricular septum, reflux of contrast medium into inferior vena cava were compared among the 3 groups. The correlations of these parameters with blood gas values were investigated. Results There were significant differences in RV, LV, RV/LV, superior vena cava and pulmonary artery diameter, leftward bowing of interventricular septum, reflux of contrast medium into inferior vena cava when compared among 3 groups （ P 〈 0. 05 ）. However, significant differences were detected in RV, LV and RV/LV between critical [ （53 ± 8 ） mm, （ 35 ± 6） ram, 1.56 ± 0. 50 ] and non-critical group [（45±7）mm, （43±9）mm, 1.09±0.31] （RV： t=3.44, P〈0.05; LV： t=3.08, P〈 0. 05 ; RV/LV ： t = 4. 62, P 〈 0.05 ）, critical group and group without PE[（40±7 ） mm, （ 43±9 ） mm,0.96±0.23] （RV： t =5.76, P〈0.05; LV： t =3.40, P 〈0.05; RV/LV： t =6.33, P〈0.05）. Superior vena eava diameter and pulmonary artery diameter were significantly different between critical group [ （24 ±4）ram, （33 ±4）mm] and group without PE [ （21±4）mm, （29 ±4）mm[（ t =2.80, P 〈0.05; t = 3.98, P 〈 0. 05 ）. Pulmonary artery diameter in non-critical group （ 31 ± 5 ）mm was significantly different from group without PE （ t = 2. 59, P = 0. 03 ）. Reflux of eontrast medium into inferior vena eava showed signifieant difference between critical group and group without PE （X2 = 5. 54, P = 0. 02 ）. There was signifieant difference in obstruction index between critical （76± 24） % and non-critieal group （ 52 ± 34 ） % （ t = - 2. 75, P = 0. 01 ）. Obstruction index and RV/LV were negatively correlated with PaO2 （ r = - 0. 525, - 0. 502 ）, while positively correlated with P（A-a） O2 （ r = 0. 753,0. 630 ） . Blood gas values differed significantly between above and below the 60%, 70% and 80% cutoff values of obstruction index. Conclusion Superior vena eava and pulmonary artery diameter, reflux of eontrast medium into inferior vena cava can be used as indirect evidence in the diagnosis of PE, while obstruction index, RV, LV, RV/LV and leftward bowing of interventricular septum can be applied as indicators of severity of PE. The severity of the obstruetion index and RV/LV assessed using CTPA are significantly correlated to the blood gas values.