Assessment On Severity In Patients Of Acute Pulmonary Embolism With CT Pulmonary Artery Obstruction Index

ObjectiveTo semi-quantitatively evaluate the severity in patients of acute pulmonary embolism (APE) with CT pulmonary artery obstruction index (PAOI) by analysis of the right ventricular function parameters and arterial blood gas parameters, and compared with ultrasonic cardiography.Materials and MethodsTotally 117 patients with APE confirmed with spiral computed tomography were retrospectively analyzed and selected as being non-severe without underlying cardiopulmonary disease. PAOI was estimated on the basis of the degree of obstruction and location of the thrombus on CT imaging according to the method described by Mastora et al, and the correlation was assessed between PAOI and right ventricular function parameters, or arterial blood gas parameters. The patients were divided into mild, moderate, or severe categories according to PAOI<30%, 30%-50% and≥50%, respectively. The differences of right ventricular function parameters and arterial blood gas parameters among the three groups were calculated. The CT scan were considered positive for right heart dysfunction if RVd/LVd>1 or the interventricular septum was straightened or bowed into the left ventricle, or both. Ultrasonic cardiography was considered positive if any of the following findings was present:right ventricular dilatation, right ventricular hypokinesis, paradoxic motion of the interventricular septum, pulmonary artery systolic pressure>30mmHg, or tricuspid regurgitant velocity>2.8m/s. The sensitivity, specificity, positive predictive value and negative predictive value of CT and ultrasonic cardiography in demonstrating right heart dysfunction were calculated and compared using PAOI≥30% as the reference standard. Right ventricular function parameters include right ventricular maximum short axis diameter (RVd) and cross-sectional area (RVs), left ventricular maximum short axis diameter (LVd) and cross-sectional area (LVs), right ventricle/left ventricular maximum short axis diameter ratio (RVd/LVd) and cross-sectional area ratio (RVs/LVs), superior vena cava (SVC), and azygos vein (AZ) in diameter, interventricular septal deviation (IVSD), inferior vena cava reflux (IVCR) and azygos vein reflux (AZR). Arterial blood gas parameters include arterial blood partial pressure of oxygen (PaO2), carbon dioxide partial pressure (PaO2), oxygen saturation (SaO2), alveolar-arterial oxygen difference (P (A-a) O2). SPSS 17.0 was used for data processing, the level of analysis significance of difference was p<0.05. Pearson and Spearman rank correlation coefficients were used to assess PAOI between right ventricular function parameters, and arterial blood gas parameters. Single-factor analysis of variance (LSD) was used to evaluate the three groups of measurement data of right ventricular function parameters or arterial blood gas parameters; Chi-Square was evaluated the difference of count data of right ventricular function parameters.Results1,There was negative correlation between PAOI with LVd, LVs and PaO2, the extent of correlation coefficient were -0.322～-0.515. There was positive correlation between PAOI with RVd, RVd/LVd,RVs/LVs, RVs, IVSD, IVCR, SVC, AZ, MPA, LPA, RPA and P(A-a)O2, the range of correlation coefficient were 0.196～0.634. The correlation coefficient was highest between PAOI and RVd/LVd. there was no correlation between PAOI and AZR, PaCO2 and SaO2.2,There were 65,32 and 20 patients in mild, moderate and severe groups, respectively. The analysis of CT right ventricular function parameters revealed that compared with mild group, in moderate group, RVd, RVd/LVd, RVs, RVs/LVs, MPA and LPA increased obviously, the incidence of IVSD and IVCR increased obviously, LVd and LVs decreased obviously, and no difference in arterial blood gas parameters; and in severe group, RVd, RVs, RVd/LVd, RVs/LVs, SVC, MPA, LPA and RPA increased obviously, the incidence of IVSD, IVCR and AZR increased obviously, LVd and LVs decreased obviously, PaO2 decreased significantly, and P(A-a)O2 increased obviously. Compared with moderate group, in severe group, RVd/LVd and RVs/LVs increased obviously and LVd decreased obviously, and no difference in arterial blood gas parameters.3,There were 52 patients who had PAOI≥30%, and 58 patients who had right ventricular dysfunction on CT. There were only 49 patients who had technically adequate ultrasonic cardiography before and after 24 hours of the CT scan, including 26 cases that had PAOI≥30%, and 24 cases which ultrasonic cardiography were positive for right heart dysfunction. Using PAOI≥30% as the reference standard, the sensitivity, specificity, positive predictive value and negative predictive value for CT in demonstrating right ventricular dysfunction were 71%,81%,79%and 74%, and for ultrasonic cardiography were 58%,61%,63%and 56%:Conclusion1,There is correlation to an extent between PAOI and right ventricular function parameters, arterial blood gas parameters. It is suggested that CT can accurately assess the degree of pulmonary embolism, and has a good correspondence with clinical.2,It is feasible to semi-quantitatively evaluate the severity of APE as mild, moderate or severe groups according to PAOI<30%,30%～50% and≥50%, and is helpful for clinician to adopt more suitable treatment in earlier period, which can improve the prognosis.3,CTPA is higher than ultrasonic cardiography in diagnosis accurately the right ventricular dysfunction. It is indicated that CTPA can estimate precisely the right ventricular dysfunction.