Study On Value Of Bedside Lung Ultrasound In Differential Diagnosis Of Cardiac Dyspnea

Objectives To research on the B-line’s appearance of cardiac dyspnea and non-cardiac(pulmonary) dyspnea by bedside lung ultrasound. The value of that bedside lung ultrasound in the differential diagnosis of cardiac dyspnea and diagnosis of acute left heart failure severity was explored. The best cutoff point of B-line in the diagnosis of cardiac dyspnea was found out, thus a new imaging diagnostic method was provided for clinical diagnosis of cardiac dyspnea.Methods 1 The patients with acute dyspnea were included from October 2014 to February 2016 in the Affiliated Hospital of North China University of Science and Technology. All patients were examined by bedside lung ultrasound and echocardiography within 2 hours before pharmacotherapy, at the same time medical history was asked and other related inspections were arranged. All patients were clearly diagnosed based on the clinical data(such as medical history, chest X-ray, NT-pro BNP,echocardiography) by two associate senior doctors. Exclusion were renal insufficiency,trauma, chest dressing and other causes of dyspnea(including pneumonia, pulmonary embolism, carcinoma, pleural effusion, pneumothorax, poisoning, etc). 158 patients met the criteria for inclusion in the study. 2 According to clinical diagnosis, the patients were divided into two groups: acute left heart failure(group I, 77 cases) and non-cardiac(pulmonary) dyspnea group(group Ⅱ, 81 cases). According to New York Heart Association, the patients of group I were divided into grade II(group a), grade III(group b) and grade IV(group c). 3 Excel was applied to establish a database, SPSS20.0statistical analysis software was used for statistical analysis. All measurement data were expressed as mean ± standard deviation(sx ±) or median(semi-guartile range)[M(P25-P75)]. The means comparison used independent t-test and ANOVA. Rank-sum test was used for the medians comparison. Chi-square test was used to compare classified variable.The correlation analysis between the two factors was conducted with Spearman. AUC and the best diagnostic threshold value were obtained by the ROC curve of the B-line diagnosing acute cardiac dyspnea.Results 1 There were no significant difference in age, sex, height and weight between group Ⅰand group Ⅱ, same to the three groups of group Ⅰ(P>0.05). 2 Between groupⅠand group Ⅱ, aortic root, main pulmonary valve annulus, left atrium, interventricular septum and posterior wall of left ventricle were no significant difference(P>0.05), so there were no significant clinical value in these indexes; while total B-line, E/E’, LVDd,NT-pro BNP, LVEF were opposite(P<0.05). 3 Among three groups of groupⅠ, E/E’,LVEF, NT-pro BNP and B-line were significantly different(P<0.05). There was great clinical value with these indexes being used to judge the severity of acute left heart failure. 4 Spearman correlation analyses were carried out to analyze the relationship between group Ⅰand group Ⅱ. Total B-line had positive correlation with NT-pro BNP,E/E’(r=0.851, 0.669 respectively), and negative correlation with LVEF(r=-0.764). The results show that total B-line was increased as the increase of NT-pro BNP, E/E’ and decrease of LVEF. 5 Total B-line had positive correlation with New York Heart Association in groupⅠ(r=0.798). The result showed that total B-line was increased as the increase of the NYHA. 6 Its area under the ROC curve of the B-line diagnosing acute cardiac dyspnea was 0.933(0.898-0.968). According to the Youden’s index, diagnostic critical value was determined for total B-line >8. This critical value had better sensitivity,specificity, positive predictive value for diagnosing acute cardiac dyspnea, so it could be better used in the differential diagnosis of cardiac and pulmonary dyspnea.Conclusions 1 Total B-line has a certain clinical value in differential diagnosis of patients with cardiac or non-cardiac(pulmonary) dyspnea. 2 Total B-line is different in the patients with different New York Heart Association. It can be used to distinguish them and help clinicians to judge the severity or the effect of treatment in patients with acute left heart failure. 3 There is great clinical value with total B-line >8 as the diagnostic boundary. 4 The bedside lung ultrasound plays an important role in differential diagnosing of cardiac dyspnea.