Study On Accurately Evaluating Compression Ratio Of Pneumothorax With MDCT

Objective 1.To explore the correlation between the size of pneumothorax and specific plane diameter of compressed lung and the corresponding plane of thorax with MDCT.Establishing the linear regression equation.2.The linear regression equation was used to evaluate the recovery of conservative pneumothorax patients.Methods 1.92 patients underwent pneumothorax were applied to measure the values of compressed and normal chest volume with MDCT retrospectively,then the results were compared with those compression volume and chest volume via post-processing software(ADW 4.6 version,GE workstation)and the accurate compression ratio was obtained.The longitudinal diameter of value H was measured from the thoracic apex to the diaphragm in the coronal view,the chest width of value W and diameter of value D were measured at the level of bronchial bifurcation of the upper and lower lobe,and the longitudinal diameter of value h,width of value w and diameter of value d of the pneumothorax lung were obtained simultaneously.The ratio of hwd/HWD?h/H?d/D?w/W was calculated.Using SPSS 24 software,linear regression analysis of Y and hwd/HWD and stepwise regression analysis of Y and h/H,d/D and w/W were done respectively.The relative regression coefficient at the right and left lung was tested respectively.The regression equation between left and right lung was compared to observe if the difference of regression equation was statistically significant.Comparing the consistency difference between univariate regression equation and multivariate regression equation to judge the superiority and inferiority of the two equations.2.Pneumothorax patients treated conservatively were divided into observation group and oxygen inhalation group.Compression ratio of before and after treatment was calculated by the better regression equation obtained from method one.Calculating average daily recovery rate =(pre-treatment compression ratio-post-treatment compression ratio)/ interval time.Using spss 24 software Mann-Whitney U test to judge the difference of daily average recovery rate between two groups.The patients in observation group and oxygen inhalation group were divided into three groups according to the standard of 20% and 30%,respectively.Kruskal-Walis H test was used to determine the difference of average daily recovery rate among the three groups.Results 1.The univariate regression equation of right lung was presented as ?=0.936-0.808x(x=hwd/HWD)(R~2=0.932,P<0.001);and the multivariate regression equation of right lung was presented as Y=1.378-0.705d/D-0.447h/H(adjusted R~2=0.881,P<0.001)?The univariate regression equation of the left lung was presented as ?=0.950-0.876x(x=hwd/HWD)(R~2=0.962,P<0.001);and the multivariate regression equation of left lung was presented as Y=1.615-0.580d/D-0.598h/H-0.288w/W(adjusted R~2=0.935,P<0.001).The regression coefficients of univariate regression and multivariate regression were statistically significant,and the regression equation was established.The difference of univariate regression equation between left lung and right lung was statistically significant.The univariate regression equation of left lung and right lung is superior to multivariate regression equation.2.The average daily recovery rate of pneumothorax in the observation group was about 1.29%.There was significant difference in daily average recovery rate between observation group(average rank 10.13)and oxygen inhalation group(average rank 20.21),U=32,Z=-3.186,P<0.01.The distribution of the average daily recovery rate of different initial compression ratios in the observation group was the same,but the difference was not statistically significant(H=2.529,P=0.282).The distribution of average recovery rate of pneumothorax with different initial compression ratios in oxygen inhalation group was not identical,and the difference was statistically significant(H=9.833,P=0.007).There was a statistically significant difference in the average daily recovery rate between the third group(<20%)and the first group(>30%)(p=0.003);and there was no significant difference between the other groups.Conclusion 1.The specific diameters of compressed lung and thoracic cavity are linearly correlated with pneumothorax compression ratio.Pneumothorax compression ratio can be accurately evaluated by regression equation.Univariate linear equation is superior to multivariate linear equation.The difference of equation between left lung and right lung was statistically significant.2.The average daily recovery rate of pneumothorax in the observation group was about 1.29%,which was similar to 1.25% reported in the literature.Oxygen inhalation can increase the average daily recovery rate of patients with pneumothorax treated conservatively.The average daily recovery rate of different initial compression ratios in the natural environment was the same.When the initial compression ratio is less than 20% and the initial compression ratio is more than 30%,the average daily recovery rate is different under the condition of oxygen absorption.