Functional Lung Volume Measurement Method For The Prediction Of Postoperative Pulmonary Function

Objective: We compared the changes of pulmonary function and the functional lung volume after lung resection surgery,and the accuracy of functional lung volume measurement method and segment-counting method for the prediction of postoperative pulmonary function was investigated.Methods: The patients in the first affiliated hospital of Dalian Medical University from January 2011 to December 2018 who underwent thoracoscopic lobectomy(56 cases)and sublobar resection(57 cases,including 9 cases of segmentectomy and 48 cases of wedge resection)were included in this retrospective study.We evaluated the changes of pulmonary function and functional lung volume before and after the first surgery,predicted the postoperative pulmonary function by functional lung volume measurement method and segment-counting method,and evaluated the correlation and consistency between the predicted and measured value.Pearson’s correlation coefficient was used to analyze the correlation between the predicted and measured values by functional lung volume measurement method and segment-counting method.Bland-Altman analysis was used to evaluate the consistency of the predicted values and actual postoperative pulmonary function.The linear regression model was used to correct the effect of confounders on the prediction of postoperative pulmonary function,and the regression equation between the factors affecting pulmonary function and the measured values was established.Results: There was no significant difference in gender,age and smoking history between the thoracoscopic lobectomy group(n=56)and sublobar resection group(n=57)(P>0.05).There was no significant difference in preoperative pulmonary function(FVC,FVC%,FEV1,FEV1%,MVV,MVV%)between the two groups(P>0.05).There was no significant difference in postoperative pulmonary function(post FVC,post FEV1,post MVV)between the two groups(P>0.05).However,the loss ratio of FEV1 and MVV after lobectomy was significantly larger than sublobar resection(P<0.05).The average functional lung volume of the left upper lobe was 999.42±300.19 mL(24.08%),the right lower lobe 982.97±256.42 mL(23.91%),the left lower lobe 912.56±281.62 mL(21.88%),the right upper lobe 844.91±277.99 mL(20.39%),and the right middle lobe396.12±116.11 mL(9.74%).In the lobectomy group,the postoperative functional lung volume of the ipsilateral unaffected lobe increased 29.18%(6.73%,52.93%).The postoperative functional lung volume of the contralateral unaffected lobe increased6.18%(1.05%,17.20%),and there was a significant difference between the two groups(P<0.05).The predicted value of postoperative pulmonary function(ppo FVC,ppo FEV1)of functional lung volume measurement method and segment-counting method can reflect the measured value of lung function(post FVC,post FEV1)of patients after lung resection surgery.There was no significant difference between the two method,but the difference between the predicted values and the measured values of the functional lung volume measurement method were smaller than that of the segment-counting method.The regression analysis showed that the measured value of preoperative pulmonary function parameters and the ratio of reduced functional lung volume to preoperative functional lung volume had significant influence on postoperative pulmonary function parameters(FVC,FEV1),and thus established the prediction of postoperative pulmonary function(FVC,FEV1)parameters regression equation,ppo FVC = 0.8 x FVC-0.784 x Δ FLV/FLV+ 0.283(r = 0.823,P < 0.001);ppo FEV1 = 0.766 x FEV1-0.694 x Δ FLV/FLV + 0.22,(r= 0.862,P < 0.001).At the same time,the feasibility of using this equation to predict the parameters of pulmonary function after wedge resection was verified.Conclusion: The predicted value of postoperative pulmonary function(ppo FVC,ppo FEV1)of functional lung volume measurement method and segment-counting method can reflect the measured value of lung function(post FVC,post FEV1)of patients after lung resection surgery.There was no significant difference between the two method,but the difference between the predicted values and the measured values of the functional lung volume measurement method were smaller than that of the segment-counting method.The improved formula based on functional lung volume measurement method further accurately predicts pulmonary function after surgery and provides a reference for postoperative pulmonary function evaluation.