The Value And Related Factors Of Pulmonary B-line Artifact In Volume Assessment Of Hemodialysis Patients

Objective: This study was to investigate the value of lung ultrasound in the evaluation of volume overload in maintenance hemodialysis(MHD)patients,to observe the changes of B-line before and after dialysis,and to analyze the related risk factors of B-line score before dialysis.Methods: Eighty patients with chronic kidney disease who received maintenance hemodialysis in the hemodialysis center and nephrology department of our hospital from December 2019 to December 2020 were selected.Body mass index(BMI),gender,duration of dialysis,primary disease,NYHA grading of cardiac function,history of diabetes and hypertension,systolic blood pressure,interdialysis weight gain,and predialysis related laboratory parameters were collected.All ultrasound examinations were performed within 30-40 minutes before and after dialysis.Lung ultrasound: 28 area scanning method is used to assess the severity of extravascular pulmonary water,the sum of the number of B-line in each area to get the B-line score,line will B < 15 patients were divided into mild edema groups,The patients were divided into mild pulmonary edema group(B-line < 15),moderate pulmonary edema group(B-line:15-29),severe pulmonary edema group:(B-line≥30).Cardiac ultrasound: Measurement of left ventricular diameter,left ventricular mass,left ventricular myocardial mass index(LVMI)= left ventricular mass/surface area.In the apical four chamber heart view,pulmonary artery systolic pressure(PASP),tricuspid sidewall systolic displacement(TAPSE),the fraction of right ventricular area change(FAC)were measured.The E/ e’values were calculated by the mitral valve early diastolic peak velocity(E peak)and the mitral valve motion velocity(e’).Using Simpson method to obtain left atrial volume index(LAVI),left ventricular ejection fraction(LVEF).The end-expiratory inferior vena cava diameter(IVCD)and end-inspiratory IVCD were measured under xiphoid process.The end-expiratory IVCD was corrected by body surface area to obtain IVCD index(IVCDi).Inferior vena cava collapse index(IVCCI)was calculated by formula.SPSS 26.0 was used for statistical analysis of the data to compare the differences in various indicators of patients with different degrees of pulmonary congestion and the differences in various ultrasonic parameters before and after dialysis,and to analyze the factors affecting the pre-dialysis B-line score.P < 0.05 was considered statistically significant.Results: B-line could be detected in most MHD patients,in which 41.2%of patients with moderate to severe pulmonary congestion,47.5% of patients with occult pulmonary congestion and had no obvious clinical symptoms.General clinical data: there were no statistically significant differences in age,gender,dialysis duration,BMI and systolic blood pressure among the three groups(P > 0.05).The proportion of diabetes,NYHA grade III-IV and hypersensitive C-reactive protein in moderate and severe groups were higher than those in mild group,and albumin was lower than that in mild group(P <0.05).In the severe group,interdialysis weight gain and neutrophils/lymphocyte ratio(NLR)is significantly higher than moderate group and mild group,the hemoglobin significantly lower than the moderate group and mild group(P < 0.05).Ultrasound parameters of heart and inferior vena cava: IVCDi,LVMI,LVDD,E/e’ values,PASP and the proportion of combined pulmonary hypertension in moderate and severe groups were significantly higher than those in mild group,and LVEF was significantly lower than that in mild group(P < 0.05).In the severe group,LAVI was higher than that in moderate and mild groups,and IVCCI was lower than that in mild group(P < 0.05).Univariate linear regression analysis showed that age,systolic blood pressure,diabetes,NYHA grade,hypersensitive C-reactive protein,NLR,albumin,hemoglobin,IVCDI,LAVI,PSAP,E/e’value,LVMI,LVDD and LVEF were correlated with B-line score(P <0.05).Further multivariate stepwise linear regression analysis showed that B-line score was positively linearly correlated with NYHA grade,LAVI,interdialysis weight gain and hypersensitive CRP.After dialysis,B-line score,IVCDI,PASP,LAVI and E/e’ values were significantly lower than those before dialysis,while LVEF was increased after dialysis,with statistical significance(P < 0.05).Conclusion: Different degrees of pulmonary congestion can be found in MHD patients by lung ultrasound examination,and the number of B-line decreases significantly after dialysis.Pulmonary ultrasound is an objective and reliable method to evaluate patients’ volume load status,which can sensitively detect the changes of extravascular pulmonary water,and can help early clinical identification of patient volume overload and guide the development of appropriate dialysis program.The existence of B-line in patients is not only related to volume overload,but also related to NYHA grading,left atrial volume index,inflammation and other factors.Clinicians should intervene in time to reduce volume overload of patients and reduce the occurrence of adverse outcomes.