The Use Of N-terminal Pro-brain Natriuretic Peptide To Assess Volume Status In Maintenance Hemodialysis Patients With Non Dominant Edema

BackgroundWith the completement of medical security system and the advance of bloodpurification technology, more patients with end stage renal disease can receive renalreplacement therapy and live long enough based on maintenance hemodialysis.Nevertheless, cardiovascular disease is the leading cause of mortality in dialysispatients. In addition to general cardiovascular risk factors, uremia-related factors areaslo leading to high cardiovascular mortality: volume overload with subsequenthypertension and left ventricular hypertrophy, chronic inflammation, accumulation ofuremic toxins as well as disturbances in the calcium-phosphate metabolism leading tovascular calcification are all contributing factors.Most of patients with ESRD exit chronic volume overload because of thediscontinuity of renal replacement therapy and irreversible loss of kidney function.Keeping the volume balance is essential to reduce the morbidity and mortality ofcardiovascular disease in patients with uremia. If the dry weight is set too high, it maylead to dialysis patients with hypertension, congestive heart failure, left ventricularhypertrophy, edema, effusion, and increasing the incidence of cardiovascular andcerebrovascular disease. If the dry weight is set too low, it may lead to dialysis patients with hypotension, shock, myocardial infarction, transient cerebral ischemia,and affecting compliance in dialysis patients. Therefore, in clinical practice, exactestimation of dry weight in hemodialysis patients remains a major challenge.Brain natriuretic peptide is a polypeptide secreted by myocardial cell in theventricular wall with stretch stimulation. Previous studies confirmed that BNP orNT-proBNP had a strong correlation with left ventricular hypertrophy and diastolicdysfunction in patients with CKD, and increasing in level of NT-proBNP might be animportant diagnostic tool for the detection and exclusion of impaired left ventricularfunction. Recently some scholars proposed, the level of BNP or NT-proBNP relatedto the extracellular volume in dialysis patients without left ventricular hypertrophy orsystolic dysfunction, but the hypothesis was not confirmed. BNP or NT-proBNPcould be used to assess volume status or not in dialysis patients remains controversial.As a method of evaluating dry weight among MHD patients, bioelectrical impedancetechnology has already been validated by isotope tracer method. In our study, weused bioelectrical impedance technology as the standard, and selected126MHDpatients as the research object, and analysed the use of NT-proBNP to assess volumestatus in maintenance hemodialysis patients with non-dominant edema.Objective1. To assess volume status in maintenance hemodialysis patients withnon-dominant edema by bioelectrical impedance technology.2. To explore the value of NT-proBNP to assess volume status in maintenancehemodialysis patients with non-dominant edema with the use of bioelectricalimpedance technology.MethodsResearch object: Enrollment took place between June2013and October2013inthe first affiliated hospital of zhengzhou university,126patients were recruited.64ofthem were woman,62of them were man.Experimental group: In mid-week dialysis session, bioimpedance measurements were performed prior to the hemodialysis session at the dialysis unit, the BCMinstrument returns measurements on overhydration (OH) in liters (L). The entirecohort based on OH value was divided into two groups, OH≤1for the normalgroup, OH>1for the hypervolemia group.Research content: At the beginning, we collected the clinical material anddetected the concentration of NT-proBNP. According to the grouping criteria, wecompared the NT-proBNP level of each group respectively, and analyzed thecorrelation between NT-proBNP and OH value. During three months, we adjustedvolume status of patients in hypervolemia group. After three months, according to theabove grouping criteria, we compared the NT-proBNP level of two groupsand analyzed the correlation between NT-proBNP and OH value again. At last, weused OH value as the standard in order to analyze the receiver operatingcharacteristic curve of NT-proBNP in maintenance hemodialysis patients withnon-dominant edema.Results1. At the beginning, baseline data of126patients:36of them were in normalgroup,90of them were in hypervolemia group, systolic blood pressure and diastolicblood pressure in hypervolemia group were higher than that in normal group, butthere were no significant differences on gender, age, BMI, weight.2. At the beginning, plasma NT-proBNP level of all subjects was higher than thenormal range (0-100pg/ml), the four quantile interval was615.50-2061.75pg/ml.Plasma NT-proBNP level of patients in hypervolemia group (n=90) was significantlyhigher than that of patients in normal group (717.00-3154.25pg/ml VS450.50-873.00pg/ml, P<0.001). NT-proBNP was positively correlated with the OH value(r=0.801, P<0.001).3. During3months, we adjusted volume status of patients in hypervolemiagroup (n=90). After three months, based on the OH value, there were41personsenrolled into the normal group. Plasma NT-proBNP level of all subjects was higherthan the normal range (0-100pg/ml), the four quantile interval was572.25-1936.75 pg/ml. Plasma NT-proBNP level of patients in hypervolemia group (n=49) wassignificantly higher than that of patients in normal group (982.50-2500.50pg/ml VS422.50-988.50pg/ml, P<0.001). NT-proBNP was positively correlated with the OHvalue (r=0.684, P<0.001).4. After3months, the OH value of90patients was significantly lower thanthat at the beginning (1.24±0.79L VS2.06±0.83L, t=11.710, P<0.001), the plasmaNT-proBNP level of90patients was also lower than that at the beginning(572.25-1936.75pg/ml VS717.00-3154.25pg/ml, Z=5.627, P<0.001).5. The receiver operating characteristic curve revealed an area under the curve of0.818for NT-proBNP when the OH value was set>1of overhydration,95%CI was(0.733-0.904), P<0.001. The cut off value of plasma NT-proBNP was set at962.5pg/ml in MHD patients with non dominant edema, the diagnostic specificity andsensitivity were79.6%and73.2%.Conclusion1. In MHD patients with non dominant edema, fluid overload was stillwidespread.2. NT-proBNP could be used to assess volume status in MHD patients with nondominant edema.