Clinical Research On Influencing Factors Of Phosphorus Clearance In Hemodialysis

Objective:Phosphorus retention is an early event in chronic renal failure (CRF) and is closely related to the development of secondary hyperparathyroidism. In addition, increase of phosphorus can also lead to the onset of metastatic calcifications and in its severest form to calciphylaxis. From an epidemiological perspective, sustained hyperphosphatemia is associated to high mortality indexes, related to calcifications of the coronary arteries, and left ventricular hypertrophy. Observation on the serum phosphorus clearance through hemodialysis(HD), with further research into the influencing factors.Method:Eighty uremic patients who were undergoing dialysis treatment in the hemopurification center at Number Four Hospital of Hebei Medical University were selected from June 2006 to February 2008. CKD according to the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF–K/DOQI) classification. All the patients were in the final stages of renal disease. Among them there were forty-three Chronic glomerulonephritis; eighteen diabetic nephrology; five polycystic kidney disease; four IgA nephrology; three benign arteriolar nephrosclerosis; three drug-interrelated kidney disease; one lupus nephritis; one obstructive nephropathy; one gouty kidney; one Alport syndrome; in total, fifty-two men and twenty-eight women, with patients ages ranging from twentty-five to eighty- five years old having being treated with dialysis from between three to eighty months. Treatment consisted of the use of a Fresenius 4008S dialysis machine utilizing a carbonate dialysis solution. The efficiency blood flow was 180～310ml/min and the dialysate flow rate was 500ml/min. Disinfector was Renalin, Reused machine is Renatron. All patients adopted internal arteriovenous fistula. In all the cases, the dialysis session duration was 4.5hours, three times per week. The dialyzer used was: F6 polysulfone with ultrafiltration coefficient of 5.5ml/h·mmHg and a surface area of 1.3m2: 19 patients; F60 polysulfone with ultrafiltration coefficient of 40ml/h·mmHg and a surface area of 1.3m2: 6 patients; APS900 polysulfone with ultrafiltration coefficient of 75ml/h·mmHg and a surface area of 1.8m2: 9 patients; cellulose acetate hollow fiber CA-HP150 with ultrafiltration coefficient of 10.2ml/h·mmHg and a surface area of 1.5m2: 36 patients; cellulose triacetate hollow fiber CT-190G with ultrafiltration coefficient of 17.4ml/h·mmHg and a surface area of 1.9m2: 10 patients, 16 patients with a dialysate calcium concentration which was standardized at 1.25mmol/L, and 64 patients were treated with a dialysate calcium concentration standardized at 1.5 mmol/L.All the patients had underwent dialysis treatment for more than three months and were all stable. Through the dialysis procedure, without dietary phosphorus intake, calcium-containing phosphate binders, urinate. No malnutrition and heart failure occurred. In order to confirm there was no brine and heparin before taking blood samples, the blood sample for predialysis was gained from the artery tubule, before the artery tubule was connected, the syringe had been sterilized. The blood sample of postdialysis was gained from the artery tubule after hemodialysis was over, blood flow rate decreased to 50ml/min before the blood sample was gained from the artery tubule that was closest to the patients. 2 ml blood was gathered once. The samples are collected and examinated within one hour. The serum concentration of phosphate, creatinine,urea,calcium and carbon dioxide-combiming power (CO2CP) in both predialysis and postdialysis. Hematocrit (HCT) was examinated by conventional method in our inspection department. Serum phosphate was presented as mean±standard deviation( x±s), the compare between before and after oneself with Paired comparison. According to the equation: SRR=[(CB–CA) /CB]×100% (CB represents the predialysis concentration of solute, CA represents the postdialysis concentration of solute), to calculated the solute reduction ratio (phosphate, urea, creatinine). We selected 14 clinical parameters, including gender, age, predialysis serum concentration of phosphate, calcium, CO2CP, predialysis haematocrit, the solute (urea, creatinine, phosphate) reduction ratio, blood flow rate, dialysate calcium concentration, ultrafiltrate volume, membrane surface area, blood chamber volume, ultrafiltrate coefficient. Simple regression has been used to relate quantitative variables. The results were considered to be statistically signifycant when the probability of type I error was less than 0.05. Multivariate analysis has been done introducing into the model only those variables that were related with phosphorus clearance in the univariate analysis.This has been a Forwards analysis in a multicolinearity study.Result:1 The postdialysis serum phosphate concentration was obvious lower than that of predialysis (0.84±0.21mmol/L, 2.00±0.53mmol/L), there was statistical significance (p<0.05).2 In the Simple regression: Serum phosphate reduction ratio was related with phosphorus plasma levels (r=0.493, p<0.05), membrane surface area (r=0.386, p<0.05), blood flow (r=0.368, p<0.05); the creatinine reduction ratio(r=0.482, p<0.05); blood chamber volume (r=0.303,p<0.05), predialysis haematocrit (r=–0.225,p<0.05);not related with gender, age, predialysis serum consistency of calcium, CO2CP, urea reduction ratio, dialysate calcium concentration, ultrafiltrate volume, ultrafiltrate coefficient (p>0.05).3 In the multivariate analysis: the predictive variables for phosphate dreduction ratio, predialysis phosphate consistency, creatinine reduction ratio, membrane surface area and blood flow (p<0.05) . Conclusion:1 Hemodialysis could effectively remove serum inorganic phosphorus.2 Predialysis phosphate consistency, membrane surface area, blood flow have gradually weaker effect on phosphorus clearance in hemodialysis, however, of those are independent factors. Besides, blood chamber volume and haematocrit, to certain extent, are effective to the phosphorus clearance, whereas patient's age, gender, CO2CP, calcium, the declining urea, dialysate calcium, ultrafiltrate volume, ultrafiltrate coefficient proved to be not related.3 It is inaccurately estimated the declinning ratio of phosphate clearance through the declining rate of creatinine, with which the two figures are independently connected.