Cálculo de Kt/V em hemodiálise: comparação entre fórmulas / Calculation of Kt/V in haemodialysis: a comparison between the formulas

INTRODUÇÃO: A qualidade da diálise oferecida aos pacientes em diálise pode ser mensurada pelo Kt/V, o qual pode ser calculado de diversas maneiras. OBJETIVO: Comparar os resultados de Kt/V obtidos por meio das fórmulas de Lowrie (L) e de Daugirdas (D) com os resultados mensurados pelo monitor de clearence on-line - Online Clearence Monitor (OCM). MÉTODO: Estudo observacional transversal com 59 pacientes em hemodiálise (HD). Os dados foram coletados na mesma sessão de diálise: (ureia pré-diálise e pós-diálise) e o resultado de Kt/V foi obtido pelo OCM da máquina Fresenius 4008S (Fresenius Medical Care AG, Bad Homburg, Alemanha). RESULTADO: Foram analisadas 95 sessões, em que prevaleceu o sexo masculino, 56% (33), com idade média de 57 + 14 anos. A hipertensão arterial com 42% (25), diabetes com 12% (7) e glomerulonefrite com 8% (5) foram as causas mais frequentes da doença renal crônica (DRC). O Kt/V médio obtido pela fórmula de L, de D e pelo OCM foi de 1,31; 1,41 e 1,32, respectivamente. A comparação entre as fórmulas de L e D mostra que há diferença estatística p = 0,008 com a correlação de Pearson de 0,950. Entre D e OCM a diferença também é significativa: p = 0,011 e r = 0,346, provavelmente devido a perda convectiva, avaliada pela equação de D e não observadas por OCM e L. A comparação entre L e OCM não foi significativa p = 0,999 e r = 0,577. CONCLUSÃO: Os dados sugerem que o OCM pode ser utilizado como um norteador para ajuste da dose de diálise em tempo real.

INTRODUCTION: The quality of delivered dialysis can be measured by the Kt/V ratio, which can be calculated in various ways. OBJECTIVE: To compare the Kt/V ratio obtained with the formulas of Lowrie (L) and Daugirdas (D) with the results measured by an Online Clearance Monitor (OCM). Method: Observational, cross-sectional study of 59 patients on hemodialysis (HD). Data were collected in the same dialysis session (predialysis and postdialysis urea) and Kt/V was calculated by the OCM of the Fresenius 4008S machine (Fresenius Medical Care AG, Bad Homburg, Germany). RESULTS: A total of 95 sessions were assessed, with a predominance of males 56% (33), and a sample mean age of 57 + 14 years. Hypertension (42%; n = 25), diabetes (12%; n = 7) and glomerulonephritides (8%; n = 5) were the most frequent causes of chronic kidney disease (CKD). Mean Kt/V values obtained with the L and D formulas and the OCM were 1.31, 1.41 and 1.32, respectively. Comparison between the L and D formulas showed a statistically significant difference (p = 0.008), with a Pearson's correlation of 0.950. The difference between the D formula and the OCM was also significant (p = 0.011 and r = 0.346), probably due to convective loss, estimated by the D formula but not by the OCM and L formula. The difference between the L formula and the OCM was not significant (p = 0.999 and r = 0.577). CONCLUSION: These data suggest that the OCM can be used as a guide to the real-time adjustment of the dialysis dose.

Effects of Lowering Dialysate Calcium Concentrations on Arterial Stiffness in Patients Undergoing Hemodialysis

BACKGROUND/AIMS: We assessed changes in hemodynamic and arterial stiffness parameters following reductions of dialysate calcium concentrations in patients undergoing hemodialysis. METHODS: In this prospective study, 20 patients on maintenance hemodialysis (10 females, 10 males) with dialysate calcium concentrations of 1.75 mmol/L were enrolled. At the start of the study, the dialysate calcium level was lowered to 1.50 mmol/L. Serial changes in biochemical, hemodynamic, and arterial stiffness parameters, including pulse wave velocity (PWV) and augmentation index (AIx), were assessed every 2 months for 6 months. We also examined changes in the calcification-inhibitory protein, serum fetuin-A. RESULTS: During the 6-month study period, serum total calcium and ionized calcium decreased consistently (9.5 +/- 1.0 to 9.0 +/- 0.7, p = 0.002 vs. 1.3 +/- 0.1 to 1.1 +/- 0.1, p = 0.035). Although no apparent changes in blood pressure were observed, heart-femoral PWW (hf-PWV) and AIx showed significant improvement (p = 0.012, 0.043, respectively). Repeated-measures ANOVA indicated a significant effect of lowering dialysate calcium on hf-PWV (F = 4.58, p = 0.004) and AIx (F = 2.55, p = 0.049). Accompanying the change in serum calcium, serum fetuin-A levels significantly increased (95.8 +/- 45.8 pmol/mL at baseline to 124.9 +/- 82.2 pmol/mL at 6 months, p = 0.043). CONCLUSIONS: Lowering dialysate calcium concentration significantly improved arterial stiffness parameters, which may have been associated with upregulation of serum fetuin-A.

Effect of chloride dialysate concentration on metabolic acidosis in aintenance hemodialysis patients

Hyperchloremia is one of the multiple etiologies of metabolic acidosis in hemodialysis (HD) patients. The aim of the present study was to determine the influence of chloride dialysate on metabolic acidosis control in this population. We enrolled 30 patients in maintenance HD program with a standard base excess (SBE) ≤2 mEq/L and urine output of less than 100 mL/24 h. The patients underwent dialysis three times per week with a chloride dialysate concentration of 111 mEq/L for 4 weeks, and thereafter with a chloride dialysate concentration of 107 mEq/L for the next 4 weeks. Arterial blood was drawn immediately before the second dialysis session of the week at the end of each phase, and the Stewart physicochemical approach was applied. The strong ion gap (SIG) decreased (from 7.5 ± 2.0 to 6.2 ± 1.9 mEq/L, P = 0.006) and the standard base excess (SBE) increased after the use of 107 mEq/L chloride dialysate (from -6.64 ± 1.7 to -4.73 ± 1.9 mEq/L, P < 0.0001). ∆SBE was inversely correlated with ∆SIG during the phases of the study (Pearson r = -0.684, P < 0.0001) and there was no correlation with ∆chloride. When we applied the Stewart model, we demonstrated that the lower concentration of chloride dialysate interfered with the control of metabolic acidosis in HD patients, surprisingly, through the effect on unmeasured anions.

Efeito benéfico da correção da acidose metabólica no estado nutricional de pacientes em hemodiálise / Beneficial effects of metabolic acidosis correction in hemodialysis patients

Objetivo: Avaliar o efeito da correção da acidose metabólica no estado nutricional de pacientes em hemodiálise. Métodos: Foram estudados, durante seis meses, 20 pacientes com acidose metabólica, definida pela média de tr~es mensurações de bicarbonato sérico pré-diálise <22 mEq/L. os pacientes dialisavam há, pelo menos, seis meses, utilizando bicarbonato de 35 mEq/L no dialisato. A correção da acidose metabólica foi feita mediante elevação do bicarbonato no dialisato para valores que não ultrapassaram 40 mEq/L, objetivando um bicarbonato sérico entre 22-26 mEq/L. Foram avaliados no início e no final do estudo: avaliação antropométrica, dietética, bioquímica e Avaliação subjetiva Global (ASG). Resultados: A avaliação nutricional na fase inicial do estudo demonstrou índice de massa corporal normal (24,23 +- 3,83 Kg/m²). A circunferência muscular do braço, a prega cutânea tricipital e a ASG classificaram homens e mulheres como desnutridos. Os consumos de calorias e proteínas foram 29,7 +- 10,1 Kcal?kg/dia e 1,31 +- 0,35 g/Kg/dia, respectivamente. A avaliação bioquímica observou albumina sérica normal e colesterol reduzido. Após correção, bicarbonato sérico e pH aumentaram de 18,2 +- 1,64 para 22 +- 1,70 (p<0,001), e de 7,32+- 0,45 para 7,37 +-0,41 (p<0,001), respectivamente. Houve melhora da ASG (21,7 +- 6,4 versus 16,8 +-6,6, p<0,0001) e aumento na ingestão calórica (1.892,61 +-454,30 versus 2.110,30 +-869,24, p<0,05). Conclusão: A suplementação de bicarbonato na solução de hemodiálise foi método efetivo para a correção da acidose metabólica, determinando aumento da ingestão calórica e melhora nos escores da ASG.

Objective: To evaluate the effect of correction of metabolic acidosis on nutritional status of hemodialysis patients. Methods: We studied for six months, 20 patients with metabolic acidosis, defined as the average of tr ~ s measurements of predialysis serum bicarbonate <22 mEq / L. patients receiving dialysis treatment for at least six months, using bicarbonate of 35 mEq / L in the dialysate. The correction of metabolic acidosis was observed in the high bicarbonate dialysate for values that exceeded 40 mEq / L, aiming for a serum bicarbonate between 22-26 mEq / L. Were assessed at baseline and at the end of the study: anthropometric, dietary, biochemical and Subjective Global Assessment (SGA). Results: The nutritional assessment in the initial phase of the study showed normal BMI (24.23 + - 3.83 kg / m²). The arm muscle circumference, triceps skinfold and the ASG men and women classified as malnourished. The intake of calories and protein were 29.7 + - 10.1 Kcal? Kg / day and 1.31 + - 0.35 g / kg / day, respectively. The biochemical evaluation showed normal serum albumin and low cholesterol. After correction, serum bicarbonate and pH increased from 18.2 + - 1.64 for 22 + - 1.70 (p <0.001), and 7.32 + - 0.45 to 7.37 + -0.41 ( p <0.001), respectively. There was improvement in ASG (21.7 + - 6.4 versus 16.8 + -6.6, p <0.0001) and increased caloric intake (1892.61 + -454.30 vs 2110.30 + -869 , 24, p <0.05). Conclusion: Supplementation of bicarbonate in the dialysis solution was an effective method for correction of metabolic acidosis, determining increased caloric intake and improvement in the scores of the ASG.

Dosis de diálisis, nutrición y crecimiento en diálisis peritoneal pediátrica / Dialysis dose, nutrition and growth among pediatric patients on peritoneal dialysis

Stunting is common among pediatric patients on peritoneal dialysis. Aim: To stablish the best profile for urea kinetic variables associated to growth inchildren on chronic peritoneal dialysis (PD). Patients and Methods: Twenty patients, aged 1 month to 14 years, 13 males, were followed for 6-12 months, with monthly measurements of weight/age and height/age Z score; plasma creatinine, BUN, protein and albumin and urine and dialysate urea nitrogen, creatinine, protein and albumin. Minimum total Kt/V was 2.1. Dialysis dose (Kt/V), Protein Equivalent of Urea Nitrogen Appearence (PNA), Protein Catabolic Rate (PCR) and Nitrogen Balance (NB) were calculated. To identify the variable(s) associated to growth, the Tree Classification Model (CART) Enterprise Miner 8.1 was applied. Results: Mean total/residual Kt/V: 3.4±1.3/1.69±1.27; Daily Protein Intake (DPI) was 3.25±1.27 g/kg/day. nPNA, PCR and NB were 1.37±0.44, 0.84±0.33 and 1.86±1.25 g/kg/day, respectively. Mean heigth/age Z score was -2.3±1.19. Eleven patients showed a positive height/age delta Z (mean 0.55±0.38) and nine showed a negative growth (mean -0.50±0.42). The main variable explaining the positive growth was a Nitrogen Balance between 0.54 and 2.37 g/kg/ day, mean 1.55±0.21 (p <0.001). The second associated variable to growth was a residual Kt/V between 0.43 and 4.6 (2.02±0.49) (p <0.05). Kt/V and nPNA showed a significant correlation, but no correlation could be found between Kt/V and NB. Conclusions: Nitrogen Balance was the main variable associated to growth in pediatric PD, with values between 0.53 to 2.38 g/kg/day. The second variable was a residual Kt/V between 0.43 and 4.6. Therapy should be reassessed with NB values less than 0.54 or above 2.37 g/kg/day....

Short term study on relative merits of acetate and bicarbonate dialysis.

We did a double blind, crossover, prospective study comparing bicarbonate and acetate containing solutions in haemodialysis. Thirty stable patients with end stage renal disease on maintenance haemodialysis while awaiting a renal transplant were each studied on three dialysis with acetate and three with bicarbonate. Nine patients developed symptoms like headache, nausea, vomiting, giddiness, and malaise and developed hypotension during acetate dialysis and three patients during bicarbonate dialysis. There were symptoms during 16.66% of acetate dialysis sessions and 5.55% of bicarbonate dialysis sessions. (P less than 0.05). There was a statistically significant decrease in PaO2 and PaCO2 on acetate dialysis at 30 minutes after initiation of dialysis. There was no significant difference in weight loss on dialysis, or in blood pressure and correction of acidosis. We conclude that bicarbonate dialysis is better tolerated, but acetate intolerance is not a major problem since we use small surface area dialysers (0.8 M2).