Validação de amostragem continua de dialisato e descrição da cinética de fósforo durante a hemodiálise

Abstract

Chronic kidney disease is an injury that causes a progressive loss of kidney function. In its most advanced form, the kidney can not perform its functions properly. One of the therapies used to remove toxins and excess water from the body, replacing kidney function, is hemodialysis. This hemodialysis should be evaluated for its quality to determine if the dose is suitable for each patient. One of the parameters used to suit this therapy recommended by most of the guidelines today is the urea Kt / V. The direct quantification of urea in the dialysate through the total collection of dialysate is considered the gold standard to verify dialysis adequacy. This method requires a continuous collection of dialysate during dialysis, a fractional collection of the dialysate to determine the phosphorus kinetics and the total collection of the same. On the other hand, applying this model in the routine of dialysis is difficult and prevents its widespread use in clinical practice. Thus, the first article aimed to validate a low volume method through a continuous sampling of dialysate liquid. For this, continuous samples of dialysate were obtained, through an infusion pump with inverted flow, through a continuous flow collector and the total dialysate collection, using a trough. The results were mean values of urea in the total dialysate collection and calculated from the 40 mL sample of the standard dialysate collection were 33.70 (11.70) g and 33.90 (11.70) g, respectively [r 0.96, p <0.0001; bias -0.2 (95% CI -1.8 to 1.4); limits of agreement -6.8 to 6.4]. The anthropometric measurement, when compared with the direct quantification method, distribution of underestimated urea volume in patients with smaller body size. In conclusion, this work shows that this new simple, low-cost, low-volume technique can provide accurate information on the total amount of solutes removed by hemodialysis. In the second article, the objective of this study was to determine the profile of the elimination of phosphorus in the liquid dialysate during the same period and to correlate the eliminated phosphorus load with the calculation of the actual Kt / V of urea. For this, blood samples were collected before and after the session to know how much each patient lost after hemodialysis. The eliminated phosphorus load was correlated with the calculation of the actual Kt / V of urea according to the Daugirdas formula. The fractionated samples of dialysate were obtained through a continuous flow manifold. Blood samples were also collected before and after a session to determine pre and post-dialysis urea values to calculate Kt / V. The eliminated phosphate loading was correlated with the actual calculation of Kt / V urea according to formula of Daugirdas. According to the results the phosphate levels (after the beginning of the session) were 1.26 ± 0.61 mg / dL and at the end of the session, the levels were reduced to 0.59 ± 0.19 mg / dL. Phosphate levels remain high in the first two hours, and there is a significant reduction after that period until the end of the session. The Kt / V of the sample was 1.35 ± 0.58 and the phosphorus load was 0.70 ± 0.40, and there was no correlation between Kt / V and the phosphorus load (r2 = -0.3607 ; p = 0.123). This study proves that Kt / V serves only as a predictor of elimination quality for a urea, and not for other solutes such as phosphorus