Low‐potassium and glucose‐free dialysis maintains urea however enhances potassium removing | Nephrology Dialysis Transplantation

Low‐potassium and glucose‐free dialysis maintains urea but enhances potassium removal | Nephrology Dialysis Transplantation
February 4, 2021 0 Comments

Summary

Background. The affect of potassium (Okay) removing on dialysis effectivity as measured by urea elimination will not be clear. On this potential, randomized, cross‐over research we investigated the magnitude of Okay removing and its impact on urea (u) elimination throughout excessive‐flux haemodialysis (HD).

Strategies. Twelve secure, non‐diabetic HD sufferers had been investigated throughout three one‐week standardized HD durations (1.8 m2 excessive‐flux polysulphone dialyser, remedy time 240 min, Qb=300 ml/min, Qd=500 ml/min, dialysate with out glucose, bicarbonate 40 mmol/l), utilizing dialysates containing 0 (0K), 1 (1K), and a pair of (2K) mmol/l of Okay. Mass removing of Okay (MOkay) and u (MU) had been measured in the course of the mid‐week remedy by partial dialysate assortment. Urea discount charge (URR) and Kt/V had been decided.

Outcomes. 0K, 1K and 2K remedies had been completely comparable. Plasma Okay (PK) constantly declined reaching secure concentrations after 180 min. Whereas 0K dialysate eliminated 117.1 mmol, 80.2 and 63.3 mmol (P<0.001) had been eliminated by 1K and 2K baths respectively. MU was not influenced by MOkay (r=0.22) and amounted to 491.1 (0K), 508.6 (1K), and 506.2 (2K) mmol (NS) respectively. Accordingly, urea clearance, URR and Kt/V had been fixed throughout 0K, 1K and 2K remedies.

Conclusions. Potassium‐free dialysate considerably enhances potassium elimination. Potassium removing has no affect on urea elimination. Excessive potassium removing, when wanted, doesn’t impair dialysis effectivity as measured by urea kinetics in excessive‐flux, glucose‐free, 40 mmol/l bicarbonate HD.

Introduction

Sufferers affected by finish‐stage renal illness (ESRD) are at excessive danger of hyperkalaemia as a consequence of diminished renal potassium excretion in addition to impaired extrarenal potassium disposal [1–3]. One of many important targets of dialysis is to take away extra potassium gathered within the interdialytic interval. Nonetheless, acute decreasing of plasma potassium ranges by haemodialysis (HD) might have haemodynamic results and result in rebound hypertension [4].

However, we really feel that ESRD sufferers can keep a traditional whole physique potassium offered they’re effectively dialysed and effectively nourished, and we’re keen to just accept a extra liberal meals consumption. Actually, we discovered a traditional whole physique potassium in sufferers dialysed 3 times weekly for 4–5 h utilizing excessive‐flux dialysers with a floor space of 1.8–2.4 m2 [5].

The speed of potassium removing from the plasma will depend on the gradient between plasma and dialysate potassium concentrations. Potassium‐free dialysate improved potassium elimination by 24 and 50%, in comparison with a dialysate potassium of 1 and a pair of mmol/l respectively, throughout low‐flux dialysis [6].

A current research by Dolson and Adrogué [7] confirmed that in low‐flux, glucose, 30 mmol/l bicarbonate HD, dialysis effectivity evaluated by way of the urea discount charge and Kt/V was considerably decreased when reducing dialysate potassium focus from 3 to 1 mmol/l. The authors defined this impact as a consequence of decreased blood move to urea‐wealthy tissues, largely skeletal muscular tissues, secondary to vasoconstriction induced by aggressive potassium removing.

The scientific implications of this end result must be seen with scepticism. The dialysis group is perhaps persuaded to favour excessive potassium concentrations within the dialysate tub and danger hyperkalaemia with a view to improve the dose of delivered dialysis measured by urea kinetics. We expect that aside from performing an enough dialysis as measured by urea kinetics, dialysis should give attention to removing of acute and persistent uraemic toxins equivalent to potassium and phosphate, which differ from urea of their distribution and elimination traits. Due to this fact, we undertook an analogous research in our dialysis inhabitants utilizing remedy modalities typical of our dialysis unit (excessive‐flux, glucose‐free, 40 mmol/l bicarbonate HD) and investigated the impact of 0K, 1K, and 2K baths on urea and potassium elimination.

Topics and strategies

Sufferers

Twelve sufferers with finish‐stage renal illness receiving upkeep excessive‐flux HD had been studied prospectively. There have been six ladies and 6 males aged 30–73 (56.2±4.1 imply±SEM) years. Six sufferers suffered from persistent glomerulonephritis, three from analgesic nephropathy, and one every from grownup polycystic kidney illness, nephrosclerosis, and reflux nephropathy respectively. Diabetic sufferers and people with coronary heart illness weren’t thought-about for this research. Six sufferers had radiocephalic fistulae, 5 had brachiocephalic fistulae, and one had a brachiosubclavian PTFE graft. Serum albumin of all sufferers was above 35 (imply 41.1±1.2) g/l and the imply predialysis haematocrit was 38.0±1.0% in the beginning of the research. Sufferers had been studied below their regular every single day situation; for that reason meals was allowed as regular. All sufferers continued to obtain their regular treatment. One affected person obtained a small dose of the cardioselective β‐blocker atenolol (50 mg day) and two obtained amlodipine (5–10 mg day) for remedy of hypertension, however none was taking digoxin, angiotensin‐changing enzyme inhibitors, angiotensin‐receptor blockers, or potassium‐binding trade resins. Medicines weren’t modified throughout the whole research interval.

Research design

This was a randomized, cross‐over, potential scientific trial. Sufferers had been investigated throughout three 1‐week standardized excessive‐flux HD durations, utilizing dialysates with out potassium (0K), and dialysates containing 1 (1K) and a pair of (2K) mmol/l of potassium. They had been randomly assigned to the completely different 1‐week research remedies. Throughout the whole research they had been handled with excessive‐flux HD utilizing a polysulphone filter (HF80, Fresenius AG, Unhealthy Homburg, Germany). HD was carried out thrice weekly, at an efficient blood move charge of 300 ml/min corrected for pre‐pump blood stress and a dialysate move of roughly 500 ml/min. Therapy time was 240 min. Extremely‐pure, bicarbonate‐buffered dialysate with Na 140.0, HCO3 40.0, Mg2+ 0.5, and Ca2+ 1.5 mmol/l was obtained by filtration by means of a 1.8 m2 polysulphone filter (Diasafe, Fresenius AG, Unhealthy Homburg, Germany). The dialysate didn’t comprise glucose. The identical two dialysis displays had been utilized for all sufferers and filter reuse was not practised. The ultrafiltration charges had been prescribed in accordance with the scientific wants and had been calculated from the affected person’s internet weight adjustments.

Potassium and urea kinetic investigations had been carried out in the course of the mid‐week remedy. Potassium and urea removing was measured by partial dialysate and ultrafiltrate assortment as described beforehand [8–10]. The gathering system was calibrated earlier than every research. The imply ratio (f=Vd/Vc) of whole dialysate quantity (Vd) to collected quantity (Vc) was 24.9±0.02 (SEM). Dialysate and ultrafiltrate had been collected in 4‐hourly samples (0–60, 61–120, 121–180 and 181–240 min). Plasma potassium (PK) and blood urea had been additionally measured in the beginning, at hourly intervals, and on the finish of the dialysis process. Blood samples had been drawn from the arteriovenous fistula in the beginning and on the finish of HD. Blood sampling on the finish of HD was carried out 5 min after the completion of remedy to keep away from vascular entry and cardiopulmonary recirculations following the suggestions of the NKF‐DOQI Scientific Apply Tips for Haemodialysis Adequacy [11]. In the course of the dialysis process, samples had been taken from the arterial line.

Effectivity of HD for urea and potassium was decided by clearance (Kd) based mostly on dialysate and ultrafiltrate assortment, urea discount ratio (URR) and Kt/V.

Biochemistry

Potassium was measured utilizing an IMT‐Modul on a Dimension RXL (DADE‐Behring, Marburg, Germany) in heparin‐plasma and dialysate. Coefficients of variation had been lower than 2%. Urea was measured in heparin‐plasma and dialysate in accordance with the urease–glutamate–dehydrogenase approach on the Dimension RLX. Coefficients of variations had been lower than 2.5%.

Evaluation

Whole dialysate plus ultrafiltrate quantity (Vd, in l) was calculated from the amount (Vc) obtained from partial dialysate and ultrafiltrate collections and from the calibration issue (f) decided in the beginning of every research. Mass of potassium and urea eliminated (MOkay, MU) was calculated from the imply solute focus within the collected dialysate and from Vd.

Dialyser urea clearance (KdU) was calculated from the quantity of solute eliminated and the realm below the curve (AUC) of the blood urea concentrations.

Single pool Kt/V (Kt/Vsp) was calculated utilizing the second‐technology components of Daugirdas [12]. Kt/V measures the amount of clearance normalized to distribution quantity obtained by a affected person. Kt/V has a precise bodily which means solely with the one‐pool fixed quantity urea kinetic mannequin [13]. The connection doesn’t seem in additional superior fashions the place quantity (V) adjustments due to ultrafiltration and the place urea switch between peripheral and central physique compartments is restricted to tissue perfusion. An equilibrated Kt/V can nonetheless be calculated both when an equilibrated put up‐dialysis urea focus is out there or when the magnitude of put up‐dialysis urea rebound will be predicted. Nonetheless, the prediction of put up‐dialysis urea rebound and equilibrated Kt/V turns into unreliable when adjustments in regional perfusion are anticipated. Due to this fact a special method was used to analyse the impact of dialysate potassium on dose of dialysis.

The one‐pool fixed quantity relationship between for Kt/V will be rearranged when it comes to mass balances in accordance with the next relationship:

formula

the place M0 and Md confer with the mass of urea in the beginning of dialysis and to the mass of urea eliminated throughout dialysis respectively. Due to this fact Kt/V additionally measures the quantity of solute remaining within the affected person on the finish of dialysis (M0−Md) relative to the quantity of solute (M0) current within the affected person in the beginning of the remedy. Utilizing this definition, mass steadiness can be utilized to find out an equilibrated Kt/V (Kt/Ve) obtained below extra sensible variable quantity and two‐pool circumstances. It follows from Eq. 1 that the distinction in Kt/Ve (ΔKt/Ve) delivered by two completely different remedy modes A and B is given as

formula

The worth ΔKt/Ve as outlined right here shouldn’t be confused with the expression of ΔKt/Vsp‐eq which is used to foretell the overestimation of dialysis dose by single‐pool urea kinetic evaluation [14]. ΔKt/Ve as outlined right here can be utilized to check the distinction in dose of dialysis between remedies when the quantity of solute eliminated throughout dialysis (Md) is measured equivalent to by partial dialysate assortment. Nonetheless, it needs to be assumed that urea technology charge will not be affected by completely different remedy modes. The preliminary quantity of solute (M0,A, M0,B) was decided from whole physique water (TBW) [15] corrected for ultrafiltration quantity (UFV) and preliminary plasma urea focus (cb0). Systematic errors within the estimation of TBW have a negligible affect on the calculation of ΔKt/Ve if the impact of two completely different remedies is measured in the identical affected person. This method is unbiased of two‐compartment results and put up‐dialysis urea rebound, and doesn’t require an equilibrated put up‐dialysis urea focus. It is a main benefit as a result of the research will be carried out with out lowering efficient remedy time or asking the affected person to remain for an equilibrated pattern.

Statistical evaluation

Evaluation of variance for repeated measures was used for assessing the statistical significance of variations in MU and MOkay between the remedies. This method was justified since QQ‐plots confirmed that the distributions of residuals of MU and MOkay had been near regular.

If a given variable confirmed important heterogeneity throughout the three teams of dialysis within the previous evaluation of variance, the variations between any two of the three teams had been assessed with two‐sided paired t‐assessments. Making use of Bonferroni correction, the ensuing P‐values had been multiplied by 3.

Stepwise a number of linear regression evaluation was carried out utilizing the blood and plasma ranges of urea and potassium respectively, to foretell the mass of urea and potassium eliminated. If the regression mannequin confirmed a excessive precision (R2⩾0.90), evaluation of Bland and Altman [16] was carried out for figuring out the energy of affiliation.

For all calculations, Stata software program, model 6.0 for Home windows 95/98 (Stata Company, 77840 Texas) was used.

Information are expressed as means±SEM.

Outcomes

All sufferers accomplished the research. The three 1‐week durations had been completely comparable. Predialysis weight, dialysate move, ultrafiltrate move, and ultrafiltration quantity weren’t completely different throughout 0K, 1K, and 2K remedies. Preliminary blood urea focus, whole physique water and urea mass of the sufferers weren’t completely different in the course of the research HDs as effectively (Desk 1).

Desk 1.

Therapy traits


 

0K


 

1K


 

2K


 

P


 

Sufferers  12  12  12 
Predialysis weight (kg)  67.3±4.7  67.0±4.7  67.0±4.6  NS 
Dialysate move (Qd) (ml/min)  27±8.0  26±6.0  40±9.0  NS 
Ultrafiltrate move (Qf) (ml/min)  10±0.8  10±0.9  8.0±0.6  NS 
Preliminary blood urea (cb0) (mmol/l)  20.10±1.40  20.26±1.56  20.11±1.55  NS 
Preliminary physique water (TBW0) (l)  37.08±2.20  37.02±2.18  36.73±2.14  NS 
Preliminary urea mass (M0) (mmol)  68±87  66±82  50±83  NS 
Ultrafiltrate quantity (l)  2.3±0.2  2.4±0.2  2.0±0.2  NS 

 

0K


 

1K


 

2K


 

P


 

Sufferers  12  12  12 
Predialysis weight (kg)  67.3±4.7  67.0±4.7  67.0±4.6  NS 
Dialysate move (Qd) (ml/min)  27±8.0  26±6.0  40±9.0  NS 
Ultrafiltrate move (Qf) (ml/min)  10±0.8  10±0.9  8.0±0.6  NS 
Preliminary blood urea (cb0) (mmol/l)  20.10±1.40  20.26±1.56  20.11±1.55  NS 
Preliminary physique water (TBW0) (l)  37.08±2.20  37.02±2.18  36.73±2.14  NS 
Preliminary urea mass (M0) (mmol)  68±87  66±82  50±83  NS 
Ultrafiltrate quantity (l)  2.3±0.2  2.4±0.2  2.0±0.2  NS 
Desk 1.

Therapy traits


 

0K


 

1K


 

2K


 

P


 

Sufferers  12  12  12 
Predialysis weight (kg)  67.3±4.7  67.0±4.7  67.0±4.6  NS 
Dialysate move (Qd) (ml/min)  27±8.0  26±6.0  40±9.0  NS 
Ultrafiltrate move (Qf) (ml/min)  10±0.8  10±0.9  8.0±0.6  NS 
Preliminary blood urea (cb0) (mmol/l)  20.10±1.40  20.26±1.56  20.11±1.55  NS 
Preliminary physique water (TBW0) (l)  37.08±2.20  37.02±2.18  36.73±2.14  NS 
Preliminary urea mass (M0) (mmol)  68±87  66±82  50±83  NS 
Ultrafiltrate quantity (l)  2.3±0.2  2.4±0.2  2.0±0.2  NS 

 

0K


 

1K


 

2K


 

P


 

Sufferers  12  12  12 
Predialysis weight (kg)  67.3±4.7  67.0±4.7  67.0±4.6  NS 
Dialysate move (Qd) (ml/min)  27±8.0  26±6.0  40±9.0  NS 
Ultrafiltrate move (Qf) (ml/min)  10±0.8  10±0.9  8.0±0.6  NS 
Preliminary blood urea (cb0) (mmol/l)  20.10±1.40  20.26±1.56  20.11±1.55  NS 
Preliminary physique water (TBW0) (l)  37.08±2.20  37.02±2.18  36.73±2.14  NS 
Preliminary urea mass (M0) (mmol)  68±87  66±82  50±83  NS 
Ultrafiltrate quantity (l)  2.3±0.2  2.4±0.2  2.0±0.2  NS 

Potassium removing

Determine 1 illustrates the impact of every dialysate potassium focus on plasma potassium focus and on hourly potassium removing. Predialysis plasma potassium concentrations had been solely barely decrease with 0K and 1K dialysis remedies in comparison with 2K dialysis remedies; values had been 4.4±0.2, 4.5±0.2 and 4.9±0.2 mmol/l (P=0.02) respectively. Throughout haemodialysis PK declined constantly reaching a nadir at 180 min and remaining fixed to the tip of the remedies. PK at completion of dialysis was clearly decrease with 0K as in comparison with 1K and 2K, attaining 2.7±0.1, 3.0±0.2 and three.5±0.1 mmol/l (P<0.001) respectively. Mass removing of potassium (MOkay) was highest in the course of the first 60 min and declined, reaching a continuing worth over the past 120 min aside from the 2K dialysis; on this case MOkay from 181 to 240 min was considerably decrease than MOkay from 121 to 180 min. Over the last 60 min potassium removing continued despite a continuing plasma potassium focus.

Our evaluation reveals that the quantity of potassium eliminated is considerably completely different between the three regimens used. After 240 min of dialysis, potassium‐free dialysate is simpler than 1K and 2K dialysate in eradicating physique potassium. Potassium removing was 117.1±10.3 mmol for 0K, 80.2±6.2 mmol for 1K, and 63.3±5.2 mmol for 2K (P<0.001). Potassium‐free dialysate eliminated 85% extra potassium than 2K and 46% greater than 1K.

Apparently, potassium removing couldn’t be predicted by modelling plasma potassium concentrations. A number of linear regression analyses demonstrated that potassium removing couldn’t be estimated by potassium plasma concentrations (R2=0.18) (Desk 2).

Fig. 1.

Potassium removal. Plasma potassium (PK) concentrations (upper) and potassium mass removed (MK) (lower) during standardized high‐flux HD with potassium‐free (0K), potassium 1 mmol/l (1K), and potassium 2 mmol/l (2K) dialysates. PK concentrations and MK were measured at 60‐min intervals. Values are means±SEM.

Potassium removing. Plasma potassium (PK) concentrations (higher) and potassium mass eliminated (MOkay) (decrease) throughout standardized excessive‐flux HD with potassium‐free (0K), potassium 1 mmol/l (1K), and potassium 2 mmol/l (2K) dialysates. PK concentrations and MOkay had been measured at 60‐min intervals. Values are means±SEM.

Fig. 1.

Potassium removal. Plasma potassium (PK) concentrations (upper) and potassium mass removed (MK) (lower) during standardized high‐flux HD with potassium‐free (0K), potassium 1 mmol/l (1K), and potassium 2 mmol/l (2K) dialysates. PK concentrations and MK were measured at 60‐min intervals. Values are means±SEM.

Potassium removing. Plasma potassium (PK) concentrations (higher) and potassium mass eliminated (MOkay) (decrease) throughout standardized excessive‐flux HD with potassium‐free (0K), potassium 1 mmol/l (1K), and potassium 2 mmol/l (2K) dialysates. PK concentrations and MOkay had been measured at 60‐min intervals. Values are means±SEM.

Supply


 

SS


 

Df


 

MS


 

Variety of obs


 

36


 

Mannequin  7068.33   5  1413.67  F (5, 30)  1.26 
Residual  33 679.02  30  1122.63  P  0.3071 
Whole  40 747.35  35  1164.21  R2  0.1735 
Potassium eliminated


 

Coef.


 

SE


 

t


 

P


 

95% CI


 

Cb0  23.34  15.04  1.55  0.13  −7.38–54.07 
cb60  4.13  32.88  0.13  0.90  −63.02–71.29 
cb120  33.47  41.16  0.81  0.42  −50.59–117.53 
cb180  −39.45  45.20  −0.87  0.39  −131.76–52.86 
cbf  −23.15  35.23  −0.66  0.52  −95.10–48.81 
cns  47.36  42.48  1.11  0.27  −39.39–134.11 
Supply


 

SS


 

Df


 

MS


 

Variety of obs


 

36


 

Mannequin  7068.33   5  1413.67  F (5, 30)  1.26 
Residual  33 679.02  30  1122.63  P  0.3071 
Whole  40 747.35  35  1164.21  R2  0.1735 
Potassium eliminated


 

Coef.


 

SE


 

t


 

P


 

95% CI


 

Cb0  23.34  15.04  1.55  0.13  −7.38–54.07 
cb60  4.13  32.88  0.13  0.90  −63.02–71.29 
cb120  33.47  41.16  0.81  0.42  −50.59–117.53 
cb180  −39.45  45.20  −0.87  0.39  −131.76–52.86 
cbf  −23.15  35.23  −0.66  0.52  −95.10–48.81 
cns  47.36  42.48  1.11  0.27  −39.39–134.11 
Supply


 

SS


 

Df


 

MS


 

Variety of obs


 

36


 

Mannequin  7068.33   5  1413.67  F (5, 30)  1.26 
Residual  33 679.02  30  1122.63  P  0.3071 
Whole  40 747.35  35  1164.21  R2  0.1735 
Potassium eliminated


 

Coef.


 

SE


 

t


 

P


 

95% CI


 

Cb0  23.34  15.04  1.55  0.13  −7.38–54.07 
cb60  4.13  32.88  0.13  0.90  −63.02–71.29 
cb120  33.47  41.16  0.81  0.42  −50.59–117.53 
cb180  −39.45  45.20  −0.87  0.39  −131.76–52.86 
cbf  −23.15  35.23  −0.66  0.52  −95.10–48.81 
cns  47.36  42.48  1.11  0.27  −39.39–134.11 
Supply


 

SS


 

Df


 

MS


 

Variety of obs


 

36


 

Mannequin  7068.33   5  1413.67  F (5, 30)  1.26 
Residual  33 679.02  30  1122.63  P  0.3071 
Whole  40 747.35  35  1164.21  R2  0.1735 
Potassium eliminated


 

Coef.


 

SE


 

t


 

P


 

95% CI


 

Cb0  23.34  15.04  1.55  0.13  −7.38–54.07 
cb60  4.13  32.88  0.13  0.90  −63.02–71.29 
cb120  33.47  41.16  0.81  0.42  −50.59–117.53 
cb180  −39.45  45.20  −0.87  0.39  −131.76–52.86 
cbf  −23.15  35.23  −0.66  0.52  −95.10–48.81 
cns  47.36  42.48  1.11  0.27  −39.39–134.11 

Urea removing

Urea removing is summarized in Determine 2. Blood urea and hourly urea removing adopted an exponential operate, differing clearly from the potassium elimination sample. In distinction to potassium kinetics, the a number of regression between predicted urea removing modelled from blood concentrations virtually completely adopted the road of id when in comparison with measured urea removing (R2=0.98) (Desk 3, Determine 3).

Blood urea concentrations on the three research dialyses had been an identical. Mass removing of urea (MU) remained fixed with 0K, 1K and 2K. MU amounted to 491.1±45.8 mmol throughout 0K, to 508.6±48.9 mmol throughout 1K and to 506.2±50 mmol throughout 2K (NS). No important correlation between cumulative potassium removing and whole urea removing might be demonstrated (Determine 4). Correspondingly, urea clearance was not influenced by the potassium content material within the dialysate. KdU was 206.1±3.0, 211.1±3.5 and 211.5±2.9 mL/min throughout 0K, 1K and 2K (NS) respectively.

Dialysis effectivity evaluated by URR and single pool Kt/V was not modified by utilizing 0, 1 or 2 mmol/l of potassium within the dialysate. URR was 75±2% with 0K, 76±2% with 1K, and 75±2% with 2K (NS). Single‐pool Kt/V assessed by blood urea kinetic was 1.73±0.12 for 0K, 1.74±0.10 for 1K, and 1.67±0.10 for 2K (NS). Preliminary physique urea content material was not completely different between remedies (Desk 1). The distinction in equilibrated Kt/V (ΔKtVe) as decided from eq. 2 was 0.08±0.05 and 0.11±0.05 models, and never completely different from zero when remedies utilizing 1K and 2K dialysate baths had been in comparison with potassium‐free remedy modes respectively (one pattern signal check, one pattern t‐check).

Fig. 2.

Urea removal. Blood urea (upper) and urea mass removed (MU) (lower) during 0K, 1K, and 2K dialysis. Note the overlap of the three blood urea curves. MU measured in 60‐min intervals were comparable during dialyses with different potassium regimen. Values are means±SEM.

Urea removing. Blood urea (higher) and urea mass eliminated (MU) (decrease) throughout 0K, 1K, and 2K dialysis. Notice the overlap of the three blood urea curves. MU measured in 60‐min intervals had been comparable throughout dialyses with completely different potassium routine. Values are means±SEM.

Fig. 2.

Urea removal. Blood urea (upper) and urea mass removed (MU) (lower) during 0K, 1K, and 2K dialysis. Note the overlap of the three blood urea curves. MU measured in 60‐min intervals were comparable during dialyses with different potassium regimen. Values are means±SEM.

Urea removing. Blood urea (higher) and urea mass eliminated (MU) (decrease) throughout 0K, 1K, and 2K dialysis. Notice the overlap of the three blood urea curves. MU measured in 60‐min intervals had been comparable throughout dialyses with completely different potassium routine. Values are means±SEM.

Fig. 3.

Urea model. Multiple linear regression between predicted urea removal obtained by modelling urea blood concentrations and urea removal (MU) (R2=0.98, P=0.00001).

Urea mannequin. A number of linear regression between predicted urea removing obtained by modelling urea blood concentrations and urea removing (MU) (R2=0.98, P=0.00001).

Fig. 3.

Urea model. Multiple linear regression between predicted urea removal obtained by modelling urea blood concentrations and urea removal (MU) (R2=0.98, P=0.00001).

Urea mannequin. A number of linear regression between predicted urea removing obtained by modelling urea blood concentrations and urea removing (MU) (R2=0.98, P=0.00001).

Fig. 4.

Correlation urea and potassium removal. Absence of correlation between potassium removal (MK) and urea removal (MU) (r=0.22).

Correlation urea and potassium removing. Absence of correlation between potassium removing (MOkay) and urea removing (MU) (r=0.22).

Fig. 4.

Correlation urea and potassium removal. Absence of correlation between potassium removal (MK) and urea removal (MU) (r=0.22).

Correlation urea and potassium removing. Absence of correlation between potassium removing (MOkay) and urea removing (MU) (r=0.22).

Supply


 

SS


 

df


 

MS


 

Variety of obs


 

36


 

Mannequin  905 962.22   2  452 981.11  F (2, 33)  784.97 
Residual  19 043.23  33  577.07  P  0.0000 
Whole


 

925 005.46


 

35


 

26 428.72


 

R2


 

0.9794


 

Urea eliminated


 

Coef.


 

SE


 

t


 

P


 

95% CI


 

cb60  22.79  5.94  3.84  0.001  10.71–34.88 
cb120  23.38  6.94  3.37  0.002  9.27–37.49 
cons  26.27  16.62  1.58  0.123  −7.53–60.08 
Supply


 

SS


 

df


 

MS


 

Variety of obs


 

36


 

Mannequin  905 962.22   2  452 981.11  F (2, 33)  784.97 
Residual  19 043.23  33  577.07  P  0.0000 
Whole


 

925 005.46


 

35


 

26 428.72


 

R2


 

0.9794


 

Urea eliminated


 

Coef.


 

SE


 

t


 

P


 

95% CI


 

cb60  22.79  5.94  3.84  0.001  10.71–34.88 
cb120  23.38  6.94  3.37  0.002  9.27–37.49 
cons  26.27  16.62  1.58  0.123  −7.53–60.08 
Supply


 

SS


 

df


 

MS


 

Variety of obs


 

36


 

Mannequin  905 962.22   2  452 981.11  F (2, 33)  784.97 
Residual  19 043.23  33  577.07  P  0.0000 
Whole


 

925 005.46


 

35


 

26 428.72


 

R2


 

0.9794


 

Urea eliminated


 

Coef.


 

SE


 

t


 

P


 

95% CI


 

cb60  22.79  5.94  3.84  0.001  10.71–34.88 
cb120  23.38  6.94  3.37  0.002  9.27–37.49 
cons  26.27  16.62  1.58  0.123  −7.53–60.08 
Supply


 

SS


 

df


 

MS


 

Variety of obs


 

36


 

Mannequin  905 962.22   2  452 981.11  F (2, 33)  784.97 
Residual  19 043.23  33  577.07  P  0.0000 
Whole


 

925 005.46


 

35


 

26 428.72


 

R2


 

0.9794


 

Urea eliminated


 

Coef.


 

SE


 

t


 

P


 

95% CI


 

cb60  22.79  5.94  3.84  0.001  10.71–34.88 
cb120  23.38  6.94  3.37  0.002  9.27–37.49 
cons  26.27  16.62  1.58  0.123  −7.53–60.08 

Dialogue

On this manuscript we report outcomes of a randomized, potential research displaying that dialysis utilizing low‐potassium dialysate baths didn’t have an effect on the removing of urea in a gaggle of secure, non‐diabetic HD sufferers with out coronary heart illness handled with excessive‐flux dialysers. This result’s in hanging distinction to an earlier report by Dolson et al. [7] who noticed {that a} 1K dialysate tub considerably decreased dialysis effectivity as measured by urea kinetics when in comparison with a 3K dialysate tub. It was not our goal to problem the outcomes reported by Dolson and Adrogué however to indicate that in a regular setting at our unit, utilizing low‐potassium dialysate didn’t have an effect on dialysis effectivity as measured by urea kinetic evaluation.

Is there an evidence for these findings?

Dialysate composition was completely different with regard to glucose and bicarbonate concentrations. Whereas dialysate within the research of Dolson contained glucose at a focus of 200 mg/100 ml, glucose‐free dialysis was delivered in our research. Thus, a significant component contributing to the distribution of potassium between extracellular and intracellular compartments was completely different in these research. With the supply of glucose and the stimulation of insulin secretion, potassium is much more sequestered into the intracellular compartment [17]. As well as, dialysate bicarbonate was 40 mmol/l in our research in comparison with 30 mmol/l within the research reported by Dolson et al. Excessive dialysate bicarbonate with increments in extracellular bicarbonate focus might contribute to intracellular potassium sequestration [18].

The present clarification for the discount in dialysis effectivity as measured by urea kinetics utilizing low‐potassium dialysate relies on the regional blood move mannequin [19]. The delayed removing of solute from the physique is especially because of the low perfusion of the locomotor system, which incorporates virtually 80% of whole physique urea. Since urea transport will be assumed as move restricted, any improve in muscle blood move will improve whole physique clearance and dialysis effectivity. And any impairment in muscle blood move will result in enhanced sequestration and delayed removing of urea from this organ system. Within the research of Dolson et al. the rise in dialysis effectivity as measured by urea kinetics utilizing a 3K dialysate tub was attributed to the vasodilatatory impact of potassium and to an elevated muscle blood move. Nonetheless, with the usage of 11 mmol/l glucose within the dialysate, and with the stimulation of insulin secretion it’s doubtless that blood move was additionally elevated on this research. Muscle blood move is greater with glucose administration and insulin secretion [20]. In our research one would anticipate a distinction in urea removing between 0K and 2K baths with glucose‐free dialysate as effectively. This was not the case. With absence of insulin, muscle blood move can be low in the beginning of dialysis and the impact of hypokalaemic vasoconstriction will be assumed to be minimal. The precise mechanism to clarify the discrepancy in urea removing between the outcomes reported by Dolson and our research stays speculative. It is vitally possible that dialysate glucose performs a key position on this query, particularly when glucose focus in dialysate is excessive (11 mmol/l). Research to make clear the significance of dialysate glucose stay to be completed in future.

Ultrafiltration volumes had been comparable in each research; nevertheless, ultrafiltration charges had been 30% decrease on this research due to the longer remedy instances (4 vs 3 h). Thus intravascular volumes had been in all probability greater, avoiding a vital discount of the regional perfusion on this research.

One of many targets of persistent HD is the removing of potassium that has gathered within the physique within the interval between two dialyses. The current research confirms the behaviour of potassium removing described by others [21]. Plasma potassium focus quickly decreased in the course of the first 60 min and stabilized over the past 60 min of dialysis. Plasma potassium reached a gentle state over the past hour of dialysis, whereas potassium continued to emerge within the dialysate. Due to this fact it may be assumed that potassium removing charge was equal to the intra‐ to extracellular mass switch charge. Though the speed of potassium removing will depend on the distinction between plasma and dialysate potassium concentrations, the quantity of potassium eliminated couldn’t be predicted by the change in intradialytic plasma potassium concentrations utilizing a statistical mannequin.

In one other research by our group [5], the most effective correlation of potassium removing on dialysis was discovered with the amount of potassium originating within the intracellular area. In distinction to potassium, urea blood concentrations throughout dialysis are predictive for the cumulative removing.

As anticipated, potassium removing was considerably larger with potassium‐free dialysate than with 1 or 2 mmol/l dialysate potassium. On a scientific foundation, potassium‐free dialysate may be very efficient for secure, non‐diabetic sufferers handled for a period of 4 h. Potassium removing throughout 0K was 117 mmol, in comparison with 78.5 mmol as revealed by others [6]. The distinction will be defined by the shortage of glucose dialysate, which tends to extend potassium removing [22]. We’re keen to just accept a extra liberal meals consumption with out sturdy potassium restriction with a view to get hold of optimum dietary parameters. Accordingly, our sufferers had a albumin degree of 41.1±1.2 g/l within the haemodiluted predialysis state. Potassium‐free dialysis seems instead for secure dialysis sufferers with out potassium dietary restriction and liable to extreme hyperkalaemia. Cautious cardiological analysis is beneficial for these sufferers, since low potassium tub focus might predispose sufferers on digoxin remedy, or with left ventricular hypertrophy, to ventricular arrhythmias [23].

This research was designed to judge the affect of dialysate potassium on urea removing and dose of dialysis. Each URR and single‐pool Kt/V revealed no affect of dialysate potassium on dose of delivered dialysis as measured by urea kinetics. The distinction in equilibrated Kt/V between remedies analysed in accordance with Eq. 2 was not considerably completely different from zero (H0=0). Nonetheless, there was a pattern for elevated dose of dialysis measured by urea removing when growing dialysate potassium. The evaluation in accordance with Eq. 2 relies on the belief that urea technology charge was unbiased of dialysate potassium focus. This assumption is supported by the small contribution of urea technology charge to urea mass steadiness throughout dialysis. Solely massive variations in urea technology charge are anticipated to invalidate the calculation in accordance with Eq. 2. Sufferers served as their very own controls in order that any potential distinction in dialysis dose (ΔKt/Ve) ought to have produced a distinction in solute removing. Regardless that the developments had been in help of the end result reported by Dolson et al., the adjustments had been removed from important. Due to this fact, the speculation that low‐potassium dialysate baths scale back dialysis effectivity as measured by urea kinetics will not be supported by our knowledge. As talked about above, glucose and its oblique impact on regional blood move distribution might play a key position on this query.

In conclusion, the current research demonstrates that potassium removing has no measurable affect on urea removing throughout excessive‐flux, glucose‐free, 40 mmol/l bicarbonate dialysis. On this setting, excessive potassium removing, when wanted, doesn’t considerably impair dialysis effectivity based mostly on urea kinetics.

Correspondence and offprint requests to: Carlos Zehnder MD, Lo Fontecilla 441, Las Condes, Santiago, Chile.

We want to thank Ms Karin Noerby and her group for glorious technical help.

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