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Extracellular buffer choice influences acid-base responses and gastrointestinal symptoms.
Peacock, J, Sparks, SA, Middlebrook, I, Hilton, NP, Tinnion, D, Leach, N, Saunders, B, McNaughton, LR
Research in sports medicine (Print). 2021;(6):505-516
Abstract
To compare the bicarbonate kinetics and gastrointestinal (GI) symptom responses between an equal dose of sodium bicarbonate and sodium citrate using delayed-release capsules. Thirteen active males (age 20.5 ± 2.1 y, height 1.8 ± 0.1 m and body mass [BM] 76.5 ± 9.6 kg) consumed either 0.3 g.kg-1 BM sodium bicarbonate, sodium citrate or a placebo, using a double-blind, randomized crossover design. Blood bicarbonate ion (HCO3-) concentration, pH and GI symptoms were measured pre-consumption and every 10 min for 180 min post-consumption. Blood HCO3- concentration (P < 0.001) and pH (P = 0.040) were significantly higher in the sodium bicarbonate condition compared with sodium citrate condition up to 3 h post-consumption. Peak blood HCO3- concentration was significantly higher with the sodium bicarbonate compared with citrate (P < 0.001). Mean GI symptom scores were lower (P = 0.037) for sodium citrate (1.5 ± 1.8 AU) than bicarbonate (2.6 ± 3.1 AU), with considerable inter-individual variability. No GI symptoms were reported following consumption of the placebo. Both substances increase HCO3- values significantly, with sodium bicarbonate causing significantly higher pH and HCO3- values than the same dose of sodium citrate, but results in slightly more severe GI symptoms.
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Association between change in serum bicarbonate and change in thyroid hormone levels in patients receiving conventional or more frequent maintenance haemodialysis.
Molfino, A, Beck, GJ, Li, M, Lo, JC, Kaysen, GA, ,
Nephrology (Carlton, Vic.). 2019;(1):81-87
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AIM: Correction of metabolic acidosis in patients with chronic kidney disease has been associated with improvement in thyroid function. We examined whether changes in bicarbonate were associated with changes in thyroid function in patients with end-stage renal disease receiving conventional or more frequent haemodialysis. METHODS In the Frequent Hemodialysis Network Trials, the relationship between changes in serum bicarbonate, free triiodothyronine (FT3) and free thyroxine (FT4) was examined among 147 and 48 patients with endogenous thyroid function who received conventional (3×/week) or more frequent (6×/week) haemodialysis (Daily Trial) or who received conventional or more frequent nocturnal haemodialysis (Nocturnal Trial). Equilibrated normalized protein catabolic rate (enPCR) was examined to account for nutritional factors affecting both acid load and thyroid function. RESULTS Increasing dialysis frequency was associated with increased bicarbonate level. Baseline bicarbonate level was not associated with baseline FT3 and FT4. Change in bicarbonate level was not associated with changes in FT3 and FT4 in the Daily Trial nor for FT4 in the Nocturnal Trial (r ≤ 0.14, P > 0.21). While, a significant correlation between change in serum bicarbonate and change in FT3 (r = 0.44, P = 0.02) was observed in the Nocturnal Trial; findings were no longer significant after adjusting for change in enPCR (r = 0.37, P = 0.08). For participants with baseline bicarbonate <23 mmol/L, no association between change in bicarbonate and change in thyroid indices were seen in the Daily Trial; for the Nocturnal Trial, findings were also not significant for change in FT3 and the association between change in bicarbonate and change in FT4 (r = 0.54, P = 0.03) was no longer significant after adjusting for enPCR (r = 0.45, P = 0.11). CONCLUSION Changes in bicarbonate were not associated with changes in thyroid hormone levels after adjusting for enPCR, as a marker of nutritional status. Future studies should examine whether improvement in acid base status improves thyroid function in haemodialysis patients with evidence of thyroid hypofunction.
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Serum Bicarbonate in Acute Heart Failure: Relationship to Treatment Strategies and Clinical Outcomes.
Cooper, LB, Mentz, RJ, Gallup, D, Lala, A, DeVore, AD, Vader, JM, AbouEzzeddine, OF, Bart, BA, Anstrom, KJ, Hernandez, AF, et al
Journal of cardiac failure. 2016;(9):738-42
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BACKGROUND Though commonly noted in clinical practice, it is unknown if decongestion in acute heart failure (AHF) results in increased serum bicarbonate. METHODS AND RESULTS For 678 AHF patients in the DOSE-AHF, CARRESS-HF, and ROSE-AHF trials, we assessed change in bicarbonate (baseline to 72-96 hours) according to decongestion strategy, and the relationship between bicarbonate change and protocol-defined decongestion. Median baseline bicarbonate was 28 mEq/L. Patients with baseline bicarbonate ≥28 mEq/L had lower ejection fraction, worse renal function and higher N-terminal pro-B-type natriuretic peptide than those with baseline bicarbonate <28 mEq/L. There were no differences in bicarbonate change between treatment groups in DOSE-AHF or ROSE-AHF (all P > .1). In CARRESS-HF, bicarbonate increased with pharmacologic care but decreased with ultrafiltration (median +3.3 vs -0.9 mEq/L, respectively; P < .001). Bicarbonate change was not associated with successful decongestion (P > .2 for all trials). CONCLUSIONS In AHF, serum bicarbonate is most commonly elevated in patients with more severe heart failure. Despite being used in clinical practice as an indicator for decongestion, change in serum bicarbonate was not associated with significant decongestion.
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High-volume online haemodiafiltration improves erythropoiesis-stimulating agent (ESA) resistance in comparison with low-flux bicarbonate dialysis: results of the REDERT study.
Panichi, V, Scatena, A, Rosati, A, Giusti, R, Ferro, G, Malagnino, E, Capitanini, A, Piluso, A, Conti, P, Bernabini, G, et al
Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 2015;(4):682-9
Abstract
BACKGROUND In haemodialysis (HD) patients, anaemia is associated with reduced survival. Despite treatment with erythropoiesis-stimulating agents (ESAs), a large number of patients with chronic kidney disease show resistance to this therapy and require much higher than usual doses of ESAs in order to maintain the recommended haemoglobin (Hb) target, and recent studies suggest that hepcidin (HEP) may mediate the ESA resistance index (ERI). High-volume online haemodiafiltration (HV-OL-HDF) has been shown to improve anaemia and to reduce the need for ESAs in HD patients; this effect is associated with a reduced inflammatory state in these patients. The aim of the REDERT study (role of haemodiafiltration on ERI) was to investigate the effect of different dialysis techniques on ERI and HEP levels in chronic dialysis patients. METHODS A single cross-over, randomized, multicentre study (A-B or B-A) was designed. Forty stable HD patients from seven different dialysis units (male 65%, mean age 67.6 ± 14.7 years and mean dialytic age 48 ± 10 months) were enrolled. Patients were randomized to the standard bicarbonate dialysis (BHD) with low-flux polysulfone (PS) membrane group or to the HV-OL-HDF group with high-flux PS membranes and exchange volume of >20 L/session. After 6 months, patients were shifted to the other dialytic group for a further 6 months. Clinical data, Hb, ESA doses and iron metabolism were recorded every month. HEP, beta2-microglobulin (b2MG) and C-reactive protein (CRP) were determined every 3 months, and ERI was calculated monthly as the weekly ESA dose per kilogram of body weight divided by Hb level. Data were analysed using paired-samples t-test, Wilcoxon signed-rank test and Spearman's correlation coefficient. RESULTS Dialysis efficiency for small molecules assessed as Kt/V was significantly increased in HV-OL-HDF from 1.47 ± 0.24 to 1.49 ± 0.16; P < 0.01. A significant reduction of b2MG was obtained in HV-OL-HDF from month 3 whereas CRP values were not significantly changed during the study period either in BHD or HV-OL-HDF.ERI was significantly reduced in HV-OL-HDF at month 3 and 6 (from 9.1 ± 6.4 UI/weekly/Kg/Hb to 6.7 ± 5.3 UI/weekly/Kg/Hb; P < 0.05) due to a higher ESA consumption in BHD in spite of similar Hb levels. HEP levels were reduced in HV-OL-HDF with respect to BHD after 3 and 6 months. Iron consumption was not significantly different during BHD or HV-OL-HDF treatment as well as transferrin, ferritin and TSAT levels. A significant positive linear correlation between HEP and ERI (r(2) = 0.258, P < 0.001) was observed. CONCLUSIONS In a uraemic patient population with low-grade inflammation treated with HV-OL-HDF, we observed a significant reduction of ERI values as well as HEP levels. The positive correlation between these two parameters supports a role for HEP in the development of ERI in the dialytic population. Moreover, the lower b2MG and the higher Kt/V achieved in HV-OL-HDF confirms the better depurative effect of this technique in comparison with BHD with respect to middle molecules and small-molecular-weight molecules.
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Acute intradialytic cardiac function and inflammatory cytokine changes during high-efficiency online hemodiafiltration with acetate-free and standard dialysis solutions.
Tiranathanagul, K, Tangvoraphonkchai, K, Srisawat, N, Susantitaphong, P, Tungsanga, K, Praditpornsilpa, K, Eiam-Ong, S
Therapeutic apheresis and dialysis : official peer-reviewed journal of the International Society for Apheresis, the Japanese Society for Apheresis, the Japanese Society for Dialysis Therapy. 2015;(3):250-8
Abstract
Acetate in standard acetate-containing bicarbonate (AC) dialysis fluid could induce peripheral vasodilatation, suppression of myocardial function, and inflammatory cytokine production, resulting in intradialytic hypotension in conventional hemodialysis (HD) patients. Online hemodiafiltration (HDF) provides superior hemodynamic stability over HD. The potentially additive hemodynamic benefits of the novel acetate-free bicarbonate (AF) dialysis fluid in online HDF have never been explored before. The present randomized, double-blind, crossover study was conducted in 22 online HDF patients to investigate the impact of AF dialysis fluid on hemodynamic and cytokine changes compared with AC dialysis fluid in online HDF. The results demonstrated the comparable changes of arterial pressure between AF and AC online HDF. During the study periods, the incidences of composite intradialytic hypotension and other adverse events were not different. The baseline and hourly changes of cardiac index, cardiac output, and peripheral vascular resistance during dialysis were comparable (P=0.534, 0.199, and 0.641, respectively). The percent reductions of NT-proBNP and cTnT were not significantly different (72.6 ± 12.3 vs. 72.6 ± 12.8%, P=0.99 and 35.2 ± 12.8 vs. 36.7 ± 12.0%, P=0.51). The changes of all pro-inflammatory cytokines (IL-2β, IL-6, IL-8, and TNF-α) and anti-inflammatory cytokine (IL-10) during dialysis were comparable between both groups. In conclusion, AF dialysis solution does not offer additional hemodynamic benefit for stable online HDF patients. The hemodynamic stability provided by online HDF might protect the adverse effects of acetate.
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In Vivo Predictive Dissolution: Comparing the Effect of Bicarbonate and Phosphate Buffer on the Dissolution of Weak Acids and Weak Bases.
Krieg, BJ, Taghavi, SM, Amidon, GL, Amidon, GE
Journal of pharmaceutical sciences. 2015;(9):2894-904
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Bicarbonate is the main buffer in the small intestine and it is well known that buffer properties such as pKa can affect the dissolution rate of ionizable drugs. However, bicarbonate buffer is complicated to work with experimentally. Finding a suitable substitute for bicarbonate buffer may provide a way to perform more physiologically relevant dissolution tests. The dissolution of weak acid and weak base drugs was conducted in bicarbonate and phosphate buffer using rotating disk dissolution methodology. Experimental results were compared with the predicted results using the film model approach of (Mooney K, Mintun M, Himmelstein K, Stella V. 1981. J Pharm Sci 70(1):22-32) based on equilibrium assumptions as well as a model accounting for the slow hydration reaction, CO2 + H2 O → H2 CO3 . Assuming carbonic acid is irreversible in the dehydration direction: CO2 + H2 O ← H2 CO3 , the transport analysis can accurately predict rotating disk dissolution of weak acid and weak base drugs in bicarbonate buffer. The predictions show that matching the dissolution of weak acid and weak base drugs in phosphate and bicarbonate buffer is possible. The phosphate buffer concentration necessary to match physiologically relevant bicarbonate buffer [e.g., 10.5 mM (HCO3 (-) ), pH = 6.5] is typically in the range of 1-25 mM and is very dependent upon drug solubility and pKa .
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Comparison of sustained low-efficiency dialysis with acetate-free and acetate-containing bicarbonate dialysate in unstable patients.
Unarokov, ZM, Mukhoedova, TV, Shuvaeva, OV
Artificial organs. 2014;(10):883-8
Abstract
This work is focused on the problem of maintenance of intradialytic hemodynamic safety in unstable patients with acute kidney injury (AKI). A hypothesis that "small" quantities of acetate in standard bicarbonate dialysate can cause pronounced acetatemia and exacerbate cardiovascular instability was tested. In this prospective randomized study, a group of patients with AKI after cardiac surgery was treated with sustained low-efficiency dialysis with either acetate-containing bicarbonate dialysate or acetate-free dialysate, where acetate is replaced by hydrochloric acid. It was demonstrated that application of acetate-containing bicarbonate dialysate results in blood acetate levels up to 12 times the normal level. Additionally, it is associated with a 3.8-fold-increased risk of hemodynamic complications in comparison with acetate-free dialysate. The choice of acetate-free or acetate-containing bicarbonate dialysate does not influence adequacy of correction of the acid-base and electrolyte content of blood.
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Plasma acetate, gluconate and interleukin-6 profiles during and after cardiopulmonary bypass: a comparison of Plasma-Lyte 148 with a bicarbonate-balanced solution.
Davies, PG, Venkatesh, B, Morgan, TJ, Presneill, JJ, Kruger, PS, Thomas, BJ, Roberts, MS, Mundy, J
Critical care (London, England). 2011;(1):R21
Abstract
INTRODUCTION As even small concentrations of acetate in the plasma result in pro-inflammatory and cardiotoxic effects, it has been removed from renal replacement fluids. However, Plasma-Lyte 148 (Plasma-Lyte), an electrolyte replacement solution containing acetate plus gluconate is a common circuit prime for cardio-pulmonary bypass (CPB). No published data exist on the peak plasma acetate and gluconate concentrations resulting from the use of Plasma-Lyte 148 during CPB. METHODS Thirty adult patients were systematically allocated 1:1 to CPB prime with either bicarbonate-balanced fluid (24 mmol/L bicarbonate) or Plasma-Lyte 148. Arterial blood acetate, gluconate and interleukin-6 (IL-6) levels were measured immediately before CPB (T1), three minutes after CPB commencement (T2), immediately before CPB separation (T3), and four hours post separation (T4). RESULTS Acetate concentrations (normal 0.04 to 0.07 mmol/L) became markedly elevated at T2, where the Plasma-Lyte group (median 3.69, range (2.46 to 8.55)) exceeded the bicarbonate group (0.16 (0.02 to 3.49), P < 0.0005). At T3, levels had declined but the differential pattern remained apparent (Plasma-Lyte 0.35 (0.00 to 1.84) versus bicarbonate 0.17 (0.00 to 0.81)). Normal circulating acetate concentrations were not restored until T4. Similar gluconate concentration profiles and inter-group differences were seen, with a slower T3 decay. IL-6 increased across CPB, peaking at T4, with no clear difference between groups. CONCLUSIONS Use of acetate containing prime solutions result in supraphysiological plasma concentrations of acetate. The use of acetate-free prime fluid in CPB significantly reduced but did not eliminate large acetate surges in cardiac surgical patients. Complete elimination of acetate surges would require the use of acetate free bolus fluids and cardioplegia solutions. TRIAL REGISTRATION Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12610000267055.
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Comparison of acetate-free citrate hemodialysis and bicarbonate hemodialysis regarding the effect of intra-dialysis hypotension and post-dialysis malaise.
Daimon, S, Dan, K, Kawano, M
Therapeutic apheresis and dialysis : official peer-reviewed journal of the International Society for Apheresis, the Japanese Society for Apheresis, the Japanese Society for Dialysis Therapy. 2011;(5):460-5
Abstract
Compared with acetate dialysate, bicarbonate dialysate has shown beneficial effects in reducing the morbidity associated with dialysis, but a small amount of acetate in bicarbonate dialysate may evoke hypotension or malaise. Acetate-free citrate hemodialysis (AFHD) may avoid these problems. In 44 hemodialysis patients bicarbonate hemodialysis (BHD) was conducted for three months, followed by a switch to AFHD for three months, and a further switch to bicarbonate hemodialysis (ReBHD). In BHD, AFHD and ReBHD, intra-dialysis hypotension and post-dialysis malaise were determined (hypotension: intra-dialysis systolic blood pressure (SBP) was expressed as a percentage of SBP at the start of hemodialysis, malaise was assessed by a self-reported 0 to 3 scale, 0: absence of malaise, 3: unbearable malaise). Compared with BHD, AFHD patients complained of less malaise but the intra-dialysis blood pressure change did not differ significantly (malaise: BHD 0.73 ± 0.76 vs. AFHD 0.32 ± 0.47, P < 0.0001, end hemodialysis SBP: BHD 93.6 ± 8.9 vs. AFHD 93.8 ± 10.1, P = NS). After switching to ReBHD from AFHD, the malaise score increased (AFHD 0.32 ± 0.47 vs. ReBHD 0.77 ± 0.89, P < 0.0001) and the intra-dialysis blood pressure dropped markedly (end hemodialysis SBP: AFHD 93.8 ± 10.1 vs. ReBHD 87.3 ± 10.5, P < 0.0001). Malaise was very severe in five patients who could not continue ReBHD. After ten days under ReBHD, ReBHD was changed to AFHD again in all patients. Although the exact mechanisms are not known, AFHD may be preferable to BHD to prevent hemodialysis-induced hypotension and malaise.
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Serum bicarbonate and long-term outcomes in CKD.
Menon, V, Tighiouart, H, Vaughn, NS, Beck, GJ, Kusek, JW, Collins, AJ, Greene, T, Sarnak, MJ
American journal of kidney diseases : the official journal of the National Kidney Foundation. 2010;(5):907-14
Abstract
BACKGROUND A low serum bicarbonate level is prevalent in chronic kidney disease (CKD); however, its relationship to long-term outcomes is unclear. STUDY DESIGN Cohort study. SETTING & PARTICIPANTS The Modification of Diet in Renal Disease (MDRD) Study examined the effects of dietary protein restriction and blood pressure control on progression of kidney disease. This analysis includes 942 screened but non-randomized individuals and 839 randomized participants with baseline serum bicarbonate measurements with stage 2-4 CKD. FACTOR Serum bicarbonate level categorized into quartiles. OUTCOMES Kidney failure, all-cause mortality, and a composite outcome of mortality and kidney failure. MEASUREMENTS Local laboratories at each participating site measured bicarbonate in fasting serum samples. Kidney failure outcomes were obtained from the US Renal Data System, and mortality data, from the National Death Index. RESULTS Mean glomerular filtration rate (GFR) was 39 ± 21 (SD) mL/min/1.73 m(2) and serum bicarbonate level was 23.3 ± 3.8 mEq/L. Kidney failure rates were 72%, 64%, 50%, and 41%; mortality rates were 31%, 25%, 21%, and 25%, and rates of the composite outcome were 78%, 71%, 58%, and 54% in bicarbonate quartiles 1, 2, 3, and 4, respectively. In analyses adjusted for demographic and cardiovascular disease factors, serum albumin level, proteinuria, and cause of kidney disease, compared with quartile 4, quartile 1 was associated with a 2.22 HR (95% CI, 1.83-2.68) of kidney failure; 1.39 HR (95% CI, 1.07-1.18) of all-cause mortality; and 1.36 HR (95% CI, 1.15-1.62) of the composite outcome. These associations were rendered nonsignificant with adjustment for GFR (kidney failure HR, 1.05 [95% CI, 0.87-1.28]; all-cause mortality HR, 0.99 [95% CI, 0.75-1.13]; composite HR, 1.04 [95% CI, 0.87-1.24]). LIMITATIONS Single baseline measurement of serum bicarbonate. CONCLUSIONS Low serum bicarbonate level was associated with increased risk of long-term outcomes in nondiabetic patients with CKD. However, this risk is not independent of baseline GFR. Clinical trials are necessary to evaluate whether bicarbonate supplementation slows the progression of CKD.