End-tidal carbon dioxide after sodium bicarbonate infusion during mechanical ventilation or ongoing cardiopulmonary resuscitation.

PURPOSE: End-tidal CO2 is used to monitor the ventilation status or hemodynamic efficacy during mechanical ventilation or cardiopulmonary resuscitation (CPR), and it may be affected by various factors including sodium bicarbonate administration. This study investigated changes in end-tidal CO2 after sodium bicarbonate administration. MATERIALS AND METHODS: This single-center, prospective observational study included adult patients who received sodium bicarbonate during mechanical ventilation or CPR. End-tidal CO2 elevation was defined as an increase of ≥20% from the baseline end-tidal CO2 value. The time to initial increase (lag time, Tlag), time to peak (Tpeak), and duration of the end-tidal CO2 rise (Tduration) were compared between the patients with spontaneous circulation (SC group) and those with ongoing resuscitation (CPR group). RESULTS: Thirty-three patients, (SC group, n = 25; CPR group, n = 8), were included. Compared with the baseline value, the median values of peak end-tidal CO2 after sodium bicarbonate injection increased by 100% (from 21 to 41 mmHg) in all patients, 89.5% (from 21 to 39 mmHg) in the SC group, and 160.2% (from 15 to 41 mmHg) in the CPR group. The median Tlag was 17 s (IQR: 12-21) and the median Tpeak was 35 s (IQR: 27-52). The median Tduration was 420 s (IQR: 90-639). The median Tlag, Tpeak, and Tduration were not significantly different between the groups. Tduration was associated with the amount of sodium bicarbonate for SC group (correlation coefficient: 0.531, p = 0.006). CONCLUSION: The administration of sodium bicarbonate may lead to a substantial increase in end-tidal CO2 for several minutes in patients with spontaneous circulation and in patients with ongoing CPR. After intravenous administration of sodium bicarbonate, the use of end-tidal CO2 pressure as a physiological indicator may be limited.

Evaluation of arterial blood gas parameters as prognostic markers in amyotrophic lateral sclerosis.

BACKGROUND: Forced vital capacity (FVC) remains difficult to determine for some patients suffering from amyotrophic lateral sclerosis (ALS) due to the rapid progression of the disease. Arterial blood gas (ABG) parameters could represent a valuable alternative. The aim of this study was therefore to evaluate the correlation between ABG parameters and FVC, along with the prognostic ability of ABG parameters, in a large cohort of ALS patients. METHODS: ALS patients (n=302) with FVC and ABG parameters available at diagnosis were included. Correlations between ABG parameters and FVC were evaluated. Cox regression was then carried out to determine the association of each parameter (ABG and clinical data) with survival. Finally, receiver operating characteristic (ROC) curves were built to predict the survival of ALS. RESULTS: Bicarbonates (HCO3 - ), oxygen partial pressure (pO2 ), carbon dioxide partial pressure (pCO2 ), base excess (BE), oxygen saturation and oxyhemoglobin were significantly correlated with FVC both in patients with spinal or bulbar onset. Univariate Cox regression showed that HCO3 - and BE were associated with survival but only in spinal forms. ABG parameters predicted the survival of ALS with a similar performance to FVC, HCO3 - being the parameter with the highest area under the curve. CONCLUSIONS: Our results suggest that there is an interest in conducting a longitudinal evaluation throughout disease progression to confirm the equal performances of FVC and ABG. This study highlights the benefits of performing ABG analysis that could be used as an interesting alternative to FVC when spirometry cannot be performed.

Serum bicarbonate stability study at room temperature - influence of time to centrifugation and air exposure on bicarbonate measurement reported according to the CRESS checklist.

OBJECTIVES: The aim was to evaluate the stability of serum bicarbonate at room temperature, depending on time to centrifugation and air exposure. METHODS: Stability study was conducted in the laboratory of Clinical Hospital Centre Rijeka, Croatia in January-February 2022. Nine samples from 10 volunteers were collected in clot activator gel tubes (Greiner Bio-One). Bicarbonate was measured on Beckman Coulter AU480 (Beckman Coulter, Brea, USA). Three tubes were left at room temperature for 30 min, three tubes for 2 h, three tubes for 4 h until centrifugation. First tube from first group (baseline) was measured immediately after centrifugation. Other measurements were expressed as percentage deviation (PD%) from baseline. First tube was remeasured after 1 and 2 h (OT_0h_1h; OT_0h_2h). Second and third tubes were opened 1 and 2 h after centrifugation (C_0h_1h; C_0h_2h). Second group of tubes was processed the same way with 2-hour centrifugation delay (WB_2h; OT_2h_1h; OT_2h_2h; C_2h_1h; C_2h_2h), and third group with 4-hour delay (WB_4h; OT_4h_1h; OT_4h_2h; C_4h_1h; C_4h_2h). PD% was compared to Maximum Permissible Difference (MPD=5.69%). MedCalc statistical software was used (MedCalc, Ostend, Belgium). RESULTS: Bicarbonate baseline mean value (range) was 27.3 (23.4-29.6) mmol/L. Obtained PD% (95%CI) were: C_0h_1h 0.46 (-1.21, 2.12); C_0h_2h 0.18 (-2.22, 2.57); OT_0h_1h -6.46 (-7.57, -5.36); OT_0h_2h -10.67 (-12.13, -9.21); WB_2h -0.15 (-2.04, 1.74); C_2h_1h 0.01 (-1.52, 1.54); C_2h_2h -0.40 (-2.65, 1.85); OT_2h_1h -5.43 (-7.30, -3.55); OT_2h_2h -11.32 (-13.57, -9.07); WB_4h -0.85 (-3.28, 1.58); C_4h_1h -2.52 (-4.93, 0.11); C_4h_2h -3.02 (-5.62, 0.43); OT_4h_1h -7.34 (-9.64, -5.05); OT_4h_2h -11.85 (-14.38, -9.33). CONCLUSIONS: Serum bicarbonate is stable for 4 h in closed uncentrifuged tubes, another 2 h in closed tubes after centrifugation, and is unstable within 1 h in opened tube.

Acid-base balance in hemodialysis patients in everyday practice.

INTRODUCTION: Abnormalities in blood bicarbonates (HCO3-) concentration are a common finding in patients with chronic kidney disease, especially at the end-stage renal failure. Initiating of hemodialysis does not completely solve this problem. The recommendations only formulate the target concentration of ≥22 mmol/L before hemodialysis but do not guide how to achieve it. The aim of the study was to assess the acid-base balance in everyday practice, the effect of hemodialysis session and possible correlations with clinical and biochemical parameters in stable hemodialysis patients. MATERIAL AND METHODS: We enrolled 75 stable hemodialysis patients (mean age 65.5 years, 34 women), from a single Department of Nephrology. We assessed blood pressure, and acid-base balance parameters before and after mid-week hemodialysis session. RESULTS: We found significant differences in pH, HCO3- pCO2, lactate before and after HD session in whole group (p < 0.001; p < 0.001; p < 0.001; p = 0.001, respectively). Buffer bicarbonate concentration had only statistically significant effect on the bicarbonate concentration after dialysis (p < 0.001). Both pre-HD acid-base parameters and post-HD pH were independent from buffer bicarbonate content. We observed significant inverse correlations between change in the serum bicarbonates and only two parameters: pH and HCO3- before hemodialysis (p = 0.013; p < 0.001, respectively). CONCLUSIONS: Despite the improvement in hemodialysis techniques, acid-base balance still remains a challenge. The individual selection of bicarbonate in bath, based on previous single tests, does not improve permanently the acid-base balance in the population of hemodialysis patients. New guidelines how to correct acid-base disorders in hemodialysis patients are needed to have less 'acidotic' patients before hemodialysis and less 'alkalotic' patients after the session.

Measuring pH and Buffer Capacity in Fluids Aspirated from the Fasted Upper Gastrointestinal Tract of Healthy Adults.

PURPOSE: The design of biorelevant conditions for in vitro evaluation of orally administered drug products is contingent on obtaining accurate values for physiologically relevant parameters such as pH, buffer capacity and bile salt concentrations in upper gastrointestinal fluids. METHODS: The impact of sample handling on the measurement of pH and buffer capacity of aspirates from the upper gastrointestinal tract was evaluated, with a focus on centrifugation and freeze-thaw cycling as factors that can influence results. Since bicarbonate is a key buffer system in the fasted state and is used to represent conditions in the upper intestine in vitro, variations on sample handling were also investigated for bicarbonate-based buffers prepared in the laboratory. RESULTS: Centrifugation and freezing significantly increase pH and decrease buffer capacity in samples obtained by aspiration from the upper gastrointestinal tract in the fasted state and in bicarbonate buffers prepared in vitro. Comparison of data suggested that the buffer system in the small intestine does not derive exclusively from bicarbonates. CONCLUSIONS: Measurement of both pH and buffer capacity immediately after aspiration are strongly recommended as "best practice" and should be adopted as the standard procedure for measuring pH and buffer capacity in aspirates from the gastrointestinal tract. Only data obtained in this way provide a valid basis for setting the physiological parameters in physiologically based pharmacokinetic models.

Biotic dissolution of autunite under anaerobic conditions: effect of bicarbonates and Shewanella oneidensis MR1 microbial activity.

Uranium is a contaminant of major concern across the US Department of Energy complex that served a leading role in nuclear weapon fabrication for half a century. In an effort to decrease the concentration of soluble uranium, tripolyphosphate injections were identified as a feasible remediation strategy for sequestering uranium in situ in contaminated groundwater at the Hanford Site. The introduction of sodium tripolyphosphate into uranium-bearing porous media results in the formation of uranyl phosphate minerals (autunite) of general formula {X1-2[(UO2)(PO4)]2-1·nH2O}, where X is a monovalent or divalent cation. The stability of the uranyl phosphate minerals is a critical factor that determines the long-term effectiveness of this remediation strategy that can be affected by biogeochemical factors such as the presence of bicarbonates and bacterial activity. The objective of this research was to investigate the effect of bicarbonate ions present in the aqueous phase on Ca-autunite dissolution under anaerobic conditions, as well as the role of metal-reducing facultative bacterium Shewanella oneidensis MR1. The concentration of total uranium determined in the aqueous phase was in direct correlation to the concentration of bicarbonate present in the solution, and the release of Ca, U and P into the aqueous phase was non-stoichiometric. Experiments revealed the absence of an extensive biofilm on autunite surface, while thermodynamic modeling predicted the presence of secondary minerals, which were identified through microscopy. In conclusion, the dissolution of autunite under the conditions studied is susceptible to bicarbonate concentration, as well as microbial presence.

[Effect of HCO3- level on the accuracy of NoSAS screening for obstructive sleep apnea hypopnea syndrome].

Objective: To evaluate the effect of arterial blood HCO3- level on the accuracy of NoSAS questionnaire screening for obstructive sleep apnea hypopnea syndrome (OSAHS). Methods: The hospitalized patients with suspected OSAHS were recruited from March 2016 to December 2017 in the First Affiliated Hospital of Guangzhou Medical University. NoSAS scores, blood gas analysis and polysomnography (PSG) were performed in these patients. Patients were divided into non OSAHS group and mild, moderate and severe OSAHS group according to the PSG results. According to the NoSAS questionnaire score, the patients were divided into OSAHS high-risk group and low risk group. The correlation between arterial blood HCO3- level and apnea hypopnea index (AHI) was analyzed. The receiver operating characteristic (ROC) curve was plotted to analyze the accuracy of HCO3- prediction OSAHS. Predictive parameters(sensitivity, specificity, positive and negative predictive values)for NoSAS scores and HCO3- level were calculated. Results: A total of 243 patients with suspected OSAHS were included, including 186 males (76.5%), 57 females (23.5%), age (49±13) years, body mass index (BMI) (26.9±4.4) kg/m2, and neck circumference (38.6±4.5) cm. The HCO3- level was positively correlated with AHI (r=0.206, P=0.001). The proportion of patients with HCO3- level ≥26 mmol/L in non-OSAHS group was lower than that in OSAHS group (13.0% vs 34.5%, P=0.004); the proportion of patients with HCO3- level ≥26 mmol/L in severe OSAHS group was higher than that in mild OSAHS group (37.7% vs 15.0%, P=0.008), and there was no difference in the ratio of patients with severe OSAHS and moderate OSAHS (37.7% vs 35.3%, P=0.767). The specificity of OSAHS predicted by HCO3- level 25 and 26 mmol/L was 69.6% and 87.0%, respectively. With the NoSAS score of 8 or 7 as cutoffs for analysis, the sensitivity for OSAHS was 61.9% and 79.2%, the specificity for OSAHS was 57.4% and 40.4%, respectively. With the addition of HCO3- level ≥ 26 mmol/L to the NoSAS score ≥ 7, the specificity for OSAHS improved to 93.6%, while the sensitivity decreased to 27.4%. Conclusion: Combined with the arterial blood HCO3- level, the specificity of the NoSAS questionnaire increases and the sensitivity decreases.

Role of Prolactin in the Regulation of Bicarbonates Biodynamics in Female Rat Model of Cholestasis of Pregnancy.

We studied possible involvement of prolactin in the regulation of bicarbonate biodynamics using female rat model of cholestasis of pregnancy induced by transplantation of the donor pituitary under the renal capsule of a recipient (hyperprolactinemia) and bile duct ligation (cholestasis). The concentration of bicarbonates in the bile and blood, their excretion, clearance, and reabsorption, as well as glomerular filtration rate and excretion of sodium ions were assessed. It was found that the main effect of prolactin was directed to the kidney-regulated pool of bicarbonates and consisted in stimulation of their clearance and inhibition of reabsorption, which led to a decrease in bicarbonate blood concentration. Parallel influence of prolactin on the clearance of bicarbonates and sodium ions was observed.

Interaction of Constitutive Nitric Oxide Synthases with Cyclooxygenases in Regulation of Bicarbonate Secretion in the Gastric Mucosa.

Neuronal NO synthase blocker 7-nitroindazole suppressed bicarbonate secretion in rat gastric mucosa induced by mild local irritation with 1 M NaCl (pH 2.0). Non-selective blocker of neuronal and endothelial synthases, Nω-nitro-L-arginine (L-NNA), did not affect HCO3- production, but inhibited secretion after pretreatment with omeprazole. Non-selective cyclooxygenase blocker indomethacin inhibited HCO3- production under conditions of normal synthase activity and in the presence of L-NNA, but was ineffective when co-administered with 7-nitroindazole. It was concluded that neuronal and endothelial synthases are involved in different mechanisms of regulation of HCO3- secretion in the gastric mucosa induced by mild irritation. Activation of neuronal synthase stimulated HCO3- production, which is mediated mainly through activation of cyclooxygenase. Theoretically, activation of endothelial synthase should suppress HCO3- production. The effect of endothelial synthase depends on acid secretion in the stomach and bicarbonate concentration in the submucosa, as it was demonstrated in experiments with intravenous NaHCO3 infusion.

[Treatment of metabolic acidosis in patients with chronic kidney disease (CKD)].

Metabolic acidosis becoming clinically apparent when glomerular filtration rate (GFR) decreases <30 ml/min/1,73m2. Although usually mild, it can have substantial adverse effects like: impair albumin biosynthesis and glucose metabolism, increase protein catabolism with a decrease of muscle mass, increase bone resorption and inhibition of its formation with growth retardation in children. At present KDIGO (Kidney Disease: Improving Global Outcomes) recommendations support oral sodium bicarbonate supplementation and maintaining HCO3 - concentration ≥22 mmol/l in all CKD patients.

Association between topiramate use and serum bicarbonate levels in a veteran population.

BACKGROUND: Topiramate has been associated with metabolic acidosis secondary to decreased serum bicarbonate. Product labeling recommends serum bicarbonate monitoring at baseline and periodically thereafter. OBJECTIVE: The study objective was to assess changes in serum bicarbonate within the first year of topiramate use in an outpatient veteran population. METHODS: This was a single-center, retrospective study conducted at the Iowa City Veterans Affairs Health Care System. Inclusion criteria required a minimum of 1 topiramate outpatient prescription between October 1, 1999, and August 31, 2012, and at least 1 serum bicarbonate level within 12 months prior to topiramate initiation. Patients with topiramate nonadherence, concurrent use of sodium bicarbonate or oral carbonic anhydrase inhibitors, and individual serum bicarbonate values obtained during inpatient hospitalizations were excluded. Change in bicarbonate was evaluated using a paired t test. Decreases in bicarbonate of ≥5 mEq/L, values <20 mEq/L, days to lowest value, and correlation between adverse drug reactions (ADRs) and topiramate discontinuation were evaluated. RESULTS: Of 546 patients reviewed, 350 were included in the analysis. There was a statistically significant decrease of 2.7 mEq/L in bicarbonate following initiation of topiramate. Only 1 patient had a bicarbonate value <17 mEq/L. There was no association between bicarbonate decrease ≥5 mEq/L and ADRs. CONCLUSIONS: A statistically significant reduction in bicarbonate levels occurred with topiramate, which was clinically insignificant. ADR occurrence did not correlate with bicarbonate levels <17 mEq/L or a decrease ≥5 mEq/L. Our results indicate that serum bicarbonate levels should only be monitored before topiramate initiation and in patients presenting with symptoms suggestive of acidosis.

Functional properties of bicarbonates and lactic acid on chicken breast retail display properties and cooked meat quality.

Whole chicken breast was injected with potassium bicarbonate (PB), sodium bicarbonate (SB), and potassium lactate (K-lactate) and salt, alone or in combination at different concentration levels. The objectives were to 1) investigate the effects of different concentration of PB, SB, and PL on instrumental color, water-holding capacity (WHC), objective tenderness, expressible moisture, and moisture content and 2) evaluate whether sodium-containing ingredients can be replaced with potassium as a potential strategy to reduce total sodium content in the finished product. Results showed that chicken breast tissue marinated with SB and PB had greater moisture retention, display characteristics, and cooked product qualities than chicken breast tissue injected with water and the nonmarinated control. The L* values (lightness) did not change over the period of retail display and were not different compared to the control (P>0.05). The chicken breast enhanced with SB, PB, and K-lactate retained better retail display color than the controls (marinated with water and nonmarinated). Increasing the potassium bicarbonate concentration from 0.5 to 1.5% significantly improved the water-holding capacity (82.17 to 92.61%; P<0.05) and led to better cook yield (83.84 to 91.96%). Shear force values were lower at the 0.5% level for both SB and PB compared to the control. PB performed better on retail display and cooked meat quality than SB. This study suggests that chicken breast tissue can be marinated with KB as a healthier alternative to phosphate or SB.

The Δ Anion Gap/Δ Bicarbonate Ratio in Early Lactic Acidosis: Time for Another Delta?

Background: The ratio of Δ anion gap and Δ bicarbonate (ΔAG/ΔHCO3) is used to detect coexisting acid-base disorders in patients with high anion gap metabolic acidosis. Classic teaching holds that, in lactic acidosis, the ΔAG/ΔHCO3 is 1:1 within the first few hours of onset and subsequently rises to 1.8:1. However, this classic 1:1 stoichiometry in early lactic acidosis was derived primarily from animal models and only limited human data. The objective of this study was to examine the ΔAG/ΔHCO3 within the first hours of the development of lactic acidosis. Methods: Data were obtained prospectively from a convenience sample of adult (age >18 years) trauma-designated patients at a single level-1 trauma center. Venous samples, including a chemistry panel and serum lactate, were drawn before initiation of intravenous fluid resuscitation. Results: A total of 108 patients were included. Of these, 63 patients had normal serum lactate levels (≤2.1 mmol/L) with a mean AG of 7.1 mEq/L, the value used to calculate subsequent ΔAG values. ΔAG/ΔHCO3 was calculated for 45 patients who had elevated serum lactate levels (>2.1 mmol/L). The mean ΔAG/ΔHCO3 for all patients with elevated serum lactate levels was 1.86 (SD, 1.40). Conclusions: The mean ΔAG/ΔHCO3 was 1.86 within the first hours of the development of lactic acidosis due to hypovolemic shock, confirming a small prior human study. This contradicts the traditional belief that, in lactic acidosis, the ΔAG/ΔHCO3 is 1:1 within the first several hours. The classic 1:1 stoichiometry was determined on the basis of animal models in which lactic acid is infused into the extracellular space, facilitating extracellular buffering of protons by bicarbonate. In contrast, our results demonstrate a higher initial ΔAG/ΔHCO3 ratio in early endogenous lactic acidosis in humans. Our analysis indicates this is likely due to unmeasured anions contributing to an elevation in AG.

Metabolic Alkalosis: A Brief Pathophysiologic Review.

Metabolic alkalosis is a very commonly encountered acid-base disorder that may be generated by a variety of exogenous and/or endogenous, pathophysiologic mechanisms. Multiple mechanisms are also responsible for the persistence, or maintenance, of metabolic alkalosis. Understanding these generation and maintenance mechanisms helps direct appropriate intervention and correction of this disorder. The framework utilized in this review is based on the ECF volume-centered approach popularized by Donald Seldin and Floyd Rector in the 1970s.  Although many subsequent scientific discoveries have advanced our understanding of the pathophysiology of metabolic alkalosis, that framework continues to be a valuable and relatively straightforward diagnostic and therapeutic model.

[Metabolic acidosis : Diagnosis and treatment]. / Metabolische Azidose : Diagnostik und Therapie.

Acid-base disorders and in particular metabolic acidosis are very common in critically ill patients and contribute significantly to morbidity and mortality. We shed light on the most common causes, the pathophysiology and treatments. Particular attention will be paid to the common practice of substituting sodium bicarbonate in the light of recent study results.

Microbial electrosynthesis feasibility evaluation at high bicarbonate concentrations with enriched homoacetogenic biocathode.

An enrichment methodology was developed for a homoacetogenic biocathode that is able to function at high concentrations of bicarbonates for the microbial electrosynthesis (MES) of acetate from carbon dioxide. The study was performed in two stages; enrichment of consortia in serum bottles and the development of a biocathode in MES. A homoacetogenic consortium was sequentially grown under increasing concentrations of bicarbonate, in serum bottles, at room temperature. The acetate production rate was found to increase with the increase in the bicarbonate concentration and evidenced a maximum production rate of 260 mg/L d-1 (15 g HCO3-/L). On the contrary, carbon conversion efficiency decreased with the increase in the bicarbonate concentration, which evidenced a maximum at 2.5 g HCO3-/L (90.16%). Following a further increase in the bicarbonate concentration up to 20 g HCO3-/L, a visible inhibition was registered with respect to the acetate production rate and the carbon conversion efficiency. Well adapted biomass from 15 g HCO3-/L was used to develop biocathodic catalyst for MES. An effective biocathode was developed after 4 cycles of operation, during which acetate production was improved gradually, evidencing a maximum production rate of 24.53 mg acetate L-1 d-1 (carbon conversion efficiency, 47.72%). Compared to the enrichment stage, the carbon conversion efficiency and the rate of acetate production in MES were found to be low. The production of acetate induced a change in the catholyte pH, from neutral conditions towards acidic conditions.

Role of Bicarbonates and Mannitol in Rhabdomyolysis: A Comprehensive Review.

Rhabdomyolysis is characterized by rapid muscle breakdown and release of intracellular muscle components into the circulation. Acute renal injury is the most common and fatal complication of rhabdomyolysis. The current literature emphasizes the importance of preventing rhabdomyolysis and finding the benefits of sodium bicarbonates and mannitol in its prevention. A PubMed database search for the keywords "Rhabdomyolysis," "Sodium bicarbonate use in rhabdomyolysis," "Mannitol use in rhabdomyolysis," and a Medical Subject Headings (MeSH) search using the keyword "Rhabdomyolysis; Acute Kidney Injury (Subheading-Prevention and control)" generated 10,005 articles overall. After a thorough application of inclusion/exclusion criteria, 37 relevant studies were selected for this literature study. This analysis demonstrates that aggressive early volume resuscitation with normal saline should continue being the principal focus of therapy, and the use of sodium bicarbonate and mannitol in practical situations is not entirely justified. This article also emphasizes the need for future research on this topic and provides recommendations for future research.

[Flecainid intoxication: Evolution, complications and care of]. / Intoxication volontaire à la flecaïnide : évolution, complications et prise en charge.

This report presents the case of a young man of 24 years old with Asperger syndrome who ingest quantities of medication whose flecainide. Resume of his stay in intensive care unit, notably serious adverse effect which ventricular tachycardia with membrane stabilizing effect and lengthening of stay in intensive care unit. Study of literature of different take care already published, with notion of mid-term leaching of flecainide which were ingest days before, at different levels all over the world.

Low Serum Bicarbonate and CKD Progression in Children.

BACKGROUND AND OBJECTIVES: Studies of adults have demonstrated an association between metabolic acidosis, as measured by low serum bicarbonate levels, and CKD progression. We evaluated this relationship in children using data from the Chronic Kidney Disease in Children study. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: The relationship between serum bicarbonate and a composite end point, defined as 50% decline in eGFR or KRT, was described using parametric and semiparametric survival methods. Analyses were stratified by underlying nonglomerular and glomerular diagnoses, and adjusted for demographic characteristics, eGFR, proteinuria, anemia, phosphate, hypertension, and alkali therapy. RESULTS: Six hundred and three participants with nonglomerular disease contributed 2673 person-years of follow-up, and 255 with a glomerular diagnosis contributed 808 person-years of follow-up. At baseline, 39% (237 of 603) of participants with nonglomerular disease had a bicarbonate level of ≤22 meq/L and 36% (85 of 237) of those participants reported alkali therapy treatment. In participants with glomerular disease, 31% (79 of 255) had a bicarbonate of ≤22 meq/L, 18% (14 of 79) of those participants reported alkali therapy treatment. In adjusted longitudinal analyses, compared with participants with a bicarbonate level >22 meq/L, hazard ratios associated with a bicarbonate level of <18 meq/L and 19-22 meq/L were 1.28 [95% confidence interval (95% CI), 0.84 to 1.94] and 0.91 (95% CI, 0.65 to 1.26), respectively, in children with nonglomerular disease. In children with glomerular disease, adjusted hazard ratios associated with bicarbonate level ≤18 meq/L and bicarbonate 19-22 meq/L were 2.16 (95% CI, 1.05 to 4.44) and 1.74 (95% CI, 1.07 to 2.85), respectively. Resolution of low bicarbonate was associated with a lower risk of CKD progression compared with persistently low bicarbonate (≤22 meq/L). CONCLUSIONS: In children with glomerular disease, low bicarbonate was linked to a higher risk of CKD progression. Resolution of low bicarbonate was associated with a lower risk of CKD progression. Fewer than one half of all children with low bicarbonate reported treatment with alkali therapy. Long-term studies of alkali therapy's effect in patients with pediatric CKD are needed.