A Comprehensive Review of Chloride Management in Critically Ill Patients

Chloride, often overshadowed in electrolyte management, emerges as a crucial player in the physiological intricacies of critically ill patients. This comprehensive review explores the multifaceted aspects of chloride, ranging from its significance in cellular homeostasis to the consequences of dysregulation in critically ill patients. The pathophysiology of hyperchloremia and hypochloremia is dissected, highlighting their intricate impact on acid-base balance, renal function, and cardiovascular stability. Clinical assessment strategies, including laboratory measurements and integration with other electrolytes, lay the foundation for targeted interventions. Consequences of dysregulated chloride levels underscore the need for meticulous management, leading to an exploration of emerging therapies and interventions. Fluid resuscitation protocols, the choice between crystalloids and colloids, the role of balanced solutions, and individualized patient approaches comprise the core strategies in chloride management. Practical considerations, such as monitoring and surveillance, overcoming implementation challenges, and embracing a multidisciplinary approach, are pivotal in translating theoretical knowledge into effective clinical practice. As we envision the future, potential impacts on critical care guidelines prompt reflections on integrating novel therapies, individualized approaches, and continuous monitoring practices. In conclusion, this review synthesizes current knowledge, addresses practical considerations, and envisions future directions in chloride management for critically ill patients. By embracing a holistic understanding, clinicians can navigate the complexities of chloride balance, optimize patient outcomes, and contribute to the evolving landscape of critical care medicine.

Water, mineral, and blood acid-base balance in calves with naturally occurring diarrhea receiving two alternative oral rehydration solutions or a placebo

Quantifying the water and mineral losses in feces is essential to determine the optimal composition of oral rehydration solutions (ORS) for diarrheic animals. In a randomized complete block design, this study evaluated water, mineral, and blood acid-base balance of calves with naturally occurring diarrhea receiving ORS or a placebo. On d 0, 45 calves (age: 18 ± 3.2 d; mean ± SD) were selected based on the presence of visual signs of diarrhea, such as dirty tail or wet feces, along with clinical symptoms evaluated by measuring the skin turgor and the degree of enophthalmos. On d 1, calves were divided into blocks of 3 animals based on blood base excess (BE) measured at 0900 h, and within each block, calves were randomly assigned to 1 of 3 treatments (15 calves per treatment) including (1) a hypertonic ORS (HYPER; Na+ = 110 mmol/L; 370 mOsm/kg; strong ion difference [SID] = 60 mEq/L), (2) a hypotonic ORS with low Na+ (HYPO; Na+ = 77 mmol/L; 278 mOsm/kg; SID = 71 mEq/L), and (3) a placebo consisting of lukewarm water with 5 g/L of whey powder (CON). Milk replacer (MR) was fed through teat buckets twice daily at 0630 h and 1700 h in 2 equally sized meals of 2.5 L from d 1 to 3 and of 3.0 L on d 4 and 5. Treatments consisting of 2.0 L lukewarm solutions were administered between milk meals from d 1 to 3 at 1200 h and 2030 h through teat buckets. Refusals of MR and treatments were recorded daily, and blood samples were collected from the jugular vein once daily at arrival in the afternoon of d 0 and at 0900 h from d 1 to 5 after arrival. Urine and feces were collected quantitatively over a 48-h period from 1200 h on d 1 to 1200 h on d 3, and a representative sample of each 24-h period was stored. In addition, the volume of extracellular fluid was evaluated on d 2 by postprandial sampling over a 4-h period relative to the injection of sodium thiosulfate at 1300 h. Total daily fluid intake (MR, treatment, and water) from d 1 to 3 was greater in HYPER (LSM ± SEM; 8.9 ± 0.36 L/d) and HYPO (7.8 ± 0.34 L/d) than in CON (6.6 ± 0.34 L/d). This resulted in a greater water balance (water intake - fluid output in urine and feces) in calves receiving ORS (59.6 ± 6.28 g/kg BW per 24 h vs. 39.6 ± 6.08 g/kg BW per 24 h). Fecal Na+ losses were greater in HYPER than in the other treatments (81 ± 12.0 mg/kg BW per 24 h vs. 24 ± 11.8 mg/kg BW per 24 h). Blood pH was higher in HYPO (7.41 ± 0.016) than CON (7.35 ± 0.016) over the 5 monitoring days, whereas HYPER (7.37 ± 0.017) did not differ with other treatments. In this experimental model, diarrheic calves were likely unable to absorb the high Na+ load from HYPER, resulting in greater Na+ losses in feces, which might have impaired the alkalinizing capacity of HYPER. In contrast, HYPO significantly sustained blood acid-base balance compared with CON, whereas HYPER did not. This suggests that low tonicity ORS with a high SID are more suitable for diarrheic calves.

Sodium L-Aspartate Supplementation Improves Repeated-Sprint Performance

Aspartate supplementation has been reported to improve endurance performance by facilitating the tricarboxylic acid cycle flux. The present study was performed to investigate the effects of aspartate supplementation on repeated-sprint performance and blood pH. Following an overnight fast, fourteen healthy males completed three sets of 10 × 6 s maximal sprints after consuming sodium L-aspartate (ASP) or placebo (PLA), in a double-blind manner. Both supplements were taken twice on each test day (2 × 4.5 g). Exercise performance (e.g., cadence and power output) and blood variables (e.g., pH and plasma amino acid levels) were measured. The ASP trial evidenced significantly higher plasma aspartate concentration during the first (ASP, 45.3 ± 9.2 μM; PLA, 6.1 ± 0.8 μM) and the second exercise sets (ASP, 24.2 ± 4.5 μM; PLA, 6.6 ± 0.9 μM) and peak cadence during the second set (ASP, 153 ± 3 rpm; PLA, 152 ± 3 rpm) compared with the PLA trial (all p < 0.05). The peak power output during the second exercise set (ASP, 743 ± 32 W; PLA, 734 ± 31 W; p = 0.060) and the blood pH immediately before (ASP, 7.280 ± 0.020; PLA, 7.248 ± 0.016; p = 0.087) and after the third exercise set (ASP, 7.274 ± 0.019; PLA, 7.242 ± 0.018; p = 0.093) tended to be higher in the ASP than in the PLA trial. In conclusion, ASP supplementation partially improved repeated-sprint performance (peak cadence during the second exercise set). However, it did not affect the mean power output.

Intravenous or Oral Acetazolamide for Treatment of Diuretic-Induced Alkalosis in Patients With Heart Failure

BACKGROUND

Acetazolamide has been used for diuretic-induced metabolic alkalosis, but the preferred dose, route, and frequency of administration remain unknown.

OBJECTIVE

The purpose of this study was to characterize dosing strategies and determine the effectiveness of intravenous (IV) and oral (PO) acetazolamide for patients with heart failure (HF) with diuretic-induced metabolic alkalosis.

METHODS

This was a multicenter, retrospective cohort study comparing the use of IV versus PO acetazolamide in patients with HF receiving at least 120 mg of furosemide for the treatment of metabolic alkalosis (serum bicarbonate CO2 ≥32). The primary outcome was the change in CO2 on the first basic metabolic panel (BMP) within 24 hours of the first dose of acetazolamide. Secondary outcomes included laboratory outcomes, such as change in bicarbonate, chloride, and incidence of hyponatremia and hypokalemia. This study was approved by the local institutional review board.

RESULTS

IV acetazolamide was given in 35 patients and PO acetazolamide was given in 35 patients. Patients in both groups were given a median of 500 mg of acetazolamide in the first 24 hours. For the primary outcome, there was a significant decrease in CO2 on the first BMP within 24 hours after patients received the IV acetazolamide (-2 [interquartile range, IQR: -2, 0] vs 0 [IQR: -3, 1], P = 0.047). There were no differences in secondary outcomes.

CONCLUSION AND RELEVANCE

IV acetazolamide resulted in significantly decreased bicarbonate within 24 hours of administration. IV acetazolamide may be preferred to treat diuretic-induced metabolic alkalosis in patients with HF.

Enteral hydration in cows: Comparison between continuous flow and bolus administration

BACKGROUND

Enteral hydration in cattle is most commonly performed as a bolus (B) via the ororuminal route, although continuous flow (CF) administration via the nasoesophageal route represents a viable alternative. Currently, no study has compared the effectiveness of these two methods. This study aimed to compare the efficiency of enteral hydration using CF and B to correct water, electrolyte and acid-base imbalances in cows.

METHODS

Protocols for the induction of dehydration were applied twice to eight healthy cows, with an interval of 1 week. In a crossover design, two types of enteral hydration were performed using the same electrolyte solution and volume equal to 12% of bodyweight (BW): CF (10 mL/kg/h, between 0 and 12 hours) and B (6% BW, twice, at 0 and 6 hours). Clinical and blood variables were determined at -24, 0, 6, 12 and 24 hours and compared using repeated-measures ANOVA.

RESULTS

Induced moderate dehydration and hypochloremic metabolic alkalosis were corrected after 12 hours using the two hydration methods, with no differences observed between the methods.

LIMITATIONS

The study was conducted with induced rather than natural imbalances, so the findings should be interpreted cautiously.

CONCLUSION

Enteral CF hydration is as effective as B hydration in reversing dehydration and correcting electrolyte and acid-base imbalances.

A Randomized Study on the Effect of Dried Fruit on Acid-Base Balance, Diet Quality, and Markers of Musculoskeletal Health in Community Dwelling Adults

OBJECTIVES

We tested whether 100 g/day of dried fruit (vs. no supplemental fruit control) for 6 months alters 24-hr urinary net acid excretion (NAE), bone resorption, weight, body composition, muscle performance, and diet quality. We explored consistency of self-selected dietary composition and potential renal acid load (PRAL).

METHODS

This randomized, single-blind, 2-armed study included 83 normal- and over-weight men and postmenopausal women (age ≥50 years) on self-reported low fruit diets. Endpoints included group differences in NAE (primary), 24-hr urinary N-telopeptide (NTX), weight, body composition, muscle performance, and diet quality.

RESULTS

At baseline, mean (±SD) age was 69 ± 8 years; 86% were Caucasian; body mass index was 24.5 ± 2.8 kg/m²; 46% female, and NAE was 32.4 ± 23.1 mmol with no significant baseline group differences. No significant group differences were noted in NAE (primary), NTX, weight, body composition, muscle performance or diet quality at 6 months. In the cohort as a whole, 6-month change in NAE was positively associated with change in NTX, but no significant associations were noted in other outcomes. PRAL on the day of the urine collection was positively associated with NAE. Comparison of two consecutive baseline 24-hr diet recalls revealed wide intra-individual variability in PRAL in self-selected diets in our participants.

CONCLUSION

In this field study of older adults consuming self-selected diets, making one change to the diet by adding 100 g/day of dried fruit (equivalent to 4 servings per day) had no significant impact on NAE when compared to a no supplemental fruit control. This null finding may be attributable to the high day-to-day variability in consumption of foods affecting NAE. Added fruit also had no significant effect on weight, fat, muscle, or bone outcomes over a 6-month period.

What the Lactate Shuttle Means for Sports Nutrition

The discovery of the lactate shuttle (LS) mechanism may have two opposite perceptions, It may mean very little, because the body normally and inexorably uses the LS mechanism. On the contrary, one may support the viewpoint that understanding the LS mechanism offers immense opportunities for understanding nutrition and metabolism in general, as well as in a sports nutrition supplementation setting. In fact, regardless of the specific form of the carbohydrate (CHO) nutrient taken, the bodily CHO energy flux is from a hexose sugar glucose or glucose polymer (glycogen and starches) to lactate with subsequent somatic tissue oxidation or storage as liver glycogen. In fact, because oxygen and lactate flow together through the circulation to sites of utilization, the bodily carbon energy flow is essentially the lactate disposal rate. Consequently, one can consume glucose or glucose polymers in various forms (glycogen, maltodextrin, potato, corn starch, and fructose or high-fructose corn syrup), and the intestinal wall, liver, integument, and active and inactive muscles make lactate which is the chief energy fuel for red skeletal muscle, heart, brain, erythrocytes, and kidneys. Therefore, if one wants to hasten the delivery of CHO energy delivery, instead of providing CHO foods, supplementation with lactate nutrient compounds can augment body energy flow.

Acute Ketone Monoester Supplementation Impairs 20-min Time-Trial Performance in Trained Cyclists: A Randomized, Crossover Trial

Acute ketone monoester (KE) supplementation can alter exercise responses, but the performance effect is unclear. The limited and equivocal data to date are likely related to factors including the KE dose, test conditions, and caliber of athletes studied. We tested the hypothesis that mean power output during a 20-min cycling time trial (TT) would be different after KE ingestion compared to a placebo (PL). A sample size of 22 was estimated to provide 80% power to detect an effect size dz of 0.63 at an alpha level of .05 with a two-tailed paired t test. This determination considered 2.0% as the minimal important difference in performance. Twenty-three trained cyclists (N = 23; peak oxygen uptake: 65 ± 12 ml·kg-1 min-1; M ± SD), who were regularly cycling >5 hr/week, completed a familiarization trial followed by two experimental trials. Participants self-selected and replicated their diet and exercise for ∼24 hr before each trial. Participants ingested either 0.35 g/kg body mass of (R)-3-hydroxybutyl (R)-3-hydroxybutyrate KE or a flavor-matched PL 30 min before exercise in a randomized, triple-blind, crossover manner. Exercise involved a 15-min warm-up followed by the 20-min TT on a cycle ergometer. The only feedback provided was time elapsed. Preexercise venous [β-hydroxybutyrate] was higher after KE versus PL (2.0 ± 0.6 vs. 0.2 ± 0.1 mM, p < .0001). Mean TT power output was 2.4% (0.6% to 4.1%; mean [95% confidence interval]) lower after KE versus PL (255 ± 54 vs. 261 ± 54 W, p < .01; dz = 0.60). The mechanistic basis for the impaired TT performance after KE ingestion under the present study conditions remains to be determined.

Relationships among biochemical measures in children with diabetic ketoacidosis

OBJECTIVES

Investigating empirical relationships among laboratory measures in children with diabetic ketoacidosis (DKA) can provide insights into physiological alterations occurring during DKA. We determined whether alterations in laboratory measures during DKA conform to theoretical predictions.

METHODS

We used Pearson correlation statistics and linear regression to investigate correlations between blood glucose, electrolytes, pH and PCO₂ at emergency department presentation in 1,681 pediatric DKA episodes. Among children with repeat DKA episodes, we also assessed correlations between laboratory measures at the first vs. second episode.

RESULTS

pH and bicarbonate levels were strongly correlated (r=0.64), however, pH and PCO₂ were only loosely correlated (r=0.17). Glucose levels were correlated with indicators of dehydration and kidney function (blood urea nitrogen (BUN), r=0.44; creatinine, r=0.42; glucose-corrected sodium, r=0.32). Among children with repeat DKA episodes, PCO₂ levels tended to be similar at the first vs. second episode (r=0.34), although pH levels were only loosely correlated (r=0.19).

CONCLUSIONS

Elevated glucose levels at DKA presentation largely reflect alterations in glomerular filtration rate. pH and PCO₂ are weakly correlated suggesting that respiratory responses to acidosis vary among individuals and may be influenced by pulmonary and central nervous system effects of DKA.

Two-pore channel protein TPC1 is a determining factor for the adaptation of proximal tubular phosphate handling

AIM

Two-pore channels (TPCs) constitute a small family of cation channels expressed in endo-lysosomal compartments. TPCs have been characterized as critical elements controlling Ca²⁺ -mediated vesicular membrane fusion and thereby regulating endo-lysosomal vesicle trafficking. Exo- and endocytotic trafficking and lysosomal degradation are major mechanisms of adaption of epithelial transport. A prime example of highly regulated epithelial transport is the tubular system of the kidney. We therefore studied the localization of TPC protein 1 (TPC1) in the kidney and its functional role in the dynamic regulation of tubular transport.

METHODS

Immunohistochemistry in combination with tubular markers were used to investigate TPC1 expression in proximal and distal tubules. The excretion of phosphate and ammonium, as well as urine volume and pH were studied in vivo, in response to dynamic challenges induced by bolus injection of parathyroid hormone or acid-base transitions via consecutive infusion of NaCl, Na₂ CO₃ , and NH₄ Cl.

RESULTS

In TPC1-deficient mice, the PTH-induced rise in phosphate excretion was prolonged and exaggerated, and its recovery delayed in comparison with wildtype littermates. In the acid-base transition experiment, TPC1-deficient mice showed an identical rise in phosphate excretion in response to Na₂ CO₃ compared with wildtypes, but a delayed NH4Cl-induced recovery. Ammonium-excretion decreased with Na₂ CO₃ , and increased with NH₄ Cl, but without differences between genotypes.

CONCLUSIONS

We conclude that TPC1 is expressed subapically in the proximal but not distal tubule and plays an important role in the dynamic adaptation of proximal tubular phosphate reabsorption towards enhanced, but not reduced absorption.

Comment: Balanced Salt Solutions for Critically Ill Patients: Nonplused and Back to Basics

The analysis of trial results of the intravenous fluids pharmacodynamics revealed problems common to all studies, such as varying study designs, clinical discretion for treatments, and heterogeneous patients. We believe that in the methodology of future research it is also necessary to pay due attention to the actual rather than theoretical physicochemical parameters of the solutions used, such as osmolality, pH, and potential excess of bases. Paying attention to these parameters of intravenous fluids will be useful for assessing their role in producing pharmacodynamic effects in critically ill patients.

The mechanisms of alkali therapy in targeting renal diseases

Chronic kidney disease (CKD) is characterized by progressive reduction in kidney function and treatments aiming at stabilizing or slowing its progression may avoid or delay the necessity of kidney replacement therapy and the increased mortality associated with reduced kidney function. Metabolic acidosis, and less severe stages of the acid stress continuum, are common consequences of CKD and some interventional studies support that its correction slows the progression to end-stage kidney disease. This correction can be achieved with mineral alkali in the form of bicarbonate or citrate salts, ingestion of diets with fewer acid-producing food components or more base-producing food components, or a pharmacological approach. In this mini-review article, we summarize the potential mechanisms involved in the beneficial effects of alkali therapy. We also discuss the perspectives in the field and challenges that must be overcome to advance our understanding of such mechanisms.

Production, physiological response, and calcium and magnesium balance of lactating Holstein cows fed different sources of supplemental magnesium with or without ruminal buffer

The objective of this study was to evaluate the effects of dietary replacement of magnesium oxide (MgO) with calcium-magnesium hydroxide [CaMg(OH)₂] and its interaction with ruminal buffer (sodium sesquicarbonate) supplementation on production, Ca and Mg balance, and overall physiological response of mid-lactation Holstein dairy cows. Sixty cows averaging 40.5 ± 7.0 kg of milk/d were used. Treatments were assigned following a 2 × 2 factorial arrangement: (1) MgO, (2) MgO + buffer, (3) CaMg(OH)₂, or (4) CaMg(OH)₂ + buffer. Diets were formulated to have 16.5% of crude protein, 1.82 Mcal/kg of net energy for lactation, 0.67% Ca, 0.39% P, and 0.25% Mg, all on a dry matter (DM) basis. Treatments were individually top dressed. Milk production, composition, and DM intake were evaluated. A subsample of 20 cows were randomly selected for the evaluation of Ca and Mg balance, blood gases, and electrolytes. Ruminal fluid was also collected for evaluation of pH and Ca and Mg solubility. Effects of Mg source, buffer, and the interaction Mg source × buffer were analyzed through orthogonal contrasts. An interaction of Mg source × buffer was found for DM intake and feed efficiency, in which cows fed CaMg(OH)₂ had a similar feed efficiency regardless of ruminal buffer inclusion; however, when cows were fed MgO, the inclusion of buffer reduced feed efficiency. No effects on body weight and milk yield were observed. Buffer addition tended to increase the concentrations of fat, protein, and solids-not-fat, without affecting the yields of these milk components. Magnesium source and buffer did not affect ruminal fluid, blood, urine, or fecal pH; however, buffer supplementation increased urinary pH. Treatment with CaMg(OH)₂ increased blood concentration of HCO₃^-, total CO₂, and base excess compared with cows fed MgO. No differences were observed in the ruminal solubility of Ca and Mg or on milk or urinary Ca and Mg excretion. Greater plasma Mg concentration was observed for animals fed MgO compared with cows fed CaMg(OH)₂; however, both sources were above the threshold recommended in the literature for dairy cows. Also, a reduction in fecal Mg excretion was observed in animals fed CaMg(OH)₂. In summary, we provide evidence that CaMg(OH)₂ could replace MgO without affecting performance, overall physiological response, or Ca and Mg balance of mid-lactating dairy Holstein cows.

Brain H+ /CO2 sensing and control by glial cells

Maintenance of constant brain pH is critically important to support the activity of individual neurons, effective communication within the neuronal circuits, and, thus, efficient processing of information by the brain. This review article focuses on how glial cells detect and respond to changes in brain tissue pH and concentration of CO2 , and then trigger systemic and local adaptive mechanisms that ensure a stable milieu for the operation of brain circuits. We give a detailed account of the cellular and molecular mechanisms underlying sensitivity of glial cells to H+ and CO2 and discuss the role of glial chemosensitivity and signaling in operation of three key mechanisms that work in concert to keep the brain pH constant. We discuss evidence suggesting that astrocytes and marginal glial cells of the brainstem are critically important for central respiratory CO2 chemoreception-a fundamental physiological mechanism that regulates breathing in accord with changes in blood and brain pH and partial pressure of CO2 in order to maintain systemic pH homeostasis. We review evidence suggesting that astrocytes are also responsible for the maintenance of local brain tissue extracellular pH in conditions of variable acid loads associated with changes in the neuronal activity and metabolism, and discuss potential role of these glial cells in mediating the effects of CO2 on cerebral vasculature.

Electrolyte, acid-base, and medication management with renal replacement therapy

Fluid and electrolyte homeostasis exhibited by the kidneys is a complex process that is challenging to regulate with artificial renal replacement therapy (RRT). RRT has been used as a treatment modality for electrolyte and acid-base disturbances in patients with acute kidney injury and chronic kidney disease. This review highlights the management of electrolyte shifts, acid-base disturbances, and medication considerations in RRT, with a focus on intermittent hemodialysis and continuous RTT in the inpatient setting.

Physiological Regulation of Growth, Hematology and Blood Gases in Chicken Embryos in Response to Low and High Incubation Humidity

Variations from a relative humidity (RH) of ∼50-60% can unfavorably alter chicken embryo development, but little is known of whether the embryo can mitigate these effects through physiological regulation. We examined effects of Low RH (25-35%), and High RH (85-93%) compared to Control RH (50-60%) on hatchability, embryonic growth, hematology and blood gases and pH. Mean hatchability was not affected by RH. Yet, Low RH decreased wet body mass of advanced embryos (days 17-19; d17-19), with lowered body water content compared with embryos of Control and High RH. However, dry body mass of developing (d11-19) embryos was not different between the three RH groups. Mean blood osmolality across development was higher in Low RH embryos and lower in High RH embryos compared with Control embryos. Mean blood lactate was higher in both Low and High RH embryos compared to Control embryos. Unexpectedly, hematological respiratory variables (Hct, [RBC], MCV, [Hb]) and blood gas variables (Po₂, Pco₂, pH, [HCO₃ ^-]) across development were not affected by RH. Mean wet body mass at hatch (d20-22) was larger in High RH embryos compared with Low RH embryos, but mean wet and dry body mass upon euthanasia on d22 was unaffected. The ability of the three populations to physiologically regulate blood respiratory variables and blood acid-base balance was then examined by observing their responses to intrinsic hypoxemia and hypercapnia created by controlled partial egg submersion in water. Hct and [RBC] responses were less disturbed by submersion in High RH embryos compared with both Control and Low RH embryos, which showed major disturbance. Acid-base regulatory responses did not differ between RH groups. We conclude that, while different incubation RHs cause large differences in tissue water content and body mass, most hematological and acid-base regulatory capabilities are regulated near Control values.

Alkali therapy protects renal function, suppresses inflammation, and improves cellular metabolism in kidney disease

Chronic kidney disease (CKD) affects about 10-13 % of the population worldwide and halting its progression is a major clinical challenge. Metabolic acidosis is both a consequence and a possible driver of CKD progression. Alkali therapy counteracts these effects in CKD patients, but underlying mechanisms remain incompletely understood. Here we show that bicarbonate supplementation protected renal function in a murine CKD model induced by an oxalate-rich diet. Alkali therapy had no effect on the aldosterone-endothelin axis but promoted levels of the anti-aging protein klotho; moreover, it suppressed adhesion molecules required for immune cell invasion along with reducing T helper cell and inflammatory monocyte invasion. Comparing transcriptomes from the murine crystallopathy model and from human biopsies of kidney transplant recipients suffering from acidosis with or without alkali therapy unveils parallel transcriptome responses mainly associated with lipid metabolism and oxidoreductase activity. Our data reveal novel pathways associated with acidosis in kidney disease and sensitive to alkali therapy and identifies potential targets through which alkali therapy may act on CKD and that may be amenable for more targeted therapies.

Effects of the Type of Intraoperative Fluid in Living Donor Kidney Transplantation: A Single-Center Retrospective Cohort Study

PURPOSE

Perioperative fluid management in kidney transplant recipients is crucial to supporting the fluid, acid-base, and electrolyte balance required for graft perfusion. However, the choice of intraoperative crystalloids in kidney transplantation remains controversial. We conducted a single-center retrospective cohort study to evaluate the impact of intraoperative fluids on acid-base and electrolyte balance and graft outcomes.

MATERIALS AND METHODS

We included 282 living donor kidney transplant recipients from January 2010 to December 2017. Patients were classified into two groups based on the type of intraoperative crystalloids used (157 patients in the half saline group and 125 patients in the balanced crystalloid solutions group, Plasma-lyte).

RESULTS

Compared with the half saline group, the Plasma-lyte group showed less metabolic acidosis and hyponatremia during surgery. Hyperkalemia incidence was not significantly different between the two groups. Changes in postoperative graft function assessed by blood urea nitrogen and creatinine were significantly different between the two groups. Patients in the Plasma-lyte group exhibited consistently higher glomerular filtration rates than those in the half saline group at 1 month and 1 year after transplantation after adjusting for demographic differences.

CONCLUSION

Intraoperative Plasma-lyte can lead to more favorable results in terms of acid-base balance during kidney transplantation. Patients who received Plasma-lyte showed superior postoperative graft function at 1 month and 1 year after transplantation. Further studies are needed to evaluate the superiority of intraoperative Plasma-lyte over other types of crystalloids in relation to graft outcomes.

Retinal oxygen saturation is associated with HbA1c but not with short-term diabetes control, internal environment, smoking and mild retinopathy - ROXINEGLYD study

PURPOSE

Purpose of this prospective uncontrolled single-centre pilot study was to find an association of retinal oxygen saturation (SatO₂ ) with acid-base balance (ABB), carboxyhaemoglobin concentration, current plasma glucose concentration (PG), mean PG and PG variability over the last 72 hr, haemoglobin A1c (HbA1c), and other conditions.

METHODS

Forty-one adults (17 men) with type 1 (N = 14) or type 2 (N = 27) diabetes mellitus, age 48.6 ± 13.5 years, diabetes duration 9 (0.1-36) years, BMI 29.4 ± 6.3 kg/m² , and HbA1c 52 ± 12.7 mmol/mol completed the study. The 4-day study comprised two visits (Day l, Day 4) including 72 hr of continuous glucose monitoring (CGM) by iPro^® 2 Professional CGM (Medtronic, MiniMed, Inc., Northridge, CA, USA). Retinal oximeter Oxymap T1 (Oxymap ehf., Reykjavik, Iceland) was used to assess SatO₂ .

RESULTS

Wilcoxon signed-rank test showed no SatO₂ difference between eyes and visits. Spearman's correlation analysis revealed a significant correlation between arterial SatO₂ and PG variability in type 2 diabetes mellitus, a positive correlation of venous SatO₂ with HbA1c and with finger pulse oximetry. However, no correlation of SatO₂ with ABB, carboxyhaemoglobin, current PG, mean PG over the 72 hr, age, diabetes duration, BMI, lipoproteinaemia, body temperature, systolic and diastolic blood pressure, heart rate, central retinal thickness and retinal nerve fibre layer thickness was found.

CONCLUSION

This study confirmed the association of venous SatO₂ with long-term but not with short-term diabetes control, ABB and other conditions. The increased SatO₂ and questionable impact of PG variability on retinal SatO₂ is a research challenge.

Pseudo-pheochromocytoma due to obstructive sleep apnea: a case report

SUMMARY

Obstructive sleep apnea (OSA) is a condition of intermittent nocturnal upper airway obstruction. OSA increases sympathetic drive which may result in clinical and biochemical features suggestive of pheochromocytoma. We present the case of a 65-year-old male with a 2.9-cm left adrenal incidentaloma on CT, hypertension, symptoms of headache, anxiety and diaphoresis, and persistently elevated 24-h urine norepinephrine (initially 818 nmol/day (89-470)) and normetanephrine (initially 11.2 µmol/day (0.6-2.7)). He was started on prazosin and underwent left adrenalectomy. Pathology revealed an adrenal corticoadenoma with no evidence of pheochromocytoma. Over the next 2 years, urine norepinephrine and normetanephrine remained significantly elevated with no MIBG avid disease. Years later, he was diagnosed with severe OSA and treated with continuous positive airway pressure. Urine testing done once OSA was well controlled revealed complete normalization of urine norepinephrine and normetanephrine with substantial symptom improvement. It was concluded that the patient never had a pheochromocytoma but rather an adrenal adenoma with biochemistry and symptoms suggestive of pheochromocytoma due to untreated severe OSA. Pseudo-pheochromocytoma is a rare presentation of OSA and should be considered on the differential of elevated urine catecholamines and metanephrines in the right clinical setting.

LEARNING POINTS

Obstructive sleep apnea (OSA) is a common condition among adults. OSA may rarely present as pseudo-pheochromocytoma with symptoms of pallor, palpitations, perspiration, headache, or anxiety. OSA should be considered on the differential of elevated urine catecholamines and metanephrines, especially in patients with negative metaiodobenzylguanidine (MIBG) scan results.

Physiological responses, self-reported health effects, and cognitive performance during exposure to carbon dioxide at 20 000 ppm

In this study, 24 subjects (20-58 years) were exposed to carbon dioxide (CO₂ ) at 770 ppm and 20 000 ppm in an exposure laboratory for 4-h, including 2 × 15 min of cycling to investigate the effects on acid-base balance, physiological responses, cognitive performance and acute health. Capillary blood analysis, heart rate, respiratory rate, divided attention, flexibility, and sustained attention from the Test Battery for Attentional Performance (TAP), critical flicker fusion frequency (CFF), and self-reported symptoms were measured before, during, and after the 4-h exposure. Blood pH decreased and partial pressure of carbon dioxide (pCO₂ ) increased significantly when exposed to 20 000 ppm CO₂ compared to 770 ppm. However, the values remained within the normal range. In addition, respiratory rate increased slightly but significantly at 20 000 ppm CO₂ . No significant changes in heart rate, CFF, task performance or acute health were found. In sum, the findings suggest that the observed changes in acid-base balance and ventilation can be classified as physiological adaptation responses. Impairment of cognitive performance is not expected from exposure to 20 000 ppm CO₂ , neither as direct effect on central nervous system function nor as a distraction related to perception of health effects.

Metabolic and blood acid-base responses to prepartum dietary cation-anion difference and calcium content in transition dairy cows

Dairy cows commonly undergo negative Ca balance accompanied by hypocalcemia after parturition. A negative dietary cation-anion difference (DCAD) strategy has been used prepartum to improve periparturient Ca homeostasis. Our objective was to determine the influence of a negative DCAD diet with different amounts of dietary Ca on the blood acid-base balance, blood gases, and metabolic adaptation to lactation. Multiparous Holstein cows (n = 81) were blocked into 1 of 3 dietary treatments from 252 d of gestation until parturition: (1) positive DCAD diet and low Ca (CON; containing +6.0 mEq/100 g DM, 0.4% DM Ca); (2) negative DCAD diet and low Ca (ND; -24.0 mEq/100 g DM, 0.4% DM Ca); or (3) negative DCAD diet plus high Ca supplementation (NDCA; -24.1 mEq/100 g DM, 2.0% DM Ca). There were 28, 27, and 26 cows for CON, ND, and NDCA, respectively. Whole blood was sampled at 0, 24, 48, and 96 h after calving for immediate determination of blood acid-base status and blood gases. Serum samples collected at -21, -14, -7, -4, -2, -1, at calving, 1, 2, 4, 7, 14, 21, and 28 d relative to parturition were analyzed for metabolic components. Results indicated that cows fed ND or NDCA had lower blood pH at calving but greater pH at 24 h after calving compared with CON. Blood bicarbonate, base excess, and total CO₂ (tCO₂) concentrations of cows in ND and NDCA groups were less than those of cows in CON at calving but became greater from 24 to 96 h postpartum. The NDCA cows had lower blood bicarbonate, base excess, and tCO₂ at 48 h and greater partial pressure of oxygen after calving compared with ND. Cows fed ND or NDCA diets had lower serum glucose concentrations than CON cows before calving but no differences were observed postpartum. Serum concentrations of total protein and albumin were greater prepartum for cows in ND and NDCA groups than for those in CON. Postpartum serum urea N and albumin concentrations tended to be higher for ND and NDCA cows. Cows fed ND or NDCA diets had elevated serum total cholesterol concentration prepartum. During the postpartum period, triglycerides and NEFA of cows fed ND or NDCA diets tended to be lower than those of CON. Cows fed the NDCA diet had greater postpartum total cholesterol in serum and lower NEFA concentration at calving than ND. In conclusion, feeding a prepartum negative DCAD diet altered blood acid-base balance and induced metabolic acidosis at calving, and improved protein and lipid metabolism. Supplementation of high Ca in the negative DCAD diet prepartum was more favorable to metabolic adaptation to lactation in dairy cows than the negative DCAD diet with low Ca.

Increasing Vegetable Intake Decreases Urinary Acidity and Bone Resorption Marker in Overweight and Obese Adults: An 8-Week Randomized Controlled Trial

BACKGROUND

Controlled intervention trials are needed to confirm a positive association from epidemiological studies between vegetable consumption and bone health.

OBJECTIVE

We investigated whether providing vegetables at the Dietary Guidelines for Americans (DGA) recommended amount affects excretion of acid and calcium in urine and bone turnover markers in serum in adults with low vegetable intake.

METHODS

In total, 102 adults (19 males and 83 females, age 18-65 y, BMI ≥25 kg/m2) consuming ≤1 serving of vegetables (128 g raw leafy or 64 g cooked vegetables) per d were recruited in a 2-arm, parallel, randomized, controlled, and community-based 8-wk feeding intervention trial. The 2 arms included a vegetable intervention (VI) during which participants received extra vegetables (∼270 g/d) and an attention control (CON) group that conducted only the testing visits. Measurements included nutrient intake, plasma carotenoids, and bone-related markers in serum and urine. Differences between CON and VI at week 8 were tested using the ANCOVA with baseline values as a covariate.

RESULTS

Compared with CON, carotenoid intake (mean ± SD) was higher (6.4 ± 3.4 compared with 2.0 ± 1.2 mg/d) (P < 0.01) and dietary potential renal acid load was lower (20 ± 13 compared with 3.4 ± 14 mEq/d) (P < 0.01) in VI. Compared with CON at week 8, urine titratable acid and Mg were 24 and 26% lower, respectively, while urine pH was 3% greater (P < 0.05) and serum C-terminal telopeptide of type I collagen (CTX) was 19% lower in VI. There were no group differences in serum concentrations of propeptide of type 1 procollagen and tartrate-resistant acid phosphatase or urinary excretion of deoxypyridinoline and CTX.

CONCLUSIONS

Consumption of vegetables at the DGA-recommended amount by adults with low vegetable intake potentially benefits bone health. This trial was registered at clinicaltrials.gov as NCT02585102.

Acid-base balance and cerebrovascular regulation

The regulation and defence of intracellular pH is essential for homeostasis. Indeed, alterations in cerebrovascular acid-base balance directly affect cerebral blood flow (CBF) which has implications for human health and disease. For example, changes in CBF regulation during acid-base disturbances are evident in conditions such as chronic obstructive pulmonary disease and diabetic ketoacidosis. The classic experimental studies from the past 75+ years are utilized to describe the integrative relationships between CBF, carbon dioxide tension (PCO₂ ), bicarbonate (HCO₃ ^- ) and pH. These factors interact to influence (1) the time course of acid-base compensatory changes and the respective cerebrovascular responses (due to rapid exchange kinetics between arterial blood, extracellular fluid and intracellular brain tissue). We propose that alterations in arterial [HCO₃ ^- ] during acute respiratory acidosis/alkalosis contribute to cerebrovascular acid-base regulation; and (2) the regulation of CBF by direct changes in arterial vs. extravascular/interstitial PCO₂ and pH - the latter recognized as the proximal compartment which alters vascular smooth muscle cell regulation of CBF. Taken together, these results substantiate two key ideas: first, that the regulation of CBF is affected by the severity of metabolic/respiratory disturbances, including the extent of partial/full acid-base compensation; and second, that the regulation of CBF is independent of arterial pH and that diffusion of CO₂ across the blood-brain barrier is integral to altering perivascular extracellular pH. Overall, by realizing the integrative relationships between CBF, PCO₂ , HCO₃ ^- and pH, experimental studies may provide insights to improve CBF regulation in clinical practice with treatment of systemic acid-base disorders.

Alterations in acid-base balance, blood gases, and hematobiochemical profiles of whole-blood and thoracic fluid in goats with contagious caprine pleuropneumonia

Background and Aim:

Contagious caprine pleuropneumonia (CCPP) is a highly contagious and fatal disease affecting goats and some wild ruminants. It is a cause of major economic losses in the goat industry in Africa, Asia, and the Middle East. This study aimed to investigate the acid-base balance, blood gases, and hematobiochemical profiles of whole-blood and fluid collected from the thoracic cavity in goats with CCPP.

Materials and Methods:

Fifty-five goats suffering from weight loss, anorexia, dyspnea, polypnea, cough, and nasal discharges due to CCPP were studied. Twenty-five healthy goats were used as controls. Diseased animals were enrolled in this study based on a positive serological latex agglutination test (LAT) that confirmed the detection of Mycoplasma capricolum subsp. capripneumoniae. The control goats were enrolled based on a negative result of the LAT.

Results:

Compared with a mean value of 7.38±0.04 in controls, the pH in the diseased group was 7.41±0.05. The blood pressure of carbon dioxide (PCO₂), pressure of oxygen (PO₂), base excess (BE), bicarbonate (HCO₃), total carbon dioxide (TCO₂), and saturation of oxygen (SO₂) were lower in goats with CCPP than in controls. However, the anion gap (AnGap) was higher in the diseased goats than in the healthy ones. Compared with the levels in blood samples, the thoracic fluid PCO₂, PO₂, BE, and SO₂ were higher while pH, HCO₃, TCO₂, and AnGap were lower. Compared with the findings in healthy goats, hematological alterations included significant increases in white blood cells and neutrophils, and a significant decrease in the red blood cell count. In the thoracic fluid, neutrophilic leukocytosis was a remarkable finding. The serum concentrations of globulin, blood urea nitrogen, and glucose, and the activities of aspartate aminotransferase (AST) and g-glutamyl transpeptidase (GGT) increased significantly compared with those in controls. In contrast, serum concentrations of albumin, calcium, and magnesium, and the activity of alkaline phosphatase (ALP) decreased significantly compared with those of healthy animals. The activities of ALP, AST, GGT, and creatine kinase and the concentration of phosphorus were higher in thoracic fluid than the serum values in the diseased group.

Conclusion:

When compared with the healthy controls, goats with CCPP have metabolic acidosis. Compared with the levels in healthy goats, the blood PCO₂, PO₂, BE, HCO₃, TCO₂, and SO₂ are low in goats with CCPP; however, the AnGap is higher in diseased goats.

Regulation of cerebral blood flow by arterial PCO2 independent of metabolic acidosis at 5050 m

KEY POINTS

We investigated the influence of arterial PCO₂ (PaCO₂ ) with and without experimentally altered pH on cerebral blood flow (CBF) regulation at sea level and with acclimatization to 5050 m. At sea level and high altitude, we assessed stepwise alterations in PaCO₂ following metabolic acidosis (via 2 days of oral acetazolamide; ACZ) with and without acute restoration of pH (via intravenous sodium bicarbonate; ACZ+HCO₃ ^- ). Total resting CBF was unchanged between trials at each altitude even though arterial pH and [HCO₃ ^- ] (i.e. buffering capacity) were effectively altered. The cerebrovascular responses to changes in arterial [H⁺ ]/pH were consistent with the altered relationship between PaCO₂ and [H⁺ ]/pH following ACZ at high altitude (i.e. leftward x-intercept shifts). Absolute cerebral blood velocity (CBV) and the sensitivity of CBV to PaCO₂ was unchanged between trials at high altitude, indicating that CBF is acutely regulated by PaCO₂ rather than arterial pH.

ABSTRACT

Alterations in acid-base balance with progressive acclimatization to high altitude have been well-established. However, how respiratory alkalosis and the resultant metabolic compensation interact to regulate cerebral blood flow (CBF) is uncertain. We addressed this via three separate experimental trials at sea level and following partial acclimatization (14 to 20 days) at 5050 m; involving: (1) resting acid-base balance (control); (2) following metabolic acidosis via 2 days of oral acetazolamide at 250 mg every 8 h (ACZ; pH: Δ -0.07 ± 0.04 and base excess: Δ -5.7 ± 1.9 mEq⋅l^-1 , trial effects: P < 0.001 and P < 0.001, respectively); and (3) after acute normalization of arterial acidosis via intravenous sodium bicarbonate (ACZ + HCO₃ ^- ; pH: Δ -0.01 ± 0.04 and base excess: Δ -1.5 ± 2.1 mEq⋅l^-1 , trial effects: P = 1.000 and P = 0.052, respectively). Within each trial, we utilized transcranial Doppler ultrasound to assess the cerebral blood velocity (CBV) response to stepwise alterations in arterial PCO₂ (PaCO₂ ), i.e. cerebrovascular CO₂ reactivity. Resting CBF (via Duplex ultrasound) was unaltered between trials within each altitude, indicating that respiratory compensation (i.e. Δ -3.4 ± 2.3 mmHg PaCO₂ , trial effect: P < 0.001) was sufficient to offset any elevations in CBF induced via the ACZ-mediated metabolic acidosis. Between trials at high altitude, we observed consistent leftward shifts in both the PaCO₂ -pH and CBV-pH responses across the CO₂ reactivity tests with experimentally reduced arterial pH via ACZ. When indexed against PaCO₂ - rather than pH - the absolute CBV and sensitivity of CBV-PaCO₂ was unchanged between trials at high altitude. Taken together, following acclimatization, CO₂ -mediated changes in cerebrovascular tone rather than arterial [H⁺ ]/pH is integral to CBF regulation at high altitude.

Effects of maternal level of dietary cation-anion difference fed to prepartum nulliparous cows on offspring acid-base balance, metabolism, and growth

The objectives were to determine the effects of dietary cation-anion difference (DCAD) fed to pregnant cows during the last 22 d of gestation on offspring acid-base balance, metabolism, growth, and health preweaning. A total of 132 nulliparous Holstein cows were enrolled at 250 (248 to 253) d of gestation in a randomized block design. Cows were blocked by genomic merit of energy-corrected milk yield and assigned randomly to diets varying in DCAD: +200 (P200, n = 43), -50 (N50, n = 45), or -150 (N150, n = 44) mEq/kg of dry matter (DM). Newborn calves (15 males and 28 females in P200, 22 males and 23 females in N50, and 18 males and 26 females in N150) were followed for the first 7 or 56 d of age if males or females, respectively. Measures of acid-base balance and concentrations of minerals in blood were measured in all calves on d 0 before colostrum feeding, and on d 1, 3, and 7. Each calf was fed 3.78 L of colostrum from the respective treatment, and apparent efficiency of IgG absorption was determined. All calves were weighed at birth, and females were weighed again at 21, 42, and 56 d of age. Concentrations in serum of total calcium (tCa), total magnesium (tMg), and total phosphorus (tP) were measured up to 56 d of age; intakes of milk and starter grain DM were measured daily from 21 to 56 d of age; and incidence of disease was recorded for the first 56 d of age in females. Treatment did not affect acid-base balance measured in all calves. Calves were born with metabolic and respiratory acidosis, which reversed by 1 d of age. In the first 24 h after birth, blood pH increased from 7.215 to 7.421 and bicarbonate from 26.2 to 31.7 mM, whereas partial pressure of CO₂ decreased from 64.1 to 48.7 mm of Hg in all treatments. Maternal DCAD did not affect colostrum IgG content fed to calves (P200 = 95.0 vs. N50 = 91.0 vs. N150 = 97.1 ± 4.1 g/L) or apparent efficiency of IgG absorption (P200 = 33.1 vs. N50 = 33.1 vs. N150 = 34.2 ± 1.9%). Males were born heavier than females, but maternal DCAD did not affect birth weight of all calves (P200 = 37.7 vs. N50 = 37.3 vs. N150 = 37.8 ± 0.7 kg) or daily weight gain in females in the first 56 d of life (P200 = 0.80 vs. N50 = 0.81 vs. N150 = 0.77 ± 0.03 kg/d). Treatment did not affect intake of milk (P200 = 1.11 vs. N50 = 1.04 vs. N150 = 1.19 ± 0.06 kg/d) or starter grain DM (P200 = 0.27 vs. N50 = 0.27 vs. N150 = 0.21 ± 0.06 kg/d), or measures of feed efficiency. Treatment did not affect concentrations of minerals in serum, morbidity, or age at morbidity. Manipulating the DCAD of pregnant nulliparous dams during late gestation did not affect offspring performance in the first 2 mo of age.

Use of a carbonic anhydrase Ca17a knockout to investigate mechanisms of ion uptake in zebrafish (Danio rerio)

In fishes, branchial cytosolic carbonic anhydrase (CA) plays an important role in ion and acid-base regulation. The Ca17a isoform in zebrafish (Danio rerio) is expressed abundantly in Na⁺-absorbing/H⁺-secreting H⁺-ATPase-rich (HR) cells. The present study aimed to identify the role of Ca17a in ion and acid-base regulation across life stages using CRISPR/Cas9 gene editing. However, in preliminary experiments, we established that ca17a knockout is lethal with ca17a^-/- mutants exhibiting a significant decrease in survival beginning at ∼12 days postfertilization (dpf) and with no individuals surviving past 19 dpf. Based on these findings, we hypothesized that ca17a^-/- mutants would display alterations in ion and acid-base balance and that these physiological disturbances might underlie their early demise. Na⁺ uptake rates were significantly increased by up to 300% in homozygous mutants compared with wild-type individuals at 4 and 9 dpf; however, whole body Na⁺ content remained constant. While Cl^- uptake was significantly reduced in ca17a^-/- mutants, Cl^- content was unaffected. Reduction of CA activity by Ca17a morpholino knockdown or ethoxzolamide treatments similarly reduced Cl^- uptake, implicating Ca17a in the mechanism of Cl^- uptake by larval zebrafish. H⁺ secretion, O₂ consumption, CO₂ excretion, and ammonia excretion were generally unaltered in ca17a^-/- mutants. In conclusion, while the loss of Ca17a caused marked changes in ion uptake rates, providing strong evidence for a Ca17a-dependent Cl^- uptake mechanism, the underlying causes of the lethality of this mutation in zebrafish remain unclear.

Laboratory Markers in the Management of Pediatric Polytrauma: Current Role and Areas of Future Research

Severe trauma is the most common cause of mortality in children and is associated with a high socioeconomic burden. The most frequently injured organs in children are the head and thorax, followed by the extremities and by abdominal injuries. The efficient and early assessment and management of these injuries is essential to improve patients' outcome. Physical examination as well as imaging techniques like ultrasound, X-ray and computer tomography are crucial for a valid early diagnosis. Furthermore, laboratory analyses constitute additional helpful tools for the detection and monitoring of pediatric injuries. Specific inflammatory markers correlate with post-traumatic complications, including the development of multiple organ failure. Other laboratory parameters, including lactate concentration, coagulation parameters and markers of organ injury, represent further clinical tools to identify trauma-induced disorders. In this review, we outline and evaluate specific biomarkers for inflammation, acid-base balance, blood coagulation and organ damage following pediatric polytrauma. The early use of relevant laboratory markers may assist decision making on imaging tools, thus contributing to minimize radiation-induced long-term consequences, while improving the outcome of children with multiple trauma.

Enteral electrolytic solutions administered in continuous flow via naso-ruminal route in adult goats

This study aimed to investigate the effects of maintenance enteral electrolytic solutions administered naso-ruminally in continuous flow in adult goats subjected to water and food restriction. Six adult non-pregnant and non-lactating female goats, aged between two and five years old, were used in a crossover (6 × 2) study. Solution 1 (SEE1) comprised: 4.5 g sodium chloride (NaCl); 1 g potassium chloride (KCl); 0.5 g magnesium chloride (MgCl); 1 g calcium chloride in 1,000 ml of water (measured osmolarity: 202 mOsm/l). Solution 2 (SEE2) comprised: 4.5 g of NaCl; 1 g of KCl; 0.5 g of MgCl; 2 g of calcium acetate in 1,000 ml of water (measured osmolarity: 212 mOsm/l). The solutions were administered naso-ruminally at a dose rate of 15 ml/kg/hr, for 12 hr. The animals were evaluated at times T-24, T0, T4, T8, T12, and T24. Both enteral electrolytic solutions were effective in expanding blood volume. SEE1 showed a low-intensity acidifying potential, while SEE2 showed behavior of a neutral enteral electrolytic solution.

Dietary Acid-Base Balance in High-Performance Athletes

Physical exercise leads to metabolic changes that affect the acid-base balance in skeletal muscles and other tissues. Nutrition is one of the factors that may influence the acid-base balance in the body. Keeping alkaline circumstances in the body is important not only for health and athletic performance in training but also during competition in many sport events. This is especially significant for athletes who practice in sport at the highest level of competition. The aim of the study was to determine the dietary acid-base balance in competitive Lithuanian high-performance athletes, and to evaluate the effect of actual diets of athletes on NEAP (net endogenous acid production), muscle mass and body mineral content during a four-year Olympic cycle. The research participants were 18.1 ± 3.3-year-old Lithuanian high performance athletes (n = 323). The actual diet was investigated using the 24 h recall dietary survey method. The measurements of body composition were performed using BIA (bioelectrical impedance analysis). The potential renal acid load of the diets of athletes (dietary PRAL) and NEAP were calculated. In 10.2% of athletes, NEAP exceeds 100 mEq · day-1 and is on average 126.1 ± 32.7 mEq · day-1. Higher NEAP in athletes is associated with lower muscle mass (β -1.2% of body weight, p < 0.001) but has no effect on the amount of minerals in the body (β 0.01% of body weight, p = 0.073). Overall, 25-30% of Lithuanian high-performance athletes use high-protein diets (2.0-4.8 g · kg-1 · day-1) leading to a dietary acid-base imbalance as well as an excessive production of endogenous acids in the body. Athletes are recommended to consume higher amounts of potassium and magnesium. An increase in calcium intake up to 1500 mg per day is recommended. In exceptional cases, periodised nutrition for athletes may involve diets complemented with bicarbonate and/or beta-alanine supplements.

Effect of Simulated Matches on Post-Exercise Biochemical Parameters in Women's Indoor and Beach Handball

This study assesses the status of hydration and the acid-base balance in female handball players in the Polish Second League before and after simulated matches in both indoor (hall) and beach (outdoor) conditions. The values of biochemical indicators useful for describing water-electrolyte management, such as osmolality, hematocrit, aldosterone, sodium, potassium, calcium, chloride and magnesium, were determined in the players’ fingertip capillary blood. Furthermore, the blood parameters of the acid-base balance were analysed, including pH, standard base excess, lactate and bicarbonate ion concentration. Additionally, the pH and specific gravity of the players’ urine were determined. The level of significance was set at p < 0.05. It was found that both indoor and beach simulated matches caused post-exercise changes in the biochemical profiles of the players’ blood and urine in terms of water-electrolyte and acid-base balance. Interestingly, the location of a simulated match (indoors vs. beach) had a statistically significant effect on only two of the parameters measured post-exercise: concentration of calcium ions (lower indoors) and urine pH (lower on the beach). A single simulated game, regardless of its location, directly affected the acid-base balance and, to a smaller extent, the water-electrolyte balance, depending mostly on the time spent physically active during the match.

Tonicity of oral rehydration solutions affects water, mineral and acid-base balance in calves with naturally occurring diarrhoea

Recommendations for composition of oral rehydration solutions (ORS) for calves, particularly concerning Na⁺, glucose, and their combined effect on tonicity, are not in line with guidelines for humans. Thus, this study aimed to determine the effect of ORS tonicity on water, mineral and acid–base balance. Seventy‐two calves were selected based on the severity of dehydration and blood base excess (BE) on day 0. Five calves that did not develop diarrhoea were removed post‐inclusion from the study. Calves were allocated to blocks of four animals based on blood BE on day 1. Within each block, calves were randomly assigned to one of four treatments: (a) hypotonic ORS with low Na⁺ and lactose (HYPO); (b) isotonic ORS with low Na⁺and glucose (ISO); (c) hypertonic ORS with high Na⁺ and glucose (HYPER); and (d) control consisting of warm water including 5 g/L of whey powder (CON). Treatments were administered twice daily over a 3‐day period, in which calves were offered 2.0 L of treatment at 1300 and 2100 hr. Calves were fed 2.5 L of milk replacer at 0700 and 1630 hr from day 1 to 3 and 3.0 L from day 4 to 5, and had access to water. Calves were monitored for 5 days in which measurements included intakes, BW, blood sampling and collection of faeces on day 1 and urine from day 1 to 3. All ORS treatments maintained normal serum Na⁺, whereas CON did not. Calves in the HYPER group had lower blood pH and greater faecal Na⁺ losses than HYPO and ISO. Plasma expansion relative to baseline was higher in low tonicity ORS (+4.8%) when compared with CON (+1.0%). Urine osmolality was 30% higher in HYPER calves. In this experiment, low tonicity ORS were more effective at restoring water, mineral and acid–base balance than the hypertonic ORS.

Body Fluid Compartments, Cell Membrane Ion Transport, Electrolyte Concentrations, and Acid-Base Balance

Measurements made in the blood, part of the extracellular compartment, are used in the clinical assessment of acid-base disorders; however, intracellular events determine much of the metabolic importance of these disorders. Intracellular and interstitial compartment acid-base balance is complex and varies in different tissues. This review considers the determination of extracellular pH in the context of ion transport processes at the interface of cells and the interstitial fluid, and between epithelial cells lining the transcellular contents of the gastrointestinal and urinary tracts that open to the external environment. A further consideration is the role of these membrane transporters in the generation of acid-base disorders and the associated disruption of electrolyte balance. This review suggests a process of internal and external balance for pH regulation similar to that of potassium, and considers the role of secretory gastrointestinal epithelia and renal epithelia with respect to normal pH homeostasis and clinical disorders. Electroneutrality of electrolytes in the extracellular fluid is a fundamental feature of reciprocal changes in Cl^- or non-Cl^- anions and HCO₃^-. Normal mechanisms for protecting cell pH and producing normal gastrointestinal and renal secretions in healthy states also may result in disease when abnormal. In a similar manner, organic anions such as ketoacid anions and lactate, normally transported as fuels between organs, result in acid-base disturbances in disease. Understanding the genomic basis of these transporters may contribute to specific treatments.

Elevated pCO2 and Hypoxia Alter the Acid-Base Homeostasis of Developing Sheepshead Minnows, Cyprinodon variegatus

Low dissolved oxygen and increased acidification are two environmental variables that concomitantly change in an estuarine environment, both of which are exacerbated by nutrient pollution and subsequent eutrophication. To better understand how estuarine residents compensate for daily fluctuations in these environmental variables, the interactive effects of acidification and hypoxia were assessed in developing sheepshead minnows (Cyprinodon variegatus) using a 2 by 2 factorial design over a 42-day exposure. Embryos were exposed to either acidic (partial pressure of CO₂, pCO₂, ~2000 μatm), hypoxic (reduced dissolved oxygen, ~2 mg l^-1), or combined acidic and hypoxic conditions and monitored for development, hatch rate, and survival. Changes in oxygen consumption, anaerobic metabolism, oxidative stress, and acid-base balance were evaluated at three life stages (embryo, larval, and juvenile fish) to discern if and how fish compensate for these stressors during development. The combination of acidification and hypoxia delayed hatching in embryos and significantly decreased oxygen consumption (p<0.001) in all three life-stages. Neither acidification, hypoxia, nor the combination of the stressors impacted the anaerobic metabolism or oxidative stress of juvenile fish, but acid-base equilibrium was disrupted by all three treatments in larval fish. Elevated carbonic anhydrase activity was observed in the multi-stress treatment in embryos and larval fish, but not in juvenile fish. These results show that developing sheepshead minnows can re-establish cellular homeostasis in compensating to acidified and hypoxic waters.

The dimeric ectodomain of the alkali-sensing insulin receptor-related receptor (ectoIRR) has a droplike shape

Insulin receptor-related receptor (IRR) is a receptor tyrosine kinase of the insulin receptor family and functions as an extracellular alkali sensor that controls metabolic alkalosis in the regulation of the acid-base balance. In the present work, we sought to analyze structural features of IRR by comparing them with those of the insulin receptor, which is its closest homolog but does not respond to pH changes. Using small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM), we investigated the overall conformation of the recombinant soluble IRR ectodomain (ectoIRR) at neutral and alkaline pH. In contrast to the well-known inverted U-shaped (or λ-shaped) conformation of the insulin receptor, the structural models reconstructed at different pH values revealed that the ectoIRR organization has a "droplike" shape with a shorter distance between the fibronectin domains of the disulfide-linked dimer subunits within ectoIRR. We detected no large-scale pH-dependent conformational changes of ectoIRR in both SAXS and AFM experiments, an observation that agreed well with previous biochemical and functional analyses of IRR. Our findings indicate that ectoIRR's sensing of alkaline conditions involves additional molecular mechanisms, for example engagement of receptor juxtamembrane regions or the surrounding lipid environment.

Buffering Capacity in Sepsis: A Prospective Cohort Study in Critically Ill Patients

Background: The concept of buffering generally refers to the ability of a system/organism to withstand attempted changes. For acid-base balance in particular, it is the body’s ability to limit pH aberrations when factors that potentially affect it change. Buffering is vital for maintaining homeostasis of an organism. The present study was undertaken in order to investigate the probable buffering capacity changes in septic patients. Materials and methods: This prospective cohort study included 113 ICU patients (96 septic and 17 critically-ill non-septic/controls). The buffering capacity indices were assessed upon ICU admission and reassessed only in septic patients, either at improvement or upon severe deterioration. Applying Stewart’s approach, the buffering capacity was assessed with indices calculated from the observed central venous-arterial gradients: a) ΔPCO₂/Δ[H⁺] or ΔpH, b) ΔSID/Δ[H⁺] or ΔpH. Results: In a generalized estimating equation linear regression model, septic patients displayed significant differences in ΔPCO₂/ΔpH [beta coefficient = –47.63, 95% CI (–80.09) – (–15.17), p = 0.004], compared to non-septic patients on admission. Lower absolute value of ΔPCO₂/ΔpH (%) on admission was associated with a significant reduction in ICU mortality (HR 0.98, 95% CI: 0.97–0.99, p = 0.02). At septic-group reassessment (remission or deterioration), one-unit increase of ΔPCO₂/Δ[H⁺] reduced the ICU death hazard by 44% (HR 0.56, 95% CI: 0.33–0.96, p = 0.03). Conclusions: In the particular cohort of patients studied, a difference in the buffering capacity was recorded between septic and non-septic patients on admission. Moreover, buffering capacity was an independent predictor of fatal ICU outcome at both assessments, ICU-admission and sepsis remission or deterioration.

Higher dietary acid load is not associated with risk of breast cancer in Iranian women

BACKGROUND

Dietary acid load (DAL) may play a key role in certain cancers, including breast cancer (BC); however, evidence showing a causal relationship is lacking.

AIM

We examined the relationship between DAL, assessed with both the potential renal acid load (PRAL) and the net endogenous acid production (NEAP) scores, and BC risk.

METHODS

We identified 150 women who had a diagnosis of BC recently and 150 age-matched apparently healthy controls. Data from dietary intake and anthropometric measures were collected from participants and eventually, PRAL and NEAP scores were obtained from nutrient intakes. Multivariate odds ratios (OR) with 95% confidence intervals (CI) were used to evaluate the relationship of BC risk with PRAL and NEAP scores.

RESULTS

The odds ratios (OR) of BC according to tertiles of PRAL and NEAP scores by multivariate logistic regression models revealed that both PRAL (P-trend = 0.8) and NEAP (P-trend = 0.1) scores were not significantly associated with BC risk. After controlling confounders, multiple logistic regressions still remained non-significant which indicated no significant associations between PRAL (P-trend = 0.9), NEAP (P-trend = 0.4) scores and risk of BC.

CONCLUSION

The results of our study suggested that there is no significant relationship between DAL and BC incidence among Iranian women.

The Effects of Endurance Exercise in Hypoxia on Acid-Base Balance, Potassium Kinetics, and Exogenous Glucose Oxidation

Purpose

To investigate the carbohydrate metabolism, acid–base balance, and potassium kinetics in response to exercise in moderate hypoxia among endurance athletes.

Methods

Nine trained endurance athletes [maximal oxygen uptake (VO_2max): 62.5 ± 1.2 mL/kg/min] completed two different trials on different days: either exercise in moderate hypoxia [fraction of inspired oxygen (FiO₂) = 14.5%, HYPO] or exercise in normoxia (FiO₂ = 20.9%, NOR). They performed a high-intensity interval-type endurance exercise consisting of 10 × 3 min runs at 90% of VO_2max with 60 s of running (active rest) at 50% of VO_2max between sets in hypoxia (HYPO) or normoxia (NOR). Venous blood samples were obtained before exercise and during the post-exercise. The subjects consumed ¹³C-labeled glucose immediately before exercise, and we collected expired gas samples during exercise to determine the ¹³C-excretion (calculated as ¹³CO₂/¹²CO₂).

Results

The running velocities were significantly lower in HYPO (15.0 ± 0.2 km/h) than in NOR (16.4 ± 0.3 km/h, P < 0.0001). Despite the lower running velocity, we found a significantly greater exercise-induced blood lactate elevation in HYPO compared with in NOR (P = 0.002). The bicarbonate ion concentration (P = 0.002) and blood pH (P = 0.002) were significantly lower in HYPO than in NOR. There were no significant differences between the two trials regarding the exercise-induced blood potassium elevation (P = 0.87) or ¹³C-excretion (HYPO, 0.21 ± 0.02 mmol⋅39 min; NOR, 0.14 ± 0.03 mmol⋅39 min; P = 0.10).

Conclusion

Endurance exercise in moderate hypoxia elicited a decline in blood pH. However, it did not augment the exercise-induced blood K⁺ elevation or exogenous glucose oxidation (¹³C-excretion) compared with the equivalent exercise in normoxia among endurance athletes. The findings suggest that endurance exercise in moderate hypoxia causes greater metabolic stress and similar exercise-induced elevation of blood K⁺ and exogenous glucose oxidation compared with the same exercise in normoxia, despite lower mechanical stress (i.e., lower running velocity).

Oral Bicarbonate Therapy in Non-Haemodialysis Dependent Chronic Kidney Disease Patients: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Metabolic acidosis is a common complication in chronic kidney disease (CKD) patients, and is associated with an accelerated decline in renal function. Oral bicarbonate therapy has been used to counteract metabolic acidosis in CKD for decades. However, until recently, there have been very few intervention studies testing the effectiveness of bicarbonate therapy at improving metabolic acidosis or its consequences in patients with CKD. In this systematic review and meta-analysis, we aimed to examine the outcomes of all published randomised controlled trials (RCTs) that investigated the effect of oral bicarbonate therapy in adults with CKD. Ovid MEDLINE^®, EMBASE^® and Cochrane Library were searched in mid-October 2018 for English literature, with no restrictions applied to the publication status or date. Seven RCTs that recruited 815 participants met our inclusion criteria after full text review. Oral bicarbonate supplementation resulted in a slightly higher estimated glomerular filtration rate (eGFR) (mean difference 3.1 mL/min per 1.73 m²; 95% CI 1.3–4.9) and serum bicarbonate levels (mean difference 3.4 mmol/L; 95% CI 1.9–4.9) at the end of follow-up (three months to five years) compared to those given placebo or conventional CKD treatment. When limited to studies reporting outcomes at one year, the positive effect of oral bicarbonate therapy on eGFR was attenuated. There were no significant treatment effects in other parameters such as systolic blood pressure (BP) and weight. These findings should be interpreted with caution and further trial evidence is needed to establish the net overall benefit or harm of oral bicarbonate therapy in CKD.

Arterial blood gas and acid-base balance in patients with pregnancy-induced hypertension syndrome

This study aimed to investigate the expression of arterial blood gas and acid-base balance in patients with pregnancy-induced hypertension syndrome and their influence on newborns. A total of 348 patients with pregnancy-induced hypertension syndrome (research group) admitted and treated in the First People's Hospital of Jining from March 2013 to March 2016 were retrospectively analyzed, and another 156 cases of healthy pregnant women who were physically examined were selected as the control group. Blood gas analysis was performed on pregnant women, and pH value, partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2), bicarbonate radical (HCO3^-) and base excess (BE) were included as test indexes. Apgar score was made for newborns for neonatal asphyxia. The evaluation was performed at 1, 5, and 10 min after birth to analyze the correlation between the maternal arterial blood pH and the neonatal Apgar score. The pH value, and PO2 and HCO3^- levels in the research group were lower than those in the control group (p<0.05). PCO2 and BE levels in the research group were higher than those in the control group (p<0.05). The incidence of neonatal mild asphyxia (Apgar score, 4-6 points) and neonatal severe asphyxia (Apgar score, <4 points) in the research group were higher than that in the control group (p<0.05). The Apgar score of newborns was positively correlated with the pH value of the arterial blood of pregnant women. Blood gas analysis in patients with pregnancy-induced hypertension syndrome is useful to a certain extent to evaluate the condition of the patient. The combination of the pH value of the patient and the Apgar score of the newborns may help improve the judgement rate of neonatal asphyxia so as to improve the quality of childbirth by early monitoring and intervention of the newborns.

Bidirectional Relationship Between Reduced Blood pH and Acute Pancreatitis: A Translational Study of Their Noxious Combination

Acute pancreatitis (AP) is often accompanied by alterations in the acid-base balance, but how blood pH influences the outcome of AP is largely unknown. We studied the association between blood pH and the outcome of AP with meta-analysis of clinical trials, and aimed to discover the causative relationship between blood pH and AP in animal models. PubMed, EMBASE, and Cochrane Controlled Trials Registry databases were searched from inception to January 2017. Human studies reporting systemic pH status and outcomes (mortality rate, severity scores, and length of hospital stay) of patient groups with AP were included in the analyses. We developed a new mouse model of chronic metabolic acidosis (MA) and induced mild or severe AP in the mice. Besides laboratory blood testing, the extent of pancreatic edema, necrosis, and leukocyte infiltration were assessed in tissue sections of the mice. Thirteen studies reported sufficient data in patient groups with AP (n = 2,311). Meta-analysis revealed markedly higher mortality, elevated severity scores, and longer hospital stay in AP patients with lower blood pH or base excess (P < 0.001 for all studied outcomes). Meta-regression analysis showed significant negative correlation between blood pH and mortality in severe AP. In our mouse model, pre-existing MA deteriorated the pancreatic damage in mild and severe AP and, vice versa, severe AP further decreased the blood pH of mice with MA. In conclusion, MA worsens the outcome of AP, while severe AP augments the decrease of blood pH. The discovery of this vicious metabolic cycle opens up new therapeutic possibilities in AP.

Adenylyl cyclase 6 in acid-base balance - adding complexity

Systemic acid-base balance is tightly controlled within a narrow range of pH. Disturbances in systemic acid-base homeostasis are associated with diverse detrimental effects. The kidney is a key regulator of acid-base balance, capable of excreting HCO₃^- or H⁺, and chronic kidney disease invariably leads to acidosis. However, the regulatory pathways underlying the fine-tuned acid-base sensing and regulatory mechanisms are still incompletely understood. In the article published recently in Clinical Science (vol 132 (16) 1779-1796), Poulson and colleagues investigated the role of adenylyl cyclase 6 (AC6) in acid-base homeostasis. They uncovered a complex role of AC6, specifically affecting acid-base balance during HCO₃^- load, which causes pronounced alkalosis in AC6-deficient mice. However, the phenotype of AC6-deficient mice appears much more complex, involving systemic effects associated with increased energy expenditure. These observations remind us that there is much to be learned about the intricate signaling pathways involved in renal control of acid-base balance and the complex ramifications of acid-base regulation.

Amino acid transporters revisited: New views in health and disease

Amino acid transporters (AATs) are membrane-bound transport proteins that mediate transfer of amino acids into and out of cells or cellular organelles. AATs have diverse functional roles ranging from neurotransmission to acid-base balance, intracellular energy metabolism, and anabolic and catabolic reactions. In cancer cells and diabetes, dysregulation of AATs leads to metabolic reprogramming, which changes intracellular amino acid levels, contributing to the pathogenesis of cancer, obesity and diabetes. Indeed, the neutral amino acid transporters (NATs) SLC7A5/LAT1 and SLC1A5/ASCT2 are likely involved in several human malignancies. However, a clinical therapy that directly targets AATs has not yet been developed. The purpose of this review is to highlight the structural and functional diversity of AATs, their diverse physiological roles in different tissues and organs, their wide-ranging implications in human diseases and the emerging strategies and tools that will be necessary to target AATs therapeutically.

H+-ATPase B1 subunit localizes to thick ascending limb and distal convoluted tubule of rodent and human kidney

The vacuolar-type H⁺-ATPase B1 subunit is heavily expressed in the intercalated cells of the collecting system, where it contributes to H⁺ transport, but has also been described in other segments of the renal tubule. This study aimed to determine the localization of the B1 subunit of the vacuolar-type H⁺-ATPase in the early distal nephron, encompassing thick ascending limbs (TAL) and distal convoluted tubules (DCT), in human kidney and determine whether the localization differs between rodents and humans. Antibodies directed against the H⁺-ATPase B1 subunit were used to determine its localization in paraffin-embedded formalin-fixed mouse, rat, and human kidneys by light microscopy and in sections of Lowicryl-embedded rat kidneys by electron microscopy. Abundant H⁺-ATPase B1 subunit immunoreactivity was observed in the human kidney. As expected, intercalated cells showed the strongest signal, but significant signal was also observed in apical membrane domains of the distal nephron, including TAL, macula densa, and DCT. In mouse and rat, H⁺-ATPase B1 subunit expression could also be detected in apical membrane domains of these segments. In rat, electron microscopy revealed that the H⁺-ATPase B1 subunit was located in the apical membrane. Furthermore, the H⁺-ATPase B1 subunit colocalized with other H⁺-ATPase subunits in the TAL and DCT. In conclusion, the B1 subunit is expressed in the early distal nephron. The physiological importance of H⁺-ATPase expression in these segments remains to be delineated in detail. The phenotype of disease-causing mutations in the B1 subunit may also relate to its presence in the TAL and DCT.