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Inspired by the Stewart-Figge acid–base approach, Gattinoni et al. recently introduced a new internal milieu parameter known as alactic base excess (ABE). The authors defined ABE as the sum of lactate and standard base excess. In the context of sepsis, ABE has been proposed as a valuable marker to discern between metabolic acidosis resulting from the accumulation of lactate and the retention of fixed acids, which can occur in cases of renal failure. Multiple studies have demonstrated that a negative ABE value (<−3 mmol/L) represents an early marker of renal dysfunction, and significantly correlates with higher mortality rates in septic patients. In conclusion, ABE is a simple and useful parameter that can be used to better interpret a patient's acid–base status, assess renal function, and general prognosis in sepsis. By incorporating ABE into clinical practice, healthcare professionals can enhance their understanding of the complex acid–base imbalances in their patients and tailor more individualized, effective treatment plans. [ABSTRACT FROM AUTHOR]

Background: The difference between serum sodium and chloride ion concentrations (SCD) may be considered as a surrogate of a strong ion difference and may help to identify patients with a worse prognosis. We aimed to assess SCD as an early prognostic marker among patients with myocardial infarction. Methods: Data of 594 consecutive patients with acute myocardial infarction treated with PCI (44.9% STEMI patients; 70.7% males) was analysed for SCD in relation to their 30‐day mortality. A restricted cubic spline regression model was used to study the relationship between mortality and SCD. Cox regression models were used to assess the association between SCD and the mortality risk. Results: Patients with Killip class ≥3 had lower SCD values in comparison to patients with Killip class ≤2: (32.0 [30.0–34.0] vs. 33.0 [31.0–36.0], p =.006). The overall 30‐day mortality was 7.7% (n = 46). There was a significant difference in SCD values between survivors and non‐survivors groups of patients (median (IQR): (33.0 [31.0–36.0] vs. 31.5 [28.0–34.0] (mmol/L), p =.002). The restricted cubic splines model confirmed a non‐linear association between SCD and mortality. Patients with SCD <30 mmol/L (in comparison to SCD ≥30 mmol/L) had an increased mortality risk (unadjusted HR 2.92, 95% CI 1.59–5.36, p =.001; and an adjusted HR 2.30, 95% CI 1.02–5.19, p =.04). Conclusions: Low SCD on admission is associated with an increased risk of 30‐day mortality in patients with acute myocardial infarction treated with PCI and may serve as a useful prognostic marker for these patients. [ABSTRACT FROM AUTHOR]

Purpose: The aims of this study were (1) to determine the associations of cardioplegic solutions with postoperative main strong ion difference (mSID), which is the difference between sodium ion concentration and chloride ion concentration ([Cl−]) and (2) to determine the associations of cardioplegic solutions with markers of organ dysfunction. Methods: In this retrospective cohort study, patients aged <5 years who underwent cardiac surgery in a tertiary teaching hospital were included. Patients were classified on the basis of the type of cardioplegic solution: modified del Nido cardioplegia (mDNC) and conventional cardioplegia (CC). The effects of mDNC on postoperative mSID and markers of organ functions were examined using propensity-matched analysis. Results: A total of 500 cases were included. mDNC solution was used in 163 patients (32.6%). After propensity score matching, patients in the mDNC group (n = 152) had significantly higher minimum mSID [28 (26, 30) mEq/L vs. 27 (25, 29) mEq/L, p = 0.02] and lower maximum [Cl−] [112 (109, 114) mEq/L vs. 113 (111, 117) mEq/L, p < 0.001] than patients in the CC group (n = 304). The incidences of low mSID and hyperchloremia in the mDNC group were significantly lower than those in the CC group (63.8 vs. 75.7%, p = 0.01 and 63.2 vs. 79.3%, p < 0.001, respectively). There was no significant difference in the incidence of postoperative acute kidney injury and B-type natriuretic peptide level between the two groups. Conclusion: The use of modified del Nido cardioplegia may reduce the incidence of abnormal mSID and hyperchloremia compared with the use of a chloride-rich cardioplegic solution. [ABSTRACT FROM AUTHOR]

This manuscript will review crystalloid (hypo-, iso-, and hyper-tonic) and colloid (synthetic and natural) fluids that are available for intravenous administration with a focus on their electrolyte, acid-base, colligative, and rheological effects as they relate to each solution's efficacy and safety. The goal is for the reader to better understand the differences between each fluid and the influence on plasma composition, key organ systems, and their implications when used therapeutically in animals with critical illness.

Objective:The diagnosis and treatment of electrolyte and acid-base imbalances in intensive care unit (ICU) patients have critical importance. The value of Stewart’s approach in revealing acid-base disorders is known. There are parameters defined according to this approach. This study investigates the impact of the chloride effect (ClEffect), sodium effect (NaEffect), sodium-chloride effect (Na-ClEffect), strong ion difference (SIDnl) and Cl/Na ratio values calculated according to Stewart’s approach on ICU mortality.Materials and Methods:Two thousand patients whose Na, Cl, K, standard base excess (SBE), pH values were recorded and SIDnl, ClEffect, NaEffect, Na-ClEffect, Acute Physiology Assessment and Chronic Health Evaluation-II (APACHE-II) and Sequential Organ Failure Assessment (SOFA) scores calculated are included in this study. ClEffect, NaEffect, Na-ClEffect, SIDnl, Cl/Na ratio values were evaluated with a multivariable logistic regression model in terms of ICU mortality.Results:Abnormal ranges of SIDnl (SIDnl 7, and SIDnl

Objective: The diagnosis and treatment of electrolyte and acid-base imbalances in intensive care unit (ICU) patients have critical importance. The value of Stewart’s approach in revealing acid-base disorders is known. There are parameters defined according to this approach. This study investigates the impact of the chloride effect (ClEffect), sodium effect (NaEffect), sodium-chloride effect (Na-ClEffect), strong ion difference (SIDnl) and Cl/Na ratio values calculated according to Stewart’s approach on ICU mortality. Materials and Methods: Two thousand patients whose Na, Cl, K, standard base excess (SBE), pH values were recorded and SIDnl, ClEffect, NaEffect, Na-ClEffect, Acute Physiology Assessment and Chronic Health Evaluation-II (APACHE-II) and Sequential Organ Failure Assessment (SOFA) scores calculated are included in this study. ClEffect, NaEffect, Na-ClEffect, SIDnl, Cl/Na ratio values were evaluated with a multivariable logistic regression model in terms of ICU mortality. Results: Abnormal ranges of SIDnl (SIDnl <30 or SIDnl ≥43) were significantly increased in nonsurvivors than survivors (p=0.026). ClEffect, NaEffect, Na-ClEffect, Cl/Na ratio and their percentages of abnormal ranges were similar between survivor and non-survivor patients.In the multivariate logistic regression model, the likelihood of mortality was 3.5-fold (2.9-4.3), 1.7-fold (1.4-2.1) and 1.2-fold (1.0-1.5) increased by APACHE-II ≥26, SOFA >7, and SIDnl <30 or SIDnl ≥43 (p<0.001, p<0.001, p=0.041, respectively). Conclusion: SIDnl is associated with ICU mortality, but pH, SBE, ClEffect, NaEffect, Na-ClEffect and Cl/ Na ratio is not. SIDnl is one of the independent variables of Stewart’s approach and is a valuable parameter in blood gas evaluations [ABSTRACT FROM AUTHOR]

• An exercise-associated reduction was seen in plasma total CO 2 , HCO 3 - and Ca++. • Insulin and glucose were unaltered by calcium propionate (CaProp) treatment. • Strong ion difference was unaltered by CaProp treatment. • Total CO 2 , Ca++ , HCO 3 - were higher in CaProp-treated horses at certain timepoints. • Calcium propionate was found to be an alkalizing agent in horses. The objective of this study was to determine if calcium propionate is an alkalizing agent in exercising Standardbreds and if it alters plasma glucose and serum insulin concentrations. This study used a randomized crossover design to test the hypotheses that calcium propionate alters total CO2 (tCO 2), Ca++, pH, strong ion difference (SID), glucose, and insulin in Standardbreds completing a simulated race test (SRT) on a high-speed equine treadmill. Blood was collected from eight horses (mean age ± SD = 16 ± 2.7 years; range = 13 - 21 years) at 10 and 5 min prior to treatment or control administration, just prior to the subsequent SRT, directly after the SRT, and at 60- and 90-min post SRT. Plasma pH and plasma concentrations of tCO 2, glucose, Ca++, and Na+, K+, Cl-, Lac- (for SID calculation) were measured in duplicate by blood gas analyzer and serum insulin by radioimmunoassay. Data were analyzed by two-way repeated-measures ANOVA. For plasma pH, Na+, K+, Cl-, Lac-, SID, insulin and glucose, no effects of treatment or treatment by sampling-timepoint interaction were found (p>0.05). Plasma tCO 2 , Ca++, pH, Na+, SID, and glucose concentrations were significantly lower, and Lac- was significantly higher, directly after the SRT compared to all other timepoints (p<0.05). Plasma tCO2, HCO 3 - and Ca++ were significantly higher in treated than in control horses at multiple sampling timepoints after treatment/control administration (p<0.05). Serum insulin concentration, measured only pre and 30 min post treatment/control administration, was unaffected by treatment. Calcium propionate is an alkalizing agent in horses. [ABSTRACT FROM AUTHOR]

Simple Summary: The purposes of the present study were to determine the effect of core body temperature on acid-base variables and determine the origins of acid-base changes in the arterial and mixed venous blood of horses during exercise and recovery. Moderate intensity exercise resulted in an increase in body temperature that, in addition to exercise, affected acid-base status and gas partial pressures. Moderate intensity exercise resulted in a mild alkalosis that had markedly different origins in arterial blood than in mixed venous blood, and this was affected by the increase in core temperature during exercise and its resolution during recovery. In order to fully understand how acid-base status changes during exercise and recovery, it is importance to quantify the changes in both arterial and mixed venous blood, with adjustment to core temperature. Acid-base assessments using jugular vein blood samples are limited in comparison. The present study determined the independent contributions of temperature, strong ion difference ([SID]), total weak acid concentration ([Atot]) and PCO2 to changes in arterial and mixed venous [H+] and total carbon dioxide concentration ([TCO2]) during 37 min of moderate intensity exercise (~50% of heart rate max) and the first 60 min of recovery. Six horses were fitted with indwelling carotid and pulmonary artery (PA) catheters, had PA temperature measured, and had blood samples withdrawn for immediate analysis of plasma ion and gas concentrations. The increase in core temperature during exercise (+4.5 °C; p < 0.001) significantly (p < 0.05) increased PO2, PCO2, and [H+], but without a significant effect on [TCO2] (p > 0.01). The physicochemical acid-base approach was used to determine contributions of independent variables (except temperature) to the changes in [H+] and [TCO2]. In both arterial and venous blood, there was no acidosis during exercise and recovery despite significant (p < 0.05) increases in [lactate] and in venous PCO2. In arterial blood plasma, a mild alkalosis with exercise was due to primarily to a decrease in PCO2 (p < 0.05) and an increase in [SID] (p < 0.1). In venous blood plasma, a near absence of change in [H+] was due to the acidifying effects of increased PCO2 (p < 0.01) being offset by the alkalizing effects of increased [SID] (p < 0.05). The effect of temperature on PO2 (p < 0.001) resulted in an increased arterio-venous PO2 difference (p < 0.001) that would facilitate O2 transfer to contracting muscle. The simultaneous changes in the PCO2 and the concentrations of the other independent acid-base variables (contributions from individual strong and weak ions as manifest in [SID] and [Atot]) show complex, multilevel control of acid-base states in horses performing even moderate intensity exercise. Correction of acid-base variables to core body temperature presents a markedly different physiological response to exercise than that provided by variables measured and presented at an instrument temperature of 37 °C. [ABSTRACT FROM AUTHOR]

Background: Traditional arterial blood gas (ABG) analysis may miss out on some metabolic acid-base disorders. We prospectively compared Stewart's approach in critically ill patients to traditional bicarbonate-anion gap-based methods (with and without correction for albumin) to diagnose acid-base disorders. Patients and methods: Five hundred ABG samples from medical or surgical patients in the ICU were analyzed with traditional bicarbonate-anion gap-based methodology with and without correction for albumin and Stewart's biochemical approach. The primary outcome identification of additional metabolic disorders diagnosed with Stewart's approach in comparison to bicarbonate system-based approaches. We also looked at the correlation between the strong ion gap (SIG) and the albumin-corrected anion gap (acAnion Gap). Results: Stewart's approach detected missed metabolic disorders in 58 (11.6%) blood gas results reported as "within normal limits" with the bicarbonate-uncorrected anion gap approach. In 50 (10%) of these ABGs, the acAnion Gap approach was able to diagnose the missed metabolic disorders. Thus, the albumin-corrected anion gap method had a similar diagnostic performance to Stewart's approach, as it missed additional disorders in only eight (1.6%) blood gases. Conclusion: In this study, we found that the acAnion Gap approach was similar in diagnostic performance to Stewart's approach. We feel that the corrected anion gap approach can be safely used if a ready calculator for Stewart's approach is not available. [ABSTRACT FROM AUTHOR]

Ozgur Kilic,1 Yucel Gultekin,2 Selcuk Yazici1 1Siyami Ersek Thoracic and Cardiovascular Surgery Center, Cardiology Department, Cardiac Intensive Care Unit, Istanbul, Turkey; 2Mersin University Hospital, General Surgery Department, Mersin, TurkeyCorrespondence: Ozgur KilicSiyami Ersek Thoracic and Cardiovascular Surgery Center, Cardiology Department, Cardiac Intensive Care Unit, Istanbul, TurkeyTel +90 505 826 09 12Email Rugzo63@hotmail.comAbstract: One of the most important tasks of physicians working in intensive care units (ICUs) is to arrange intravenous fluid therapy. The primary indications of the need for intravenous fluid therapy in ICUs are in cases of resuscitation, maintenance, or replacement, but we also load intravenous fluid for purposes such as fluid creep (including drug dilution and keeping venous lines patent) as well as nutrition. However, in doing so, some facts are ignored or overlooked, resulting in an acid-base disturbance. Regardless of the type and content of the fluid entering the body through an intravenous route, it may impair the acid-base balance depending on the rate, volume, and duration of the administration. The mechanism involved in acid-base disturbances induced by intravenous fluid therapy is easier to understand with the help of the physical-chemical approach proposed by Canadian physiologist, Peter Stewart. It is possible to establish a quantitative link between fluid therapy and acid–base disturbance using the Stewart principles. However, it is not possible to accomplish this with the traditional approach; moreover, it may not be noticed sometimes due to the normalization of pH or standard base excess induced by compensatory mechanisms. The clinical significance of fluid-induced acid-base disturbances has not been completely clarified yet. Nevertheless, as fluid therapy may be the cause of unexplained acid-base disorders that may lead to confusion and elicit unnecessary investigation, more attention must be paid to understand this issue. Therefore, the aim of this paper is to address the effects of different types of fluid therapies on acid-base balance using the simplified perspective of Stewart principles. Overall, the paper intends to help recognize fluid-induced acid-base disturbance through bedside evaluation and choose an appropriate fluid by considering the acid-base status of a patient.Keywords: Stewart approach, fluid therapy, acid-base disturbance, strong ion difference, total weak acid concentration

Abstract Objective Physicochemical approach such as strong ion difference provides a novel concept in understanding and managing acid–base disturbance in patients. However, its application in pediatrics is limited. This study aimed to evaluate a correlation between the physicochemical approach and blood gas pH for acid–base determination in critically ill pediatric patients. Results A total of 130 pediatric patients were included, corresponding to 1338 paired measures for analyses. Of these, the metabolic subgroup (743 paired measures) was defined. Among physicochemical parameters, the effective strong ion difference showed the best correlation with the blood gas pH in the whole cohort (R = 0.398; p

The present study determined the independent contributions of temperature, strong ion difference ([SID]), total weak acid concentration ([Atot]) and PCO2 to changes in arterial and mixed venous [H+] and total carbon dioxide concentration ([TCO2]) during 37 min of moderate intensity exercise (~50% of heart rate max) and the first 60 min of recovery. Six horses were fitted with indwelling carotid and pulmonary artery (PA) catheters, had PA temperature measured, and had blood samples withdrawn for immediate analysis of plasma ion and gas concentrations. The increase in core temperature during exercise (+4.5 °C; p < 0.001) significantly (p < 0.05) increased PO2, PCO2, and [H+], but without a significant effect on [TCO2] (p > 0.01). The physicochemical acid-base approach was used to determine contributions of independent variables (except temperature) to the changes in [H+] and [TCO2]. In both arterial and venous blood, there was no acidosis during exercise and recovery despite significant (p < 0.05) increases in [lactate] and in venous PCO2. In arterial blood plasma, a mild alkalosis with exercise was due to primarily to a decrease in PCO2 (p < 0.05) and an increase in [SID] (p < 0.1). In venous blood plasma, a near absence of change in [H+] was due to the acidifying effects of increased PCO2 (p < 0.01) being offset by the alkalizing effects of increased [SID] (p < 0.05). The effect of temperature on PO2 (p < 0.001) resulted in an increased arterio-venous PO2 difference (p < 0.001) that would facilitate O2 transfer to contracting muscle. The simultaneous changes in the PCO2 and the concentrations of the other independent acid-base variables (contributions from individual strong and weak ions as manifest in [SID] and [Atot]) show complex, multilevel control of acid-base states in horses performing even moderate intensity exercise. Correction of acid-base variables to core body temperature presents a markedly different physiological response to exercise than that provided by variables measured and presented at an instrument temperature of 37 °C.

The administration of oral rehydration solutions (ORS) is an effective method to treat dehydration and acidosis in calves suffering from diarrhea. The ORS can be prepared in water or milk. The aim of the present study was to elucidate how fluid and acid-base balance change after feeding milk compared with ORS prepared in water or milk to diarrheic calves. Calves (n = 30) with naturally acquired diarrhea were sequentially assigned in a 2:1 ratio to the following pretreatments: milk and water-ORS (pretreatment 1; n = 20 calves) or milk-ORS (pretreatment 2; n = 10 calves), respectively. The assignment was done on the day of diarrhea diagnosis. On d 3 ± 1 following assignment to pretreatment group, and after a fasting period of 9 h, diarrheic calves were subjected to the following treatments: 2 L of milk (pretreatment 1; n = 10 calves), water-ORS (pretreatment 1; n = 10 calves), or milk-ORS (pretreatment 2; n = 10 calves). Blood samples were taken before and at several time points until 6 h after feeding. Plasma protein, osmolality, and electrolytes were determined and a blood gas analysis was performed. Change in plasma volume was calculated according to plasma protein, and water intake during the experimental period was recorded. Plasma volume was increased 30 min after feeding water-ORS or milk but the increase was less pronounced after feeding milk compared with water-ORS. After feeding milk-ORS, no significant increase in plasma volume could be detected. Because of the pretreatment, plasma osmolality was higher in calves fed milk-ORS, but no change in plasma osmolality after feeding was detected. No difference in water consumption between the treatment groups was noted within the observed 6-h period. The pH was increased after feeding milk-ORS, whereas water-ORS and milk-feeding did not increase pH in blood. Pretreatment with milk-ORS resulted in higher baseline d -lactate concentration, but feeding milk-ORS reduced d -lactate values after feeding. In calves with diarrhea, plasma volume increased more quickly and to a greater extent after feeding water-ORS; thus, we recommend treating diarrheic calves with water-ORS before supplying milk. Nevertheless, diarrheic calves need milk to fulfill their energy needs. The administration of ORS in milk combined with free water access is more advisable than feeding milk exclusively because milk has no alkalinizing ability and contains less sodium. However, the effects of milk-ORS feeding on d -lactate levels in diarrheic calves need further elucidation. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the acid‐base status of sick goats using the simplified strong ion difference (sSID) approach, to establish the quantitative contribution of sSID variables to changes in blood pH and HCO3− and to determine whether clinical, acid‐base, and biochemical variables on admission are associated with the mortality of sick goats. Animals One hundred forty‐three sick goats. Methods: Retrospective study. Calculated sSID variables included SID using 6 electrolytes unmeasured strong ions (USI) and the total nonvolatile buffer ion concentration in plasma (Atot). The relationship between measured blood pH and HCO3−, and the sSID variables was examined using forward stepwise linear regression. Cox proportional hazard models were constructed to assess associations between potential predictor variables and mortality of goats during hospitalization. Results: Hypocapnia, hypokalemia, hyperchloremia, hyperlactatemia, and hyperproteinemia were common abnormalities identified in sick goats. Respiratory alkalosis, strong ion acidosis, and Atot acidosis were acid‐base disorders frequently encountered in sick goats. In sick goats, the sSID variables explained 97% and 100% of the changes in blood pH and HCO3−, respectively. The results indicated that changes in the respiratory rate (<16 respirations per minute), USI, and pH at admission were associated with increased hazard of hospital mortality in sick goats. Conclusions and Clinical Importance: The sSID approach is a useful methodology to quantify acid‐base disorders in goats and to determine the mechanisms of their development. Clinicians should consider calculation of USI in sick goats as part of the battery of information required to establish prognosis. [ABSTRACT FROM AUTHOR]

Background: Use of different analyzers to measure electrolytes in the same horse can lead to different interpretation of acid‐base balance when using the simplified strong ion difference (sSID) approach. Objective: Investigate the level of agreement between 2 analyzers in determining electrolytes concentrations, sSID variables, and acid‐base disorders in sick horses. Animals One hundred twenty‐four hospitalized horses. Methods: Retrospective study using paired samples. Electrolytes were measured using a Beckman Coulter AU480 Chemistry analyzer (PBMA) and a Nova Biomedical Stat Profile (WBGA), respectively. Calculated sSID variables included strong ion difference, SID4; unmeasured strong ions, USI; and total nonvolatile buffer ion concentration in plasma (Atot). Agreement between analyzers was explored using Passing‐Bablok regression and Bland‐Altman analysis. Kappa (κ) test evaluated the level of agreement between analyzers in detecting acid‐base disorders. Results: Methodologic differences were identified in measured Na+ and Cl− and calculated values of SID4 and USI. Mean bias (95% limits of agreement) for Na+, Cl−, SID4, and USI were: −1.2 mmol/L (−9.2 to 6.8), 4.4 mmol/L (−4.4 to 13), −5.4 mmol/L (−13 to 2), and −6.2 mmol/L (−14 to 1.7), respectively. The intraclass correlation coefficient for SID4 and USI was.55 (95%CI: −0.2 to 0.8) and.2 (95%CI: −0.15 to 0.48), respectively. There was a poor agreement between analyzers for detection of SID4 (κ = 0.20, 95%CI, 0.1 to 0.31) or USI abnormalities (κ = −0.04, 95%CI, −0.11 to 0.02). Conclusions and Clinical Importance: Differences between analyzer methodology in measuring electrolytes led to a poor agreement between the diagnosis of acid‐base disorders in sick horses when using the sSID approach. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objective: Complex metabolic acid-base disturbances can be seen in critically ill patients infected with the SARS-CoV-2 virus. For arterial blood gas (ABG) analysis, base excess (BE) approach enables limited evaluation of the etiological factors. The Stewart’s physicochemical approach, on the other hand, may not reveal etiological agents adequately. In this study, we aimed to compare BE approach versus physicochemical method for the evaluation of metabolic acid-base disturbances in critically ill patients infected with SARS-CoV-2. Method: Between March 2020 and May 2020, ABG analysis results of a total of 113 patients (71 males, 42 females) infected with SARS-CoV-2 and hospitalized in the adult intensive care units were retrospectively analyzed. The patients were divided into groups according to the BE approach and evaluated for physicochemical components. The ABG and some electrolyte values were compared among groups. Results: The most common acidotic components according to the Stewart’s method were hyperphosphatemia (84.9%), but low strong ion difference (SID) acidosis (62.2%) in patients with metabolic acidosis according to the BE approach. Low SID acidosis (50%) and hyperphosphatemia (30.9%) in patients with normal BE and hyperphosphatemia (77.7%) in patients with metabolic alkalosis according to the BE approach were observed. In patients with metabolic acidosis according to BE approach, 71.6% of the patients had hypoalbuminemia and 24.5% of the cases had high SID alkalosis among the Stewart’s alkalosis components. Strong ion gap (SIG) acidosis was seen in 11.1% and low SID acidosis was seen in 11.1% in patients with metabolic acidosis according to the BE approach. Conclusion: Physiochemical approach seems to provide additional information regarding the etiological factors and unravel the invisible part of the iceberg for the evaluation of metabolic acid-base disturbances in critically ill patients infected with the SARS-CoV-2 virus. [ABSTRACT FROM AUTHOR]

Objectives: We designed a novel respiratory dialysis system to remove CO2 from blood in the form of bicarbonate. We aimed to determine if our respiratory dialysis system removes CO2 at rates comparable to low-flow extracorporeal CO2 removal devices (blood flow < 500 mL/min) in a large animal model.Design: Experimental study.Setting: Animal research laboratory.Subjects: Female Yorkshire pigs.Interventions: Five bicarbonate dialysis experiments were performed. Hypercapnia (PCO2 90-100 mm Hg) was established in mechanically ventilated swine by adjusting the tidal volume. Dialysis was then performed with a novel low bicarbonate dialysate.Measurements and Main Results: We measured electrolytes, blood gases, and plasma-free hemoglobin in arterial blood, as well as blood entering and exiting the dialyzer. We used a physical-chemical acid-base model to understand the factors influencing blood pH after bicarbonate removal. During dialysis, we removed 101 (±13) mL/min of CO2 (59 mL/min when normalized to venous PCO2 of 45 mm Hg), corresponding to a 29% reduction in PaCO2 (104.0 ± 8.1 vs 74.2 ± 8.4 mm Hg; p < 0.001). Minute ventilation and body temperature were unchanged during dialysis (1.2 ± 0.4 vs 1.1 ± 0.4 L/min; p = 1.0 and 35.3°C ± 0.9 vs 35.2°C ± 0.6; p = 1.0). Arterial pH increased after bicarbonate removal (7.13 ± 0.04 vs 7.21 ± 0.05; p < 0.001) despite no attempt to realkalinize the blood. Our modeling showed that dialysate electrolyte composition, plasma albumin, and plasma total CO2 accurately predict the measured pH of blood exiting the dialyser. However, the final effluent dose exceeded conventional doses, depleting plasma glucose and electrolytes, such as potassium and phosphate.Conclusions: Bicarbonate dialysis results in CO2 removal at rates comparable with existing low-flow extracorporeal CO2 removal in a large animal model, but the final dialysis dose delivered needs to be reduced before the technique can be used for prolonged periods. [ABSTRACT FROM AUTHOR]

Purpose: To place in context the potential value of isolated plasma strong ion difference (SID) calculations and strong ion gap (SIG) calculations versus suggested cut-down versions such as SIDa adj and the BICgap respectively.Methods: Stewart's physical chemical approach is seen as a mathematical model of isolated plasma not displacing traditional Copenhagen and Boston approaches. Scanning tools for unmeasured ions based on the Principle of Electrical Neutrality such as the SIG and suggested cut-down versions such as the albumin adjusted anion gap and the BICgap are evaluated for accuracy and clinical usefulness.Results: Plasma SID and abbreviations such as SIDa adj are not independent variables in vivo since they vary with PCO due to Gibbs Donnan ion traffic. They can also exhibit positive and negative bias, and SID values must be partnered with non-volatile weak acid concentrations when evaluating metabolic acid-base status. The BICgap calculation is a cut down version of the SIG fixed for pH 7.4. It includes phosphate but is otherwise similar in form to the albumin corrected anion gap, with similar sensitivity and specificity characteristics.Conclusions: Clinicians are unlikely to find SID calculations or cut-down versions such as the SIDa adj clinically useful. The albumin corrected anion gap is in current use and easily determined by mental arithmetic from point of care anion gap printouts plus recent plasma albumin measurements. Any slight advantage of the BICgap would be offset by the complexity of its calculation. [ABSTRACT FROM AUTHOR]

Objective: Physicochemical approach such as strong ion difference provides a novel concept in understanding and managing acid–base disturbance in patients. However, its application in pediatrics is limited. This study aimed to evaluate a correlation between the physicochemical approach and blood gas pH for acid–base determination in critically ill pediatric patients. Results: A total of 130 pediatric patients were included, corresponding to 1338 paired measures for analyses. Of these, the metabolic subgroup (743 paired measures) was defined. Among physicochemical parameters, the effective strong ion difference showed the best correlation with the blood gas pH in the whole cohort (R = 0.398; p < 0.001) and the metabolic subgroup (R = 0.685; p < 0.001). Other physicochemical parameters (i.e., the simplified and the apparent strong ion difference, the strong ion gap, and the sodium chloride gap) and the traditional measures (standard base excess, lactate, chloride and bicarbonate) also showed varying degrees of correlation. This study revealed the positive correlation between physicochemical parameters and the blood gas pH, serving as a connecting dot for further investigations using physicochemical approach to evaluate acid–base disturbance in pediatric population. [ABSTRACT FROM AUTHOR]

Objectives: To investigate whether lipopolysaccharide (LPS) is present in plasma of calves with naturally occurring diarrhea. The second objective was to determine whether plasma [LPS] correlates with clinical, hematological, biochemical, and acid‐base variables, and whether [LPS] differs between surviving and nonsurviving diarrheic calves. Design: Prospective observational study (January 2012–May 2014). Setting: Veterinary teaching hospital. Animals: Thirty‐four calves <28 days old admitted for diagnosis and treatment of diarrhea and 30 healthy control calves. Measurements and Main Results: Admission demographics, physical examination, blood gas, biochemistry analysis, and outcome data were recorded. Plasma concentration of LPS was determined using a bovine LPS ELISA assay. Plasma [LPS] was detected in both healthy and diarrheic calves. Plasma [LPS] was significantly higher in diarrheic than healthy calves (median: 0.99 ng/mL; Interquartile range (IQR): 0.068, vs 0.88 ng/mL; 0.065 ng/mL, respectively; P < 0.001). Plasma [LPS] was higher in nonsurviving (1.04 ng/mL; 0.07 ng/mL) than in surviving calves (0.98 ng/mL; 0.022 ng/mL; P < 0.001). Plasma [LPS] was higher in beef (1.07 ng/mL; 0.182 ng/mL) than in dairy diarrheic calves (0.99 ng/mL; 0.022 ng/mL; P < 0.001). In diarrheic calves, plasma [LPS] correlated with [l‐lactate] (r2 = 0.496; P = 0.002); hypoglycemia (r2 = −0.453; P = 0.007); increased unmeasured strong ions (r2 = 0.332; P = 0.050), [Mg2+] (r2 = 0.475; P = 0.004), and [phosphate] (r2 = 0.468; P = 0.005), and increased aspartate aminotransferase activity (r2 = 0.348; P = 0.003). Conclusions: This study highlights a potential role of LPS in the pathogenesis of metabolic derangements such as hyperlactatemia, hypoglycemia, and increased concentration of unmeasured strong anions in diarrheic calves. Further investigation evaluating the effect of LPS on l‐lactate and glucose metabolism in diarrheic calves is warranted. [ABSTRACT FROM AUTHOR]

Latar belakang. Pemberian cairan resusitasi pada syok akan memengaruhi status asam basa tubuh melalui pengaruhnya terhadap strong ion difference (SID) berdasarkan teori Stewart. Normal salin (NS) dan ringer laktat sering digunakan sebagai cairan resusitasi namun terdapat kekhawatiran bahwa penggunaan NS dapat menyebabkan asidosis hiperkloremik dan masalah ini belum banyak diteliti pada anak. Tujuan. Membandingkan perubahan SID dan pH plasma setelah pemberian cairan RL dan NS pada syok. Metode. Dilakukan uji klinik terbuka acak terkontrol di UPIA RSMH bulan Juli 2014 sampai Maret 2015. Randomisasi blok dilakukan pada 44 subjek penelitian rentang usia 2 bulan sampai 14 tahun. Hasil. Terdapat 23 subjek pada kelompok RL dan 21 pada kelompok NS. Pada kelompok RL, rerata SID dan pH setelah resusitasi tidak mengalami perubahan bermakna (SID 32,96±5,26 menjadi 32,32±6,34 mEq/L, p=0,089; pH 7,40 menjadi 7,42 dengan p=0,346). Pada kelompok NS (SID 34,44±8,1 menjadi 32,4±7,24 mEq/L, p=0,354; pH 7,290 menjadi 7,345 dengan p=0,434). Antara kelompok RL dan NS, tidak ditemukan perbedaan bermakna dalam rerata selisih SID (􀀧SID RL -1,22 mEq/L dan NS -1,97 mEq/L dengan p=0,177) dan pH (􀀧pH RL 0,013±0,088 dan NS 0,032±0,11 dengan p=0,534). Ditemukan penurunan bermakna kadar kalium pada kelompok NS setelah resusitasi (4,32±1,05 menjadi 3,73 ± 1,06 mEq/L, p=0,032). Kesimpulan. Resusitasi cairan dengan RL dan NS memberikan perubahan SID dan pH yang tidak berbeda pada kasus syok anak di unit perawatan intensif anak.

Three distinct approaches are currently used in assessing acid-base disorders: the traditional - physiological or bicarbonate-centered approach, the base-excess approach, and the “modern” physicochemical approach proposed by Peter Stewart, which uses the strong ion difference (particularly the sodium chloride difference) and the concentration of nonvolatile weak acids (particularly albumin) and partial pressure of carbon dioxide (pCO2) as independent variables in the assessment of acid-base status. The traditional approach developed from the pioneering work of Henderson and Hasselbalch and the base-excess are still most widely used in clinical practice, even though there are a number of problems identified with this approach. The approach works well clinically and is recommended for use whenever serum total protein, albumin and phosphate concentrations are normal. Although Stewart’s approach has been largely ignored by physiologists, it is increasingly used by anesthesiologists and intensive care specialists, and is recommended for use whenever serum’s total protein, albumin or phosphate concentrations are markedly abnormal, as in critically ill patients. Although different in their concepts, the traditional and modern approaches can be seen as complementary, giving in principle, the same information about the acid-base status.

Each day there is a production of acid by the body's metabolic processes. To maintain balance, these acids need to be excreted or metabolised. Normally, the body can respond very effectively to changes in acid production. Multiple homeostatic mechanisms interact to ensure a stable concentration of hydrogen ions [H + ] exists so that enzymes can function efficiently. Pathological derangement of pH will slow reactions or even permanently denature proteins. The most useful investigation into acid-base balance in the acute setting is a blood gas. A blood gas can help with diagnosis, assessing physiological state, reviewing response to treatment, and prognosis in resuscitation. Having a structured approach to reviewing blood gases can be invaluable in paediatric practice and having a knowledge of how acid-base turnover, buffering, compensation, respiratory and renal excretion co-exist will help you understand what is going on particularly in situations where there is a critically ill child. This review aims to revise acid-base physiology and provide a structure to interpreting a blood gas, with particular emphasis on metabolic conditions. [ABSTRACT FROM AUTHOR]

Acid–base disorders are frequently present in critically ill patients. Metabolic acidosis is associated with increased mortality, but it is unclear whether as a marker of the severity of the disease process or as a direct effector. The understanding of the metabolic component of acid–base derangements has evolved over time, and several theories and models for precise quantification and interpretation have been postulated during the last century. Unmeasured anions are the footprints of dissociated fixed acids and may be responsible for a significant component of metabolic acidosis. Their nature, origin, and prognostic value are incompletely understood. This review provides a historical overview of how the understanding of the metabolic component of acid–base disorders has evolved over time and describes the theoretical models and their corresponding tools applicable to clinical practice, with an emphasis on the role of unmeasured anions in general and several specific settings. [ABSTRACT FROM AUTHOR]

The physical-chemical approach to determine urinary pH is relatively new and has not yet been used in pathological conditions in animals. The main objective of this paper was to demonstrate the validity of this theory in the urine of sheep with hypochloremic metabolic alkalosis. An experimental-type study was conducted to induce hypochloremic metabolic alkalosis in sheep. During the control and induction periods, calculated pH, measured pH, net acid excretion, ammonium and strong ion difference (SID) in urine were examined every 24 hours until development of paradoxical aciduria or physical deterioration of subjects. Pearson's correlation (ρ) was determined between measured and calculated pH based on SID in urine. A high correlation between measured and calculated urine pH was observed using SID calculated from net acid excretion (ρ = 0.874). The correlation between calculated SID and urine pH was significant (ρ = 0.839). However, the correlation between SID and measured urine pH was moderate (ρ = 0.588). It is concluded that there is a high correlation between pH calculated from SID using net acid excretion and pH measured in the urine of sheep with hypochloremic metabolic alkalosis. This indicates that urine pH depends strongly on SID and, therefore, a reduction in pH can be explained by a decrease in SID. [ABSTRACT FROM AUTHOR]

Background: In resuscitation, normal saline could cause hyperchloremic metabolic acidosis, while balanced electrolyte solution is a crystalloid fluid resembling blood plasma with lower chloride content. This study compared the effect of normal saline and balanced electrolyte solution Ringerfundin (BES) as the resuscitation fluid in diabetic ketoacidosis (DKA) patients. Parameters applied in this study were standard base excess (SBE) as resuscitation's result indicator and strong ion difference (SID) to measure chloride's influence in developing hyperchloremic acidosis. Methods: A prospective, randomized, single blind controlled trial was conducted at the Emergency Department of Cipto Mangunkusumo Hospital. Thirty subjects with blood sugar >250 mg/dl, arterial pH <7.35 mg/dl, and positive blood ketone were randomly allocated to receive either normal saline (NS) or RingerfundinO (BES) as the standardized resuscitation protocol. Data analysis was performed using the unpaired T-test and the Mann Whitney test to compare the SBE and the SID means between both groups. Additional parameters were the level of consciousness, blood sugar level, vital signs, blood gas analysis, lactate, electrolyte, and blood ketone. Results: The mean SID in the BES group was significantly greater than the NS group of all measurements (p<0.05). The BES group had significantly higher mean SBE compared to the NS group at 18 hours (-4.88±5.69 vs -9.68±5.64; p=0.009), 24 hours (-3.99±4.27 vs -8.7±5.35; p=0.023), and 48 hours (-4.06±4.11 vs -7.01±5.46; p=0.009). BES resulted in non¬significant higher delta SBE and sId than NS. Additional parameters were not different between both groups. Conclusion: This study showed that fluid resuscitation of DKA patients with BES resulted in slightly but not significantly higher mean actual SBE and SID than NS. suggesting that BES as an alternative fluid resuscitation to prevent hyperchloremic acidosis in diabetic ketoacidosis patients was not superior to NS. [ABSTRACT FROM AUTHOR]

Objective To establish reference intervals for traditionally- and Stewart's approach-determined acid-base parameters in a population of clinically healthy dogs. Design Prospective study (June 2011-September 2012). Setting Veterinary teaching hospital. Animals Two hundred twenty-four client-owned, clinically healthy dogs. Interventions Blood was collected from the jugular vein and the dorsal pedal artery. Measurements and Main Results In the whole blood samples, pH, PCO2, and PO2 were measured and HCO3−, standard and total bicarbonate, base excess, oxygen content, and alveolar-arterial oxygen differences were calculated. Plasma sodium, potassium, chloride, calcium, albumin, and lactate concentrations were measured and the following parameters were calculated separately for venous and arterial samples: anion gap, anion gap corrected for albumin and phosphate, sodium chloride difference and ratio, chloride gap, strong ion difference, strong ion gap, and unmeasured anions. Conclusion Reference intervals for traditionally- and Stewart's approach-determined acid-base parameters were established for venous and arterial blood in dogs. [ABSTRACT FROM AUTHOR]

Crystalloids have become the fluid of choice in critically ill patients and in the operating room both for fluid resuscitation and fluid maintenance. Among crystalloids, NaCl 0.9% has been the most widely used fluid. However, emerging evidence suggests that administration of 0.9% saline could be harmful mainly through high chloride content and that the use of fluid with low chloride content may be preferable in major surgery and intensive care patients. Administration of NaCl 0.9% is the leading cause of metabolic hyperchloraemic acidosis in critically ill patients and side effects might target coagulation, renal function, and ultimately increase mortality. More balanced solutions therefore may be used especially when large amount of fluids are administered in high-risk patients. In this review, we discuss physiological background favouring the use of balanced solutions as well as the most recent clinical data regarding the use of crystalloid solutions in critically ill patients and patients undergoing major surgery. [ABSTRACT FROM AUTHOR]

Reasons for performing study Acid-base imbalances observed in human paediatric patients are associated with outcome. Likewise, neonatal foals may have different acid-base imbalances associated with diagnosis or prognosis. Objectives To determine acid-base imbalances by the quantitative method in ill neonatal foals and assess their association with diagnosis and prognosis. Study design Observational prospective clinical study. Methods This study included 65 ill neonatal foals (32 septic, 33 nonseptic) admitted to an equine referral hospital from 2005 to 2011with acid-base parameters determined on admission and a control group of 33 healthy neonatal foals. Blood pH, pCO2, sodium, potassium, chloride, L-lactate, albumin and phosphate concentrations were determined. Bicarbonate, globulin, measured strong ion difference ( SIDm), nonvolatile weak buffer concentrations (Atot), base excess and its components were calculated. Analysis of covariance ( ANCOVA) and multiple linear regression statistical analyses were performed. Results are summarised as mean ± s.d. for normally distributed variables and median [25-75th percentiles] for non-normally distributed ones. Results A total of 63% of ill foals had respiratory alkalosis and 58.5% had SIDm acidosis. The combination of both alterations was detected in 21 of 65 ill foals and abnormal pH was found in 24 of 65. Compared with healthy foals, ill foals had significantly lower SIDm (nonseptic 31.6 ± 6.3 [P<0.01] and septic 32.0 ± 6.4 [P<0.01] vs. control 40.3 ± 3.1 mmol/l), potassium (nonseptic 3.5 [3.3-3.8; P<0.01] and septic 3.6 [3.2-4.3; P = 0.01] vs. control 4.2 [3.8-4.5] mEq/l) and higher L-lactate (nonseptic 5.1 ± 4.2 [P = 0.01] and septic 5.0 ± 3.7 [P = 0.03] vs. control 2.5 ± 1.3 mmol/l). Significantly higher L-lactate and venous pCO2 were found in nonsurviving (6.4 ± 3.5 mmol/l [P = 0.04] and 51 ± 13 mmHg [P<0.01]) compared with surviving foals. Conclusions The most common acid-base imbalances observed in ill foals were respiratory alkalosis, SIDm acidosis or mixed respiratory alkalosis with strong ion acidosis. Increased venous pCO2 and blood L-lactate concentration were associated with poor outcome. [ABSTRACT FROM AUTHOR]