Etiology and Management of Acute Metabolic Acidosis: An Update

Effect of different hypoxic and hypobaric interventions on blood gas and erythrocyte-related indicators in rats

OBJECTIVES

To explore the effects of hypoxic and hypobaric conditions on blood gas and erythrocyte-related indicators in rats.

METHODS

SD male rats were exposed to low-pressure hypoxic conditions simulating an altitude of 6500 m in a small or a large experimental cabin. Abdominal aortic blood samples were collected and blood gas indicators, red blood cells (RBCs) count, and hemoglobin (Hb) content were measured. The effects of exposure to different hypoxia times, different hypoxia modes, normal oxygen recovery after hypoxia, and re-hypoxia after hypoxia preconditioning on blood gas indicators, RBCs count and Hb content were investigated.

RESULTS

The effect of blood gas indicators was correlated with the length of exposure time of hypoxia and the reoxygenation after leaving the cabin. Hypoxia caused acid-base imbalance and its severity was associated with the duration of hypoxia; hypoxia also led to an increase in RBCs count and Hb content, and the increase was also related to the time exposed to hypoxia. The effects of reoxygenation on acid-base imbalance in rats caged in a small animal cabin were more severe that those in a large experimental cabin. Acetazolamide alleviated the effects of reoxygenation after leaving the cabin. Different hypoxia modes and administration of acetazolamide had little effect on RBCs count and Hb content. Normal oxygen recovery can alleviate the reoxygenation and acid-base imbalance of hypoxic rats after leaving the cabin and improve the increase in red blood cell and hemoglobin content caused by hypoxia. The improvement of hypoxia preconditioning on post hypoxia reoxygenation is not significant, but it can alleviate the acid-base imbalance caused by hypoxia in rats and to some extent improve the increase in red blood cell and hemoglobin content caused by hypoxia.

CONCLUSIONS

Due to excessive ventilation and elevated RBCs count and Hb content after hypoxia reoxygenation, oxygen partial pressure and other oxygenation indicators in hypoxic rats are prone to become abnormal, while blood gas acid-base balance indicators are relatively stable, which are more suitable for evaluating the degree of hypoxia injury and related pharmacological effects in rats.

Clinical efficacy of sodium bicarbonate in treating pediatric metabolic acidosis with varying level of acid-base balance parameters: a real-world study

BACKGROUND

Sodium bicarbonate (SB) infusion is commonly used to correct metabolic acidosis, but its clinical efficacy remains controversial. This study aims to investigate whether acid-base balance parameters should be a consideration for administering SB treatment.

METHODS

Children with metabolic acidosis (pH < 7.35 and bicarbonate < 22 mmol/L) who were treated with or without 50 mg/ml SB injection were grouped and extracted from a retrospective cohort database of the Pediatric Intensive Care Unit. The interaction between acid-base balance parameters and SB treatment on mortality was analyzed through mortality curves and cross-effect models. Logistic regression was conducted to estimate the risk of death following SB treatment in the overall children as well as in subgroups, and potential confounding factors were adjusted for. After employing propensity score matching to account for confounding factors, further analysis was performed to evaluate the effectiveness of SB treatment within each chloride subgroup.

RESULTS

A total of 5865 children with metabolic acidosis were enrolled, of which 2462 (42.0%) received SB treatment. In the overall population, it was found that SB treatment did not reduce hospital mortality or 28-day mortality. Interactions between acid-base balance parameters (chloride and anion gap) and SB treatment on mortality were observed. Subgroup analysis clarified that when chloride levels were below 107 mmol/L, children treated with SB had higher in-hospital mortality (29.8% vs 14.9%) and 28-day mortality (26.5% vs 13.4%), with adjusted ORs of 2.065 (95% CI, 1.435-2.97) and 1.947 (95% CI, 1.332-2.846), respectively. In contrast, when chloride levels were greater than or equal to 113 mmol/L, children treated with SB had a shorter stay in the PICU (median: 1.1 days vs 5.1 days, adjusted p = 0.004) and lower in-hospital mortality (4.3% vs 10.3%) and 28-day mortality (4.0% vs 8.4%), with adjusted ORs of 0.515 (95% CI, 0.337-0.788) and 0.614 (95% CI, 0.391-0.965), respectively. After controlling for confounding factors through matching, the impact of SB treatment on the risk of death in each chloride subgroup was consistent with the aforementioned results. However, treatment with SB did not significantly increase the risk of death in newborns or children with moderate to severe metabolic acidosis when chloride levels were below 107 mmol/L (p > 0.05).

CONCLUSIONS

The use of sodium bicarbonate for treating metabolic acidosis has been found to increase mortality in children with low chloride levels but decrease mortality in those with high chloride levels in this study. Further prospective multi-center clinical studies and basic research are needed to validate these findings.

Severe acidosis due to 5-oxoprolinase inhibition by flucloxacillin in a patient with shoulder prosthesis joint infection

Abstract. We report a case of a 64-year-old female patient with severe metabolic acidosis. Inhibition of 5-oxoprolinase by flucloxacillin was found to be the cause of the metabolic derailment.

Emergent Hemodialysis Followed by Continuous Renal Replacement Therapy: A Management Challenge in a Patient With Life-Threatening Metabolic Acidosis of Multifactorial Etiology

Metabolic acidosis is a frequently encountered laboratory finding in daily clinical practice. Rapid pH correction is almost always preferred and necessary while performing workup to identify the causative factors. We present the case of a 73-year-old male presenting with progressive dyspnea and severe metabolic acidosis. He had a pH of 6.6, bicarbonate of 1.8 mg/dL, lactic acid of 18.1 mg/dL, and pCO2 of 14.1 mmHg. The intensivist and nephrologist made a joint decision to rapidly correct the pH using bicarbonate and emergent hemodialysis. Subsequently, continuous renal replacement therapy (CRRT) was started, leading to a favorable outcome. Our patient's most likely etiology of lactic acidosis was metformin because he had a very high lactic acid, high anion gap metabolic acidosis, and acute renal failure on presentation. From our case and literature review, we suggest using hemodialysis, CRRT, and bicarbonate replacement for a better prognosis in patients with critical acidosis in view of frank renal failure and concurrent metformin use.

Acute metformin administration increases mean power and the early Power phase during a Wingate test in healthy male subjects

The present study tested the hypothesis that acute metformin would increase peak power measured during a Wingate test. Fourteen men (24 ± 6 years; 75.8 ± 10.2 kg; 177 ± 7 cm) participated in four test sessions, conducted in a crossover, counterbalanced, double-blind model. The first and second sessions consisted of anthropometric measurements and one Wingate test per day to assess test-retest reliability. In the last two sessions, the Wingate tests were performed on metformin (500 mg capsule, 1 hour before) or placebo (cellulose capsule, 1 hour before) condition. No differences were found between the placebo and metformin for peak power (1056.8 ± 215.8 W vs. 1095.2 ± 199.3 W, respectively; p = 0.24). Mean power (630.9 ± 87.8 W vs. 613.1 ± 94.8 W, respectively; p=0.01) and total work (18928 ± 2633 kJ vs. 18393 ± 2845 kJ, respectively; p = 0.01) in the metformin condition were higher than the placebo. The power were greater in metformin when compared to the placebo in moments 3 (p = 0.01), 4 (p = 0.01), 5 (p = 0.04), 6 (p = 0.04), 7 (p = 0.02), 8 (p = 0.03) and 9 (p = 0.01) seconds. There were no differences between conditions for the peak lactate (p = 0.08) and the rating of perceived exertion (p = 0.84). Acute metformin administration increased the early power phase and the mean power of a Wingate test.

Pseudohyponatremia and falsely increased serum osmolal gap caused by paraprotein in a patient with severe metabolic acidosis – a case study

Introduction: The aim of the study is to present a case study of a 63-year-old male with pseudohyponatremia, falsely increased serum osmolal gap and severe metabolic acidosis.

Material and Methods: Venous whole blood (direct sodium selective electrode measurement) and serum (indirect sodium selective electrode measurement) were used to measure sodium concentration. Serum cholesterol, triacylglycerides and total protein were measured to confirm pseudohyponatremia. Base excess in extracellular fluid and serum bicarbonate concentrations were employed as markers of metabolic acidosis. Serum protein electrophoresis and free light chain analysis were used for the detection of paraproteins.

Results: Venous whole blood acid base analysis showed a pH of 7.171, negative base excess in extracellular fluid of – 18.6 mmol/L and sodium concentration of 140 mmol/L. Serum test measurement revealed serum sodium concentration of 130 mmol/L, osmolal gap of 24 mmol/kg, creatinine concentration of 702 µmol/L, HCO3- concentration of 6.1 mmol/L and total protein concentration of 134.9 g/L. Serum paraprotein IgG kappa with a concentration of 86 g/L and a serum free light chains kappa/lambda ratio of 223.5, along with the final diagnosis of multiple myeloma were detected. Toxic alcohol ingestion was considered, both methanol and ethylene glycol tests were negative.

Conclusions: High paraprotein concentrations in serum may lead to pseudohyponatremia when measured by indirect ion selective electrodes. Multiple myeloma frequently leads to renal failure with metabolic acidosis.