The synergism of cytosolic acidosis and reduced NAD+/NADH ratio is responsible for lactic acidosis-induced vascular smooth muscle cell impairment in sepsis.

BACKGROUND: During sepsis, serve vascular dysfunctions lead to life-threatening multiple organ failure, due to vascular smooth muscle cells (VSMC) impairments, resulting in vasoplegia, hypotension and hypoperfusion. In addition, septic patients have an altered cell metabolism that leads to lactic acidosis. Septic patients suffering from lactic acidosis have a high risk of mortality. In addition, septic survivors are at risk of secondary vascular disease. The underlying mechanisms of whether and how lactic acidosis leads to the changes in VSMCs is not well understood. The aim of this study was to comprehensively investigate the effect of lactic acidosis on VSMCs and additionally compare the effects with those induced by pure acidosis and sodium lactate. METHODS: Primary human aortic smooth muscle cells (HAoSMCs) were treated for 48 h with lactic acidosis (LA_pH 6.8), hydrochloric acid (HCl_pH 6.8), sodium lactate (Na+-lactate_pH 7.4) and the respective controls (ctrl._pH 7.4; hyperosmolarity control: mannitol_pH 7.4) and comparatively analyzed for changes in (i) transcriptome, (ii) energy metabolism, and (iii) phenotype. RESULTS: Both types of acidosis led to comparable and sustained intracellular acidification without affecting cell viability. RNA sequencing and detailed transcriptome analysis revealed more significant changes for lactic acidosis than for hydrochloric acidosis, with lactate being almost ineffective, suggesting qualitative and quantitative synergism of acidosis and lactate. Bioinformatic predictions in energy metabolism and phenotype were confirmed experimentally. Lactic acidosis resulted in strong inhibition of glycolysis, glutaminolysis, and altered mitochondrial respiration which reduced cellular ATP content, likely due to increased TXNIP expression and altered NAD+/NADH ratio. Hydrochloric acidosis induced significantly smaller effects without changing the NAD+/NADH ratio, with the ATP content remaining constant. These metabolic changes led to osteo-/chondrogenic/senescent transdifferentiation of VSMCs, with the effect being more pronounced in lactic acidosis than in pure acidosis. CONCLUSIONS: Overall, lactic acidosis exerted a much stronger effect on energy metabolism than pure acidosis, whereas lactate had almost no effect, reflecting the qualitative and quantitative synergism of acidosis and lactate. As a consequence, lactic acidosis may lead to acute functional impairments of VSMC, sustained perturbations of the transcriptome and cellular dedifferentiation. Moreover, these effects may contribute to the acute and prolonged vascular pathomechanisms in septic patients.

Metformin-Associated Lactic Acidosis-Is This on Your Radar?

BACKGROUND: Metformin is a biguanide hyperglycemic agent used to manage non-insulin-dependent diabetes mellitus. Adverse reactions include mainly mild gastrointestinal adverse effects, but severe complications, such as metformin-associated lactic acidosis (MALA) can occur. Metformin is excreted renally and, therefore, not recommended in patients with renal impairment. The reported incidence of MALA is 3 cases per 100,000 patient-years. CASE REPORT: A 79-year-old woman with a complex medical history, including end-stage renal disease on dialysis and type 2 diabetes, presented to the emergency department (ED) for altered mental status. Prior to arrival, she was found to be hypoglycemic. Her laboratory results were significant for creatinine of 6.56 mg/dL and an anion gap of 52 mmol/L. The venous blood gas revealed a venous pH of 6.857 [reference range (7.32-7.43)], pCO2 of 15.9 mm Hg (40.6-60 mm Hg), HCO3 of 2.7 mmol/L (21-30 mmol/L), lactate of 27 mmol/L (0.5-2 mmol/L), and ammonia of 233 µmol/L. The patient was dialyzed emergently in the ED; repeat laboratory test results showed blood urea nitrogen of 10 mg/dL, creatinine of 1.65 mg/dL, carbon dioxide of 26 mmol/L, and anion gap of 13 mmol/L. The repeat ammonia was 16 µmol/L. The patient's metabolic encephalopathy resolved, and she was discharged home on hospital day 3. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: MALA has a high mortality rate (36%). Laboratory markers have not been found to be a reliable predictor of mortality. Sodium bicarbonate is controversial, but a pH < 7.15 indicates consideration of its use. A pH < 7.1 and a lactate level > 20 mmol/L indicate the need for emergent hemodialysis. Prompt recognition and management in the ED with early hemodialysis can result in good patient outcomes, with a return to their baseline function despite severe laboratory findings.

Imitating the respiratory activity of the brain stem by using artificial neural networks: exploratory study on an animal model of lactic acidosis and proof of concept.

Artificial neural networks (ANNs) are versatile tools capable of learning without prior knowledge. This study aims to evaluate whether ANN can calculate minute volume during spontaneous breathing after being trained using data from an animal model of metabolic acidosis. Data was collected from ten anesthetized, spontaneously breathing pigs divided randomly into two groups, one without dead space and the other with dead space at the beginning of the experiment. Each group underwent two equal sequences of pH lowering with pre-defined targets by continuous infusion of lactic acid. The inputs to ANNs were pH, ΔPaCO2 (variation of the arterial partial pressure of CO2), PaO2, and blood temperature which were sampled from the animal model. The output was the delta minute volume (ΔVM), (the change of minute volume as compared to the minute volume the animal had at the beginning of the experiment). The ANN performance was analyzed using mean squared error (MSE), linear regression, and the Bland-Altman (B-A) method. The animal experiment provided the necessary data to train the ANN. The best architecture of ANN had 17 intermediate neurons; the best performance of the finally trained ANN had a linear regression with R2 of 0.99, an MSE of 0.001 [L/min], a B-A analysis with bias ± standard deviation of 0.006 ± 0.039 [L/min]. ANNs can accurately estimate ΔVM using the same information that arrives at the respiratory centers. This performance makes them a promising component for the future development of closed-loop artificial ventilators.

Possible cannabinoid-induced lactic acidosis requiring emergent dialysis.

Lactic acidosis is a common finding in the intensive care unit and is associated with increased mortality. We present the case of a 42-year-old male with alcohol use disorder and cirrhosis who developed sudden onset shortness of breath while smoking marijuana. He was found to have a lactic acid level of 25.6 mmol/L with a significant anion gap metabolic acidosis requiring emergent dialysis. He was hypertensive without evidence of tissue hypoperfusion. His profound type B lactic acidosis was primarily attributed to a rare manifestation of cannabinoid toxicity. At a clinic visit 3 months later, he was doing well and had not smoked marijuana since his discharge.

Epinephrine induced lactic acidosis during the management of anaphylactic shock: a case report.

In a case of contrast media-induced anaphylactic shock managed with epinephrine, a 57-year-old male developed lactic acidosis without cardiogenic shock or global hypoperfusion, highlighting epinephrine's potential to trigger lactic acidosis. Despite previous management of similar reactions with antihistamines and corticosteroids, this case required intensive care unit admission and emergency intervention, with lactate levels peaking alarmingly. The rapid resolution of acidosis following epinephrine discontinuation underscores the need for careful monitoring and the consideration of alternative vasopressor strategies in severe anaphylaxis, illustrating the complex relationship between epinephrine's metabolic effects and anaphylaxis-induced tissue hypoperfusion.

Survival and Vision Restoration Following Severe Metformin-associated Metabolic Acidosis With Transient Blindness: A Case Report and Review of the Literature.

Metformin-associated lactic acidosis (MALA) is a life-threatening condition that may occur as a side effect of biguanides. This condition has a mortality rate of approximately 55 % depending on the severity. Typical symptoms include abdominal pain, nausea, vomiting, and diarrhea, but may also manifest with severe symptoms such as blindness, distributive shock, and renal failure requiring ICU level care. We present the case of a female in her early 70s who arrived at the emergency department with altered mental status and new-onset blindness, later diagnosed with severe acidosis (pH 6.607). She was intubated for hemodynamic instability and continuous renal replacement therapy (CRRT) was started to address her acid-base status. Her metformin concentration was found to be exceptionally high at 34 mcg/ml, significantly surpassing the normal range of 1-2 mcg/ml. Fortunately, the patient survived and was subsequently transferred to the medical floors in stable condition. Physicians should perform medication review and consider "MALA" as a potential etiology of severe acidosis when forming a differential diagnosis.

Impact of postoperative hyperlactatemia in orthotopic heart transplantation.

BACKGROUND: Hyperlactatemia (HL) is a common phenomenon after cardiac surgery which is related to tissue hypoperfusion and hypoxia and associated with poor outcomes. It is also often seen in the postoperative period after orthotopic heart transplantation (OHTx), but the association between HL and outcomes after OHTx is not well known. We evaluated the incidence and outcome of HL after OHTx. METHODS: This was a retrospective study of 209 patients who underwent OHTx between January 2011 and December 2020. Patients were classified into 3 groups according to their peak lactate levels within the first 72 h postoperatively: group 1, normal to mild hyperlactatemia (<5 mmol/L, n = 42); group 2, moderate hyperlactatemia (5-10 mmol/L, n = 110); and group 3, severe hyperlactatemia (>10 mmol/L, n = 57). The primary composite endpoint was all-cause mortality or postoperative initiation of veno-arterial extracorporeal membrane oxygenation (VA ECMO) within 30 days. Secondary endpoints included duration of mechanical ventilation, intensive care unit length of stay, and hospital length of stay. RESULTS: Patients with higher postoperative peak lactate levels were more commonly transplanted from left ventricular assist device support (33.3 % vs 50.9 % vs 64.9, p < 0.01) and had longer cardiopulmonary bypass time [127 min (109-148) vs 141 min (116-186) vs 153 min (127-182), p = 0.02]. Composite primary endpoint was met in 18 patients (8.6 %) and was significantly more common in patients with higher postoperative peak lactate levels (0.0 % vs 6.4 % vs 19.3 %, p < 0.01). CONCLUSIONS: Severe hyperlactatemia following orthotopic heart transplant was associated with an increased risk of post-transplant VA ECMO initiation and mortality at 30 days.

A case of pediatric Perthes' disease with unexplained hyperlactatemia at the time of initial surgery and anesthetic management with remimazolam for the subsequent surgery.

BACKGROUND: The causes of perioperative hyperlactatemia vary, but they are generally associated with hypoperfusion. Here, we report the case of a pediatric patient who developed unexplained hyperlactatemia during anesthesia with propofol and sevoflurane, which recurred during a second surgery under anesthesia with remimazolam. CASE PRESENTATION: An 8-year-old boy with Perthes disease and no remarkable past or family history was scheduled for an osteotomy. Anesthesia was induced with propofol and rocuronium and then maintained with sevoflurane and remifentanil. The patient developed lactic acidosis without hemodynamic instability during anesthesia, with a normal lactate/pyruvate ratio after surgery, suggesting a lack of hypoperfusion. We used remimazolam instead of propofol during the second surgery 6 months later, considering the possibility of drug-induced lactic acidosis, including malignant hyperthermia and propofol infusion syndrome, where the unexplained hyperlactatemia recurred. CONCLUSIONS: Distinguishing the causes of hyperlactatemia, particularly in the absence of other symptoms, is challenging. The lactate/pyruvate ratio during episodes of hyperlactatemia can provide insights into the underlying pathology.

Malignancy Associated Type B Lactic Acidosis: A Rare, yet Fascinating Oncological Emergency.

Type B lactic acidosis has been described infrequently in hematologic malignancies, but even less often in solid tumors. Since 1978, there have been only 58 cases of solid tumor associated Type B lactic acidosis described in the literature. Lung cancer (neuroendocrine) is the most common tumor; others frequently have a poorly/undifferentiated histology. The prognosis is dismal. Malignancy associated type B lactic acidosis is not associated with hypoxemia. The most highlighted pathogenetic mechanism is the Warburg effect (aerobic glycolysis of tumor cells causing excess lactate). We describe a patient with metastatic GI neuroendocrine carcinoma with profound lactic acidosis, who died within 24 hours. When extremely ill cancer patients present with lactic acidosis, sepsis is usually a primary concern. This case highlights the need for providers to consider malignancy associated lactic acidosis (MA-LA) in the differential diagnosis, particularly in patients with advanced malignancies, of lung origin, of neuroendocrine or poorly/undifferentiated histologic subtypes. The implications and approach are distinct from Type A/D lactic acidosis, and would involve treatment of the underlying malignancy at the earliest.

Association between hypomagnesemia and serum lactate levels in patients with sepsis: a retrospective observational study.

BACKGROUND: Sepsis-3 emphasizes the recognition of sepsis-induced cellular metabolic abnormalities, and utilizes serum lactate level as a biomarker of cellular metabolic abnormalities. Magnesium plays an important role as a cofactor in glucose metabolism, although it is not well known that magnesium deficiency causes elevated serum lactate levels. Additionally, it remains unclear how magnesium status affects the role of serum lactate levels as a marker of metabolic abnormalities in sepsis. Thus, this study aimed to investigate the association between serum magnesium and lactate levels in patients with sepsis and explore this relationship from the perspectives of time course and circulatory abnormalities. METHODS: This retrospective observational study of adult patients with sepsis was performed at the 16-bed intensive care unit of Jichi Medical University Hospital between June 2011 and December 2017. The relationship between serum magnesium and lactate levels for 5 days from intensive care unit admission was investigated along the time course. Multivariate logistic regression analysis was performed to evaluate the association between serum magnesium and lactate levels during intensive care unit admission. RESULTS: Among 759 patients included, 105 had hypomagnesemia (magnesium level < 1.6 mg/dL), 558 had normal serum magnesium levels (1.6-2.4 mg/dL), and 96 had hypermagnesemia (magnesium level > 2.4 mg/dL) at intensive care unit admission. From intensive care unit admission to day 5, the hypomagnesemia group had higher serum lactate levels and a higher frequency of lactic acidosis than the normal magnesium level and hypermagnesemia groups (70% vs. 51.6% vs. 50%; P < 0.001). Hypomagnesemia at intensive care unit admission was independently associated with lactic acidosis, i.e., lactic acid level > 2 mmol/L (odds ratio, 2.76; 95% confidence interval, 1.60-4.76; P < 0.001). CONCLUSIONS: Hypomagnesemia was associated with serum lactate levels in the early and post-resuscitation phases of sepsis. Further studies are needed to elucidate whether the magnesium status is associated with sepsis-induced cellular and metabolic abnormalities.

Linezolid Toxicity: A Clinical Case Report.

Linezolid plays a clinically important role; however, it is responsible for severe pharmacological interactions and side effects, such as myelosuppression, serotonin syndrome, and lactic acidosis. We report a case of an 80-year-old man treated with venlafaxine for depression. He was admitted with a right femur fracture and submitted to surgical intervention, complicated by local infection. In collected pus was identified multiple microorganisms including Enterococcus faecium resistant to vancomycin. The therapeutic was adjusted to linezolid. On the 36th day of treatment, he developed hypertension, poor peripheral perfusion, and generalized tremor. He was disoriented, with marbled skin, myoclonus, and sinus tachycardia; and apyretic, with no signs of respiratory distress or joint/surgical wound inflammatory signs. Blood tests showed hyperlacticemia and discrete elevation of C-reactive protein but in a decrescent trend, with no other relevant alterations. The diagnosis of lactic acidosis and probable serotonin syndrome secondary to linezolid was made, supported by improvement after the drug suspension.

Exploring the relationship between hyperlactatemia and anemia.

Hyperlactatemia and anemia commonly coexist and their crosstalk is a longstanding mystery with elusive mechanisms involved in physical activities, infections, cancers, and genetic disorders. For instance, hyperlactatemia leads to iron restriction by upregulating hepatic hepcidin expression. Increasing evidence also points to lactate as a crucial signaling molecule rather than merely a metabolic byproduct. Here, we discuss the mutual influence between anemia and hyperlactatemia. This opinion calls for a reconsideration of the multifaceted roles of lactate and lactylation in anemia and emphasizes the need to fill knowledge gaps, including the dose dependence of lactate's effects, its sources, and its subcellular localization.

Severe Lactic Acidosis and Hypoglycemia Associated With Burkitt Lymphoma and the Warburg Effect.

Type B lactic acidosis secondary to the Warburg effect is a rare metabolic complication associated with hematological malignancies. Type B lactic acidosis occurs without tissue dysoxia due to increased aerobic glycolysis and excess lactic acid formation, commonly known as the Warburg effect. Here, we present a case of Burkitt lymphoma in a 69-year-old female with severe type B lactic acidosis and hypoglycemia that was effectively treated by the prompt initiation of chemotherapy. Type B lactic acidosis has been mostly described with hematological malignancies and rarely with solid malignancies. It is considered one of the oncological emergencies, and initiation of chemotherapy as soon as possible has been beneficial compared to alkali therapy. Lactic acidosis associated with malignancies carries a poor prognosis and high mortality.

Severe Lactic Acidosis Due to Inappropriate Use of Biktarvy in a Patient With AIDS.

Bictegravir-emtricitabine-tenofovir alafenamide is an approved medication for the treatment of acquired immunodeficiency syndrome (AIDS). This medication, also called Biktarvy, includes an integrase strand inhibitor combined with nucleoside reverse transcriptase inhibitors (NRTIs) to prevent viral DNA synthesis and lead to improvements in disease progression and mortality in patients with AIDS. A rare but previously documented adverse effect of NRTIs present in Biktarvy is lactic acidosis. NRTIs can cause lactic acidosis through mitochondrial impairment, as mitochondria depend on DNA polymerase gamma for replication. This enzyme is very similar to HIV's reverse transcriptase. Inhibition of mitochondrial production results in increased anaerobic metabolism and lactic acid production. We present a case where an inappropriately high dosage of Biktarvy in a patient with septic shock led to persistent lactic acidosis despite clinical improvement. After a thorough medication review, Biktarvy was temporarily held, and the lactic acidosis resolved. This clinical presentation stresses the importance of maintaining wide differentials for lactic acidosis and thorough medication reconciliation.

Metformin toxicity in the intensive care unit: A case series and review of the literature.

Metformin toxicity is a life-threatening condition with high morbidity and mortality. Toxicity predominantly occurs in the setting of acute renal dysfunction, as the drug is solely eliminated by the kidneys. While this risk is widely known to clinicians, diagnosing metformin toxicity is challenging because commercially available serum metformin levels require days to weeks to result. Therefore, the intensivist must rely on medical history, clinical presentation, and routine laboratory findings to make the preliminary diagnosis. Treatment of metformin toxicity includes supportive fluid hydration, vasopressors, and emergent hemodialysis (HD). We report three critically ill patients who had near-fatal severe metformin-induced lactic acidosis. Their metformin levels were markedly higher than the toxicity threshold reported by the Federal Drug Agency. These patients made a prompt and complete recovery after the initiation of HD. We also review the pathophysiology, clinical presentation, diagnosis, and treatment of metformin toxicity.

Clinical Warburg Effect in a Patient With Mantle Cell Lymphoma: A Case Report.

The clinical Warburg effect is a rare occurrence in cancer biology where tumor cells primarily utilize glycolysis for energy production, leading to significant hypoglycemia and lactate formation. This presentation is associated with a poor prognosis for the patient. In this context, we describe the case of a 53-year-old woman with stage IV mantle cell lymphoma who developed the clinical Warburg effect with solely arrhythmia and without neurological symptoms. She received prompt treatment for glucose stabilization and underwent inpatient chemotherapy. This case underscores the importance of early intervention to reduce tumor burden and highlights the effectiveness of hemodialysis in stabilizing metabolic acidosis. Further investigation into this approach is warranted.

Resolution of insulin resistance, lactic acidosis, and decrease in mechanical support requirements in patients post orthotopic heart transplant with the use of long-acting insulin glargine.

OBJECTIVE: This study investigates the efficacy of using a long-acting insulin analog, along with the infusion of regular insulin, in achieving appropriate glycemic control and correcting lactic acidosis in patients post orthotopic heart transplant who demonstrate severe lactic acidosis and insulin resistance. METHODS: This was a retrospective study of two cohorts (IRB FLA 20-003) of patients post orthotopic heart transplant with severe lactic acidosis and insulin resistance who were admitted to a tertiary intensive care unit and treated with (group 1) or without long-acting insulin analog (group 2) within the first 24 h of admission to the intensive care unit. Insulin resistance is defined as the requirement for intravenous regular insulin infusion of more than 20 units/h without the ability to achieve appropriate serum glucose level (120-180 mg /dL). Severe lactic acidosis is defined as arterial lactic acid of more than 10 mmol/L. The following parameters were investigated: time to correct lactic acidosis, duration of postoperative mechanical ventilation, the need for periprocedural mechanical circulatory support, and 28-day mortality. RESULTS: The 28-day mortality was zero in both groups. Two patients required periprocedural mechanical support in group one, and ten patients required mechanical support in group two (RR = 0.224, 95%, confidence interval 0.052-0.95, Z = 2.029, p = 0.042). Three patients required tracheostomy in group one, and four patients required tracheostomy in group two (RR 0.84, 95 confidence interval 0.20-3.48, Z = 0.23, P = 0.81). Wilcoxon rank-sum test was used to compare time to correct lactic acidosis, with lactic acid resolution being faster in group one ([Formula: see text]1 = 19.7 h, SD ± 12.6 h [Formula: see text]2 = 29.3 h, SD ± 19.6 h, Z-value - 2.02, p-value 0.043). The duration of mechanical ventilation was less in group one ([Formula: see text]1 = 29 h, SD ± 12.7 h, [Formula: see text]2 = 55.1 h, SD ± 44.5 h, Z-value: - 1.92, p-value 0.05). CONCLUSION: Administration of low-dose long-acting insulin glargine led to the resolution of the lactic acidosis, insulin resistance, and decreased requirements for pressor and inotropic support, which led to decreased need for mechanical circulatory support.

Metformin adverse event profile: a pharmacovigilance study based on the FDA Adverse Event Reporting System (FAERS) from 2004 to 2022.

BACKGROUND: Metformin has the potential for treating numerous diseases, but there are still many unrecognized and unreported adverse events (AEs). METHODS: We selected data from the United States FDA Adverse Event Reporting System (FAERS) database from the first quarter (Q1) of 2004 to the fourth quarter (Q4) of 2022 for disproportionality analysis to assess the association between metformin and related adverse events. RESULTS: In this study 10,500,295 case reports were collected from the FAERS database, of which 56,674 adverse events related to metformin were reported. A total of 643 preferred terms (PTs) and 27 system organ classes (SOCs) that were significant disproportionality conforming to the four algorithms simultaneously were included. The SOCs included metabolic and nutritional disorders (p = 0.00E + 00), gastrointestinal disorders (p = 0.00E + 00) and others. PT levels were screened for adverse drug reaction (ADR) signals such as acute pancreatitis (p = 0.00E + 00), melas syndrome, pemphigoid (p = 0.00E + 00), skin eruption (p = 0.00E + 00) and drug exposure during pregnancy (p = 0.00E + 00). CONCLUSION: Most of our results were consistent with the specification, but some new signals of adverse reactions such as acute pancreatitis were not included. Therefore, further studies are needed to validate unlabeled adverse reactions and provide important support for clinical monitoring and risk identification of metformin.

Impact of Primary Tumor Resection on Type B Lactic Acidosis in a Case of Metastatic Colon Cancer.

Malignancies seldom lead to hyperlactatemia or lactic acidosis. The elimination of the primary tumor is anticipated to result in the amelioration of lactate levels in such situations. A patient with obstructing descending colon cancer was subjected to surgical intervention as their serum lactate levels reached 3.6 mmol/L. The tumor was removed, and the ischemic bowel proximal to it was excised as well. The patient demonstrated signs of recuperation; however, their serum lactate levels persisted at levels exceeding 6.5 mmol/L. Consequently, the patient was subjected to further investigation and surgical intervention. A CT scan of the brain and abdomen indicated metastases to the liver and brain, respectively. The presence of metastases in colonic malignancies may impede the normalization of hyperlactatemia even after excising the primary tumor. The interpretation of lactate levels can be challenging and radiological assessments, including abdominal reexploration, may be required to ascertain the diagnosis.