Failed Emergence After Pediatric Epilepsy Surgery: Is Propofol-Related Infusion Syndrome to Blame?

Propofol infusion syndrome was first reported in the literature by Bray in 1998. He described a series of fatal outcomes after a presenting constellation of symptoms observed in pediatric patients who had received prolonged propofol infusions. Profound metabolic acidosis and bradycardia are the disease’s hallmark features, which can further develop expeditiously to rhabdomyolysis, renal failure, and heart failure. It has been subsequently theorized that a triggering mechanism or a precipitating factor sets up the progressive physiologic spiral which can ensue. The name of the disease was expanded to Propofol Related Infusion Syndrome (PRIS), as propofol alone was no longer considered the culprit. The disease process is rare and can present with an insidious onset in some cases, causing much speculation of whether there is a proper grasp of the disease entity in its entirety as currently reported. The case discussed in this article depicts an adverse neurologic outcome following a craniotomy for temporal lobectomy in a child with lesional epilepsy. Since there was no obvious causative factor for these findings, PRIS became a diagnosis that was robustly discussed among the involved services.

Acute poisoning with acetamiprid, a type of neonicotinoid insecticide causing severe lactic acidosis: A case report

Acetamiprid is a type of neonicotinoid that belongs to the new class of insecticides. It is fatally toxic to insects by acting as an agonist to nicotinic acetylcholine receptors. Cases with neonicotinoids including acetamiprid poisoning in humans were reported around the world. Only one case with acetamiprid poisoning associated with severe adverse effects has been described from Sri Lanka. Serious side effects will occur if it is consumed in excess amount. Here, we described a case of acetamiprid poisoning in a man who developed severe lactic acidosis, myocardial suppression, hyperglycemia, and intestinal obstruction following accidental intake of acetamiprid insecticide. The patient was managed conservatively as there is no specific management mentioned in the literature.

Severe Lactic Acidosis Due to Acute Intoxication by Emtricitabine/Tenofovir Alafenamide

A 46-year-old female with a history of generalized anxiety disorder was admitted after intentional ingestion of an unknown amount of emtricitabine/tenofovir alafenamide (Descovy®) in a suicidal attempt. Patient was emergently intubated secondary to severe agitation and inability to protect airways. Patient developed severe lactic acidosis early in the admission, secondary as to a possible mitochondrial toxicity. Failed attempts to fluid resuscitation with Lactate Ringer®, eventually warranted to start the patient on norepinephrine infusion. Metabolic acidosis remained refractory to bicarbonate bolus and infusion. Hypothermia and hypoglycemia were corrected. Despite the initial approach, the patient remained acidotic, and the nephrology was consulted for emergent continuous renal replacement therapy (CRRT). After three days of intensive care unit stay and CRRT, the patient improved and was successfully decannulated. Her metabolic profile also showed remarkable improvement and the metabolic lactic acidosis resolved. The previous formulation of tenofovir with disoproxil fumarate is associated with severe lactic acidosis due to inhibition of mammalian mitochondrial DNA polymerase. Risk factors include liver cirrhosis, chronic kidney disease, hepatitis B and C coinfection, and metformin use. The new pharmaceutical formulation of tenofovir with alafenamide (TAF) has caused a significant decrease in the incidence of lactic acidosis. However, its real incidence and the usual plasma level to induce toxicity and mitochondrial dysfunction are unknown. The aim of this report is to highlight the risk of severe lactic acidosis with the use of TAF.

Concealed Malignancy as a Rare Cause of Refractory Lactic Acidosis: A Fatal Case

Lactic acidosis is a state in which there is a buildup of lactate in the body to form an excessively low pH in the blood. Elevated lactate levels are often thought to be indicative of relative tissue hypoxia or type A lactic acidosis. Shock, severe anemia, and thromboembolic events can all cause elevated lactate due to tissue hypoperfusion. Malignancy can also lead to an elevation in lactate, a phenomenon described as type B lactic acidosis. Here, we report a case of a 66-year-old male with elevated lactate level, which was refractory to medical treatment. Despite adequate management, including continuous renal replacement therapy, the lactate continued to rise, and consequently, the patient died due to cardiac arrest. Type B lactic acidosis must be considered in patients with elevated lactate levels without hypotension as it has a high mortality rate.

Lactic acidosis, a potential toxicity from drug-drug interaction related to concomitant ribociclib and metformin in preexisting renal insufficiency: A case report

Background

Ribociclib, one of the cyclin‐dependent kinases (CDK) 4 and 6 inhibitors, in combination with endocrine therapies has been approved in the treatment of hormonal receptor positive, HER‐2 negative metastatic breast cancer worldwide. Long‐term usage of ribociclib with concomitant drugs, potential drug–drug interaction may develop which can limit the therapeutic value of CDK4/6 inhibitor.

Case

A 62‐year‐old with history of non‐insulin dependent diabetic, dyslipidemia, and essential hypertension was diagnosed with HR‐positive, HER‐2 negative metastatic breast cancer and treated with fulvestrant plus ribociclib. Four weeks after administration, elevated serum creatinine was observed, and then severe lactic acidosis with acute respiratory failure was subsequently reported. Ribociclib and fulvestrant were temporarily discontinued. Three days after renal replacement therapy, her clinical was stabilized. Combination ribociclib with metformin resulted in high plasma metformin levels and dangerous consequences. Hence, special precaution should be considered during concomitant treatment with sensitive transporter substrates.

Conclusion

Metformin associated lactic acidosis may potentially occur after combination with ribocilib, an uncommon but lethal complication from the interaction of these drugs, especially in patients who had preexisting renal impairment.

Machine Learning Consensus Clustering Approach for Patients with Lactic Acidosis in Intensive Care Units

BACKGROUND

Lactic acidosis is a heterogeneous condition with multiple underlying causes and associated outcomes. The use of multi-dimensional patient data to subtype lactic acidosis can personalize patient care. Machine learning consensus clustering may identify lactic acidosis subgroups with unique clinical profiles and outcomes.

METHODS

We used the Medical Information Mart for Intensive Care III database to abstract electronic medical record data from patients admitted to intensive care units (ICU) in a tertiary care hospital in the United States. We included patients who developed lactic acidosis (defined as serum lactate ≥ 4 mmol/L) within 48 h of ICU admission. We performed consensus clustering analysis based on patient characteristics, comorbidities, vital signs, organ supports, and laboratory data to identify clinically distinct lactic acidosis subgroups. We calculated standardized mean differences to show key subgroup features. We compared outcomes among subgroups.

RESULTS

We identified 1919 patients with lactic acidosis. The algorithm revealed three best unique lactic acidosis subgroups based on patient variables. Cluster 1 (n = 554) was characterized by old age, elective admission to cardiac surgery ICU, vasopressor use, mechanical ventilation use, and higher pH and serum bicarbonate. Cluster 2 (n = 815) was characterized by young age, admission to trauma/surgical ICU with higher blood pressure, lower comorbidity burden, lower severity index, and less vasopressor use. Cluster 3 (n = 550) was characterized by admission to medical ICU, history of liver disease and coagulopathy, acute kidney injury, lower blood pressure, higher comorbidity burden, higher severity index, higher serum lactate, and lower pH and serum bicarbonate. Cluster 3 had the worst outcomes, while cluster 1 had the most favorable outcomes in terms of persistent lactic acidosis and mortality.

CONCLUSIONS

Consensus clustering analysis synthesized the pattern of clinical and laboratory data to reveal clinically distinct lactic acidosis subgroups with different outcomes.

Machine Learning Prediction Models for Mortality in Intensive Care Unit Patients with Lactic Acidosis

Background: Lactic acidosis is the most common cause of anion gap metabolic acidosis in the intensive care unit (ICU), associated with poor outcomes including mortality. We sought to compare machine learning (ML) approaches versus logistic regression analysis for prediction of mortality in lactic acidosis patients admitted to the ICU. Methods: We used the Medical Information Mart for Intensive Care (MIMIC-III) database to identify ICU adult patients with lactic acidosis (serum lactate ≥4 mmol/L). The outcome of interest was hospital mortality. We developed prediction models using four ML approaches consisting of random forest (RF), decision tree (DT), extreme gradient boosting (XGBoost), artificial neural network (ANN), and statistical modeling with forward stepwise logistic regression using the testing dataset. We then assessed model performance using area under the receiver operating characteristic curve (AUROC), accuracy, precision, error rate, Matthews correlation coefficient (MCC), F1 score, and assessed model calibration using the Brier score, in the independent testing dataset. Results: Of 1919 lactic acidosis ICU patients, 1535 and 384 were included in the training and testing dataset, respectively. Hospital mortality was 30%. RF had the highest AUROC at 0.83, followed by logistic regression 0.81, XGBoost 0.81, ANN 0.79, and DT 0.71. In addition, RF also had the highest accuracy (0.79), MCC (0.45), F1 score (0.56), and lowest error rate (21.4%). The RF model was the most well-calibrated. The Brier score for RF, DT, XGBoost, ANN, and multivariable logistic regression was 0.15, 0.19, 0.18, 0.19, and 0.16, respectively. The RF model outperformed multivariable logistic regression model, SOFA score (AUROC 0.74), SAP II score (AUROC 0.77), and Charlson score (AUROC 0.69). Conclusion: The ML prediction model using RF algorithm provided the highest predictive performance for hospital mortality among ICU patient with lactic acidosis.

Metabolic Acidosis in Leukemia

In 2020, the incidence of leukemia was 474,519 with 311,594 mortality worldwide. In 2021, the American Cancer Society (ACS) has estimated 61,090 new cases of leukemia to occur within the United States. It has also been reported that the most common cause of death in children from one to fourteen years old is oncological, with leukemia being the most frequent cause. A phenomenon known as the Warburg effect has been affiliated with cancer. The Warburg effect is a metabolic abnormality of lactic acidosis in malignancies, with most cases presenting as hematological malignancies such as leukemia. Although many theories have been formulated to clarify the role of the Warburg effect, the exact role still remains uncertain. Four suggested theories on why the Warburg effect happens to include cell signaling, adenosine triphosphate (ATP) synthesis, biosynthesis, and the tumor microenvironment. The Warburg effect occurs in leukemia with the help of enzymes such as pyruvate kinases M2 (PKM2), lactate dehydrogenase A (LDHA), pyruvate dehydrogenase kinase 1 (PDK1), and fibroblast growth factor receptor 1 (FGFR1). In this literature, we explain the proposed hypotheses of the Warburg effect, along with the molecular mechanism of how leukemia is able to produce lactic acid, with the intent to better understand this phenomenon.

Intravascular large B-cell lymphoma presenting with fever and refractory acidosis

Intravascular large B-cell lymphoma (IVLBCL) is a rare form of diffuse large B-cell lymphoma, characterized by malignant B-cells primarily localized to the lumina of small- and medium-sized blood vessels without lymphadenopathy. Two patients initially presented with fever of unknown origin and persistent lactic acidosis without evidence of tissue hypoxia. Neither patient had an identifiable source of infection and both underwent peripheral blood smear demonstrating leukocytosis with a neutrophilic predominance and thrombocytopenia without evidence of hematologic malignancy. One had previously had a bone marrow biopsy which was unremarkable. Both patients’ condition deteriorated rapidly, progressing to multiorgan failure requiring pressors and mechanical ventilation, which ultimately resulted in cardiopulmonary arrest. At autopsy, each patient demonstrated malignant lymphocytoid cells, staining positive for CD20, localized to the lumina of small- and medium-sized vessels in multiple organs, including the lungs, liver, spleen, and kidneys, among others, allowing for the diagnosis of IVLBCL. IVLBCL is exceedingly rare, which in combination with significant variability in presentation, can make identification and diagnosis challenging. Diagnosis requires biopsy, therefore a high index of suspicion is needed to obtain an adequate tissue sample, whether pre- or postmortem. In the presented cases, both patients exhibited type B lactic acidosis with an unknown etiology that was ultimately determined at autopsy.

Prenatal onset of the neuroradiologic phenotype of pyruvate carboxylase deficiency due to homozygous PC c.1828G > A mutations

Pyruvate carboxylase (PC) deficiency (MIM# 266150) is an autosomal recessive disorder with three subtypes. Patients homozygous for the c.1828G > A mutation in the PC gene belong to type A, which typically has infantile onset, severe to profound developmental delay, hypotonia, and lactic acidemia. We report the neuroimaging abnormalities in a 33-week gestation infant homozygous for the c.1828G > A mutation. Brain magnetic resonance imaging on day 10 of life revealed increased T2 signal within the subcortical and periventricular white matter, an immature gyral pattern, large periventricular cysts with mass effect on the lateral ventricles, and dilatation of the occipital and temporal horns. Magnetic resonance spectroscopy showed reduced creatine and NAA peaks, a relatively high choline peak and no lactate peak. These findings were observed prior to the neonate experiencing any episodes of decompensation with lactic acidosis. The presence of these brain anomalies at this gestational age, prior to any metabolic decompensation, supports the essential role of PC in normal brain morphogenesis and the resulting in-utero brain anomalies secondary to its deficiency. Our experience with this affected premature infant and many others we have managed with the same founder mutation suggests that the clinical phenotypes of the type A and the more severe type B PC deficient patients are on a spectrum rather than distinct subtypes.

Approach to Patients With High Anion Gap Metabolic Acidosis: Core Curriculum 2021

The anion gap (AG) is a mathematical construct that compares the blood sodium concentration with the sum of the chloride and bicarbonate concentrations. It is a helpful calculation that divides the metabolic acidoses into 2 categories: high AG metabolic acidosis (HAGMA) and hyperchloremic metabolic acidosis-and thereby delimits the potential etiologies of the disorder. When the [AG] is compared with changes in the bicarbonate concentration, other occult acid-base disorders can be identified. Furthermore, finding that the AG is very small or negative can suggest several occult clinical disorders or raise the possibility of electrolyte measurement artifacts. In this installment of AJKD's Core Curriculum in Nephrology, we discuss cases that represent several very common and several rare causes of HAGMA. These case scenarios highlight how the AG can provide vital clues that direct the clinician toward the correct diagnosis. We also show how to calculate and, if necessary, correct the AG for hypoalbuminemia and severe hyperglycemia. Plasma osmolality and osmolal gap calculations are described and when used together with the AG guide appropriate clinical decision making.

A Rare Case of Severe Lactic Acidosis in a Patient With Mantle Cell Lymphoma

Lactic acidosis is an extremely rare paraneoplastic manifestation of hematological malignancies, and often carries an extremely poor prognosis. Mantle cell lymphoma is an aggressive and rare form of non-Hodgkin lymphoma. To the best of our knowledge, it is extremely rare to have severe lactic acidosis in patients with mantle cell lymphoma. In this article, we are reporting a rare case of mantle cell lymphoma diagnosed with typical cluster differentiation (CD markers) in bone marrow examination with persistent lactic acidosis refractory to intravenous hydration that responded well to chemotherapy. Malignant lactic acidosis is a medical emergency that needs rapid evaluation and identification that shows improved prognosis after the introduction of chemotherapy.

Serious adverse events with tedizolid and linezolid: pharmacovigilance insights through the FDA adverse event reporting system

BackgroundTo investigate the adverse event (AE) profile of tedizolid and linezolid in post-marketing surveillance.Research design and methodsWe queried the worldwide FDA Adverse Event Reporting System and selected all records where tedizolid and linezolid were reported as suspect by removing potential duplicates. Disproportionality analysis was performed investigating designated medical events (DMEs) and specific AEs of clinical interest reported with tedizolid. The reporting odds ratios (RORs) were calculated, deemed significant by a lower limit of the 95% confidence interval (LL95%CI)>1, using linezolid as comparator. Case-by-case assessment of AEs reported in at least three cases with tedizolid was performed.ResultsOverall, 271 and 11,259 reports mentioning respectively tedizolid and linezolid were recorded, of which respectively 59 and 4,473 patients with DMEs or selected AEs were found. No difference emerged for the selected AEs except for increased reporting of hepatic failure (N = 3; LL95%CI = 1.06) with tedizolid considering reports collected after 2014. Extensive off-label use in terms of therapeutic indications (83.6%) and treatment duration was reported with tedizolid.ConclusionsSimilar AE reporting between the two oxazolidinones was found. Considering limitations of pharmacovigilance, this hypothesis of comparable safety profile should be tested prospectively through dedicated real-world studies.

Treatment of Refractory Lactic Acidosis With Thiamine Administration in a Non-alcoholic Patient

Lactate, or lactic acid, is an end-product of anaerobic metabolism. The build-up of lactate in the body is commonly due to type A lactic acidosis, resulting from an inability to meet the body's oxygen delivery demands. When lactic acidosis persists, other causes need to be ruled out. Here, we describe the case of a 63-year-old female who initially presented with hypoglycemia and was found to have significant lactic acidosis. Her blood sugar levels improved with dextrose supplementation; however, lactic acidosis persisted despite fluid hydration and empiric antibiotics. After excluding other causes of lactic acidosis, she was started on intravenous thiamine due to suspicion of thiamine deficiency secondary to poor nutrition. Lactic acid levels improved drastically after starting thiamine supplementation. Thiamine is a water-soluble vitamin that plays an essential role as a cofactor in several biochemical reactions. Thiamine deficiency is a rare, underdiagnosed cause of type B lactic acidosis, with early diagnosis and intervention playing crucial roles in preventing severe cardiac and neurological impairment.

Metabolic impact of pathogenic variants in the mitochondrial glutamyl-tRNA synthetase EARS2

Glutamyl-tRNA synthetase 2 (encoded by EARS2) is a mitochondrial aminoacyl-tRNA synthetase required to translate the 13 subunits of the electron transport chain encoded by the mitochondrial DNA. Pathogenic EARS2 variants cause combined oxidative phosphorylation deficiency, subtype 12 (COXPD12), an autosomal recessive disorder involving lactic acidosis, intellectual disability, and other features of mitochondrial compromise. Patients with EARS2 deficiency present with variable phenotypes ranging from neonatal lethality to a mitigated disease with clinical improvement in early childhood. Here, we report a neonate homozygous for a rare pathogenic variant in EARS2 (c.949G>T; p.G317C). Metabolomics in primary fibroblasts from this patient revealed expected abnormalities in TCA cycle metabolites, as well as numerous changes in purine, pyrimidine, and fatty acid metabolism. To examine genotype-phenotype correlations in COXPD12, we compared the metabolic impact of reconstituting these fibroblasts with wild-type EARS2 versus four additional EARS2 variants from COXPD12 patients with varying clinical severity. Metabolomics identified a group of signature metabolites, mostly from the TCA cycle and amino acid metabolism, that discriminate between EARS2 variants causing relatively mild and severe COXPD12. Taken together, these findings indicate that metabolomics in patient-derived fibroblasts may help establish genotype-phenotype correlations in EARS2 deficiency and likely other mitochondrial disorders.

Evaluation of the Prognostic Value of Lactate and Acid-Base Status in Patients Presenting to the Emergency Department

Background

Lactate levels predict mortality in a wide range of patients presenting to the Emergency Department (ED); however, the effect of co-existing acidosis is unknown. Here, we investigated the effect of acidosis on in-hospital mortality for patients with hyperlactataemia.

Methodology

This is a retrospective cohort study of adults cared for in the resuscitation area of one ED who received a metabolic panel on arrival. The primary outcome was in-hospital mortality for patients with normal lactate (0.0-2.0 mmol/L), intermediate lactate (2.1-4.0 mmol/L), or high lactate (>4.0 mmol/L), with and without acidosis. Odds ratios (ORs) were calculated to assess the differences in mortality rates between groups stratified by lactate and acid-base status.

Results

A total of 4,107 metabolic panels were collected and 3,238 were assessed. In total, 510 (15.8%) and 784 (24.2%) patients had a normal lactate and acidosis/no acidosis; 587 (18.1%) and 842 (26.0%) had intermediate lactate and acidosis/no acidosis; and 388 (12.0%) and 127 (3.9%) had high lactate and acidosis/no acidosis, respectively. The overall mortality was 5%. Mortality was 4.3%/0.6% in the normal lactate, 5.6%/2.6% in the intermediate lactate, and 19.3%/3.9% in the high lactate groups, with and without acidosis, respectively. Combining base excess <-6 and lactate >4 mmol/L had a sensitivity of 39%, specificity of 96%, positive predictive value of 32%, and negative predictive value of 98% for in-hospital mortality (OR: 14.0; 95% confidence interval: 9.77-20.11).

Conclusions

In an undifferentiated cohort of ED patients presenting to the resuscitation area lactaemia associated with acidosis is a more accurate predictor of in-hospital mortality than hyperlactataemia.

COXPD9 in an individual from Puerto Rico and literature review

Defects of mitoribosome assembly with destabilization of mitochondrial ribosomal proteins and subsequent aberrant mitochondrial translation machinery are one of the emerging categories of human mitochondrial disease. Mitochondrial translation deficiency constitutes a growing cause of combined oxidative phosphorylation deficiency and overall causes a set of clinically heterogeneous multi-systemic diseases. We present here the sixth individual with combined oxidative phosphorylation deficiency-9 (COXPD9) secondary to a likely pathogenic homozygous MRPL3 variant c.571A > C; p.(Thr191Pro). MRPL3 encodes a large mitochondrial ribosome subunit protein, impairing the mitochondrial translation and resulting in multisystem disease. Similar to previously reported individuals, this reported female proband presented with psychomotor retardation, sensorineural hearing loss, hypertrophic cardiomyopathy, failure to thrive, and lactic acidosis. Further, she has additional, previously unreported, features including Leigh syndrome, cataracts, hypotonia, scoliosis, myopathy, exercise intolerance, childhood-onset cardiomyopathy, and microcephaly. This subject is the oldest reported individual with COXPD9. This report also summarizes the clinical and molecular data of the previously reported individuals with COXPD9 to describe the full phenotypic spectrum.

A Unique Case of Pyruvate Carboxylase Deficiency

Pyruvate carboxylase (PC) converts pyruvate to oxaloacetate, which is an important step in gluconeogenesis. Pyruvate carboxylase deficiency (PCD) is a rare inherited metabolic disorder characterized by movement disorders, neurologic disturbances, hypoglycemia, lactic acidosis, hyperammonemia, and elevated levels of pyruvate and alanine in plasma. The prognosis for PCD is poor. Most children die within the first six months of life, and those who survive longer have neurological damage and mental disability. This is due to the accumulation of lactic acid and toxic components in the blood. Here we describe the case of a 21-month-old male presenting with abnormal movements and new-onset seizures. His family history is relevant because of parental consanguinity. A genetic analysis showed a novel mutation, homozygous c. 2630A>G (p. Gln877Arg) variant, in the PC gene, a mutation not previously described in the English literature.

Lessons of the month 1: Salbutamol induced lactic acidosis: clinically recognised but often forgotten

We present the case of an 83-year-old woman, with known asthma, admitted with increasing dyspnoea, wheeze and a productive cough. In addition to maintenance inhaled therapy, the patient was also on long-term mirtazapine and furosemide. Following acute treatment with nebulised salbutamol she became increasingly dyspnoeic and developed a metabolic acidosis with a significantly raised blood lactate level. After cessation of ß₂-adrenergic medication, the patient's clinical condition improved with resolution of her lactic acidosis; salbutamol induced lactic acidosis was diagnosed. This clinical scenario is common but not well described. Here we discuss the mechanisms, investigation and management of raised serum lactate and lactic acidosis in the context of acute asthma and the possible interactions of polypharmacy and comorbidities in the acute medical setting.

Clinical Use and Adverse Drug Reactions of Linezolid: A Retrospective Study in Four Belgian Hospital Centers

In Belgium, linezolid is indicated for pneumonia and skin and soft tissue infections, but is more broadly used, due to its oral bioavailability and activity against multiresistant organisms. This could increase the risk of adverse drug reactions (ADR), notably hematological disorders (anemia, thrombocytopenia), neuropathy, or lactic acidosis. We analyzed linezolid clinical use in relationship with occurrence of ADR in Belgian hospitals and highlighted risk factors associated with the development of thrombocytopenia. A retrospective analysis of electronic medical records and laboratory tests of adult patients treated with linezolid in four Belgian hospitals in 2016 allowed the collection of ADR for 248 linezolid treatments. Only 19.7% of indications were in-label. ADR included 43 thrombocytopenia, 17 anemia, 4 neuropathies, and 4 increases in lactatemia. In a multi-variate analysis, risk factors of thrombocytopenia were a treatment duration > 10 days, a glomerular filtration rate < 60 mL/min, and a Charlson index ≥ 4. Off-label use of linezolid is frequent in Belgium, and ADR more frequent than reported in the summary of product characteristics, but not statistically associated with any indication. This high prevalence of ADR could be related to a high proportion of patients presenting risk factors in our population, highlighting the importance of detecting them prospectively.

Severe type-B lactic acidosis in a patient with bilateral renal Burkitt's lymphoma

INTRODUCTION

Lactic acidosis (LA) can be categorized as type A, which occurs in the presence of tissue hypoxia, or type B, occurring in the absence of tissue hypoxia. Hematologic malignancies are an uncommon cause of type B LA.

CASE PRESENTATION

A 63-year-old man, HIV-negative, with a history of diabetes mellitus, hypothyroidism, and non-alcoholic fatty liver disease (NAFLD), presented to the ED complaining of acute-on-chronic lumbar pain, and was found to have high serum anion gap (AG) LA. The rest of chemistry and infectious workup was within normal limits. Despite bicarbonate therapy and fluid resuscitation, the patient remained with persistent AG metabolic acidosis and increasing lactic acid up to 14.5 mmol/L. An abdominal computerized tomography (CT) revealed multiple bilateral enhancing lesions in the kidneys, as well as gastric wall thickening. Upper gastrointestinal endoscopy with biopsy showed a high-grade Burkitt's lymphoma. Further staging showed bone marrow involvement and extensive abdominal adenopathy. After two cycles of inpatient chemotherapy with dose-adjusted EPOCH-R (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin and rituximab), the patient developed multifocal pneumonia complicated by respiratory failure. Following a prolonged ICU stay, after discussion with the family members, a decision of withdrawal of life-sustaining therapy was reached.

CONCLUSION

Persistent LA, without identifiable causes of tissue hypoxia, should prompt clinicians to suspect non-hypoxic etiologies, including occult high-grade malignancies. Hematological malignancies constitute an extremely rare cause of type-B LA, carrying a poor prognosis.

The first case with FBXL4 mutation successfully treated with a parenteral ketogenic diet for lactic acidosis

BACKGROUND

The ketogenic diet (KD) is a low-carbohydrate, high-fat diet that has been used as an effective nonpharmacological treatment in many neurological and metabolic disorders for a long time. The effectiveness of the KD is revealed in mitochondrial disorders, mainly in pyruvate dehydrogenase deficiency.

CASE REPORT

A 4-year-old girl who was diagnosed with an F-box and leucine-rich repeat protein 4 (FBXL4) gene mutation was hospitalized with sepsis. She was first given standard parenteral nutrition (PN) because of gastrointestinal problems. During the disease course, lactic acidosis became prominent and did not respond to pharmacological treatment; standard PN was gradually switched to parenteral KD, and lactate levels decreased after parenteral KD. The patient was discharged with an enteral KD.

CONCLUSION

This is the first case of mitochondrial depletion syndrome effectively treated with parenteral KD for lactic acidosis.

Intoxication with Fireball Whiskey causing severe lactic acidosis

Propylene glycol is a viscous, colorless liquid that has been approved by the US Food and Drug Administration for use as a preservative in foods and as a solvent in pharmaceuticals. Compared with methanol and ethylene glycol, it is regarded as a relatively safe alcohol. There have been several reports of severe lactic acidosis in the setting of iatrogenic unintentional overdosing of medications that use propylene glycol as a diluent, including lorazepam and diazepam. The laboratory findings may include high metabolic acidosis and high osmolal gap. Propylene glycol is also one of the ingredients used in Fireball Whiskey. We present two cases of severe lactic acidosis in the setting of Fireball Whiskey use.

Prospective evaluation of plasma lactate parameters for prognosticating dogs with shock

OBJECTIVE

To determine whether admission venous plasma lactate concentration, serially calculated lactate variables, or the Acute Patient Physiologic and Laboratory Evaluation (APPLE_fast ) score could discriminate hospital survivors from non-survivors in dogs presenting to the emergency department with clinical signs of shock.

DESIGN

Prospective case series performed over a 24-month period.

SETTING

Large urban private teaching hospital.

ANIMALS

Seventy-one dogs admitted to the ICU with initial peripheral venous plasma lactate concentration > 2.5 mmol/L and clinical and hemodynamic parameters consistent with shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Heart rate, systolic blood pressure, temperature, initial venous plasma lactate, and APPLE_fast score were recorded at admission. Lactate concentrations were serially recorded at predefined time points and used to calculate lactate variables, including lactime (time lactate > 2.5 mmol/L), lactate clearance ([lactate_initial - lactate_delayed ]/ lactate_initial × 100), and LAC_AREA (area under the lactate concentration versus time curve). Primary outcome was survival to discharge. Overall survival rate was 61%. Admission plasma lactate did not differ between groups (P = 0.28). Lactime was shorter in survivors vs non-survivors (P = 0.03). Lactate clearance at hours (h) 1, 4, 10, and 16 was greater in survivors vs non-survivors (P < 0.05). Final plasma lactate clearance differed between groups (P < 0.05). LAC_AREA at time intervals 1 to 4 hours, 4 to 10 hours, 10 to 16 hours, and 16 to 24 hours was larger in non-survivors vs survivors (P < 0.05). Total LAC_AREA did not differ between groups (P = 0.51). Admission APPLE_fast was not different between survivors and non-survivors (P = 0.16).

CONCLUSIONS

While neither single APPLE_fast nor admission plasma lactate concentration could discriminate between hospital survivors and non-survivors, measures of lactate clearance can prognosticate survival in dogs with shock.