Severe lactic acidosis and rhabdomyolysis following metformin and ramipril overdose

Therapeutic Plasma Exchange in Severe Rhabdomyolysis: A Case-Control Study

INTRODUCTION

 Rhabdomyolysis is a serious condition that can cause acute kidney injury (AKI), compartment syndrome, severe metabolic and electrolyte derangement leading to arrhythmias, and even death. Total plasma exchange (TPE) has been used as a treatment modality to clear myoglobin, but the evidence is limited. In this study, we aim to investigate the use of TPE in critically ill rhabdomyolysis patients.

METHODS

 We retrospectively chart reviewed adult patients admitted to the intensive care unit (ICU) with a diagnosis of rhabdomyolysis between 2012 and 2021. We dichotomized patients into two groups based on whether TPE was used or not in addition to standard care. PRISMA machines with TPE2000 filters and either 5% albumin or fresh frozen plasma were used in the TPE group.

RESULTS

 The patients' age ranged from 23 years to 87 years (mean 49.4, SD 18.1), and 51% were male. Initial creatinine ranged from 0.6 to 16mg/dL (mean 3.4, SD 2.7), creatinine phosphokinase (CPK) from 403-93,232 U/L, and myoglobin from 934 to >20,000. The Sequential Organ Failure Assessment (SOFA)scores on admission ranged from 6 to 17 (mean 7.23, SD 3.40). Overall, 28.78% (N=19) of the patients received therapeutic plasma exchange. The overall mortality in our study was 31.9%, with the length of ICU stay ranging from 1-25 days (mean 7.10, SD 5.91) among survivors. Older age and the presence of shock were predictive of mortality in univariate and multivariate analyses. There was no statistically significant association in mortality between the TPE and non-TPE groups (36.84% in TPE vs. 36.17% in the non-TPE group, OR 0.7209, p=0.959). Only two patients in the non-TPE group developed CKD/ESRD on long-term follow-up.

CONCLUSION

Our study showed that TPE administration in critically ill patients with rhabdomyolysis did not improve mortality or length of ICU stay. Further studies are required to elucidate its indication and effect on long-term renal outcomes.

Comparison of decision tree with common machine learning models for prediction of biguanide and sulfonylurea poisoning in the United States: an analysis of the National Poison Data System

BACKGROUND

Biguanides and sulfonylurea are two classes of anti-diabetic medications that have commonly been prescribed all around the world. Diagnosis of biguanide and sulfonylurea exposures is based on history taking and physical examination; thus, physicians might misdiagnose these two different clinical settings. We aimed to conduct a study to develop a model based on decision tree analysis to help physicians better diagnose these poisoning cases.

METHODS

The National Poison Data System was used for this six-year retrospective cohort study.The decision tree model, common machine learning models multi layers perceptron, stochastic gradient descent (SGD), Adaboosting classiefier, linear support vector machine and ensembling methods including bagging, voting and stacking methods were used. The confusion matrix, precision, recall, specificity, f1-score, and accuracy were reported to evaluate the model's performance.

RESULTS

Of 6183 participants, 3336 patients (54.0%) were identified as biguanides exposures, and the remaining were those with sulfonylureas exposures. The decision tree model showed that the most important clinical findings defining biguanide and sulfonylurea exposures were hypoglycemia, abdominal pain, acidosis, diaphoresis, tremor, vomiting, diarrhea, age, and reasons for exposure. The specificity, precision, recall, f1-score, and accuracy of all models were greater than 86%, 89%, 88%, and 88%, respectively. The lowest values belong to SGD model. The decision tree model has a sensitivity (recall) of 93.3%, specificity of 92.8%, precision of 93.4%, f1_score of 93.3%, and accuracy of 93.3%.

CONCLUSION

Our results indicated that machine learning methods including decision tree and ensembling methods provide a precise prediction model to diagnose biguanides and sulfonylureas exposure.

Continuous extracorporeal clearance in metformin-associated lactic acidosis and metformin-induced lactic acidosis: a systematic review

INTRODUCTION

Metformin poisoning with lactic acidosis is an uncommon yet clinically serious condition related to the inhibition of normal aerobic metabolism. Toxicity may occur after an acute overdose although it is much more common after a systemic insult, such as acute kidney injury, in the setting of chronic use. Hemodialysis is currently the preferred extracorporeal treatment modality (Grade 1D evidence) although some patients may be too hemodynamically unstable to tolerate it. Continuous renal replacement therapy is considered an alternative if hemodialysis is unavailable but an evaluation of survival amongst this specific treatment class is lacking.

OBJECTIVES

To assess overall survival and provide an updated review of the toxicokinetic elimination parameters of patients receiving continuous renal replacement therapy for metformin poisoning.

METHODS

A comprehensive search was performed using the EMBASE and MEDLINE libraries from inception until November 30, 2021. Data was extracted and findings were summarized. Toxicokinetic parameters were analyzed and confirmed for accuracy when data permitted.

RESULTS

Eighty-three reports met inclusion criteria. These consisted of only low-quality evidence including 75 case reports, four case series, and four descriptive retrospective reviews. Overall survival among patients suffering from metformin toxicity who received continuous extracorporeal treatment was 85.8%. When stratified between metformin-induced lactic acidosis and metformin-associated lactic acidosis, survival was 75.0% and 87.4%, respectively. Available continuous renal replacement therapy toxicokinetic parameters were quite heterogeneous. Errors in previously published toxicokinetic calculations were noted in only two instances. The overall average and median peak metformin concentrations were 70.5 mg/L and 41.9 mg/L, respectively. The average and median extracorporeal clearance rates were 39.0 mL/min and 42.1 mL/min (range 9.0-58.7 mL/min). The average and median elimination half-life parameters were 27.5 h and median 23.0 h. Elimination half-life ranged from seven to 74 h. There was no meaningful relationship between peak metformin concentration and continuous extracorporeal treatment half-life at lower concentrations, though at very high concentrations (over 200 mg/L), there was a trend towards a half-life below 20 h. There is insufficient data to robustly evaluate overall survival in relation to the extracorporeal clearance rate. Finally, there was no relevant relationship between maximal lactate concentration and survival, nor nadir pH and survival, for patients with either type of metformin toxicity.

CONCLUSIONS

This retrospective systematic analysis of published cases treating metformin related lactic acidosis with continuous renal replacement therapy notes an overall slightly greater survival percentage compared to previous publications of individuals requiring any modality of renal replacement therapy. Because of publication bias, these results should be interpreted with caution and serve as hypothesis generating for future research. Prospective study focusing on the most clinically meaningful endpoint - survival - will help elucidate if continuous modalities are non-inferior to intermittent hemodialysis in metformin toxicity.

Distinguishing characteristics of exposure to biguanide and sulfonylurea anti-diabetic medications in the United States

OBJECTIVES

Biguanides and sulfonylureas are anti-hyperglycemic drugs commonly used in the United States. Poisoning with these drugs may lead to serious consequences. The diagnosis of biguanide and sulfonylurea poisoning is based on history, clinical manifestations, and laboratory studies.

METHODS

This study is a six-year retrospective cohort analysis based on the National Poison Data System. Clinical effects of 6183 biguanide and sulfonylurea exposures were identified using binary logistic regression.

RESULTS

The mean age of patients with biguanide and sulfonylurea exposure was 39.27 ± 28.91 and 28.91 ± 30.41 years, respectively. Sulfonylurea exposure is most commonly seen via unintentional exposure, while biguanide exposure frequently occurs as a result of intentional ingestion. Minor and moderate outcomes commonly developed following biguanide and sulfonylurea exposure, respectively. Sulfonylurea exposure was less likely to develop clinical effects abdominal pain, metabolic acidosis, diarrhea, nausea, vomiting, and elevated creatinine than patients ingesting biguanides. However, sulfonylurea exposure was more likely to cause dizziness or vertigo, tremor, drowsiness or lethargy, agitation, diaphoresis, and hypoglycemia.

CONCLUSIONS

Our study is the first to use a wide range of national data to describe the clinical characteristics that differentiate the toxicologic exposure to biguanides and sulfonylureas. Sulfonylurea exposure is commonly seen via unintentional exposure, while metformin exposure is frequently seen via intentional exposure. Sulfonylurea toxicity is more likely to cause agitation, dizziness or vertigo, tremor, diaphoresis, and hypoglycemia, while metformin exposure induces abdominal pain, acidosis, diarrhea, nausea, vomiting, and elevated creatinine.

Evaluation of Clinical and Venous Blood Parameters as Surrogate Indicators in Assessing the Need for Fasciotomy in Lower Limb Compartment Syndrome

Acute compartment syndrome in the lower limb, a surgical emergency, may cause ischemic damage to muscles and neurological deficits leading to loss of function of the limb which may even require amputation, thus drastically affecting the quality of life of a patient. Fasciotomy for decompression is suggested when the differential pressure in the compartment of the leg is ≤30 mm Hg. However, compartment pressure measurement is not always feasible. Surgeons often find themselves in a dilemma in deciding the right treatment option for the patient: fasciotomy or conservative management. Since there is no universally accepted reference standard for the diagnosis of acute compartment syndrome at present, there is a need for definitive diagnostic variables so as to not delay fasciotomy in patients who need it, as well as to avoid unnecessary fasciotomies, especially when compartment pressures cannot be measured. In this observational study including 71 patients, based on the compartment pressures of the affected limb, treatment was done either with fasciotomy or conservative approach, and various clinical and biochemical parameters were evaluated in between these two groups. Statistically significant difference was found in the venous blood gas parameters between patients managed conservatively and with fasciotomy (MANOVA, P = .001). The results revealed the association of lower venous blood bicarbonate levels (independent sample t test, P = .021) and the presence of paresthesia (Fisher exact test, P = .0016) with the fasciotomy group. Also, pain on passive stretching of the affected limb was found to be significantly associated with a delta pressure of ≤30 mm Hg in any compartment (Fisher exact test, P = .002). These variables may thus be used as an alternative to the measurement of compartment pressure to assess the requirement of fasciotomy.

Metformin-associated lactic acidosis: reinforcing learning points

Metformin-associated lactic acidosis (MALA) carries a high mortality rate. It is seen in patients with type 2 diabetes on metformin or patients who attempt suicide with metformin overdose. We present the case of a man in his early 20s with type 2 diabetes, hypertension and hypothyroidism who presented with agitation, abdominal pain and vomiting after ingesting 50-60 g of metformin; he developed severe lactic acidosis (blood pH 6.93, bicarbonate 7.8 mEq/L, lactate 28.0 mEq/L). He was managed with intravenous 8.4% bicarbonate infusion and continuous venovenous haemodiafiltration. He also developed acute renal failure (ARF) requiring intermittent haemodialysis and continuous haemodiafiltration. MALA is uncommon and causes changes in different vital organs and even death. The primary goals of therapy are restoration of acid-base status and removal of metformin. Early renal replacement therapy for ARF can result in rapid reversal of the acidosis and good recovery, even with levels of lactate normally considered to be incompatible with survival.

Recurrent hypoglycemia secondary to metformin toxicity in the absence of co-ingestions: a case report

BACKGROUND

Metformin toxicity is well known to cause lactic acidosis. Multiple cases of hypoglycemia due to isolated metformin overdose have been reported. Increased glucose consumption secondary to anaerobic metabolism has been reported as a possible explanation.

CASE PRESENTATION

A 23-year-old Arabic woman took 30 g of metformin. In the emergency department, 4 hours after of the event, she was fatigued but vitally stable. During her hospitalization, she had severe lactic acidosis, hypotension corrected with fluid boluses and vasopressors, and multiple episodes of hypoglycemia (6.3 mg/dL, 38 mg/dL, and 42 mg/dL), requiring multiple 50% dextrose-water boluses. The three hypoglycemic episodes occurred coincident with severe lactic acidosis. She improved after 24 hours of continuous renal replacement therapy.

CONCLUSIONS

Hypoglycemia can be induced by metformin toxicity in the absence of co-ingestants. A possible explanation of metformin-induced hypoglycemia is increased glucose consumption due to anaerobic metabolism, decreased oral intake, decreased liver glucose production, and decreased glucose absorption.

A Klebsiella pneumoniae liver abscess presenting with myasthenia and tea-colored urine: A case report and review of 77 cases of bacterial rhabdomyolysis

RATIONALE

Rhabdomyolysis is a well-known syndrome in clinical practice, although rhabdomyolysis caused by a liver abscess is rarely reported and the patient may lack symptoms that are associated with a primary site of infection. Early recognition of this possibility is needed to avoid diagnostic delay and facilitate treatment. We report the case of a 71-year-old woman with a Klebsiella pneumoniae (KP) pyogenic liver abscess who presented with myasthenia and tea-colored urine and also review the 77 reported cases of bacterial rhabdomyolysis.

PATIENT CONCERNS

The patient was 71 years old and presenting with a 7-day history of myasthenia and a 3-day history of tea-colored urine, but without fever or abdominal pain.

DIAGNOSES

Laboratory testing in our case revealed rhabdomyolysis, and blood culture revealed KP. Abdominal ultrasonography revealed a hypoechoic enclosed mass, and computed tomography (CT) revealed an enclosed low-density mass (8.3 × 6.6 × 6.1 cm). The main diagnoses were a pyogenic liver abscess with rhabdomyolysis.

INTERVENTIONS

Empirically intravenous piperacillin-sulbactam and intravenous potassium treatment, as well as fluid infusions and other supportive treatments were provided after admission. After the diagnosis was confirmed and susceptibility test results were available, we adjusted the antibiotics to cefoperazone and sulbactam, which were maintained for 6 weeks.

OUTCOMES

The patient's symptoms relieved and the abnormal laboratory parameters corrected. Follow-up abdominal ultrasonography at 24 months after her discharge revealed that the abscess had disappeared.

LESSONS

Early recognition and careful consideration of the underlying cause of rhabdomyolysis are critical to improving the patient's prognosis. Thus, physicians should carefully consider the underlying cause in elderly patients who present with rhabdomyolysis, as they may lack symptoms of a primary infection.

McArdle disease: a "pediatric" disorder presenting in an adult with acute kidney injury

Rhabdomyolysis is characterized by the acute breakdown of skeletal muscle, resulting in the release of muscle cell contents, subsequent myoglobinuria, and in severe cases, acute renal failure. A number of etiologies have been identified in acute rhabdomyolysis, in which drugs and trauma account for the majority of cases. One etiological category that is commonly overlooked in the adult population is an underlying genetic defect. This may be challenging to diagnose due to its rarity in the adult demographic and the marked heterogeneity, often requiring a high level of clinical suspicion before investigation is pursued. Once diagnosed, however, appropriate steps can be taken to reduce future episodes of rhabdomyolysis, further renal injury, and other systemic complications. Here, we report a case of an adult patient presenting with acute rhabdomyolysis secondary to McArdle disease, a genetic disease causing defective glycogenolysis. The case highlights the importance of recognizing the potential of undiagnosed "pediatric" disorders in adulthood and particularly for underlying genetic causes of rhabdomyolysis.

Contralateral compartment syndrome inoculated by invasive group A streptococcus

Compartment syndrome is a rare but a well-documented complication in patients with trauma-induced group A streptococcus infection. Here, we present a case of a male who developed compartment syndrome on the left lower extremity after an injury inoculated by group A streptococcus on the right lower extremity. The patient was resuscitated with antibiotics, urgent fasciotomy, and immunoglobulin. The patient was eventually transferred to a burn center for further care.

Extracorporeal treatment with high-volume continuous venovenous hemodiafiltration and charcoal-based sorbent hemoperfusion for severe metformin-associated lactic acidosis

We present a case of a 49-year-old female with an alleged history of ingestion of approximately 100 tablets of metformin (850 mg each). Investigations revealed severe lactic acidosis with lactate levels of 13.5 mmol/L and pH of 7.17. This indicates severe toxicity and is associated with a high mortality. Charcoal-based sorbent hemoperfusion was done as a desperate effort, as patient continued to deteriorate despite supportive care and high-volume continuous venovenous hemodiafiltration. The patient survived despite metformin-associated lactic acidosis related to severe metformin toxicity.

Metformin-associated lactic acidosis: Current perspectives on causes and risk

Although metformin has become a drug of choice for the treatment of type 2 diabetes mellitus, some patients may not receive it owing to the risk of lactic acidosis. Metformin, along with other drugs in the biguanide class, increases plasma lactate levels in a plasma concentration-dependent manner by inhibiting mitochondrial respiration predominantly in the liver. Elevated plasma metformin concentrations (as occur in individuals with renal impairment) and a secondary event or condition that further disrupts lactate production or clearance (e.g., cirrhosis, sepsis, or hypoperfusion), are typically necessary to cause metformin-associated lactic acidosis (MALA). As these secondary events may be unpredictable and the mortality rate for MALA approaches 50%, metformin has been contraindicated in moderate and severe renal impairment since its FDA approval in patients with normal renal function or mild renal insufficiency to minimize the potential for toxic metformin levels and MALA. However, the reported incidence of lactic acidosis in clinical practice has proved to be very low (<10 cases per 100,000 patient-years). Several groups have suggested that current renal function cutoffs for metformin are too conservative, thus depriving a substantial number of type 2 diabetes patients from the potential benefit of metformin therapy. On the other hand, the success of metformin as the first-line diabetes therapy may be a direct consequence of conservative labeling, the absence of which could have led to excess patient risk and eventual withdrawal from the market, as happened with earlier biguanide therapies. An investigational delayed-release metformin currently under development could potentially provide a treatment option for patients with renal impairment pending the results of future studies. This literature-based review provides an update on the impact of renal function and other conditions on metformin plasma levels and the risk of MALA in patients with type 2 diabetes.

Extracorporeal Treatment for Metformin Poisoning: Systematic Review and Recommendations From the Extracorporeal Treatments in Poisoning Workgroup

BACKGROUND

Metformin toxicity, a challenging clinical entity, is associated with a mortality of 30%. The role of extracorporeal treatments such as hemodialysis is poorly defined at present. Here, the Extracorporeal Treatments In Poisoning workgroup, comprising international experts representing diverse professions, presents its systematic review and clinical recommendations for extracorporeal treatment in metformin poisoning.

METHODS

A systematic literature search was performed, data extracted, findings summarized, and structured voting statements developed. A two-round modified Delphi method was used to achieve consensus on voting statements and RAND/UCLA Appropriateness Method to quantify disagreement. Anonymized votes and opinions were compiled and discussed. A second vote determined the final recommendations.

RESULTS

One hundred seventy-five articles were identified, including 63 deaths: one observational study, 160 case reports or series, 11 studies of descriptive cohorts, and three pharmacokinetic studies in end-stage renal disease, yielding a very low quality of evidence for all recommendations. The workgroup concluded that metformin is moderately dialyzable (level of evidence C) and made the following recommendations: extracorporeal treatment is recommended in severe metformin poisoning (1D). Indications for extracorporeal treatment include lactate concentration greater than 20 mmol/L (1D), pH less than or equal to 7.0 (1D), shock (1D), failure of standard supportive measures (1D), and decreased level of consciousness (2D). Extracorporeal treatment should be continued until the lactate concentration is less than 3 mmol/L (1D) and pH greater than 7.35 (1D), at which time close monitoring is warranted to determine the need for additional courses of extracorporeal treatment. Intermittent hemodialysis is preferred initially (1D), but continuous renal replacement therapies may be considered if hemodialysis is unavailable (2D). Repeat extracorporeal treatment sessions may use hemodialysis (1D) or continuous renal replacement therapy (1D).

CONCLUSION

Metformin poisoning with lactic acidosis appears to be amenable to extracorporeal treatments. Despite clinical evidence comprised mostly of case reports and suboptimal toxicokinetic data, the workgroup recommended extracorporeal removal in the case of severe metformin poisoning.

Use of metformin in diseases of aging

Metformin is the most commonly prescribed medication for type 2 diabetes (T2DM) in the world. It has primacy in the treatment of this disease because of its safety record and also because of evidence for reduction in the risk of cardiovascular events. Evidence has accumulated indicating that metformin is safe in people with stage 3 chronic kidney disease (CKD-3). It is estimated that roughly one-quarter of people with CKD-3 and T2DM in the United States (well over 1 million) are ineligible for metformin treatment because of elevated serum creatinine levels. This could be overcome if a scheme, perhaps based on pharmacokinetic studies, could be developed to prescribe reduced doses of metformin in these individuals. There is also substantial evidence from epidemiologic studies to indicate that metformin may not only be safe, but may actually benefit people with heart failure (HF). Prospective, randomized trials of the use of metformin in HF are needed to investigate this possibility.

Apparent lisinopril overdose requiring hemodialysis

PURPOSE

A case of apparent overdose of angiotensin-converting-enzyme inhibitors requiring hemodialysis is reported.

SUMMARY

A 51-year-old white man (weight, 85 kg; height, 178 cm; body mass index, 28) with a history of hypertension, low back pain, and anxiety apparently took 27 lisinopril 10-mg tablets (3.18 mg/kg body weight) over a period of 3 or fewer days. The friend who brought him to the emergency department reported that the patient was hard to rouse and was speaking incoherently on the day of admission. Over the previous few days, the patient reportedly had visual hallucinations, incoherence, and inarticulate speech. Laboratory tests, electrocardiography, and computed tomography were performed. The patient was judged to have high-anion-gap metabolic acidosis, acute kidney injury, severe hyperkalemia, and rhabdomyolysis. He was given three doses of albuterol via a nebulizer, three doses of calcium gluconate 1 g i.v., two doses of sodium bicarbonate 100 meq i.v., two doses of sodium polystyrene sulfonate 30 g orally, three doses of insulin 10 units i.v., and three doses of dextrose 25 g (as 50% dextrose injection) i.v. He then underwent emergent hemodialysis and was admitted to the intensive care unit. The patient's confusion abated, kidney function improved, and acid-base and electrolyte imbalances resolved. The patient was discharged after 15 days.

CONCLUSION

A man who had evidently taken an overdose of lisinopril had multiorgan dysfunction in the absence of hypotension. The abnormalities resolved after he was treated for acidosis and hyperkalemia and received hemodialysis to remove the lisinopril.

Rhabdomyolysis in an HIV-infected patient following coronary angiography: case report and literature review

Rhabdomyolysis is a rare, but possible, complication of combination antiretroviral therapy (cART). We report a unique case of an HIV-positive patient on cART who came to our attention for suspected ischaemic heart disease. Coronary angiography was carried out and complicated in the following days by rhabdomyolysis. We discuss the possible links between rhabdomyolysis, iodinated contrast media and HAART.

Metformin-Associated Lactic Acidosis following Intentional Overdose Successfully Treated with Tris-Hydroxymethyl Aminomethane and Renal Replacement Therapy

A 43-year-old woman was brought to the hospital with severe metabolic acidosis (pH 6.56, bicarbonate 3 mmol/L, and lactate 18.4 mmol/L) and a serum creatinine of 162 μmol/L with a serum potassium of 7.8 mmol/L. A delayed diagnosis of metformin-associated lactic acidosis was made, and she was treated with tris-hydroxymethyl aminomethane (THAM) and renal replacement therapy (RRT). Following a complete recovery, she admitted to ingesting 180 tablets (90 grams) of metformin. Her peak serum metformin concentration was 170 μg/mL (therapeutic range 1-2 μg/mL). Our case demonstrates an intentional metformin overdose resulting in lactic acidosis in a nondiabetic patient who was successfully treated with THAM and RRT.

Severe lactic acidosis and acute renal failure following ingestion of metformin and kerosene oil: a case report

Introduction

Kerosene is a freely accessible hydrocarbon used in Sri Lankan (and other Asian) households for cooking and for lighting lamps. Kerosene poisoning is rarely reported among adults and its toxicological effects are not well known. Metformin is a commonly used oral hypoglycemic drug and its overdose leads primarily to lactic acidosis. Combined poisoning of metformin and kerosene and their interactions have not been reported.

Case presentation

An 18-year-old, previously healthy, unmarried Sinhalese woman was referred following ingestion of 17.5 g of metformin and approximately 200 mL of kerosene oil in a suicide attempt. She had vomiting, burning epigastric pain, and a hypoglycemic seizure (capillary blood glucose of 42 mg/dL). Subsequently, she developed severe lactic acidosis followed by acute renal insufficiency, was treated with sodium bicarbonate, and underwent intermittent hemodialysis with bicarbonate. She recovered completely.

Conclusions

This report proposes possible interactions that occur between metformin and kerosene that augment toxicity when the two are ingested together. It also stresses the importance of early treatment with intermittent hemodialysis in severe lactic acidosis with maintenance of blood glucose.

Metformin-associated lactic acidosis in Chinese patients with type II diabetes

Metformin is a widely used antidiabetic agent that is generally considered safe. However, metformin-associated lactic acidosis (MALA), though not common, occurs from time to time and results in significantly high mortality. A series of 23 MALA cases in a local major hospital in Hong Kong is reported in this article to demonstrate the epidemiological data, risk factors, clinical features as well as the clinical outcomes for better understanding of this disease entity. It is the first MALA case series in which plasma metformin levels were assessed. However, the results show that plasma metformin levels in MALA bear no diagnostic and prognostic values. Risk factors of mortality were identified as shock and high plasma lactate levels. The majority of patients were found to have significantly raised creatinine versus a normal baseline value before the acute illness. Concomitant illnesses taking place alongside MALA were common. With a high utility rate of renal replacement therapy (82.6%) in the study group, the mortality rate was 30.4%.

Management of metformin-associated lactic acidosis by continuous renal replacement therapy

BACKGROUND

Metformin-associated lactic acidosis (MALA) is a severe metabolic failure with high related mortality. Although its use is controversial, intermittent hemodialysis is reported to be the most frequently used treatment in conjunction with nonspecific supportive measures. Our aim was to report the evolution and outcome of cases managed by continuous renal replacement therapy (CRRT).

METHODOLOGY AND PRINCIPAL FINDINGS

Over a 3-year period, we retrospectively identified patients admitted to the intensive care unit for severe lactic acidosis caused by metformin. We included patients in our study who were treated with CRRT because of shock. We describe their clinical and biological features at admission and during renal support, as well as their evolution. We enrolled six patients with severe lactic acidosis; the mean pH and mean lactate was 6.92±0.20 and 14.4±5.1 mmol/l, respectively. Patients had high illness severity scores, including the Simplified Acute Physiology Score II (SAPS II) (average score 63±12 points). Early CRRT comprised either venovenous hemofiltration (n = 3) or hemodiafiltration (n = 3) with a mean effluent flow rate of 34±6 ml/kg/h. Metabolic acidosis control and metformin elimination was rapid and there was no rebound. Outcome was favorable in all cases.

CONCLUSIONS AND SIGNIFICANCE

Standard use of CRRT efficiently treated MALA in association with symptomatic organ supportive therapies.

[Acid-base disturbances in intensive-care patients]

BACKGROUND

Acid-base disturbances may cause a variety of symptoms, multi-organ failure and compromised immune defense. The aim of this paper is to provide an overview of acid-base disturbances in intensive-care patients.

MATERIAL AND METHOD

The article is based on a non-systematic search in Pub Med, a textbook on intensive care and the authors' clinical experience.

RESULTS

The Henderson-Hasselbalch equation describes acid-base status by changes in pCO2 and bicarbonate. Changes in pCO2 reflect the respiratory and bicarbonate the metabolic status. Standard base excess describes the metabolic part more exactly. Anion gap is calculated as a supplement. The Stewart method, describes acid-base status through three independent variables (pCO2, weak acids and strong ion difference [SID]) that regulate the dependent variables pH and bicarbonate concentration.

INTERPRETATION

The Henderson-Hasselbalch equation and standard base excess do not consider which acids or bases that are involved, The anion gap may disclose unmeasured anions and distinguish hyperchloremic acidosis from other types of metabolic acidosis, but the calculation is associated with uncertainty. The Stewart method describes the involved ions, but complicated equations makes it unsuitable in clinical practice. A combination of standard base excess and anion gap corrected for albumin levels provide a good description of acid-base status.

Continuous Venovenous Haemodiafiltration for Metformin-induced Lactic Acidosis

A 74-year-old man with cardiac failure and renal impairment was admitted to the cardiothoracic intensive care unit with metformin-induced lactic acidosis and shock. He was successfully treated with high-dose (80 ml/kg/hour) continuous venovenous haemodiafiltration. Lactic acidosis is a known complication of metformin and is associated with a high mortality. The use of high-dose continuous venovenous haemodiafiltration for this condition has not previously been reported.

Survival following Profound Lactic Acidosis and Cardiac Arrest: Does Metformin Really Induce Lactic Acidosis?

We report the case of a 63-year-old man who suffered a witnessed pulseless electrical activity cardiac arrest on presentation to the emergency department. Despite a profound post-arrest acidosis (pH 6.48) he went on to make an unexpectedly good recovery. He was treated for metformin-associated lactic acidosis (MALA) and septic shock, although the origin of the sepsis was never confirmed. We discuss the growing evidence against the existence of MALA as a lone diagnosis and the aetiology of post-cardiac arrest metabolic acidosis.

Metabolic acidosis in the critically ill: part 2. Causes and treatment

The correct identification of the cause, and ideally the individual acid, responsible for metabolic acidosis in the critically ill ensures rational management. In Part 2 of this review, we examine the elevated (corrected) anion gap acidoses (lactic, ketones, uraemic and toxin ingestion) and contrast them with nonelevated conditions (bicarbonate wasting, renal tubular acidoses and iatrogenic hyperchloraemia) using readily available base excess and anion gap techniques. The potentially erroneous interpretation of elevated lactate signifying cell ischaemia is highlighted. We provide diagnostic and therapeutic guidance when faced with a high anion gap acidosis, for example pyroglutamate, in the common clinical scenario 'I can't identify the acid--but I know it's there'. The evidence that metabolic acidosis affects outcomes and thus warrants correction is considered and we provide management guidance including extracorporeal removal and fomepizole therapy.