Causes Of Lactic Acidosis - Deranged Physiology
A discussion of the causes of a high anion gap metabolic acidosis are frequently required by the CICM SAQs, and lactate often comes up as a differential. Beyond that, there are a series of questions which ask specifically about the causes of lactic acidosis. These questions are numerous. There is practically one in every paper. Question 4.1 from the first paper of 2016 Question 3.3 from the second paper of 2015 Question 27 from the second paper of 2014 Question 23 from the second paper of 2013 Question 26.4 from the second paper of 2013 Question 28 from the second paper of 2012 Question 9.1 from the first paper of 2011 Question 15.3 from the second paper of 2009 Question 3.3 from the second paper of 2009 Many of these questions for some reason focus repetitively on the plight of a certain middle-aged diabetic with a history of alcohol abuse. A specific feature of these questions is the use of red cell transketolase as a test of thiamine deficiency, reminding the candidates that this is an important differential. Lactic acidosis is discussed at greater length in a series of chapters dedicated to acid-base disturbances in their various forms and permutations. In order to simplify revision, a tabulated list of aetiologies is offered below, organised according to an increasingly irrelevant classification system from the 1980s. The massively flawed Cohen-Woods classification Type A lactic acidosis: impaired tissue oxygenation Type B1 lactic acidosis, due to a disease state NRTIs (nucleoside reverse transcriptase inhibitors) Continue reading >>
Lactate And Lactic Acidosis
The integrity and function of all cells depend on an adequate supply of oxygen. Severe acute illness is frequently associated with inadequate tissue perfusion and/or reduced amount of oxygen in blood (hypoxemia) leading to tissue hypoxia. If not reversed, tissue hypoxia can rapidly progress to multiorgan failure and death. For this reason a major imperative of critical care is to monitor tissue oxygenation so that timely intervention directed at restoring an adequate supply of oxygen can be implemented. Measurement of blood lactate concentration has traditionally been used to monitor tissue oxygenation, a utility based on the wisdom gleaned over 50 years ago that cells deprived of adequate oxygen produce excessive quantities of lactate. The real-time monitoring of blood lactate concentration necessary in a critical care setting was only made possible by the development of electrode-based lactate biosensors around a decade ago. These biosensors are now incorporated into modern blood gas analyzers and other point-of-care analytical instruments, allowing lactate measurement by non-laboratory staff on a drop (100 L) of blood within a minute or two. Whilst blood lactate concentration is invariably raised in those with significant tissue hypoxia, it can also be raised in a number of conditions not associated with tissue hypoxia. Very often patients with raised blood lactate concentration (hyperlactatemia) also have a reduced blood pH (acidosis). The combination of hyperlactatemia and acidosis is called lactic acidosis. This is the most common cause of metabolic acidosis. The focus of this article is the causes and clinical significance of hyperlactatemia and lactic acidosis. The article begins with a brief overview of normal lactate metabolism. Normal lactate production and Continue reading >>
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Lactic acidosis is a medical condition characterized by the buildup of lactate (especially L-lactate) in the body, which results in an excessively low pH in the bloodstream. It is a form of metabolic acidosis, in which excessive acid accumulates due to a problem with the body's metabolism of lactic acid. Lactic acidosis is typically the result of an underlying acute or chronic medical condition, medication, or poisoning. The symptoms are generally attributable to these underlying causes, but may include nausea, vomiting, rapid deep breathing, and generalised weakness. The diagnosis is made on biochemical analysis of blood (often initially on arterial blood gas samples), and once confirmed, generally prompts an investigation to establish the underlying cause to treat the acidosis. In some situations, hemofiltration (purification of the blood) is temporarily required. In rare chronic forms of lactic acidosis caused by mitochondrial disease, a specific diet or dichloroacetate may be used. The prognosis of lactic acidosis depends largely on the underlying cause; in some situations (such as severe infections), it indicates an increased risk of death. Classification The Cohen-Woods classification categorizes causes of lactic acidosis as: Type A: Decreased tissue oxygenation (e.g., from decreased blood flow) Type B B1: Underlying diseases (sometimes causing type A) B2: Medication or intoxication B3: Inborn error of metabolism Signs and symptoms Lactic acidosis is commonly found in people who are unwell, such as those with severe heart and/or lung disease, a severe infection with sepsis, the systemic inflammatory response syndrome due to another cause, severe physical trauma, or severe depletion of body fluids. Symptoms in humans include all those of typical m Continue reading >>
Bench-to-bedside Review: Is There A Place For Epinephrine In Septic Shock?
Bench-to-bedside review: Is there a place for epinephrine in septic shock? The use of epinephrine in septic shock remains controversial. Nevertheless, epinephrine is widely used around the world and the reported morbidity and mortality rates with it are no different from those observed with other vasopressors. In volunteers, epinephrine increases heart rate, mean arterial pressure and cardiac output. Epinephrine also induces hyperglycemia and hyperlactatemia. In hyperkinetic septic shock, epinephrine consistently increases arterial pressure and cardiac output in a dose dependent manner. Epinephrine transiently increases lactate levels through an increase in aerobic glycolysis. Epinephrine has no effect on splanchnic circulation in dopamine-sensitive septic shock. On the other hand, in dopamine-resistant septic shock, epinephrine has no effect on tonometric parameters but decreases fractional splanchnic blood flow with an increase in the gradient of mixed venous oxygen saturation (SVO2) and hepatic venous oxygen saturation (SHO2). In conclusion, epinephrine has predictable effects on systemic hemodynamics and is as efficient as norepinephrine in correcting hemodynamic disturbances of septic shock. Moreover, epinephrine is cheaper than other commonly used catecholamine regimens in septic shock. The clinical impact of the transient hyperlactatemia and of the splanchnic effects are not established. EpinephrineSeptic ShockMean Arterial PressureDobutamineAerobic Glycolysis Early goal directed therapy [ 1 ] is now considered as a gold standard in the early phase of septic shock. Fluid therapy and vasoactive therapy may be immediately required in order to maintain acceptable blood pressure levels. Invasive or non-invasive assessment of hemodynamic status, although essential to Continue reading >>
hyperlactaemia: a level from 2 to 5 mmol/L normal production is 20 mmols/kg/day, enters the circulation and undergoes hepatic and renal metabolism (Cori cycle) all tissues can produce lactate under anaerobic conditions lactic acid has a pK value of about 4 so it is fully dissociated into lactate and H+ at body pH (i.e. it is a strong ion) during heavy exercise, the skeletal muscles contribute most of the much increased circulating lactate during pregnancy, the placenta is an important producer of lactate (can pass to fetus as well) major source in sepsis and ARDS is the lung lactate is metabolised predominantly in the liver (60%) and kidney (30%) the heart can also use lactate for ATP production 50% is converted into glucose (gluconeogenesis) and 50% into CO2 and water (citric acid cycle) this results in no net acid accumulation but requires aerobic metabolism the small amount of lactate that is renally filtered (180mmol/day) is fully reabsorbed (ii) impaired hepatic metabolism of lactate (large capacity to clear) clinically there is often a combination of the above to produce a persistent lactic acidosis anaerobic muscular activity (sprinting, generalised convulsions) tissue hypoperfusion (shock, cardiac arrest, regional hypoperfusion -> mesenteric ischaemia) reduced tissue oxygen delivery (hypoxaemia, anaemia) or utilisation (CO poisoning) Type B No Evidence of Inadequate Tissue Oxygen Delivery once documented the cause must be found and treated appropriately D lactate is isomer of lactate produced by intestinal bacterial and not by humans it is not detected on standard lactate assays a bed side test may be able to be developed to help with diagnosis of mesenteric ischaemia venous samples are equivalent to arterial in clinical practice do not need to take off tourniq Continue reading >>
Epinephrine-induced Lactic Acidosis In The Setting Of Status Asthmaticus.
Epinephrine-induced lactic acidosis in the setting of status asthmaticus. Murphy FT(1), Manown TJ, Knutson SW, Eliasson AH. (1)Department of Medicine, Walter Reed Army Medical Center, Washington, DC 20307-5000, USA. A relationship between intravenous epinephrine infusion and the development oflactic acidosis has been well described. We report a temporal association betweenthe administration of subcutaneous epinephrine and the development of lacticacidosis in the setting of status asthmaticus. A 20-year-old woman with a historyof asthma came to the emergency service in acute respiratory distress and wastreated with subcutaneous epinephrine. Six hours later, serial arterial blood gasstudies revealed the onset of a primary metabolic acidosis. Additional diagnosticstudies revealed a serum lactate level of 9.5 mumol/L. The lactic acidosisresolved within 15 hours. The patient never exhibited signs of hypotension,hypoxemia, or sepsis, and other potential etiologies for lactic acidosis wereexcluded. We believe the events of this case constitute a new observation andtheorize a mechanism of peripheral vasoconstriction and transient tissuehypoperfusion mediated by the subcutaneous epinephrine. Continue reading >>
Epinephrine-induced Lactic Acidosis Following Cardiopulmonary Bypass.
Epinephrine-induced lactic acidosis following cardiopulmonary bypass. Department of Intensive Care, Royal North Shore Hospital, St. Leonards, NSW, Australia. To determine if lactic acidosis occurring after cardiopulmonary bypass could be attributed to the metabolic or other effects of epinephrine administration. Postsurgical cardiothoracic intensive therapy unit. Thirty-six adult patients, without acidosis, requiring vasoconstrictors for the management of hypotension after cardiopulmonary bypass. Randomized administration of either epinephrine or norepinephrine by infusion. Hemodynamic and metabolic data were collected before commencement of vasoconstrictor therapy (time 0) and then 1 hr (time 1), 6 to 10 hrs (time 2), and 22 to 30 hrs (time 3) later. Six of the 19 patients who received epinephrine developed lactic acidosis. None of the 17 patients receiving norepinephrine developed lactic acidosis. In the epinephrine group, but not in the norepinephrine group, lactate concentration increased significantly at times 1 and 2 (p = .01), while pH and base excess decreased (p < or = .01). Blood glucose concentration was higher in the epinephrine group at time 2 (p = .02), while the cardiac index (p < .03) and the mixed venous Po2 (p = .04) were higher at time 1. compared with the norepinephrine group, the patients receiving epinephrine had higher femoral venous lactate concentrations (p = .03), increased lower limb blood flow (p = .05), and increased femoral venous oxygen saturations (p = .04). The use of epinephrine after cardiopulmonary bypass precipitates the development of lactic acidosis in some patients. This phenomenon is presumably a beta-mediated effect, and is associated with an increase in whole-body and lower limb blood flow and a decrease in whole-body and tran Continue reading >>
Effect Of Severe Acidosis On Vasoactive Effects Of Epinephrine And Norepinephrine In Human Distal Mammary Artery - Sciencedirect
Volume 147, Issue 5 , May 2014, Pages 1698-1705 Acidosis is a very common pathologic process in perioperative management. However, how to correct severe acidosis to improve the efficacy of vasoconstrictors in hemodynamically unstable patients is still debated. The present study investigated whether severe extracellular acidosis influences the vasoactive properties of vasoconstrictors on human isolated arteries. Segments of intact distal internal mammary arteries were removed from 41 patients undergoing artery bypass grafting. The arterial rings were washed in Krebs-Henseleit solution and suspended in an organ bath. The rings were set at a pretension equivalent of 100 mm Hg, and the relaxation response to 10 M acetylcholine was verified. Concentrationresponse curves for epinephrine, norepinephrine, methoxamine (1A/D-adrenoceptor agonist), phenylephrine (equipotent agonist of 1A/B-adrenoceptors), and clonidine (2-adrenoceptor agonist) were achieved under control conditions (pH 7.40) and under acidic conditions by substitution of the Krebs-Henseleit solution with a modified solution. Decreasing the pH from 7.40 to 7.20, 7.0, or 6.80 did not significantly alter the potency and efficacy of epinephrine and norepinephrine, although the standardized effect size was sometimes large. Severe acidosis (pH6.80) did not significantly change the potency and efficacy of phenylephrine and clonidine, although it increased the efficacy and potency of methoxamine (P<.001 and P=.04 vs paired control conditions, respectively). Extracellular acidosis did not impair the vasoactive properties of epinephrine and norepinephrine in human medium-size arteries until pH 6.80. The results of the present study also suggest that acidosis might potentiate arterial responsiveness to vasoconstrictors, mos Continue reading >>
Patient professional reference Professional Reference articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use. You may find one of our health articles more useful. Description Lactic acidosis is a form of metabolic acidosis due to the inadequate clearance of lactic acid from the blood. Lactate is a byproduct of anaerobic respiration and is normally cleared from the blood by the liver, kidney and skeletal muscle. Lactic acidosis occurs when the body's buffering systems are overloaded and tends to cause a pH of ≤7.25 with plasma lactate ≥5 mmol/L. It is usually caused by a state of tissue hypoperfusion and/or hypoxia. This causes pyruvic acid to be preferentially converted to lactate during anaerobic respiration. Hyperlactataemia is defined as plasma lactate >2 mmol/L. Classification Cohen and Woods devised the following system in 1976 and it is still widely used: Type A: lactic acidosis occurs with clinical evidence of tissue hypoperfusion or hypoxia. Type B: lactic acidosis occurs without clinical evidence of tissue hypoperfusion or hypoxia. It is further subdivided into: Type B1: due to underlying disease. Type B2: due to effects of drugs or toxins. Type B3: due to inborn or acquired errors of metabolism. Epidemiology The prevalence is very difficult to estimate, as it occurs in critically ill patients, who are not often suitable subjects for research. It is certainly a common occurrence in patients in high-dependency areas of hospitals. The incidence of symptomatic hyperlactataemia appears to be rising as a consequence of the use of antiretroviral therapy to treat HIV infection. It appears to increase in those taking stavudine (d4T) regimens. Causes of lactic acid Continue reading >>
2. After successful resuscitation from cardiac arrest lactate level is proportional to 'time to ROSC'. 1. Hypermetabolic states: exercise, sepsis, seizures, malignant hyperthermia, severe asthma, catecholamines, theophylline. (a) Respiratory: low FiO2, hypoventilation, hypoxic lung disease. (b) Cardiovascular: hypovolaemia, cardiogenic shock, hypotension. (c) Peripheral vascular failure: vasodilators, sepsis, anaphylaxis, spinal shock. 1.Drug-Induced: phenformin, metformin, ethanol, methanol, salicylates, sorbitol, fructose, xylitol, cyanide poisoning. 2. Enzyme deficiency: G6PD, F1,6diphosphatase 5. Other: sepsis, diabetes, renal failure, pancreatitis, lymphoma, leukaemia. pyruvate + NADH + H+ lactate + NAD+. Major lactate production sites: gut and skeletal muscle, ARDS lung. Metabolised by liver, heart, kidney, & muscle. Normal plasma lactate:pyruvate ratio = 10:1-20:1 = cytoplasmic redox state, but may not be same as the mitochondrial redox state. (a) High pyruvate production eg. high metabolic rate (exercise, stress, trauma, 2-agonsits, catecholamines, severe asthma.) (b) Intracellular acidosis eg. ischaemia. (c) High NADH:NAD+ ratio eg. hypoxia, mitochondrial disorder. (d) Low uptake & metabolism by liver: common cause in severe sepsis. Lactic acidosis may mask mild ketoacidosis: low redox state more BOHB (not measured by ketone tests) & less AcAc. 1. IV sample from drip arm with CSL running. 2. Lactate-containing dialysate fluid in use. 3. -agonist therapy: salbutamol, adrenaline Continue reading >>
Understanding Lactate In Sepsis & Using It To Our Advantage
You are here: Home / PULMCrit / Understanding lactate in sepsis & Using it to our advantage Understanding lactate in sepsis & Using it to our advantage Once upon a time a 60-year-old man was transferred from the oncology ward to the ICU for treatment of neutropenic septic shock. Over the course of the morning he started rigoring and dropped his blood pressure from 140/70 to 70/40 within a few hours, refractory to four liters of crystalloid. In the ICU his blood pressure didn't improve with vasopressin and norepinephrine titrated to 40 mcg/min. His MAP remained in the high 40s, he was mottled up to the knees, and he wasn't making any urine. Echocardiography suggested a moderately reduced left ventricle ejection fraction, not terrible but perhaps inadequate for his current condition. Dobutamine has usually been our choice of inotrope in septic shock. However, this patient was so unstable that we chose epinephrine instead. On an epinephrine infusion titrated to 10 mcg/min his blood pressure improved immediately, his mottling disappeared, and he started having excellent urine output. However, his lactate level began to rise. He was improving clinically, so we suspected that the lactate was due to the epinephrine infusion. We continued the epinephrine, he continued to improve, and his lactate continued to rise. His lactate level increased as high as 15 mM, at which point the epinephrine infusion was being titrated off anyway. Once the epinephrine was stopped his lactate rapidly normalized. He continued to improve briskly. By the next morning he was off vasopressors and ready for transfer back to the ward. This was eye-opening. It seemed that the epinephrine infusion was the pivotal intervention which helped him stabilize. However, while clinically improving him, the epineph Continue reading >>
Lactic Acidosis | Md Nexus
Cohen-Woods Classification of Lactic Acidosis Type A: due to decreased perfusion or oxygenation However, these may cause type A lactic acidosis in some cases Type B2: due to medication or intoxication Type B3: due to inborn error of metabolism Mitochondrial Encephalomyopathy + Lactic Acidosis + Stroke-Like Episodes (MELAS) Tumors May Benefit from Acidosis: acidic microenvironment is critical for tumorigenesis, angiogenesis, and metastasis Physiology: decreased lactate clearance (with severe liver metastases)+ increased glycolytic activity of tumor (Warburg Effect) + tissue tumor hypoxia Treatment: bicarbonate administration may increase lactic acid production Tumor Lysis Syndrome (see Tumor Lysis Syndrome , [[Tumor Lysis Syndrome]]) Anaphylaxis (see Anaphylaxis , [[Anaphylaxis]]) Physiology: decreased oxygen delivery to tissues + epinephrine-induced 2-adrenergic receptor stimulation Congestive Heart Failure (CHF)/Cardiogenic Shock (see Congestive Heart Failure , [[Congestive Heart Failure]] and Cardiogenic Shock , [[Cardiogenic Shock]]): common etiology of lactic acidosis Physiology: decreased oxygen delivery to tissues + epinephrine-induced 2-adrenergic receptor stimulation Hemorrhagic Shock (see Hemorrhagic Shock , [[Hemorrhagic Shock]]): common etiology of lactic acidosis Physiology: decreased oxygen delivery to tissues + epinephrine-induced 2-adrenergic receptor stimulation Hypovolemic Shock (see Hypovolemic Shock , [[Hypovolemic Shock]]): common etiology of lactic acidosis Physiology: decreased oxygen delivery to tissues + epinephrine-induced 2-adrenergic receptor stimulation Sepsis (see Sepsis , [[Sepsis]]): common etiology of lactic acidosis Physiology: decreased lactate clearance (likely due to inhibition of pyruvate dehydrogenase + epinephrine-induced 2-adrene Continue reading >>
Lactic Acidosis - [email protected] [email protected]
Posted by Carla Rothaus December 11th, 2014 When lactic acidosis accompanies low-flow states or sepsis, mortality rates increase sharply. A new review summarizes our current understanding of the pathophysiological aspects of lactic acidosis, as well as the approaches to its diagnosis andmanagement. Lactic acidosis results from the accumulation of lactate and protons in the body fluids and is often associated with poor clinical outcomes. The effect of lactic acidosis is governed by its severity and the clinical context. Mortality is increased by a factor of nearly three when lactic acidosis accompanies low-flow states or sepsis, and the higher the lactate level, the worse theoutcome. Hyperlactatemia occurs when lactate production exceeds lactate consumption. In tissue hypoxia, whether global or localized, lactate is overproduced and underutilized as a result of impaired mitochondrial oxidation. Even if systemic oxygen delivery is not low enough to cause generalized hypoxia, microcirculatory dysfunction can cause regional tissue hypoxia and hyperlactatemia. Hyperlactatemia can also result from aerobic glycolysis, a term denoting stimulated glycolysis that depends on factors other than tissue hypoxia. Activated in response to stress, aerobic glycolysis is an effective, albeit inefficient, mechanism for rapid generation of ATP. In the hyperdynamic stage of sepsis, epinephrine-dependent stimulation of the (beta)2-adrenoceptor augments the glycolytic flux both directly and through enhancement of the sarcolemmal Na+,K+-ATPase (which consumes large quantities of ATP). Other disorders associated with elevated epinephrine levels, such as severe asthma (especially with overuse of beta2-adrenergic agonists), extensive trauma, cardiogenic or hemorrhagic shock, and pheochromocytoma, Continue reading >>
The Role Of Catecholamines In Metabolic Acidosis.
The role of catecholamines in metabolic acidosis. Catecholamines (noradrenaline and adrenaline) are catabolic hormones secreted during stress. They initiate many metabolic processes including increased production of both ketoacids and lactic acid. Support for a direct participation of these hormones in the development and/or maintenance of ketoacidosis includes: (1) the high incidence of stress (approx. 70%) as a precipitating factor for ketoacidosis; (2) the elevated plasma levels of noradrenaline (norepinephrine) in patients with ketoacidosis; (3) the rise in plasma concentrations of ketone bodies during catecholamine infusion; and (4) the reduction in the incidence of ketoacidosis with beta-adrenergic pharmacological blockade. Support for a direct participation of catecholamines in the development and/or maintenance of lactic acidosis includes: (1) the common association of stress and lactic acidosis; (2) the rise in plasma lactate concentration during adrenaline (epinephrine) infusion; (3) the precipitation of lactic acidosis by adrenaline intoxication and phaeochromocytoma; and (4) the vasoconstrictor effects of catecholamines leading to tissue anoxia and lactic acid production. Thus, in susceptible patients, catecholamines may be principal determinants of whether ketoacidosis and/or lactic acidosis develops. Continue reading >>
Lactic Acidosis: Background, Etiology, Epidemiology
Author: Kyle J Gunnerson, MD; Chief Editor: Michael R Pinsky, MD, CM, Dr(HC), FCCP, MCCM more... In basic terms, lactic acid is the normal endpoint of the anaerobic breakdown of glucose in the tissues. The lactate exits the cells and is transported to the liver, where it is oxidized back to pyruvate and ultimately converted to glucose via the Cori cycle. In the setting of decreased tissue oxygenation, lactic acid is produced as the anaerobic cycle is utilized for energy production. With a persistent oxygen debt and overwhelming of the body's buffering abilities (whether from chronic dysfunction or excessive production), lactic acidosis ensues. [ 1 , 2 ] (See Etiology.) Lactic acid exists in 2 optical isomeric forms, L-lactate and D-lactate. L-lactate is the most commonly measured level, as it is the only form produced in human metabolism. Its excess represents increased anaerobic metabolism due to tissue hypoperfusion. (See Workup.) D-lactate is a byproduct of bacterial metabolism and may accumulate in patients with short-gut syndrome or in those with a history of gastric bypass or small-bowel resection. [ 3 ] By the turn of the 20th century, many physicians recognized that patients who are critically ill could exhibit metabolic acidosis unaccompanied by elevation of ketones or other measurable anions. In 1925, Clausen identified the accumulation of lactic acid in blood as a cause of acid-base disorder. Several decades later, Huckabee's seminal work firmly established that lactic acidosis frequently accompanies severe illnesses and that tissue hypoperfusion underlies the pathogenesis. In their classic 1976 monograph, Cohen and Woods classified the causes of lactic acidosis according to the presence or absence of adequate tissue oxygenation. (See Presentationand Differe Continue reading >>