The effect of lactated Ringer's solution on blood and urine levels of lactate isomers

D-lactic acidosis: an underrecognized complication of short bowel syndrome

D-lactic acidosis or D-lactate encephalopathy is a rare condition that occurs primarily in individuals who have a history of short bowel syndrome. The unabsorbed carbohydrates act as a substrate for colonic bacteria to form D-lactic acid among other organic acids. The acidic pH generated as a result of D-lactate production further propagates production of D-lactic acid, hence giving rise to a vicious cycle. D-lactic acid accumulation in the blood can cause neurologic symptoms such as delirium, ataxia, and slurred speech. Diagnosis is made by a combination of clinical and laboratory data including special assays for D-lactate. Treatment includes correcting the acidosis and decreasing substrate for D-lactate such as carbohydrates in meals. In addition, antibiotics can be used to clear colonic flora. Although newer techniques for diagnosis and treatment are being developed, clinical diagnosis still holds paramount importance, as there can be many confounders in the diagnosis as will be discussed subsequently.

D-lactic acidosis

D-lactic acidosis, also referred to as D-lactate encephalopathy, is a rare neurologic syndrome that occurs in individuals with short bowel syndrome or following jejuno-ileal bypass surgery. Symptoms typically present after the ingestion of high-carbohydrate feedings. Neurologic symptoms include altered mental status, slurred speech, and ataxia, with patients often appearing drunk. Onset of neurologic symptoms is accompanied by metabolic acidosis and elevation of plasma D-lactate concentration. In these patients, malabsorbed carbohydrate is fermented by an abnormal bacterial flora in the colon, which produces excessive amounts of D-lactate. High amounts of D-lactate are absorbed into the circulation, resulting in an elevated concentration of D-lactate in the blood. Development of neurologic symptoms has been attributed to D-lactate, but it is unclear if this is the cause or whether other factors are responsible. This review examines the pathophysiology of the production and accumulation of D-lactate while exploring the potential factors contributing to the development of neurologic manifestations. Methods of diagnosis and treatment are reviewed. Areas requiring further investigation are identified.

D-lactic acidosis. A review of clinical presentation, biochemical features, and pathophysiologic mechanisms

This report describes a case of d-lactic acidosis observed by the authors and then reviews all case reports of d-lactic acidosis in the literature in order to define its clinical and biochemical features and pathogenetic mechanisms. The report also reviews the literature on metabolism of d-lactic acid in humans. The clinical presentation of d-lactic acidosis is characterized by episodes of encephalopathy and metabolic acidosis. The diagnosis should be considered in a patient who presents with metabolic acidosis and high serum anion gap, normal lactate level, negative Acetest, short bowel syndrome or other forms of malabsorption, and characteristic neurologic findings. Development of the syndrome requires the following conditions 1) carbohydrate malabsorption with increased delivery of nutrients to the colon, 2) colonic bacterial flora of a type that produces d-lactic acid, 3) ingestion of large amounts of carbohydrate, 4) diminished colonic motility, allowing time for nutrients in the colon to undergo bacterial fermentation, and 5) impaired d-lactate metabolism. In contrast to the initial assumption that d-lactic acid is not metabolized by humans, analysis of published data shows a substantial rate of metabolism of d-lactate by normal humans. Estimates based on these data suggest that impaired metabolism of d-lactate is almost a prerequisite for the development of the syndrome.

Effects of sodium acetate, bicarbonate and lactate on acid-base status in anaesthetized dogs

Equal doses of sodium acetate, bicarbonate and lactate (6.6 mEq/L) infused intravenously over 30 min into three groups of halothane-anaesthetized dogs caused changes in acid-base status. Arterial carbon dioxide tension (PaCO2), pHa, base excess (BE) and standard bicarbonate (SB) increased. Sodium bicarbonate caused the most rapid and greatest changes. The bicarbonate group was significantly different (P less than 0.05) from the other groups at 15 and 30 min after the start of infusion for pHa, BE and SB. The greater effects of bicarbonate are due to its production of alkalinization without a requirement for metabolism; acetate and lactate require oxidation to be effective. The acetate and bicarbonate groups were not statistically different at 45 min after the onset of drug infusion, but both had significantly higher SB and BE mean values than the lactate group. All measurements made after 45 min revealed no significant differences among groups. Thus, after the earlier differences noted above, the three alkalinizers caused similar effects on acid-base status. PaCO2 was elevated in all groups, but there were no differences among groups. Cardiovascular effects caused by infusion of the three drugs were minimal.

Fluid resuscitation in live Escherichia coli shock in puppies

The infusion of live E. coli in the puppy produces a severe and usually lethal model of pediatric septic shock with characteristic reduction in cardiac output and blood pressure. Hemodynamic abnormalities are partially reversed with fluid resuscitation alone, and large volumes, supplemented with albumin well within tolerated fluid loads, produce the most pronounced corrections of these derrangements. Certain metabolic changes appear to be unique to the young animal and their correction is less successful regardless of resuscitation regimen. These findings suggest that the initial fluid management of the bacteremic pediatric patient should include Ringer's lactate and 5% albumin at approximately 105% of patient's blood volume. Further resuscitation fluid, as well as the role of steroids and antibiotics, remain work currently being carried out in our laboratory.

Plasma acetate concentrations during canine haemorrhagic shock

Acetate, pyruvate, lactate and NEFA concentrations, as well as acid-base-parameters were followed during bleeding, stable hypotension and re-infusion in five dogs. Mean arterial blood pressures were kept at 30 mmHg during the shock phase. An increase in acetate concentrations (P less than 0.01) was found in arterial as well as in venous plasma samples. The maximal mean acetate concentration was 0.19 mmol/l (during reinfusion) as compared to 0.06 mmol/l prior to bleeding. There was no difference between arterial and inferior caval venous concentrations. A definite correlation (r = 0.81, P less than 0.02) was found between blood pyruvate and plasma acetate concentrations. There was no correlation between plasma glucose or NEFA and acetate concentrations or between blood excess lactate and plasma acetate. The plasma acetate accumulation was negligible compared to the concomitant lactate accumulation (1:60), and did not contribute to the metabolic acidosis of shock. The correlation between acetate and pyruvate concentrations may indicate that pyruvate is the main substrate of acetate production in hypovolemic shock.