Dataset Information

Does reduced oxygen delivery cause lactic acidosis in falciparum malaria? An observational study.

ABSTRACT:

Background

Lactic acidosis with an elevated lactate-pyruvate ratio suggesting anoxia is a common feature of severe falciparum malaria. High lactate levels are associated with parasitized erythrocyte sequestration in the microcirculation. To assess if there is an additional contribution to hyperlactataemia from relatively inadequate total oxygen delivery, oxygen consumption and delivery were investigated in patients with malaria.

Methods

Adult Bangladeshi and Indian patients with uncomplicated (N = 50) or severe (N = 46) falciparum malaria or suspected bacterial sepsis (N = 27) and healthy participants as controls (N = 26) were recruited at Chittagong Medical College Hospital, Chittagong, Bangladesh and Ispat General Hospital, Rourkela, India. Oxygen delivery (DO₂I) was estimated from pulse oximetry, echocardiographic estimates of cardiac index and haematocrit. Oxygen consumption (VO₂I) was estimated by expired gas collection.

Results

VO₂I was elevated in uncomplicated median (IQR) 185.1 ml/min/m² (135-215.9) and severe malaria 192 ml/min/m² (140.7-227.9) relative to healthy persons 107.9 ml/min/m² (69.9-138.1) (both p < 0.001). Median DO₂I was similar in uncomplicated 515 ml/min/m² (432-612) and severe 487 ml/min/m² (382-601) malaria and healthy persons 503 ml/min/m² (447-517) (p = 0.27 and 0.89, respectively). The VO₂/DO₂ ratio was, therefore, increased by similar amounts in both uncomplicated 0.35 (0.28-0.44) and severe malaria 0.38 (0.29-0.48) relative to healthy participants 0.23 (0.17-0.28) (both p < 0.001). VO₂I, DO₂I and VO₂/DO₂ did not correlate with plasma lactate concentrations in severe malaria.

Conclusions

Reduced total oxygen delivery is not a major contributor to lactic acidosis in severe falciparum malaria.

SUBMITTER: Kingston HW

PROVIDER: S-EPMC6434797 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Does reduced oxygen delivery cause lactic acidosis in falciparum malaria? An observational study.

Kingston Hugh W HW Ghose Aniruddha A Rungpradubvong Voravut V Herdman M Trent MT Plewes Katherine K Ishioka Haruhiko H Leopold Stije J SJ Maude Richard J RJ Intharabut Benjamas B Mohanty Sanjib S Day Nicholas P J NPJ White Nicholas J NJ Hossain Md Amir MA Anstey Nicholas M NM Dondorp Arjen M AM

Malaria journal 20190325 1

<h4>Background</h4>Lactic acidosis with an elevated lactate-pyruvate ratio suggesting anoxia is a common feature of severe falciparum malaria. High lactate levels are associated with parasitized erythrocyte sequestration in the microcirculation. To assess if there is an additional contribution to hyperlactataemia from relatively inadequate total oxygen delivery, oxygen consumption and delivery were investigated in patients with malaria.<h4>Methods</h4>Adult Bangladeshi and Indian patients with u ...[more]

PMID: 30909915

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Project description:The global prevalence of type 2 diabetes (T2D) is expected to exceed 642 million people by 2040. Metformin is a widely used biguanide T2D therapy, associated with rare but serious events of lactic acidosis, in particular with predisposing conditions (e.g., renal failure or major surgery). Imeglimin, a recently approved drug, is the first in a new class (novel mode of action) of T2D medicines. Although not a biguanide, Imeglimin shares a chemical moiety with Metformin and also modulates mitochondrial complex I activity, a potential mechanism for Metformin-mediated lactate accumulation. We interrogated the potential for Imeglimin to induce lacticacidosis in relevant animal models and further assessed differences in key mechanisms known for Metformin's effects. In a dog model of major surgery, Metformin or Imeglimin (30-1000 mg/kg) was acutely administered, only Metformin-induced lactate accumulation and pH decrease leading to lactic acidosis with fatality at the highest dose. Rats with gentamycin-induced renal insufficiency received Metformin or Imeglimin (50-100 mg/kg/h), only Metformin increased lactatemia and H+ concentrations with mortality at higher doses. Plasma levels of Metformin and Imeglimin were similar in both models. Mice were chronically treated with Metformin or Imeglimin 200 mg/kg bid. Only Metformin produced hyperlactatemia after acute intraperitoneal glucose loading. Ex vivo measurements revealed higher mitochondrial complex I inhibition with Metformin versus slight effects with Imeglimin. Another mechanism implicated in Metformin's effects on lactate production was assessed: in isolated rat, liver mitochondria exposed to Imeglimin or Metformin, only Metformin (50-250 µM) inhibited the mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH). In liver samples from chronically treated mice, measured mGPDH activity was lower with Metformin versus Imeglimin. These data indicate that the risk of lactic acidosis with Imeglimin treatment may be lower than with Metformin and confirm that the underlying mechanisms of action are distinct, supporting its potential utility for patients with predisposing conditions.

Project description:IntroductionHepatic mitochondrial dysfunction may play a critical role in the pathogenesis of metformin-induced lactic acidosis. However, patients with severe metformin intoxication may have a 30 to 60% decrease in their global oxygen consumption, as for generalized inhibition of mitochondrial respiration. We developed a pig model of severe metformin intoxication to validate this clinical finding and assess mitochondrial function in liver and other tissues.MethodsTwenty healthy pigs were sedated and mechanically ventilated. Ten were infused with a large dose of metformin (4 to 8 g) and five were not (sham controls). Five others were infused with lactic acid to clarify whether lactic acidosis per se diminishes global oxygen use. Arterial pH, lactatemia, global oxygen consumption (VO2) (metabolic module) and delivery (DO2) (cardiac output by thermodilution) were monitored for nine hours. Oxygen extraction was computed as VO2/DO2. Activities of the main components of the mitochondrial respiratory chain (complex I, II and III, and IV) were measured with spectrophotometry (and expressed relative to citrate synthase activity) in heart, kidney, liver, skeletal muscle and platelets taken at the end of the study.ResultsPigs infused with metformin (6 ± 2 g; final serum drug level 77 ± 45 mg/L) progressively developed lactic acidosis (final arterial pH 6.93 ± 0.24 and lactate 18 ± 7 mmol/L, P < 0.001 for both). Their VO2 declined over time (from 115 ± 34 to 71 ± 30 ml/min, P < 0.001) despite grossly preserved DO2 (from 269 ± 68 to 239 ± 51 ml/min, P = 0.58). Oxygen extraction accordingly fell from 43 ± 10 to 30 ± 10% (P = 0.008). None of these changes occurred in either sham controls or pigs infused with lactic acid (final arterial pH 6.86 ± 0.16 and lactate 22 ± 3 mmol/L). Metformin intoxication was associated with inhibition of complex I in the liver (P < 0.001), heart (P < 0.001), kidney (P = 0.003), skeletal muscle (P = 0.012) and platelets (P = 0.053). The activity of complex II and III diminished in the liver (P < 0.001), heart (P < 0.001) and kidney (P < 0.005) while that of complex IV declined in the heart (P < 0.001).ConclusionsMetformin intoxication induces lactic acidosis, inhibits global oxygen consumption and causes mitochondrial dysfunction in liver and other tissues. Lactic acidosis per se does not decrease whole-body respiration.

Dataset Information

Does reduced oxygen delivery cause lactic acidosis in falciparum malaria? An observational study.

Background

Methods

Results

Conclusions

Publications

Does reduced oxygen delivery cause lactic acidosis in falciparum malaria? An observational study.

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