Change in Lactate Levels After Hemodialysis in Patients With End-Stage Renal Disease

Factors associated with elevated blood lactate levels in patients undergoing maintenance hemodialysis

Factors associated with chronic elevation of the blood lactate levels in patients undergoing chronic maintenance hemodialysis (hereinafter, hemodialysis patients) have not yet been thoroughly investigated. The purpose of the present study was to clarify factors associated with elevated blood lactate levels in hemodialysis patients. We divided the hemodialysis patients into two groups according the blood lactate levels (the high blood lactate group [> 2 mmol/L] and normal blood lactate group), and conducted a retrospective comparison of the following items between the two groups: (1) the creatinine generation rate (%CGR) and the geriatric nutrition risk index (GNRI) as indices of the nutritional status; (2) the left ventricular ejection fraction (LVEF) and E/A, an indicator of diastolic function; (3) the ankle-brachial index (ABI) and transcutaneous partial pressure of oxygen as indices of the adequacy of circulation in the peripheral blood vessels of the lower extremities; (4) the white blood cell count and serum level of C-reactive protein (CRP) before dialysis as markers of an inflammatory state. The mean age and serum CRP level were significantly higher in the high blood lactate group than in the normal blood lactate group. There were no significant differences in the markers of the nutritional status, cardiac function, or adequacy of circulation in the peripheral blood vessels of the lower extremities between the two groups. Advanced age and a state of chronic inflammation appear to be associated with elevated blood lactate levels in patients undergoing chronic maintenance hemodialysis.

Multiorgan recovery in a cadaver body using mild hypothermic ECMO treatment in a murine model

BACKGROUND

Transplant candidates on the waiting list are increasingly challenged by the lack of organs. Most of the organs can only be kept viable within very limited timeframes (e.g., mere 4-6 h for heart and lungs exposed to refrigeration temperatures ex vivo). Donation after circulatory death (DCD) using extracorporeal membrane oxygenation (ECMO) can significantly enlarge the donor pool, organ yield per donor, and shelf life. Nevertheless, clinical attempts to recover organs for transplantation after uncontrolled DCD are extremely complex and hardly reproducible. Therefore, as a preliminary strategy to fulfill this task, experimental protocols using feasible animal models are highly warranted. The primary aim of the study was to develop a model of ECMO-based cadaver organ recovery in mice. Our model mimics uncontrolled organ donation after an "out-of-hospital" sudden unexpected death with subsequent "in-hospital" cadaver management post-mortem. The secondary aim was to assess blood gas parameters, cardiac activity as well as overall organ state. The study protocol included post-mortem heparin-streptokinase administration 10 min after confirmed death induced by cervical dislocation under full anesthesia. After cannulation, veno-arterial ECMO (V-A ECMO) was started 1 h after death and continued for 2 h under mild hypothermic conditions followed by organ harvest. Pressure- and flow-controlled oxygenated blood-based reperfusion of a cadaver body was accompanied by blood gas analysis (BGA), electrocardiography, and histological evaluation of ischemia-reperfusion injury. For the first time, we designed and implemented, a not yet reported, miniaturized murine hemodialysis circuit for the treatment of severe hyperkalemia and metabolic acidosis post-mortem.

RESULTS

BGA parameters confirmed profound ischemia typical for cadavers and incompatible with normal physiology, including extremely low blood pH, profound negative base excess, and enormously high levels of lactate. Two hours after ECMO implantation, blood pH values of a cadaver body restored from < 6.5 to 7.3 ± 0.05, pCO2 was lowered from > 130 to 41.7 ± 10.5 mmHg, sO2, base excess, and HCO3 were all elevated from below detection thresholds to 99.5 ± 0.6%, - 4 ± 6.2 and 22.0 ± 6.0 mmol/L, respectively (Student T test, p < 0.05). A substantial decrease in hyperlactatemia (from > 20 to 10.5 ± 1.7 mmol/L) and hyperkalemia (from > 9 to 6.9 ± 1.0 mmol/L) was observed when hemodialysis was implemented. On balance, the first signs of regained heart activity appeared on average 10 min after ECMO initiation without cardioplegia or any inotropic and vasopressor support. This was followed by restoration of myocardial contractility with a heart rate of up to 200 beats per minute (bpm) as detected by an electrocardiogram (ECG). Histological examinations revealed no evidence of heart injury 3 h post-mortem, whereas shock-specific morphological changes relevant to acute death and consequent cardiac/circulatory arrest were observed in the lungs, liver, and kidney of both control and ECMO-treated cadaver mice.

CONCLUSIONS

Thus, our model represents a promising approach to facilitate studying perspectives of cadaveric multiorgan recovery for transplantation. Moreover, it opens new possibilities for cadaver organ treatment to extend and potentiate donation and, hence, contribute to solving the organ shortage dilemma.

Strategies for optimizing urea removal to enable portable kidney dialysis: A reappraisal

BACKGROUND

Portable hemodialysis has the potential to improve health outcomes and quality of life for patients with kidney failure at reduced costs. Urea removal, required for dialysate regeneration, is a central function of any existing/potential portable dialysis device. Urea in the spent dialysate coexists with non-urea uremic toxins, nutrients, and electrolytes, all of which will interfere with the urea removal efficiency, regardless of whether the underlying urea removal mechanism is based on urease conversion, direct urea adsorption, or oxidation. The aim of the current review is to identify the amount of the most prevalent chemicals being removed during a single dialysis session and evaluate the potential benefits of an urea-selective membrane for portable dialysis.

METHODS

We have performed a literature search using Web of Science and PubMed databases to find available articles reporting (or be able to calculate from blood plasma concentration) > 5 mg of individually quantified solutes removed during thrice-weekly hemodialysis sessions. If multiple reports of the same solute were available, the reported values were averaged, and the geometric mean of standard deviations was taken. Further critical literature analysis of reported dialysate regeneration methods was performed using Web of Science and PubMed databases.

RESULTS

On average, 46.0 g uremic retention solutes are removed in a single conventional dialysis session, out of which urea is only 23.6 g. For both urease- and sorbent-based urea removal mechanisms, amino acids, with 7.7 g removal per session, could potentially interfere with urea removal efficiency. Additionally for the oxidation-based urea removal system, plentiful nutrients such as glucose (24.0 g) will interfere with urea removal by competition. Using a nanofiltration membrane between dialysate and oxidation unit with a molecular weight cutoff (MWCO) of ~200 Da, 67.6 g of non-electrolyte species will be removed in a single dialysis session, out of which 44.0 g are non-urea molecules. If the membrane MWCO is further decreased to 120 Da, the mass of non-electrolyte non-urea species will drop to 9.3 g. Reverse osmosis membranes have been shown to be both effective at blocking the transport of non-urea species (creatinine for example with ~90% rejection ratio), and permissive for urea transport (~20% rejection ratio), making them a promising urea selective membrane to increase the efficiency of the oxidative urea removal system.

CONCLUSIONS

Compiled are quantified solute removal amounts greater than 5 mg per session during conventional hemodialysis treatments, to act as a guide for portable dialysis system design. Analysis shows that multiple chemical species in the dialysate interfere with all proposed portable urea removal systems. This suggests the need for an additional protective dialysate loop coupled to urea removal system and an urea-selective membrane.

l-lactate kinetics after abdominal aortic surgery and intestinal ischemia - An observational cohort study

BACKGROUND

Postoperative intestinal ischemia is a severe complication in abdominal aortic surgery. Early diagnosis is needed for adequate and timely treatment. We studied the postoperative kinetics of l-lactate in vascular patients to assess its value as a marker for early postoperative intestinal ischemia detection.

MATERIAL AND METHODS

We performed a prospective non-randomized single-center observational cohort study in eighty elective patients, fifty operated on for abdominal aortic aneurysm (AAA) and thirty for aortoiliac occlusive disease (AIOD). Serum l-lactate was measured preoperatively, intraoperatively, and postoperatively at defined timepoints up to postoperative day 7. Intestinal ischemia was detected using MRI enterocolography. We have used univariate logistic regression and receiver operating characteristics curves for the evaluation of marker accuracy.

RESULTS

We recorded 6 cases of postoperative intestinal ischemia (7.5%), five non-transmural and one transmural. Two patients died because of this complication (mortality 33%). The comparison of AAA and AIOD cohorts showed a significant difference in l-lactate levels at one intraoperative timepoint, which was attributable to procedure differences. The only preoperative factor associated with higher l-lactate levels at some timepoints was chronic kidney disease. Patients suffering postoperative intestinal ischemia had elevated serum l-lactate levels at multiple timepoints. The most accurate timepoint for diagnosis was 24 h after the declamping of the vascular reconstruction (DC24H), the second was 10 min after declamping. Sensitivity, specificity, positive and negative predictive values at timepoint DC24H were 100%, 82%, 32%, and 100%, respectively.

CONCLUSION

Serum l-lactate levels might help in the early detection of postoperative intestinal ischemia after aortic surgery if proper timepoints are used. Cutoff values need to be established in large-scale prospective studies.

Changes in blood glucose and lactate concentrations with hemodialysis

INTRODUCTION

Blood glucose concentrations are recognized to vary during hemodialysis (HD), with hypoglycemia reported with glucose-free dialysates. As glucose can be converted to lactate, and conversely lactate to glucose, we wished to study factors associated with peri-dialytic changes in blood glucose.

METHODS

We prospectively collected data including patient profile, dialysis prescription, hemodynamic parameters, medications, dialysis adequacy and monthly blood tests for three consecutive months. All patients used a 100 mg/dl glucose dialysate. Linear mixed model, general estimated equation and binary logistic regression were used for analysis.

RESULTS

We studied 157 sessions in 55 patients, median age 67.1 (58.5-72.6) years, 67% male, 71% diabetic, 40% prescribed insulin, dialysis vintage 20.4 (10.7-57.7) months. Mean single pool Kt/Vurea and normalized protein nitrogen appearance rate (nPNA) were 1.70 ± 0.34 and 1.01 ± 0.30 g/kg/day respectively. Hypoglycemia (<70 mg/dl) occurred during 10 sessions (6.4%). 25% of non-diabetes experienced hypoglycemia. The % change in peri-dialytic blood glucose was associated with the % change in lactate (estimate of fixed effect = 0.23 p < 0.001) and pre-HD glucose (estimate of fixed effect = 0.09, p < 0.001). The fall in glucose was not associated with urea clearance, consumption of food, administration of insulin or antidiabetic medications, nPNA, body mass index, or pyridoxine concentrations.

CONCLUSIONS

Peri-dialytic hypoglycemia cannot simply be explained by dialyzer clearance, as the corresponding fall in lactate would potentially suggest increased gluconeogenesis. Despite using a glucose containing dialysate, asymptomatic hypoglycemia occurred in 6.4% of sessions, suggesting a role for peri-dialytic blood glucose monitoring and avoiding fasting during dialysis.

The timing of last hemodialysis influences the prognostic value of serum lactate levels in predicting mortality of end-stage renal disease patients with sepsis in the emergency department

Sepsis is a life-threatening condition, and serum lactate levels have been used to predict patient prognosis. Studies on serum lactate levels in patients undergoing regular hemodialysis who have sepsis are limited. This study aimed to determine the predictive value of serum lactate levels for sepsis-related mortality among patients who underwent last hemodialysis at three different times before admission to the emergency department (ED).This retrospective cohort study was conducted from January 2007 to December 2013 in southern Taiwan. All hemodialysis patients with sepsis, receiving antibiotics within 24 hours of sepsis confirmation, admitted for at least 3 days, and whose serum lactate levels were known were examined to determine the difference in the serum lactate levels of patients who underwent last hemodialysis within 4 hours (Groups A), in 4-12 hours (Group B), and beyond 12 hours (Group C) before visited to the ED. All the continuous variables, categorical variables and mortality were compared by using Kruskal-Wallis test or Mann-Whitney test, the χ2 or Fisher exact tests, and multiple logistic regression model, respectively.A total of 490 patients were enrolled in the study, and 8.0% (39), 21.5% (84), and 74.9% (367) of the patients were in Group A, Group B and Group C, respectively; the serum lactate levels (2.91 vs 2.13 vs 2.79 mmol/L, respectively; P = .175) and 28-day in-hospital mortality (17.9% vs 14.6% vs 22.9%) showed no statistically significant difference between 3 groups. The association between serum lactate levels and 28-day in-hospital mortality was reliable in Group B (P = .002) and Group C (P < .001), but it was unreliable in Group A (P = .629).Serum lactate level has acceptable sensitivity in predicting 28-day in-hospital mortality among patients with sepsis who undergo last hemodialysis after 4 hours, but is not reliable when the last hemodialysis takes place within 4 hours.

Renal gluconeogenesis: an underestimated role of the kidney in systemic glucose metabolism

Glucose levels are tightly regulated at all times. Gluconeogenesis is the metabolic pathway dedicated to glucose synthesis from non-hexose precursors. Gluconeogenesis is critical for glucose homoeostasis, particularly during fasting or stress conditions. The renal contribution to systemic gluconeogenesis is increasingly recognized. During the post-absorptive phase, the kidney accounts for ∼40% of endogenous gluconeogenesis, occurring mainly in the kidney proximal tubule. The main substrate for renal gluconeogenesis is lactate and the process is regulated by insulin and cellular glucose levels, but also by acidosis and stress hormones. The kidney thus plays an important role in the maintenance of glucose and lactate homoeostasis during stress conditions. The impact of acute and chronic kidney disease and proximal tubular injury on gluconeogenesis is not well studied. Recent evidence shows that in both experimental and clinical acute kidney injury, impaired renal gluconeogenesis could significantly participate in systemic metabolic disturbance and thus alter the prognosis. This review summarizes the biochemistry of gluconeogenesis, the current knowledge of kidney gluconeogenesis, its modifications in kidney disease and the clinical relevance of this fundamental biological process in human biology.

Serum metabolomics approach to monitor the changes in metabolite profiles following renal transplantation

Systemic metabolic changes after renal transplantation reflect the key processes that are related to graft accommodation. In order to describe and better understand these changes, the ¹HNMR based metabolomics approach was used. The changes of 47 metabolites in the serum samples of 19 individuals were interpreted over time with respect to their levels prior to transplantation. Considering the specific repeated measures design of the experiments, data analysis was mainly focused on the multiple analyses of variance (ANOVA) methods such as ANOVA simultaneous component analysis and ANOVA-target projection. We also propose here the combined use of ANOVA and classification and regression trees (ANOVA-CART) under the assumption that a small set of metabolites the binary splits on which may better describe the graft accommodation processes over time. This assumption is very important for developing a medical protocol for evaluating a patient's health state. The results showed that besides creatinine, which is routinely used to monitor renal activity, the changes in levels of hippurate, mannitol and alanine may be associated with the changes in renal function during the post-transplantation recovery period. Specifically, the level of hippurate (or histidine) is more sensitive to any short-term changes in renal activity than creatinine.