Methylprednisolone for Heart Surgery in Infants - A Randomized, Controlled Trial.

BACKGROUND: Although perioperative prophylactic glucocorticoids have been used for decades, whether they improve outcomes in infants after heart surgery with cardiopulmonary bypass is unknown. METHODS: We conducted a multicenter, prospective, randomized, placebo-controlled, registry-based trial involving infants (<1 year of age) undergoing heart surgery with cardiopulmonary bypass at 24 sites participating in the Society of Thoracic Surgeons Congenital Heart Surgery Database. Registry data were used in the evaluation of outcomes. The infants were randomly assigned to receive prophylactic methylprednisolone (30 mg per kilogram of body weight) or placebo, which was administered into the cardiopulmonary-bypass pump-priming fluid. The primary end point was a ranked composite of death, heart transplantation, or any of 13 major complications. Patients without any of these events were assigned a ranked outcome based on postoperative length of stay. In the primary analysis, the ranked outcomes were compared between the trial groups with the use of odds ratios adjusted for prespecified risk factors. Secondary analyses included an unadjusted odds ratio, a win ratio, and safety outcomes. RESULTS: A total of 1263 infants underwent randomization, of whom 1200 received either methylprednisolone (599 infants) or placebo (601 infants). The likelihood of a worse outcome did not differ significantly between the methylprednisolone group and the placebo group (adjusted odds ratio, 0.86; 95% confidence interval [CI], 0.71 to 1.05; P = 0.14). Secondary analyses (unadjusted for risk factors) showed an odds ratio for a worse outcome of 0.82 (95% CI, 0.67 to 1.00) and a win ratio of 1.15 (95% CI, 1.00 to 1.32) in the methylprednisolone group as compared with the placebo group, findings suggestive of a benefit with methylprednisolone; however, patients in the methylprednisolone group were more likely than those in the placebo group to receive postoperative insulin for hyperglycemia (19.0% vs. 6.7%, P<0.001). CONCLUSIONS: Among infants undergoing surgery with cardiopulmonary bypass, prophylactic use of methylprednisolone did not significantly reduce the likelihood of a worse outcome in an adjusted analysis and was associated with postoperative development of hyperglycemia warranting insulin in a higher percentage of infants than placebo. (Funded by the National Center for Advancing Translational Sciences and others; STRESS ClinicalTrials.gov number, NCT03229538.).

Echocardiographic measured shunt velocity does not predict pulmonary blood flow in patients with Blalock-Thomas-Taussig shunt.

INTRODUCTION: Catheterisation is the gold standard used to evaluate pulmonary blood flow in patients with a Blalock-Thomas-Taussig shunt. It involves risk and cannot be performed frequently. This study aimed to evaluate if echocardiographic measurements obtained in a clinical setting correlate with catheterisation-derived pulmonary blood flow in patients with a Blalock-Thomas-Taussig shunt as the sole source of pulmonary blood flow. METHODS: Chart review was performed retrospectively on consecutive patients referred to the catheterisation lab with a Blalock-Thomas-Taussig shunt. Echocardiographic parameters included peak, mean, and diastolic gradients across the Blalock-Thomas-Taussig shunt and forward and reverse velocity time integral across the distal transverse aorta. In addition to direct correlations, we tested a previously published formula for pulmonary blood flow calculated as velocity time integral across the shunt × heart rate × Blalock-Thomas-Taussig shunt area. Catheterisation parameters included pulmonary and systemic blood flow as calculated by the Fick principle. RESULTS: 18 patients were included. The echocardiography parameters and oxygen saturation did not correlate with catheterisation-derived pulmonary blood flow, systemic blood flow, or the ratio of pulmonary to systemic blood flow. As the ratio of reverse to forward velocity time integral across the transverse aorta increased, the probability of shunt stenosis decreased. CONCLUSION: Echocardiographic measurements obtained outside the catheterisation lab do not correlate with catheterisation-derived pulmonary blood flow. The ratio of reverse to forward velocity time integral across the transverse aortic arch may be predictive of Blalock-Thomas-Taussig shunt narrowing; this finding should be investigated further.

Vitamin therapy in sepsis.

Vitamins are essential micronutrients with key roles in many biological pathways relevant to sepsis. Some of these relevant biological mechanisms include antioxidant and anti-inflammatory effects, protein and hormone synthesis, energy generation, and regulation of gene transcription. Moreover, relative vitamin deficiencies in plasma are common during sepsis and vitamin therapy has been associated with improved outcomes in some adult and pediatric studies. High-dose intravenous vitamin C has been the vitamin therapy most extensively studied in adult patients with sepsis and septic shock. This includes three randomized control trials (RCTs) as monotherapy with a total of 219 patients showing significant reduction in organ dysfunction and lower mortality when compared to placebo, and five RCTs as a combination therapy with thiamine and hydrocortisone with a total of 1134 patients showing no difference in clinical outcomes. Likewise, the evidence for the role of other vitamins in sepsis remains mixed. In this narrative review, we present the preclinical, clinical, and safety evidence of the most studied vitamins in sepsis, including vitamin C, thiamine (i.e., vitamin B1), and vitamin D. We also present the relevant evidence of the other vitamins that have been studied in sepsis and critical illness in both children and adults, including vitamins A, B2, B6, B12, and E. IMPACT: Vitamins are key effectors in many biological processes relevant to sepsis. We present the preclinical, clinical, and safety evidence of the most studied vitamins in pediatric sepsis. Designing response-adaptive platform trials may help fill in knowledge gaps regarding vitamin use for critical illness and association with clinical outcomes.

Correction to: Towards a Better Understanding of Cognitive Deficits in Absence Epilepsy: a Systematic Review and Meta-Analysis.

Due to an error during the editorial phase, a correction regarding Fig. 2 is added to the original article: "Towards a Better Understanding of Cognitive Deficits in Absence Epilepsy: a Systematic Review and Meta-Analysis". Please see below correct Fig. 2.

Neurocognitive and behavioural profile in Panayiotopoulos syndrome.

AIM: To determine neurocognitive performance and behavioural problems in children with Panayiotopoulos syndrome. METHOD: All 18 children (10 females, 8 males; mean age 4y 7mo; SD 1y 10mo) diagnosed with Panayiotopoulos syndrome at the Kempenhaeghe Epilepsy Center in the Netherlands between 2010 and 2017 were analysed retrospectively. All underwent a neuropsychological/behavioural assessment, an academic assessment, and a 24-hour electroencephalogram. RESULTS: Mean full-scale IQ (93.5; range 76-123; p=0.04) and performance IQ (93.2; range 76-126; p=0.04) were within the normal range, although significantly lower compared to the normative mean. Verbal IQ (96.3; range 76-118) and processing speed (96.1; range 74-114) were not significantly lower. Simple auditory/visual reaction times, visual attention, visual-motor integration, and verbal memory were significantly lower compared to normative values. On average, patients with Panayiotopoulos syndrome were 8 months behind in arithmetic speed and 11 months behind in reading speed for the number of months in school. Behavioural questionnaires revealed significantly higher scores on reported internalizing behavioural problems. INTERPRETATION: Children with Panayiotopoulos syndrome demonstrated diffuse cognitive dysfunction in full-scale IQ, performance IQ, visual attention, visual-motor integration, and verbal memory. A high incidence of internalizing behavioural problems was reported. This strongly suggests neuropsychological and behavioural comorbidity in children with Panayiotopoulos syndrome. WHAT THIS PAPER ADDS: Children with Panayiotopoulos syndrome are at risk for cognitive deficits in various cognitive domains. Children with Panayiotopoulos syndrome are also prone to internalizing behavioural problems. Mild-to-severe academic underachievement was present in more than half of the children with Panayiotopoulos syndrome.

Towards a Better Understanding of Cognitive Deficits in Absence Epilepsy: a Systematic Review and Meta-Analysis.

Cognition in absence epilepsy (AE) is generally considered undisturbed. However, reports on cognitive deficits in AE in recent years have suggested otherwise. This review systematically assesses current literature on cognitive performance in children with AE. A systematic literature search was performed in Pubmed, Embase, Cochrane and Web of Science. All studies reporting on cognitive performance in children with AE were considered. In total 33 studies were eligible for inclusion. Neuropsychological tests were classified into the following domains: intelligence; executive function; attention; language; motor & sensory-perceptual examinations; visuoperceptual/visuospatial/visuoconstructional function; memory and learning; achievement. Random-effect meta-analyses were conducted by estimating the pooled mean and/or pooling the mean difference in case-control studies. Full-scale IQ in children with AE was estimated at 96.78 (95%CI:94.46-99.10) across all available studies and in case-control studies IQ was on average 8.03 (95%CI:-10.45- -5.61) lower. Verbal IQ was estimated at 97.98 (95%CI:95.80-100.16) for all studies and 9.01 (95%CI:12.11- -5.90) points lower in case-control studies. Performance IQ was estimated at 97.23 (93.24-101.22) for all available studies and 5.32 (95%CI:-8.27-2.36) points lower in case-control studies. Lower performance was most often reported in executive function (cognitive flexibility, planning, and verbal fluency) and attention (sustained, selective and divided attention). Reports on school difficulties, neurodevelopmental problems, and attentional problems were high. In conclusion, in contrast to common beliefs, lower than average neurocognitive performance was noted in multiple cognitive domains, which may influence academic and psychosocial development.

Lower myelin-water content of the frontal lobe in childhood absence epilepsy.

OBJECTIVE: The frontal lobe in childhood absence epilepsy (CAE) might be affected due to the suggested involvement of the frontal lobe during absence seizures and reports on attentional deficits. Previously, subtle white matter abnormalities have been reported in CAE. However, the impact of one of the most characteristic components of the white matter, the myelin content, remains underdetermined. Therefore, this study investigated whether the myelin content in frontal areas is adversely affected in CAE compared to controls. METHODS: Seventeen children with childhood absence epilepsy (mean age ± standard deviation [SD], 9.2 ± 2.1 years) and 15 age- and sex-matched controls (mean age ± SD, 9.8 ± 1.8 years) underwent neuropsychological assessment and a magnetic resonance imaging (MRI) examination. T2 relaxometry scans were used to distinguish myelin-water from tissue water and to determine the myelin-water fraction (MWF) in the frontal, temporal, parietal, occipital, and insular lobes. A linear regression model including age and sex as covariates was used to investigate group differences. Furthermore, the relationship of MWF with cognitive performance and epilepsy characteristics was determined. RESULTS: The frontal lobe revealed a significantly lower myelin-water content in children with CAE compared to controls over the developmental age range of 6-12 years (5.7 ± 1.0% vs 6.6 ± 1.1%, P = 0.02). This association was not found for any of the other four lobes (P > 0.10). No significant relation was found between myelin-water content and cognitive performance or epilepsy characteristics. SIGNIFICANCE: The lower frontal myelin-water content of children with CAE in comparison with healthy controls probably reflects an altered neurodevelopmental aspect in CAE, of which the underlying mechanisms still need to be unraveled.

Fluid Management: Pharmacologic and Renal Replacement Therapies.

OBJECTIVES: Focusing on critically ill children with cardiac disease, we will review common causes of fluid perturbations, clinical recognition, and strategies to minimize and treat fluid-related complications. DATA SOURCE: MEDLINE and PubMed. CONCLUSIONS: Meticulous fluid management is vital in critically ill children with cardiac disease. Fluid therapy is important to maintain adequate blood volume and perfusion pressure in order to support cardiac output, tissue perfusion, and oxygen delivery. However, fluid overload and acute kidney injury are common and are associated with increased morbidity and mortality. Understanding the etiologies for disturbances in volume status and the pathophysiology surrounding those conditions is crucial for providing optimal care.

Eosinophilic esophagitis in children following cardiac transplantation: association with post-transplant lymphoproliferative disorder and other transplant outcomes.

Although cardiac transplantation is life-saving, morbidities from immunosuppression are significant. EoE is a complication of calcineurin inhibitors following liver transplant causing feeding intolerance, weight loss, vomiting, and dysphagia. There are limited reports of EoE following heart transplantation. We performed a retrospective single-center review of pediatric cardiac transplant patients from 2000 to 2010. A case-control analysis of patients with and without EoE was performed evaluating heart transplantation outcomes such as rates of rejection, CAV, PTLD, and graft loss. Eighty-six transplants were performed in 84 patients; 34 (40%) underwent diagnostic endoscopy, and 10 (12%) had EoE. Median time to diagnosis of EoE was 3.7 yr (IQR: 2.0-5.2). There were no differences in demographics or use of induction medications between patients with or without EoE. Patients with EoE had fewer episodes of treated rejection (1.0 vs. 2.5; p = 0.04). Four of 10 (40%) EoE patients had PTLD compared with only 2/24 (8%) of those without EoE (p = 0.048; OR 7.33 [95% CI: 1.1-50.2]). There were no differences in CAV or graft loss between groups. EoE should be considered as a cause of GI symptoms in children after cardiac transplantation and may be associated with fewer rejection episodes and increased rates of PTLD, thus representing a marker of over-immunosuppression.

Dietary fibre and fatty acids in chronic obstructive pulmonary disease risk and progression: a systematic review.

Dietary intake attracts increasing interest in the risk for and progression of chronic obstructive pulmonary disease (COPD). In particular, dietary fibre and fatty acids have drawn specific attention for their immunomodulating potential. The study aimed to review the current evidence on the potential roles of dietary fibre or fatty acid intake in the risk and progression of COPD. Pubmed, EMBASE, Cochrane Collaboration Database and conference databases for original studies in adults addressing the association between fibre or fatty acid intake and COPD in terms of risk, lung function and respiratory symptoms were searched. Nine articles were included of which four reported on dietary fibre and five on fatty acids. Data of studies could not be pooled because of methodological diversity. Greater intake of dietary fibre has been consistently associated with reduced COPD risk, better lung function and reduced respiratory symptoms. Results on the associations between fatty acids and COPD are inconsistent. Dietary quality deserves further attention in developing COPD prevention and management programs.

Early postoperative fluid overload precedes acute kidney injury and is associated with higher morbidity in pediatric cardiac surgery patients.

OBJECTIVE: Fluid overload has been independently associated with increased morbidity and mortality in pediatric patients with renal failure, acute lung injury, and sepsis. Pediatric patients who undergo cardiopulmonary bypass are at risk for poor cardiac, pulmonary, and renal outcomes. They are also at risk of fluid overload from cardiopulmonary bypass, which stimulates inflammation, release of antidiuretic hormone, and capillary leak. This study tested the hypothesis that patients with fluid overload in the early postcardiopulmonary bypass period have worse outcomes than those without fluid overload. We also examined the timing of the association between postcardiopulmonary bypass acute kidney injury and fluid overload. DESIGN, SETTING, AND PATIENTS: Secondary analysis of a prospective observational study of 98 pediatric patients after cardiopulmonary bypass at a tertiary care, academic, PICU. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Early postoperative fluid overload, defined as a fluid balance 5% above body weight by the end of postoperative day 1, occurred in 30 patients (31%). Patients with early fluid overload spent 3.5 days longer in the hospital, spent 2 more days on inotropes, and were more likely to require prolonged mechanical ventilation than those without early fluid overload (all p < 0.001). Fluid overload was associated with the development of acute kidney injury and more often preceded it than followed it. Conversely, acute kidney injury was not associated with more fluid accumulation. Patients with fluid overload were administered higher fluid volume over the study period, 395.4 ± 150 mL/kg vs. 193.2 ± 109.1 mL/kg (p < 0.001), and had poor urinary response to diuretics. Cumulative fluid administered was an excellent predictor of pediatric-modified Risk, Injury, Failure, Loss, and End-stage "Failure" (area under the receiver-operating characteristic curve, 0.963; 95% CI, 0.916-1.000; p = 0.002). CONCLUSIONS: Early postoperative fluid overload is independently associated with worse outcomes in pediatric cardiac surgery patients who are 2 weeks to 18 years old. Patients with fluid overload have higher rates of postcardiopulmonary bypass acute kidney injury, and the occurrence of fluid overload precedes acute kidney injury. However, acute kidney injury is not consistently associated with fluid overload.

Urine Quantification Following Furosemide for Severe Acute Kidney Injury Prediction in Critically Ill Children.

A standardized, quantified assessment of furosemide responsiveness predicts acute kidney injury (AKI) in children after cardiac surgery and AKI progression in critically ill adults. The purpose of this study was to determine if response to furosemide is predictive of severe AKI in critically ill children outside of cardiac surgery. We performed a multicenter retrospective study of critically ill children. Quantification of furosemide response was based on urine flow rate (normalized for weight) measurement 0 to 6 hours after the dose. The primary outcome was presence of creatinine defined severe AKI (Kidney Disease Improving Global Outcomes stage 2 or greater) within 7 days of furosemide administration. Secondary outcomes included mortality, duration of mechanical ventilation and length of stay. A total of 110 patients were analyzed. Severe AKI occurred in 20% ( n = 22). Both 2- and 6-hour urine flow rate were significantly lower in those with severe AKI compared with no AKI ( p = 0.002 and p < 0.001). Cutoffs for 2- and 6-hour urine flow rate for prediction of severe AKI were <4 and <3 mL/kg/hour, respectively. The adjusted odds of developing severe AKI for 2-hour urine flow rate of <4 mL/kg/hour was 4.3 (95% confidence interval [CI]: 1.33-14.15; p = 0.02). The adjusted odds of developing severe AKI for 6-hour urine flow rate of <3 mL/kg/hour was 6.19 (95% CI: 1.85-20.70; p = 0.003). Urine flow rate in response to furosemide is predictive of severe AKI in critically ill children. A prospective assessment of urine flow rate in response to furosemide for predicting subsequent severe AKI is warranted.

Predictive power of serum cystatin C to detect acute kidney injury and pediatric-modified RIFLE class in children undergoing cardiac surgery.

OBJECTIVE: Acute kidney injury is a frequent and serious complication of cardiopulmonary bypass. In current clinical practice, serum creatinine is used to detect acute kidney injury. Cystatin C is a novel biomarker for kidney function that has been shown to be superior to serum creatinine in predicting acute kidney injury in adults after cardiopulmonary bypass. The aim of this study was to determine whether early cystatin C levels predict acute kidney injury associated with cardiopulmonary bypass in pediatric patients undergoing cardiac surgery and if cystatin C could predict pediatric-modified RIFLE (Risk, Injury, Failure, Loss, End-stage kidney disease) class and renal injury as determined by estimated glomerular filtration rate. We also investigated whether ultrafiltration during cardiopulmonary bypass affects cystatin C levels. DESIGN: Prospective, observational cohort study. SETTING: Cardiac intensive care unit in a tertiary, academic pediatric hospital. PATIENTS: One hundred pediatric patients who underwent cardiac surgery involving cardiopulmonary bypass. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Acute kidney injury was defined as a 50% increase in serum creatinine from a preoperative baseline anytime through postoperative day 4. Severity of acute kidney injury was determined by pediatric RIFLE class using estimated glomerular filtration rate criteria only. Renal injury was also determined by an absolute estimated glomerular filtration rate <80 mL/min/1.73 m. Cystatin C levels were measured before and after ultrafiltration. Twenty-eight patients (28%) developed acute kidney injury. Cystatin C predicted acute kidney injury as early as 8 hrs after surgery. When applying pediatric RIFLE criteria to the entire study, 30 patients reached "risk" and five developed "injury." Cystatin C was a good predictor of the development of "injury" (under the receiver operating characteristic curve, 0.834-0.875) and of renal injury by estimated glomerular filtration rate (under the receiver operating characteristic curve, 0.717-0.835) (all p < .05). Cystatin C levels decreased perioperatively and correlated with volume of fluid removed by ultrafiltration. CONCLUSIONS: Cystatin C is an early predictor of acute kidney injury in children after cardiopulmonary bypass. Cystatin C is a good predictor of pediatric RIFLE classification and of decreased estimated glomerular filtration rate after cardiopulmonary bypass. Serum cystatin C may be cleared by ultrafiltration.

The effect of cardiopulmonary bypass on the hypothalamic-pituitary-adrenal axis in children.

OBJECTIVE: The pathophysiology of low-cardiac-output syndrome after cardiopulmonary bypass is incompletely understood, but adrenal insufficiency has been proposed as a contributing factor. Our objective was to examine the effect of cardiopulmonary bypass on the hypothalamic-pituitary-adrenal axis, specifically adrenal responsiveness, in patients with congenital heart disease undergoing surgery. We hoped to correlate bound and free cortisol values both postoperatively and after adrenocorticotropic hormone stimulation, in conjunction with corticosteroid-binding globulin levels, with clinical outcomes to determine whether these variables are sensitive indicators of adrenal axis function. DESIGN: Prospective cohort study. SETTING: A children's hospital. PATIENTS: Fifty-two pediatric heart surgery patients undergoing cardiopulmonary bypass. INTERVENTION: Total cortisol and corticosteroid-binding globulin levels were obtained pre- and postoperatively and after a postoperative cosyntropin stimulation test. Free cortisol was calculated by using Coolens' method. MEASUREMENTS AND MAIN RESULTS: Nine of 51 (17.6%) patients had low (<3 µg/dL) baseline postoperative total cortisol, median 1.6 µg/dL, yet all nine had normal (>9 µg/dL increase from postoperative baseline) stimulation tests. The corticosteroid-binding globulin levels declined from a mean of 29 mg/L preoperatively to 22 mg/L postoperatively (p < .001) and showed marked variability between patients. Patients with free cortisol δ >6 µg/dL (n = 18, 35%) had a longer length of stay (median 9 vs. 5 days; p = .002), higher inotrope scores (median 13.3 vs. 10.8; p = .05), greater fluid requirement (median 73.5 vs. 55.6 mL/kg; p = .007), and longer ventilator times (median 41.5 vs. 20 hrs; p = .013). CONCLUSIONS: Although hypothalamic-pituitary-adrenal axis dysfunction may play a role in low-cardiac-output syndrome among children undergoing congenital heart surgery, using total cortisol to investigate such dysfunction may be inadequate. Decreased corticosteroid-binding globulin levels and marked free cortisol increase after stimulation were associated with worse clinical outcomes. Further investigation into the cortisol-corticosteroid-binding globulin complex and its relationship to free cortisol is necessary to examine the problem of adrenal insufficiency from a more integrated perspective.

Comparison of gastrointestinal morbidity after Norwood and hybrid palliation for complex heart defects.

This study aimed to compare the incidence of gastrointestinal complications among infants with single-ventricle heart defects after three first-stage palliation strategies: Norwood-modified Blalock-Taussig shunt (mBTS), Norwood right ventricle-to-pulmonary artery conduit (Sano), and hybrid procedures. A retrospective chart review was performed in a pediatric cardiac intensive care unit at a tertiary care medical center. The subjects were 32 neonates who had undergone single-ventricle palliation including 13 Norwood-mBTS, 11 Sano, and 8 hybrid procedures. The measurements included baseline as well as pre- and postoperative patient characteristics. The primary outcome was postoperative intraabdominal complications, and the secondary outcomes were feeding intolerance and necrotizing enterocolitis (NEC). Intraabdominal complications occurred for 34%, feeding intolerance for 13%, and NEC for 13% of the patients. The hybrid patients had a higher incidence of intraabdominal complications (75%) than the Norwood-mBTS (31%) or Sano (9%) patients (P = 0.01). The relative risk for intraabdominal complications in the hybrid group was 3.6 (95% confidence interval [CI], 1.5-8.7). In the multivariate analysis, the hybrid procedure remained an independent predictor of intraabdominal complications (hazard ratio, 8.4; 95% CI, 2.0-34.5). The hybrid, Norwood-mBTS, and Sano patients did not differ significantly in terms of feeding intolerance (25, 15, and 0%, respectively; P = 0.25) or NEC (25, 8, and 9%; P = 0.46). Gastrointestinal morbidity was common regardless of the palliative approach, although the hybrid patients had the highest incidence of intraabdominal complications. This supports the need for caution in using enteral nutrition with all single-ventricle patients, including the hybrid population. Patients undergoing the hybrid procedure may benefit from implementation of standardized feeding protocols.

Using next generation sequencing of alpine plants to improve fecal metabarcoding diet analysis for Dall's sheep.

OBJECTIVES: Dall's sheep (Ovis dalli dalli) are important herbivores in the mountainous ecosystems of northwestern North America, and recent declines in some populations have sparked concern. Our aim was to improve capabilities for fecal metabarcoding diet analysis of Dall's sheep and other herbivores by contributing new sequence data for arctic and alpine plants. This expanded reference library will provide critical reference sequence data that will facilitate metabarcoding diet analysis of Dall's sheep and thus improve understanding of plant-animal interactions in a region undergoing rapid climate change. DATA DESCRIPTION: We provide sequences for the chloroplast rbcL gene of 16 arctic-alpine vascular plant species that are known to comprise the diet of Dall's sheep. These sequences contribute to a growing reference library that can be used in diet studies of arctic herbivores.

Hyperlactatemia: An Update on Postoperative Lactate.

While hyperlactatemia in postoperative cardiac surgery patients was once believed to solely reflect hypoperfusion, either from the accumulated "oxygen debt" during bypass or ongoing inadequate perfusion, our understanding of lactate generation, clearance, and management has evolved. A contemporary understanding of lactate balance is critical to the management of the postoperative patient with hyperlactatemia. In this review, we summarize the current understanding of lactate metabolism in pediatric patients following cardiac surgery and highlight two types of hyperlactatemia: type A, which is secondary to inadequate oxygen delivery and tissue hypoxia, and type B, which in postoperative pediatric cardiac surgery patients largely reflects increased glycolysis driven by the stress response. Both types may coexist; thus, it is imperative that providers first assess the patient for evidence of hypoperfusion. In patients with evidence of adequate perfusion, a type B component is often associated with a concomitant balanced (normal anion gap) metabolic acidosis and hyperglycemia. These patients will benefit from a more nuanced approach to their type B hyperlactatemia, as many will have a benign course and may be managed expectantly.