Blood lactate levels differ significantly between surviving and nonsurviving patients within the same risk-adjusted Classification for Congenital Heart Surgery (RACHS-1) group after pediatric cardiac surgery

Association between Serum Lactate and Morbidity and Mortality in Neonates: A Systematic Review and Meta-Analysis

OBJECTIVE

Lactate is a marker of hypoperfusion in critically ill patients. Whether lactate is useful for identifying and stratifying neonates with a higher risk of adverse outcomes remains unknown. This study aimed to investigate the association between lactate and morbidity and mortality in neonates.

METHODS

A meta-analysis was performed to determine the association between blood lactate levels and outcomes in neonates. Ovid MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov were searched from inception to 1 May 2021. A total of 49 observational studies and 14 data accuracy test studies were included. The risk of bias was assessed using the Newcastle-Ottawa Scale for observational studies and the QUADAS-2 tool for data accuracy test studies. The primary outcome was mortality, while the secondary outcomes included acute kidney injury, necessity for renal replacement therapy, neurological outcomes, respiratory morbidities, hemodynamic instability, and retinopathy of prematurity.

RESULTS

Of the 3184 articles screened, 63 studies fulfilled all eligibility criteria, comprising 46,069 neonates. Higher lactate levels are associated with mortality (standard mean difference, -1.09 [95% CI, -1.46 to -0.73]). Using the estimated sensitivity (0.769) and specificity (0.791) and assuming a prevalence of 15% for adverse outcomes (median of prevalence among studies) in a hypothetical cohort of 10,000 neonates, assessing the lactate level alone would miss 346 (3.46%) cases (false negative) and wrongly diagnose 1776 (17.76%) cases (false positive).

CONCLUSIONS

Higher lactate levels are associated with a greater risk of mortality and morbidities in neonates. However, our results do not support the use of lactate as a screening test to identify adverse outcomes in newborns. Research efforts should focus on analyzing serial lactate measurements, rather than a single measurement.

Vasoactive-ventilation-renal score and outcomes in infants and children after cardiac surgery

Introduction

There is a need to index important clinical characteristics in pediatric cardiac surgery that can be obtained early in the postoperative period and accurately predict postoperative outcomes.

Methodology

A prospective cohort study was conducted in the pediatric cardiac ICU and ward on all children aged <18 years undergoing cardiac surgery for congenital heart disease from September 2018 to October 2020. The vasoactive-ventilation-renal (VVR) score was analyzed to predict outcomes of cardiac surgeries with a comparison of postoperative variables.

Results

A total of 199 children underwent cardiac surgery during the study period. The median (interquartile range) age was 2 (0.8-5) years, and the median weight was 9.3 (6-16) kg. The most common diagnoses were ventricular septal defect (46.2%) and tetralogy of Fallot (37.2%). At the 48th h, area under the curve (AUC) (95% CI) values were higher for the VVR score than those for other clinical scores measured. Similarly, at the 48th h, AUC (95% CI) values were higher for the VVR score than those for the other clinical scores measured for the length of stay and mechanical ventilation.

Discussion

The VVR score at 48 h postoperation was found to best correlate with prolonged pediatric intensive care unit (PICU) stay, length of hospitalization, and ventilation duration, with the greatest AUC-receiver operating characteristic (0.715, 0.723, and 0.843, respectively). The 48-h VVR score correlates well with prolonged ICU, hospital stay, and ventilation.

Risk factors and in-hospital mortality of postoperative hyperlactatemia in patients after acute type A aortic dissection surgery

Background

Hyperlactatemia may be caused by increased production due to tissue hypoxia or non-hypoxia. The aim of this study was first to identify risk factors for postoperative hyperlactatemia (POHL) after Stanford type A acute aortic dissection surgery (AADS) and construct a predictive model, and second to evaluate the impact of POHL on prognosis.

Methods

This retrospective study involved patients undergoing AADS from January 2016 to December 2019 in Wuhan Union Hospital. Multivariate logistic regression analysis was performed to identify independent risk factors for POHL. A nomogram predicting POHL was established based on these factors and was validated in the original dataset. The receiver operating characteristic curve was drawn to assess the ability of postoperative lactate levels to predict the in-hospital mortality.

Results

A total of 188 patients developed POHL after AADS (38.6%). Male gender, surgery history, red blood cell transfusion and cardiopulmonary bypass time were identified as independent predictors. The C-index of the prediction model for POHL was 0.72, indicating reasonable discrimination. The model was well calibrated by visual inspection and goodness-of-fit test (Hosmer–Lemeshow χ² = 10.25, P = 0.25). Decision and clinical impact curves of the model showed good clinical utility. The overall in-hospital mortality rate was 10.1%. Postoperative lactate levels showed a moderate predictive power for postoperative in-hospital mortality (C-index: 0.72).

Conclusion

We developed and validated a prediction model for POHL in patients undergoing AADS, which may have clinical utility in personal risk evaluation and preventive interventions. The POHL could be a good predictor for in-hospital mortality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02244-7.

Relationship Between Lactate Levels and Length of Hospital Stay in Infants with Lower Respiratory Tract Infection

Background: Increased lactate concentrations are directly related to the severity of shock and mortality rates. There are limited data regarding the prognostic value of lactate among lower respiratory tract infections. We aimed to investigate the impact of lactate levels on admission on the clinical outcomes of children with lower respiratory tract infections. Methods: We performed a retrospective study of hospitalized patients aged 1-12 months. We recorded data on patient demographics, clinical, laboratory, treatment, and outcomes. The primary outcome measure was the length of hospital stay, and the secondary outcome was transfer to the pediatric intensive care unit (PICU) and/or mortality rates. Results: A total of 304 infants were included in the study. There were 198 infants with lactate levels of >2 mmol/L. Lactic acidosis was present in 6 infants, with a mean hospital stay of 8 ± 3 days. Only 1 (0.3%) patient required intubation, and 5 (1.6%) were transferred to the PICU. The overall mortality rate was 0%. Lactate levels (≤2 and >2 mmol/L) were not related to the length of hospital stay, transfer to PICU/discharge, and the need for intubation (P = 0.16, 0.8, and 0.46, respectively). The length of hospital stay was not correlated with lactate levels on admission (r = 0.01, P = 0.84), pCO₂ (r = 0.03, P = 0.52), pH (r = 0.07, P = 0.19), C-reactive protein (r = 0.06, P = 0.28), and oxygen saturation (r = -0.02, P = 0.72). Conclusions: Lactate levels on admission did not predict the length of hospital stay in children with lower respiratory infections and were not related to the need for transfer to the intensive care unit. We suggest using lactate levels in combination with clinical, laboratory, and physical examination findings as predictors of disease severity.

Core-Peripheral Temperature Gradient and Skin Temperature as Predictors of Major Adverse Events Among Postoperative Pediatric Cardiac Patients

OBJECTIVE

During episodes of low cardiac output, sympathetic neurohumoral responses with peripheral vasoconstriction result in an increase in the core-peripheral temperature gradient (CPTG). However, assessment of CPTG as a surrogate of low cardiac output and a predictor of outcomes in pediatric cardiac patients rarely has been performed. In this retrospective study, the authors assessed the prognostic abilities of CPTG, skin temperature, and serum lactate level for predicting clinical outcomes.

DESIGN

A retrospective single-center study.

SETTING

Referral high-volume pediatric center.

PATIENTS

Patients younger than four months of age with congenital heart disease who underwent cardiac surgery with cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was a composite of one or more of the following major adverse events (MAEs) that occurred within seven days after surgery: death from any cause, cardiac arrest, emergency chest reopening, and requirement for extracorporeal membrane oxygenation. A total of 661 patients were included in the study. Univariate logistic regression analyses showed no significant difference in the odds for MAEs with CPTG at admission and at six hours after surgery and in the odds for MAEs with skin temperature at admission. On the other hand, the odds for MAEs increased significantly with increase in serum lactate level at admission (odds ratio [OR]: 1.54, 95% confidence interval [CI]: 1.26-1.87, p < 0.001) and at six hours after surgery (OR: 1.94, 95% CI: 1.50-2.51, p < 0.001). Areas under the receiver operating curve at admission for predicting MAEs were 0.531 for CPTG, 0.557 for skin temperature, and 0.713 for serum lactate. Multivariate logistic regression analysis showed neither CPTG nor skin temperature at any time point was significantly associated with MAEs.

CONCLUSIONS

Both CPTG and skin temperature had low performance for prediction of MAEs in children after cardiac surgery. Either of those markers, especially at admission, should not be used as a single marker for assessing the condition of a patient.

MiRNA-124a: a Potential Biomarker for Neurological Deficits Following Cardiac Surgery in Pediatric Patients

Brain injury is a major source of patient morbidity after cardiac surgery in children. New early accurate biomarkers are needed for the diagnosis of patients at risk for cerebral postoperative damage. Specific circulating miRNAs have been found as suitable biomarkers for many diseases. We tested whether miRNA-124a reflects neurological injury in pediatric patients following heart surgery. Serum samples were obtained from 34 patients before and six hours after heart surgery. MiRNAs-124a was quantified by RQ-PCR. MiRNA-124a levels six hours after heart surgery correlated with the neurological outcome of the patients. In children with neurological deficits, miRNA-124a levels increased while in those with no neurological deficits the levels decreased. MiRNA-124a was able, at six hours after the operation, to identify patients who are at risk for the appearance of neurological deficits. Circulating miRNA-124a is a potential biomarker for the appearance of neurological deficits in pediatric patients following heart surgery. Graphical Abstract.

Hyperlactatemia and Patient Outcomes After Pediatric Cardiac Surgery

Elevated serum lactate level, or hyperlactatemia, is often associated with alterations in tissue perfusion, increased risk for complications in the postoperative period, and patient mortality. Measuring lactate levels is a relatively simple and noninvasive method of obtaining useful data about an impending clinical deterioration in a seemingly hemodynamically stable patient. This article evaluates the current practice of measuring lactate levels in pediatric patients after cardiac surgery and the association between these levels and patient outcomes. The article addresses periods of increased risk for decreased perfusion, the critical postoperative period, use of lactate measurements in conjunction with a risk scoring system for pre-and postoperative congenital heart disease patients, and the implications of elevated lactate levels in nursing practice.

Metabolomic Fingerprinting of Infants Undergoing Cardiopulmonary Bypass: Changes in Metabolic Pathways and Association With Mortality and Cardiac Intensive Care Unit Length of Stay

Background Mortality for infants undergoing complex cardiac surgery is >10% with a 30% to 40% risk of complications. Early identification and treatment of high-risk infants remains challenging. Metabolites are small molecules that determine the minute-to-minute cellular phenotype, making them ideal biomarkers for postsurgical monitoring and potential targets for intervention. Methods and Results We measured 165 serum metabolites by tandem mass spectroscopy in infants ≤120 days old undergoing cardiopulmonary bypass. Samples were collected prebypass, during rewarming, and 24 hours after surgery. Partial least squares-discriminant analysis, pathway analysis, and receiver operator characteristic curve analysis were used to evaluate changes in the metabolome, assess altered metabolic pathways, and discriminate between survivors/nonsurvivors as well as upper/lower 50% intensive care unit length of stay. Eighty-two infants had preoperative samples for analysis; 57 also had rewarming and 24-hour samples. Preoperation, the metabolic fingerprint of neonates differed from older infants ( R2=0.89, Q2=0.77; P<0.001). Cardiopulmonary bypass resulted in progressive, age-independent metabolic disturbance ( R2=0.92, Q2=0.83; P<0.001). Multiple pathways demonstrated changes, with arginine/proline ( P=1.2×10-35), glutathione ( P=3.3×10-39), and alanine/aspartate/glutamate ( P=1.4×10-26) metabolism most affected. Six subjects died. Nonsurvivors demonstrated altered aspartate ( P=0.007) and nicotinate/nicotinamide metabolism ( P=0.005). The combination of 24-hour aspartate and methylnicotinamide identified nonsurvivors versus survivors (area under the curve, 0.86; P<0.01), as well as upper/lower 50% intensive care unit length of stay (area under the curve, 0.89; P<0.01). Conclusions The preoperative metabolic fingerprint of neonates differed from older infants. Large metabolic shifts occurred after cardiopulmonary bypass, independent of age. Nonsurvivors and subjects requiring longer intensive care unit length of stay showed distinct changes in metabolism. Specific metabolites, including aspartate and methylnicotinamide, may differentiate sicker patients from those experiencing a more benign course.

Correlation between serum lactate levels and outcome in pediatric patients undergoing congenital heart surgery

Background

This study aimed to investigate the correlation between perioperative arterial lactate levels and morbidity and mortality in children undergoing cardiac surgery.

Methods

A total of 236 patients who underwent open heart surgery due to congenital heart disease (121 males, 115 females; mean age 56.4 month (median: 42 month): range, 1 day to 204 month) between June 2014 and May 2016 were retrospectively analyzed. The arterial blood gas analysis results at baseline (after insertion of arterial cannula), during the cooling and warming-up phases in cardiopulmonary bypass, during the sternal closure, and at 0, 6, 12, and 24 hours in the postoperative intensive care unit stay were recorded. The patients were divided into two groups according to their lactate levels: Group 1 (lactate level <4.5 mmol/L, n=183) and Group 2 (lactate level ≥4.5 mmol/L, n=53). Correlation between the lactate groups and demographic data, intraoperative and postoperative variables, postoperative complications, and mortality were investigated.

Results

Sixty-nine patients (29.2%) had cyanotic heart disease. A total of 53 patients (22.5%) had lactate levels of ≥4.5 mmol/L. At least one complication occurred in 41% of the patients. Development of at least one complication (p=0.027) and mortality rate (p<0.001) were significantly higher in the patients with lactate levels of ≥4.5 mmol/L. Seventeen patients (7.2%) died in the postoperative period, and 15 of them had lactate levels of ≥4.5 mmol/L at least once within the first 24 hours. In terms of mortality, lactate levels of ≥4.5 mmol/L at any time, prolonged mechanical ventilation (>48 hours), and undergoing complex surgery (high the Risk-adjusted Classification for Congenital Heart Surgery-1 score, category 4-6) were the independent risk factors for mortality.

Conclusion

Blood arterial lactate level of ≥4.5 mmol/L was found to be a risk factor for postoperative morbidity and mortality in pediatric patients undergoing congenital heart surgery.

Cardiopulmonary Resuscitation in Infants and Children With Cardiac Disease: A Scientific Statement From the American Heart Association

Cardiac arrest occurs at a higher rate in children with heart disease than in healthy children. Pediatric basic life support and advanced life support guidelines focus on delivering high-quality resuscitation in children with normal hearts. The complexity and variability in pediatric heart disease pose unique challenges during resuscitation. A writing group appointed by the American Heart Association reviewed the literature addressing resuscitation in children with heart disease. MEDLINE and Google Scholar databases were searched from 1966 to 2015, cross-referencing pediatric heart disease with pertinent resuscitation search terms. The American College of Cardiology/American Heart Association classification of recommendations and levels of evidence for practice guidelines were used. The recommendations in this statement concur with the critical components of the 2015 American Heart Association pediatric basic life support and pediatric advanced life support guidelines and are meant to serve as a resuscitation supplement. This statement is meant for caregivers of children with heart disease in the prehospital and in-hospital settings. Understanding the anatomy and physiology of the high-risk pediatric cardiac population will promote early recognition and treatment of decompensation to prevent cardiac arrest, increase survival from cardiac arrest by providing high-quality resuscitations, and improve outcomes with postresuscitation care.

Predictors of severe postoperative hyperglycemia after cardiac surgery in infants: a single-center, retrospective, observational study

PURPOSE

Hyperglycemia is a common issue in infants after cardiac surgery for congenital heart disease. Poor glycemic control is suspected to be associated with adverse postoperative outcomes. This study was performed to investigate clinical factors contributing to hyperglycemia in the perioperative period in infats.

METHODS

A total of 69 infants (aged 1-12 months) who were admitted to Yokohama City University Hospital Intensive Care Unit (ICU) after surgical repair of congenital heart diseases with cardiopulmonary bypass (CPB) were retrospectively analysed. Hyperglycemia was defined as blood glucose ≥ 250 mg/dL on ICU admission. Clinical background, operative factors, and postoperative factors were compared between the hyperglycemic and non-hyperglycemic groups. Additionally, multivariate analysis was performed to identify factors contributing to hyperglycemia.

RESULTS

Nineteen (27.5%) and 50 (72.5%) infants were classified into the hyperglycemic and non-hyperglycemic groups, respectively. Hyperglycemic infants were significantly younger, shorter, and weighed less, with a higher rate of chromosomal abnormalities. Intraoperatively, they also experienced longer CPB and surgery times and had higher peak lactate levels and higher inotropic requirements. Hyperglycemia was related to longer mechanical ventilation and longer ICU stays. Multivariate analysis detected intraoperative hyperglycemia, longer CPB time, younger age and chromosomal abnormality as significant factors.

CONCLUSION

Adding to hyperglycemia during the operation, longer CPB time younger age and chromosomal abnormality were identified as predictors of high blood glucose levels at ICU admission.

Pilot randomized controlled trial on early and late remote ischemic preconditioning prior to complex cardiac surgery in young infants

BACKGROUND

Remote ischemic preconditioning involves providing a brief ischemia-reperfusion event to a tissue to create subsequent protection from a more severe ischemia-reperfusion event to a different tissue/organ. The few pediatric remote ischemic preconditioning studies in the literature show conflicting results.

AIM

We conducted a pilot randomized controlled trial to determine the feasibility of conducting a larger trial and to gather provisional data on the effect of early and late remote ischemic preconditioning on outcomes of infants after surgery for congenital heart disease.

METHODS

This single-center, double-blind randomized controlled trial of remote ischemic preconditioning vs control (sham-remote ischemic preconditioning) in young infants going for surgery for congenital heart disease at the Stollery Children's Hospital. Remote ischemic preconditioning was performed at 24-48 h preoperatively and immediately prior to cardiopulmonary bypass. Remote ischemic preconditioning stimulus was performed with blood pressure cuffs around the thighs. Primary outcomes were feasibility and peak blood lactate level on day 1 postoperatively.

RESULTS

Fifty-two patients were randomized but seven patients became ineligible after randomization leaving 45 patients included in the study. In the included patients, 7 (15%) had protocol deviations (five infants did not have the preoperative intervention and two did not receive the intervention in the operating room). From a comfort point of view, only one subject in the control group and two in the Remote ischemic preconditioning group received sedation during the preoperative intervention. There were no study-related adverse events and no complications to the limbs subjected to preconditioning. There were no significant differences between the Remote ischemic preconditioning group and the control group in the highest blood lactate level on day 1 postoperatively (mean difference, 1.28; 95%CI, -0.22, 2.78; P-value = 0.093).

CONCLUSION

In infants who underwent surgery for congenital heart disease, our pilot randomized controlled trial on early and late remote ischemic preconditioning proved to be feasible but did not find any significant difference in acute outcomes. A larger trial may be necessary.

Hyperlactatemia and serial lactate measurements in sick cats

OBJECTIVES

To document the incidence of hyperlactatemia in sick cats hospitalized for emergency care and to evaluate the prognostic utility of serial lactate measurements in cats with hyperlactatemia.

DESIGN

Prospective observational study over a 10-month period (July 2010-May 2011).

SETTING

Private veterinary referral center with 24-hour hospital care.

ANIMALS

One hundred and twenty-three privately owned cats admitted to a private referral center.

INTERVENTIONS

Blood was collected by direct venipuncture from the jugular or medial saphenous vein at the time of hospital admission and at 6 and 24 hours following admission.

MEASUREMENTS AND MAIN RESULTS

The median plasma lactate concentration for all cats at admission (T0) was 1.89 mmol/L (17.0 mg/dL) (range: 0.3-12.48). Twenty-three percent (28/123) of cats admitted were hyperlactatemic (ie, >2.87 mmol/L; >25.86 mg/dL) upon admission. Lactate concentration at presentation and serial lactate measurements were not found to be related with survival to discharge or correlated with duration of hospitalization. The overall survival rate of all cats in this study was 81%.

CONCLUSIONS

This study demonstrated that the incidence of hyperlactatemia in sick cats being admitted for hospitalization in a private referral center was 23%, and that lactate concentration on admission and serial lactate measurements over time were not prognostic in this group of hospitalized cats. Future studies are needed to evaluate the prognostic utility of lactate and serial lactate measurements in specific disease states and in a larger population of critically ill cats.

Retuning mortality risk prediction in paediatric cardiac surgery: the additional role of early postoperative metabolic and respiratory profile

OBJECTIVES

The existing risk stratification scores for paediatric patients undergoing cardiac surgery include the Aristotle Basic Complexity (ABC) Score, the Risk Adjustment in Congenital Heart Surgery-1 (RACHS-1) Score and the Aristotle Comprehensive Complexity (ACC) Score. They are all based on the nature of the surgical operation (ABC and RACHS-1 Scores) with possible adjustment for a number of patient conditions (ACC Score). The present study investigates if the early postoperative parameters may be used to improve the preoperative mortality risk prediction.

METHODS

A retrospective study on 1392 consecutive patients aged ≤12 years old, undergoing cardiac surgery with cardiopulmonary bypass and without a residual right-to-left shunt was conducted. The ABC Score and metabolic and respiratory postoperative parameters at arrival in the intensive care unit were tested for association and discriminative power for operative mortality.

RESULTS

The ABC yielded a c-statistic of 0.746. Additional independent predictors of operative mortality were postoperative hypoxia [Formula: see text] and arterial blood lactates. In a multivariable model including the ABC Score, postoperative hypoxia and arterial blood lactates remained independently associated with operative mortality. A modified ABC Score was created, consisting of the ABC Score plus 1.5 points in case of postoperative hypoxia plus 1 point per each 1 mmol/l of arterial blood lactates. The new model was significantly (P = 0.043) more discriminative than the ABC Score, with a c-statistic of 0.803.

CONCLUSIONS

Early postoperative respiratory and metabolic parameters increased the accuracy and discrimination of the ABC Score. An external validation is needed to confirm our results.

An unusual cause of persisting hyperlactatemia in a neonate undergoing open heart surgery

Being a reflection of the degree of global tissue anoxia, serum lactate levels therefore can be used as a marker of organ damage and eventual outcome. A statistically significant association was observed between serum lactate levels and subsequent mortality and morbidity in critically ill adults, children, and neonates. In cardiac critical care, hyperlactatemia is usually multifactorial in origin, resulting from a combination of etiologies. Many centers are using serial lactate levels in conjugation with other parameters of cellular oxygen delivery, consumption, or extraction to monitor prognosis after pediatric cardiac surgery. A single initial lactate level has a lesser predictive value for morbidity and mortality after pediatric cardiac surgery than its failure to fall within 48 hours of surgery. In case of persistently high lactate levels with no other evidence of cellular hypoperfusion, other possibilities must be considered. There has been an established association of lactic acidosis with thiamine deficiency, but this has not yet been reported in newborns undergoing congenital cardiac surgery. We present one such rare case.

Early renal replacement therapy during pediatric cardiac extracorporeal support increases mortality

BACKGROUND

Acute kidney injury is a common comorbidity for children placed on extracorporeal membrane oxygenation (ECMO) because of primary cardiac disease. Continuous venovenous hemofiltration (CVVH) can optimize fluid status and lessen inflammatory response during ECMO. However, published data are derived primarily from children without primary cardiac disease.

METHODS

A retrospective analysis of our institutional ECMO database from 2002 to 2011 was performed. To limit the bias that CVVH initiation was after evidence of end-organ injury, we considered "early CVVH" to be instituted within 48 hours of ECMO initiation. Multivariate logistic regression was undertaken to adjust for covariates.

RESULTS

Of 153 cardiac ECMO patients, 59 (39%) received early CVVH. Time from ECMO initiation to CVVH initiation was 1.7±0.7 days (median 1 day). Pre-ECMO and post-ECMO serum creatinine levels were similar in both groups. However, peak serum creatinine was 1.1±0.4 mg/dL (median 1.0 mg/dL) in the ECMO and CVVH group and 0.9±0.4 mg/dL (median 0.8 mg/dL) in the ECMO alone group (p=0.003). Patients who received CVVH had a higher mortality (p<0.0001), were less likely to have had ECPR (p=0.004), and had a longer duration on ECMO (p<0.0001). In multivariate analysis subjects receiving CVVH support within 48 hours of ECMO cannulation were 3 times more likely to die during their hospitalization (odds ratio 3.02; 95% confidence interval 1.32 to 6.9, p=0.009) after adjusting for other significant risk factors.

CONCLUSIONS

Early CVVH in pediatric cardiac patients requiring ECMO is associated with increased mortality. Early CVVH in the cardiac ECMO population does not appear justified.

Biomarkers and clinical tools in critically ill children: are we heading toward tailored drug therapy?

In pediatric critical care, validated biomarkers are essential for guiding drug therapy. The aim of this article is to present examples of current biomarker developments in its full breadth, including biochemical substances, physiological measurements and clinical scoring tools, with a focus on the field of circulatory, renal and neurophysiologic failure. Within each field we consecutively discuss the rationale for the selected biomarkers, studies in critically ill children, biomarker validation stage and biomarker use or potential use in drug studies and clinical drug dosing. This article demonstrates that there is paucity of properly validated biomarkers. Nevertheless, recent developments in, for instance, the field of sepsis, point us toward a future wherein, for critically ill children, drug therapy may be personalized using proteomic profiling instead of a small number of biomarkers, in order to establish a personal and dynamic disease profile.

Resting energy expenditure after Fontan surgery in children with single-ventricle heart defects

BACKGROUND

Data on resting energy expenditure (REE) and oxygen consumption (VO(2)) after pediatric cardiopulmonary bypass (CPB) will facilitate optimal nutrient prescription.

METHODS

The authors measured continuous REE and VO(2), using an in-line indirect calorimetery (IC) in 30 consecutive children with single-ventricle physiology immediately after Fontan surgery. REE during steady state at 8 hours after surgery was compared with standard equation-estimated energy expenditure (EEE). Patients were classified into 3 groups: hypermetabolic (measured REE [MREE]/EEE ratio >1.2), hypometabolic (MREE/EEE ratio <0.8), and normometabolic (MREE/EEE ratio 0.8-1.2). Demographic, anthropometric, and perioperative clinical characteristics were examined for their correlation with metabolic status.

RESULTS

In 26 of 30 patients with completed IC, mean REE at 8 hours after surgery was 57 ± 20 kcal/kg/d, and mean VO(2) was 110 ± 35 mL/min. Mean values of VO(2) and REE did not change within the first 24 hours after surgery. There was poor correlation between MREE at 8 hours and the EEE using the World Health Organization equation (r = 0.32, P = .11). Most patients (n = 19, 73%) were either normometabolic or hypometabolic. Lack of hypermetabolism was significantly associated with higher intraoperative serum lactate level and positive fluid balance compared with the rest of the group.

CONCLUSIONS

The authors report a low prevalence of hypermetabolism in children with single-ventricle defects after Fontan surgery. Measured REE had poor correlation with equation-estimated energy expenditure in a majority of the cohort. The absence of increased energy expenditure after CPB will influence energy prescription in this group.

Levosimendan infusion in newborns after corrective surgery for congenital heart disease: randomized controlled trial

PURPOSE

To evaluate the safety and efficacy of levosimendan in neonates with congenital heart disease undergoing cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

Neonates undergoing risk-adjusted classification for congenital heart surgery (RACHS) 3 and 4 procedures were randomized to receive either a 72 h continuous infusion of 0.1 μg/kg/min levosimendan or standard post-CPB inotrope infusion.

RESULTS

Sixty-three patients (32 cases and 31 controls) were recruited. There were no differences between groups regarding demographic and baseline clinical data. No side effects were observed. There were no significant differences in mortality (1 vs. 3 patients, p = 0.35), length of mechanical ventilation (5.9 ± 5 vs. 6.9 ± 8 days, p = 0.54), and pediatric cardiac intensive care unit (PCICU) stay (11 ± 8 vs. 14 ± 14 days, p = 0.26). Low cardiac output syndrome occurred in 37 % of levosimendan patients and in 61 % of controls (p = 0.059, OR 0.38, 95 % CI 0.14-1.0). Postoperative heart rate, with a significant difference at 6 (p = 0.008), 12 (p = 0.037), and 24 h (p = 0.046), and lactate levels, with a significant difference at PCICU admission (p = 0.015) and after 6 h (p = 0.048), were lower in the levosimendan group. Inotropic score was significantly lower in the levosimendan group at PCICU admission, after 6 h and after 12 h, (p < 0.0001). According to multivariate analysis, a lower lactate level 6 h after PCICU admission was independently associated with levosimendan administration after correction for CPB time and the need for deep hypothermic circulatory arrest.

CONCLUSIONS

Levosimendan infused in neonates undergoing cardiac surgery was well tolerated with a potential benefit of levosimendan on postoperative hemodynamic and metabolic parameters of RACHS 3-4 neonates.

Lactate levels predict mortality and need for peritoneal dialysis in children undergoing congenital heart surgery

BACKGROUND

The purpose of this study was to investigate whether an initial post-operative lactate level is a predictor of mortality, need for peritoneal dialysis (PD), duration of intubation or length of stay (LOS) in the intensive care unit (ICU) in children undergoing cardiac surgery.

METHOD

A retrospective, observational follow-up study was conducted in 206 children undergoing cardiac surgery from 2006 to 2007. Multivariate logistics regression analyses were performed to determine whether the lactate level was an independent risk factor. The lactate concentration at arrival in the ICU, outcome and risk factors (patient demographics, surgical complexity, duration of cardiopulmonary bypass and inotropic score) were obtained from the electronic patient data management program and medical records.

RESULT

The median (interquartile range) lactate level was 1.9 mmol/l (1.3-2.7) in children immediately after cardiac surgery and a mortality of 3.9%. Eight percent of the children had a lactate level higher than 4.5 mmol/l. An increased lactate level ≥4.5 mmol/l resulted in an odds ratio (95% confidence intervals) of 8.4 (1.5-46.1) for mortality and an odds ratio of 16.9 (2.7-106.8) for PD after adjusting for Risk Adjustment for Congenital Heart Surgery 1. Because of the low number of deaths, limited confounder analysis was performed. Duration of intubation and LOS in the ICU were not associated with the initial lactate level when adjusting for confounders.

CONCLUSION

The initial post-operative lactate level was a predictor of mortality and need for PD in children undergoing surgery for congenital heart disease.

Lactate and acid base as a hemodynamic monitor and markers of cellular perfusion

BACKGROUND

: The intra- and postoperative monitoring of lactate and acid-base has been advocated in pediatric cardiac critical care as surrogate markers of cardiac output, oxygen delivery, and cellular perfusion. Many clinicians use lactate and base excess routinely as markers of tissue perfusion and to assess the effectiveness of their intervention. This review discusses the strengths and weaknesses of using these measurements in pediatric cardiac critical care.

METHODOLOGY

: A search of MEDLINE, EMBASE, PubMed, and the Cochrane Database was conducted to find controlled trials of lactate and base excess. Adult and pediatric data were considered. Guidelines published by the Society of Critical Care Medicine, the American Heart Association, the American Academy of Pediatrics, and the International Liaison Committee on Resuscitation were reviewed including further review of references cited.

RESULTS AND CONCLUSIONS

: Many factors other than tissue hypoxia may contribute to hyperlactemia in critical illness. Although the presence of hyperlactemia on admission appears to be associated with intensive care unit mortality and morbidity in some retrospective analyses, significant overlap between survivors and nonsurvivors means that nonsurvivors cannot be predicted from admission lactate measurement. Persistently elevated postoperative lactate is associated with increased morbidity and mortality in the pediatric cardiac population. To date there is no randomized control trial of goal-directed therapy in adult or pediatric cardiac care that includes normalization of lactate as a target. Overall equivalent time measurements of base excess, anion gap, and pH have a low predictive value for morbidity and mortality in children after cardiac surgery. Lactate is one of a cluster of markers of cellular perfusion and oxygen delivery. Alone, as a single measurement, it has minimal predictive value and is nondiscriminatory for survival.

The importance of blood lactate clearance as a predictor of early mortality following the modified Norwood procedure

OBJECTIVE

Optimisation of Norwood physiology, with focus on systemic perfusion, has beneficial effects on haemodynamic stability and perioperative mortality following the Norwood procedure for hypoplastic left heart syndrome. Early identification of high-risk patients during the postoperative phase might allow for institution of alternative management strategies with the possibility of avoiding poor outcome. Several studies have suggested that arterial blood lactate level, as an index of systemic perfusion and oxygen delivery, can to some extent predict mortality following paediatric cardiac surgery, though these studies have included heterogeneous groups of patients with only few Norwood patients. We sought to determine whether the blood lactate profile could be used to derive a simple, clinically applicable decision algorithm to direct therapy in a pre-emptive manner and perhaps identify patients for elective extracorporeal life support following the Norwood procedure.

METHODS

We retrospectively analysed all patients at our institution who had undergone modified Norwood procedures between March 2002 and May 2008. All patients had received right ventricle-pulmonary artery conduits. Patients with systemic-pulmonary shunts were excluded. Outcome measures included 7-day and 30-day mortality. Serial arterial blood lactate measurements were taken in all patients for at least 72h. Conditional inference tree modelling was used to determine the discriminatory value of the lactate profile and other pre- and intra-operative risk factors in terms of selecting survivors.

RESULTS

As many as 221 patients were included. The 7-day ICU mortality was 26/219 (11.8%) with total 30-day mortality of 35/219 (15.8%). There were 21 interstage deaths. Mortality modelling demonstrated that an inability to clear blood lactate levels to <6.76mmoll(-1) within the first 24h was highly discriminatory in terms of predicting death within the first 30 days. A total of 11 out of 12 patients in this group died. Other risk factors examined, including weight, ascending aorta size, cardiopulmonary bypass and ischaemic times, were not as predictive in our model.

CONCLUSION

We have identified minimum blood lactate level within the first 24h after the Sano-Norwood procedure as a highly discriminatory predictor of perioperative mortality. These patients might benefit from elective institution of early mechanical circulatory support.