Prediction of severe bacterial infection in children with an emergency department diagnosis of infection

Lactate as a Screening Tool for Critical Illness in a Pediatric Emergency Department

OBJECTIVES

Lactate has in some pediatric emergency departments (PEDs) gained acceptance as a screening tool for critical illness, with cut-off values of 2.0 to 2.5 mmol/L. We aimed to investigate if lactate could predict the need of acute resuscitation in patients in a PED.

PATIENTS AND METHODS

This retrospective observational cohort study included patients aged 0 to 17 years admitted to the PED at Copenhagen University Hospital in Denmark from January 1, 2019 to January 1, 2021. Patients were included if they had lactate measured as part of their routine blood sampling because of acute PED evaluation. Area under the receiver operating characteristic (ROC) curve (AUC) was calculated to assess the ability of lactate to predict the need of acute resuscitation. In patients without need of acute resuscitation, we calculated the lactate upper limit as the 95th percentile, and significant predictors were included in a multiple linear regression model.

RESULTS

A total of 1355 children were included. Fourteen (1%) children with a need of acute resuscitation had a median lactate of 1.7 mmol/L (interquartile range, 1.4-2.3) versus 1.6 mmol/L (interquartile range, 1.3-2.1) in children without need of resuscitation ( P > 0.05). The AUC for lactate to predict acute resuscitation was 0.56 (95% confidence interval, 0.54-0.59). In children without need of acute resuscitation, the 95th percentile of lactate was 3.2 mmol/L, and 392 (29.8%) had lactate greater than 2.0 mmol/L. Increasing age and venous sampling were associated with lower lactate. Lactate was not associated with sex, pediatric early warning score, or duration of hospital admission. The 95th percentile of lactate after inhaled beta-2-agonists was 5.0 mmol/L.

CONCLUSIONS

In children evaluated in a PED, lactate achieved a low AUC, suggesting a poor ability of predicting acute resuscitation. In children without need of acute resuscitation, the 95th percentile for lactate was 3.2 mmol/L, higher than the generally accepted cut-off values. This is important to recognize to avoid concern in otherwise clinically stable children. Our data did not support the use of lactate as a screening tool for early recognition of critical illness in a PED.

The evolving value of older biomarkers in the clinical diagnosis of pediatric sepsis

Sepsis remains the leading cause of childhood mortality worldwide. The evolving definition of pediatric sepsis is extrapolated from adult studies. Although lacking formal validation in the pediatric population, this working definition has historically proven its clinical utility. Prompt identification of pediatric sepsis is challenging as clinical picture is often variable. Timely intervention is crucial for optimal outcome, thus biomarkers are utilized to aid in immediate, yet judicious, diagnosis of sepsis. Over time, their use in sepsis has expanded with discovery of newer biomarkers that include genomic bio-signatures. Despite recent scientific advances, there is no biomarker that can accurately diagnose sepsis. Furthermore, older biomarkers are readily available in most institutions while newer biomarkers are not. Hence, the latter's clinical value in pediatric sepsis remains theoretical. Albeit promising, scarce data on newer biomarkers have been extracted from research settings making their clinical value unclear. As interest in newer biomarkers continue to proliferate despite their ambiguous clinical use, the literature on older biomarkers in clinical settings continue to diminish. Thus, revisiting the evolving value of these earliest biomarkers in optimizing pediatric sepsis diagnosis is warranted. This review focuses on the four most readily available biomarkers to bedside clinicians in diagnosing pediatric sepsis. IMPACT: The definition of pediatric sepsis remains an extrapolation from adult studies. Older biomarkers that include C-reactive protein, procalcitonin, ferritin, and lactate are the most readily available biomarkers in most pediatric institutions to aid in the diagnosis of pediatric sepsis. Older biomarkers, although in varying levels of reliability, remain to be useful clinical adjuncts in the diagnosis of pediatric sepsis if used in the appropriate clinical context. C-reactive protein and procalcitonin are more sensitive and specific among these older biomarkers in diagnosing pediatric sepsis although evidence varies in different age groups and clinical scenarios.

Serum lactate is associated with increased illness severity in immunocompromised pediatric hematology oncology patients presenting to the emergency department with fever

Introduction

Determining which febrile pediatric hematology/oncology (PHO) patients will decompensate from severe infection is a significant challenge. Serum lactate is a well-established marker of illness severity in general adult and pediatric populations, however its utility in PHO patients is unclear given that chemotherapy, organ dysfunction, and cancer itself can alter lactate metabolism. In this retrospective analysis, we studied the association of initial serum lactate in febrile immunosuppressed PHO patients with illness severity, defined by the incidence of clinical deterioration events (CDE) and invasive bacterial infection (IBI) within 48 hours.

Methods

Receiver operating characteristic (ROC) curves were reported using initial lactate within two hours of arrival as the sole predictor for CDE and IBI within 48 hours. Using a generalized estimating equations (GEE) approach, the association of lactate with CDE and IBI within 48 hours was tested in univariate and multivariable analyses including covariates based on Quasi-likelihood under Independence Model Criterion (QIC). Additionally, the association of lactate with secondary outcomes (i.e., hospital length of stay (LOS), intensive care unit (PICU) admission, PICU LOS, non-invasive infection) was assessed.

Results

Among 897 encounters, 48 encounters had ≥1 CDE (5%), and 96 had ≥1 IBI (11%) within 48 hours. Elevated lactate was associated with increased CDE in univariate (OR 1.77, 95%CI: 1.48-2.12, p<0.001) and multivariable (OR 1.82, 95%CI: 1.43-2.32, p<0.001) analyses, longer hospitalization (OR 1.15, 95%CI: 1.07-1.24, p<0.001), increased PICU admission (OR 1.68, 95%CI: 1.41-2.0, p<0.001), and longer PICU LOS (OR 1.21, 95%CI: 1.04-1.4, p=0.01). Elevated lactate was associated with increased IBI in univariate (OR 1.40, 95%CI: 1.16-1.69, p<0.001) and multivariable (OR 1.49, 95%CI: 1.23-1.79, p<0.001) analyses. Lactate level was not significantly associated with increased odds of non-invasive infection (p=0.09). The QIC of the model was superior with lactate included for both CDE (305 vs. 325) and IBI (563 vs. 579).

Conclusions

These data demonstrated an independent association of elevated initial lactate level and increased illness severity in febrile PHO patients, suggesting that serum lactate could be incorporated into future risk stratification strategies for this population.

Development and validation of machine learning-driven prediction model for serious bacterial infection among febrile children in emergency departments

Serious bacterial infection (SBI) in children, such as bacterial meningitis or sepsis, is an important condition that can lead to fatal outcomes. Therefore, since it is very important to accurately diagnose SBI, SBI prediction tools such as ‘Refined Lab-score’ or ‘clinical prediction rule’ have been developed and used. However, these tools can predict SBI only when there are values of all factors used in the tool, and if even one of them is missing, the tools become useless. Therefore, the purpose of this study was to develop and validate a machine learning-driven model to predict SBIs among febrile children, even with missing values. This was a multicenter retrospective observational study including febrile children <6 years of age who visited Emergency departments (EDs) of 3 different tertiary hospitals from 2016 to 2018. The SBI prediction model was trained with a derivation cohort (data from two hospitals) and externally tested with a validation cohort (data from a third hospital). A total of 11,973 and 2,858 patient records were included in the derivation and validation cohorts, respectively. In the derivation cohort, the area under the receiver operating characteristic curve (AUROC) of the RF model was 0.964 (95% confidence interval [CI], 0.943–0.986), and the area under the precision-recall curve (AUPRC) was 0.753 (95% CI, 0.681–0.824). The conventional LR (CLR) model showed corresponding values of 0.902 (95% CI, 0.894–0.910) and 0.573 (95% CI, 0.560–0.586), respectively. In the validation cohort, the AUROC (95% CI) of the RF model was 0.950 (95% CI, 0.945–0.956), the AUPRC was 0.605 (95% CI, 0.593–0.616), and the CLR presented corresponding values of 0.815 (95% CI, 0.789–0.841) and 0.586 (95% CI, 0.553–0.619), respectively. We developed a machine learning-driven prediction model for SBI among febrile children, which works robustly despite missing values. And it showed superior performance compared to CLR in both internal validation and external validation.

Big Tests in Little People

Can laboratory tests that are routinely used in adult patients also be used in pediatric patients? Does the current literature support the routine use of troponin, brain natriuretic peptide, D-dimer, and lactate in children? Adult problems such as acute coronary syndrome and pulmonary embolism are rare in pediatrics, and there is a paucity of literature on how blood tests commonly used to help diagnose these conditions in adults play a role in the diagnosis and management of children. This article presents the literature about 4 common blood tests and examines the clinical applications of each.

Elevated arterial lactate level as an independent risk factor for pancreatic infection in moderately severe acute pancreatitis

PURPOSE

The present study aimed to research the relationships between arterial lactate levels and pancreatic infection in moderately severe acute pancreatitis.

METHODS

This study retrospectively analyzed data from 503 patients with moderately severe acute pancreatitis from January 1, 2013, to March 31, 2018. The baseline characteristics on admission were compared between patients with and without elevated arterial lactate levels. The parameters and laboratory data were compared between patients with and without pancreatic infections at admission. Univariate and multivariate logistic regression analyses were used to assess the value of elevated arterial lactate levels for identifying high-risk patients. P ≤ 0.05 was considered statistically significant.

RESULTS

A total of 49 (9.2%) patients were diagnosed with pancreatic infections. Compared with patients without pancreatic infections, pancreatic infection patients had significantly increased arterial lactate levels at admission (1.5 ± 0.7 vs. 2.5 ± 0.9; P < 0.01). Multivariate logic analysis still showed that higher arterial lactate levels in moderately severe acute pancreatitis was an independent risk factor for developing pancreatic infections (hazard ratio: 6.31, 95% CI 3.01-13.24; P < 0.01). Arterial lactate level ≥2.1 mmol/L and procalcitonin level ≥0.5 ng/mL at admission had area under the receiver operating characteristic curves of 0.83 and 0.72, with sensitivity of 67.2% and 87%, and specificity of 82.0% and 60%, respectively, for the prediction of pancreatic infection in moderately severe acute pancreatitis.

CONCLUSIONS

Our results indicate that a higher arterial lactate level is independently associated with pancreatic infection in patients with moderately severe acute pancreatitis and may be used as a tool to identify high-risk patients.

Association Between Initial Emergency Department Lactate and Use of Vasoactive Medication in Children With Septic Shock

OBJECTIVES

Current guidelines emphasize early recognition of pediatric septic shock using clinical examination findings. Elevated serum lactate has been associated with increased mortality in adult patients with septic shock. Our objective was to determine the association between the initial serum lactate obtained in the pediatric emergency department (PED) from patients treated for septic shock and the use of vasoactive medication within 24 hours.

METHODS

This was a retrospective study from 2008 through 2012 of PED patients at a tertiary care children's hospital. Patients younger than 18 years treated for septic shock were included if they had a serum lactate obtained in the PED.

RESULTS

Eight hundred sixty-four PED encounters met inclusion criteria. Median initial PED lactate was 2.1 mmol/L (interquartile range, 1.4-3.2 mmol/L). Overall, 121 patients (14%) received vasoactive medication within 24 hours of the initial PED lactate. A multivariable logistic regression analysis demonstrated associations between initial lactate levels of 3.1 to 5 mmol/L (odds ratio, 1.82; 95% confidence interval, 1.02-3.26) and 5.1 mmol/L or greater (odds ratio, 5.00; 95% confidence interval, 2.56-9.76) and the use of vasoactive medication within 24 hours. Other factors associated with use of vasoactive medication within 24 hours included hypotension, abnormal pulses, and mental status changes.

CONCLUSIONS

Increased initial lactate is associated with use of vasoactive medication within 24 hours in PED patients with septic shock.

Point-of-care C reactive protein to identify serious infection in acutely ill children presenting to hospital: prospective cohort study

OBJECTIVE

Acute infection is the most common presentation of children to hospital. A minority of these infections are serious, but early recognition and adequate management are essential. We aimed to develop improved tools to assess children attending ambulatory hospital care, integrating clinical features with point-of-care C reactive protein (CRP).

DESIGN

Prospective observational diagnostic study.

SETTING AND PATIENTS

5517 acutely ill children (1 month-16 years) presenting to 106 paediatricians at six outpatient clinics and six emergency departments in Belgium.

INDEX TEST

Point-of-care CRP alongside vital signs and objective symptoms measurements.

MAIN OUTCOME

Hospital admission for >24 hours with a serious infection <5 days after presentation.

RESULTS

An algorithm was developed consisting of clinical features and CRP. This achieved 97.1% (95% CI 94.3% to 98.7%) sensitivity and 99.6% (95% CI 99.2% to 99.8%) negative predictive value, excluding serious infections in 36.4% of children. It stratifies patients into three groups based on CRP level: high-risk group with CRP >75 mg/L (26.8% risk of infection), intermediate-risk group with CRP 20-75 mg/L and at least one of seven clinical features (8.1%), and lower risk group with CRP <20 mg/L with at least one of the 11 features (3.8%). Children in intermediate-risk or low-risk groups with normal clinical assessment have 0.6% and 0.4% risk of serious infections, respectively.

CONCLUSIONS

Conducting a CRP test may first enable children to be stratified into three risk groups, guiding assessment of clinical features that could be performed by junior doctors or nurses. In one-third of acutely ill children, the algorithm could exclude serious infection. Prospective validation of the algorithm is needed.

CLINICAL TRIAL REGISTRATION

NCT02024282 (post-results).

Importance of measuring lactate levels in children with sepsis

Sepsis is a major public health problem as well as one of the leading causes of preventable death in children because of failure to recognise the early signs and symptoms and to resuscitate rapidly. Blood lactate levels are used to assess the severity of sepsis and the effectiveness of resuscitation. Lactate levels are easily obtainable and should be checked in all patients admitted with suspected sepsis within six hours of presentation. The test should be repeated four and eight-hours post-diagnosis of sepsis. For the diagnosis of sepsis, patients' clinical symptoms, along with the combined analysis of partial pressure of oxygen, carbon dioxide and lactate levels, should be used. A multitude of factors can cause elevated lactate levels and so clinicians should use elevated levels cautiously by considering all other aetiologies. This article, which focuses on practice in Australia but makes reference to the UK, discusses the importance of measuring lactate levels in sepsis, the pathophysiology of lactate production, causes of elevated lactate levels, lactate measurement, nursing management of patients with elevated lactate levels, limitations of using lactate as a biomarker for diagnosing sepsis and implications for practice.

Close correlation between arterial and central venous lactate concentrations of children in shock: A cross-sectional study

BACKGROUND

Arterial lactate (aLact) has been widely used to guide therapeutic decisions in children with shock. We evaluated the feasibility of central venous lactate (cvLact) in assessing aLact among children with shock.

METHODS

Pairs of arterial and central venous samples for lactate concentrations were collected simultaneously during the shock and hemodynamically stable states. The results were analyzed by using a Cobas 8000 analyzer.

RESULTS

Sixty-four blood paired samples were collected from 48 patients. The overall correlation between central venous and arterial lactate concentrations was r=0.962, p<0.0001, r²=0.965. The regression equation was aLact=(0.978×cvLact)-0.137. A similar correlation was found between central venous and arterial lactate concentrations during the states of shock and stable hemodynamics (r=0.970, p<0.0001, r²=0.966 and r=0.935, p<0.0001, r²=0.962, respectively). The mean difference between central venous and arterial lactate concentrations was 0.20mmol/l (95% CI: 0.08 to 0.32) and the limits of agreement were -0.74mmol/l (95% CI: -0.94 to -0.53) and 1.13 (95% CI: 0.93 to 1.34).

CONCLUSIONS

In situations of shock where a central venous catheter is required, samples from a central vein present an acceptable and timely alternative to arterial samples for quantitating lactate concentrations.

Profile of C-reactive protein, white cells and neutrophil populations in febrile children from rural north-eastern Tanzania

Introduction

C-reactive protein (CRP), white blood cell (WBC) and absolute neutrophil counts (ANC) are important inflammatory biomarkers in the early diagnosis of infections. However, little is known on their profile and usefulness in fever case management in children attending outpatient clinic in rural north-eastern Tanzania.

Methods

Patients aged between 2 and 59 months presenting with fever at Korogwe District Hospital were enrolled. Venous blood was collected for evaluation of serum CRP, WBC and ANC. Individual patient diagnosis was based on integrated management of childhood illness (IMCI) guidelines and laboratory investigations (blood and urine cultures).

Results

A total of 867 patients were enrolled, out of which 691 (79.7%) had complete clinical and laboratory data available for analysis. Acute upper respiratory tract infection 284 (41.1%), acute gastroenteritis 127 (18.4%) and pneumonia 100 (14.5%) were the most frequent diagnoses. The geometric mean levels of serum CRP, WBC and ANC were 10.4 (95% CI: 9.2 - 11.8), 11.5 (95% CI: 11.1 - 11.9) and 5.5 (95% CI: 5.2 - 5.8), respectively. CRP≤20, WBC≤15 (10³cells/µL) and ANC≤10 10³cells/µL) were observed in the majority of the patients with upper respiratory tract infection, pneumonia, acute gastroenteritis and non-specific febrile illness. Only serum CRP levels were positively correlated with positive blood cultures at a calculated cut-off value of 37.3 mg/L, giving a specificity of 77.8% and sensitivity of 74.2%.

Conclusion

CRP assessment together with IMCI guidelines may be useful in assisting the diagnosis and management of paediatric febrile infections in Tanzania.

Increased constituent ratios of Klebsiella sp., Acinetobacter sp., and Streptococcus sp. and a decrease in microflora diversity may be indicators of ventilator-associated pneumonia: a prospective study in the respiratory tracts of neonates

Ventilator-associated pneumonia (VAP) is a common complication and cause of death in neonates on mechanical ventilation. However, it is difficult to define the causes of VAP. To understand the causes of VAP, we undertook a prospective study based on the diversity of the microflora in VAP. The experimental group consisted of newborns who suffered from respiratory distress syndrome (RDS) and VAP, while the control group suffered from RDS without VAP. Sputa were collected within 1, 3, and 5 days of ventilation and were divided into six groups. DNA was extracted from the samples, and the 16S rDNA was PCR amplified, separated using denaturing gradient gel electrophoresis (DGGE), cloned and sequenced. The resulting sequences were compared using BLAST. The DGGE pictures were measured, and the richness, Shannon-Wiener index, and cluster maps were analyzed. No differences were found regarding the constituent ratio of any genus between the Non-VAP and VAP group within 1 day after intubation. After 1 to 3 days, the constituent ratios of Klebsiella sp., Acinetobacter sp., and Streptococcus sp. in the VAP group were higher than those in the Non-VAP group, and the ratios of Serratia sp. and Achromobacter sp. were lower. After 3 to 5 days, the ratios of Klebsiella sp., Acinetobacter sp., Serratia sp., and Achromobacter sp. were lower than those in the Non-VAP group. The richness and Shannon-Wiener index of the Non-VAP group were higher than those of the VAP group from 1 to 3 days after intubation, while no differences were found within 1 day and from 3 to 5 days. We conclude that during the first three days of intubation, the microflora diversity in the lower respiratory tract was reduced due to VAP, and the greater constituent ratios of Klebsiella sp., Acinetobacter sp., and Streptococcus sp. in the sputum may be indicators of VAP.

CD15s is a potential biomarker of serious bacterial infection in infants admitted to hospital

Early recognition of serious bacterial infection (SBI) in children is essential for better treatment outcome. Flow cytometry analysis of neutrophil surface molecules has been more frequently utilized as a tool for diagnosis of infection. The infants (n = 105) under 6 months of age presenting to the pediatric emergency department with fever without apparent source who were hospitalized with suspicion of having SBI were enrolled in this prospective study. Sixty-nine infants were included into the training pool and were classified into bacterial or viral infection group. Validation pool consisted of 36 infants. The values of white blood cells counts, absolute neutrophil count (ANC), C-reactive protein (CRP), procalcitonin (PCT), neutrophil CD11b, CD15s and CD64 expression, and the percentage (%CD15s+) and absolute count (AC-CD15s+) of CD15s+ neutrophils were determined. In infants with SBI, %CD15s+ was 10.5 times more likely to be higher than the cut-off value. ANC, CRP, PCT, CD64, and AC-CD15s+ were also found as useful biomarkers for differentiation between bacterial and viral infection. The best fit multivariate logistic regression model included CRP, PCT, and %CD15s+ as strong predictors of SBI. The model's sensitivity (87 %) and specificity (83 %) indicated high model's accuracy. After validation on independent dataset, model's accuracy maintained high: 86 % sensitivity and 93 % specificity, confirming its reliability and supporting CRP, PCT, and %CD15s+ as real predictors. The findings of this study support assumption made in the literature on significance of CD15s in inflammation processes. Also, this study demonstrated for the first time that CD15s is potentially valuable biomarker of SBI in infants.

Sepsis and septic shock

Early recognition of sepsis and septic shock in children relies on obtaining an attentive clinical history, accurate vital signs, and a physical examination focused on mental status, work of breathing, and circulatory status. Laboratory tests may support the diagnosis but are not reliable in isolation. The goal of septic shock management is reversal of tissue hypoperfusion. The therapeutic end point is shock reversal. Mortality is significantly better among children when managed appropriately. Every physician who cares for children must strive to have a high level of suspicion and keen clinical acumen for recognizing the rare but potentially seriously ill child.

The utility of early lactate testing in undifferentiated pediatric systemic inflammatory response syndrome

OBJECTIVES

Failure to recognize shock contributes to inadequate early resuscitation in many children with sepsis. Serum lactate levels are used to identify adult patients with septic shock, but physical examination diagnosis alone is recommended in pediatric sepsis. The authors sought to test the utility of lactate testing in pediatric emergency department (ED) patients with systemic inflammatory response syndrome (SIRS). The hypothesis was that early hyperlactatemia (serum lactate ≥ 4.0 mmol/L) would be associated with increased risk of organ dysfunction.

METHODS

This was a prospective cohort study of children younger than 19 years with SIRS presenting to a pediatric ED. The primary outcome was organ dysfunction within 24 hours of triage; secondary outcomes included disposition, serious bacterial infection (SBI), treatments, and mortality. Study personnel measured venous lactate level on a point-of-care meter, with clinicians blinded to results, and patients received usual care.

RESULTS

A total of 239 subjects were enrolled; 18 had hyperlactatemia. The hyperlactatemia group had a relative risk of 5.5 (95% confidence interval [CI] = 1.9 to 16.0) of developing 24-hour organ dysfunction. As a test for organ dysfunction, hyperlactatemia had a positive likelihood ratio of 5.0, a sensitivity of 31% (95% CI = 13% to 58%), and specificity of 94% (95% CI = 90% to 96%). Subjects with hyperlactatemia were significantly more likely to receive intravenous (IV) antibiotics and fluid boluses; despite increased therapy, they were at significantly increased risk for intensive care unit (ICU) admission and bacterial infection.

CONCLUSIONS

Among undifferentiated children with SIRS, early hyperlactatemia is significantly associated with increased risk of organ dysfunction, resuscitative therapies, and critical illness. The addition of serum lactate testing to the currently recommended clinical assessment may improve early identification of pediatric sepsis requiring resuscitation.