Biomarkers for Estimating Risk of Hospital Mortality and Long-Term Quality-of-Life Morbidity After Surviving Pediatric Septic Shock: A Secondary Analysis of the Life After Pediatric Sepsis Evaluation Investigation

Editor's Choice Articles for July

This is another excellent issue of Pediatric Critical Care Medicine (PCCM) for July; congratulations to our authors and many thanks to all reviewers. This month, my Editor's Choice articles cover three topics: clinical pathophysiology in pediatric patients supported using extracorporeal membrane oxygenation (ECMO); unplanned extubation of endotracheal tubes in pediatric cardiac ICU (CICU) patients; and sepsis biomarkers in the low-middle income (LMIC) resource setting. The PCCM Connections for Readers focuses on a novel pediatric theme in lung mechanics physiology, i.e., mechanical power in pediatric acute respiratory distress syndrome (PARDS).

The Role of Coagulase-Negative Staphylococci Biofilms on Late-Onset Sepsis: Current Challenges and Emerging Diagnostics and Therapies

Infections are one of the most significant complications of neonates, especially those born preterm, with sepsis as one of the principal causes of mortality. Coagulase-negative staphylococci (CoNS), a group of staphylococcal species that naturally inhabit healthy human skin and mucosa, are the most common cause of late-onset sepsis, especially in preterms. One of the risk factors for the development of CoNS infections is the presence of implanted biomedical devices, which are frequently used for medications and/or nutrient delivery, as they serve as a scaffold for biofilm formation. The major concerns related to CoNS infections have to do with the increasing resistance to multiple antibiotics observed among this bacterial group and biofilm cells’ increased tolerance to antibiotics. As such, the treatment of CoNS biofilm-associated infections with antibiotics is increasingly challenging and considering that antibiotics remain the primary form of treatment, this issue will likely persist in upcoming years. For that reason, the development of innovative and efficient therapeutic measures is of utmost importance. This narrative review assesses the current challenges and emerging diagnostic tools and therapies for the treatment of CoNS biofilm-associated infections, with a special focus on late-onset sepsis.

Acute phase proteins in cats: Diagnostic and prognostic role, future directions, and analytical challenges

While clinical studies on acute phase proteins (APPs) have significantly increased in the last decade, and most commercial labs are now offering major APPs in their biochemical profiles, APP testing has not been widely adopted by veterinary clinical pathologists and veterinarians. Measurement of APP concentration is a useful marker for detecting the presence or absence of inflammation in cats with various diseases. APPs can also be reliably measured in different biological fluids (eg, effusions and urine) to improve their diagnostic utility. Measurement of APPs can be extremely beneficial in cats with feline infectious peritonitis (FIP) to discriminate between FIP and non-FIP cats with similar clinical presentations. Additional benefits come from multiple and sequential measurements of APPs, particularly in the assessment of therapeutic efficacy. APPs are more sensitive than WBC counts for early detection of inflammation and to demonstrate an early remission or recurrence of the diseases. Given the potential utility of APPs, more studies are warranted, with a particular focus on the applications of APPs to guide the length of antimicrobial therapies, as suggested by the antimicrobial stewardship policy. New inflammatory markers have been discovered in human medicine, with a higher specificity for distinguishing between septic versus nonseptic inflammatory diseases. It is desirable that these new markers be investigated in veterinary medicine, to further test the power of APPs in diagnostic setting.

β-lactam precision dosing in critically ill children: Current state and knowledge gaps

There has been emerging interest in implementing therapeutic drug monitoring and model-informed precision dosing of β-lactam antibiotics in critically ill patients, including children. Despite a position paper endorsed by multiple international societies that support these efforts in critically ill adults, implementation of β-lactam precision dosing has not been widely adopted. In this review, we highlight what is known about β-lactam antibiotic pharmacokinetics and pharmacodynamics in critically ill children. We also define the knowledge gaps that present barriers to acceptance and implementation of precision dosing of β-lactam antibiotics in critically ill children: a lack of consensus on which subpopulations would benefit most from precision dosing and the uncertainty of how precision dosing changes outcomes. We conclude with opportunities for further research to close these knowledge gaps.

Outcomes Associated With Timing of Neurologic Dysfunction Onset Relative to Pediatric Sepsis Recognition

OBJECTIVES

To compare outcomes associated with timing-early versus late-of any neurologic dysfunction during pediatric sepsis.

DESIGN

Secondary analysis of a cross-sectional point prevalence study.

SETTING

A total of 128 PICUs in 26 countries.

PATIENTS

Less than 18 years with severe sepsis on 5 separate days (2013-2014).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were categorized as having either no neurologic dysfunction or neurologic dysfunction (i.e., present at or after sepsis recognition), which was defined as Glasgow Coma Scale score less than 5 and/or fixed dilated pupils. Our primary outcome was death or new moderate disability (i.e., Pediatric Overall [or Cerebral] Performance Category score ≥3 and change ≥1 from baseline) at hospital discharge, and 87 of 567 severe sepsis patients (15%) had neurologic dysfunction within 7 days of sepsis recognition (61 at sepsis recognition and 26 after sepsis recognition). Primary site of infection varied based on presence of neurologic dysfunction. Death or new moderate disability occurred in 161 of 480 (34%) without neurologic dysfunction, 45 of 61 (74%) with neurologic dysfunction at sepsis recognition, and 21 of 26 (81%) with neurologic dysfunction after sepsis recognition (p < 0.001 across all groups). On multivariable analysis, in comparison with those without neurologic dysfunction, neurologic dysfunction whether at sepsis recognition or after was associated with increased odds of death or new moderate disability (adjusted odds ratio, 4.9 [95% CI, 2.3-10.1] and 10.7 [95% CI, 3.8-30.5], respectively). We failed to identify a difference between these adjusted odds ratios of death or new moderate disability that would indicate a differential risk of outcome based on timing of neurologic dysfunction (p = 0.20).

CONCLUSIONS

In this severe sepsis international cohort, the presence of neurologic dysfunction during sepsis is associated with worse outcomes at hospital discharge. The impact of early versus late onset of neurologic dysfunction in sepsis on outcome remains unknown, and further work is needed to better understand timing of neurologic dysfunction onset in pediatric sepsis.

Assessment of Patient Health-Related Quality of Life and Functional Outcomes in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To describe health-related quality of life (HRQL) and functional outcomes in pediatric acute respiratory distress syndrome (ARDS) and to determine risk factors associated with poor outcome defined as death or severe reduction in HRQL at 28 days or ICU discharge.

DESIGN

Prospective multisite cohort-outcome study conducted between 2019 and 2020.

SETTING

Eight academic PICUs in the United States.

PATIENTS

Children with ARDS based on standard criteria.

INTERVENTIONS

Patient characteristics and illness severity were collected during PICU admission. Parent proxy-report measurements were obtained at baseline, day 28/ICU discharge, month 3, and month 9, utilizing Pediatric Quality of Life Inventory and Functional Status Scale (FSS). A composite outcome evaluated using univariate and multivariate analysis was death or severe reduction in HRQL (>25% reduction in the Pediatric Quality of Life Inventory at day 28/ICU discharge.

MEASUREMENTS AND MAIN RESULTS

This study enrolled 122 patients with a median age of 3 years (interquartile range, 1-12 yr). Common etiologies of ARDS included pneumonia ( n = 63; 52%) and sepsis ( n = 27; 22%). At day 28/ICU discharge, half (50/95; 53%) of surviving patients with follow-up data reported a greater than 10% decrease in HRQL from baseline, and approximately one-third of participants ( n = 19/61; 31%) reported a greater than 10% decrease in HRQL at 9 months. Trends in FSS were similar. Of 104 patients with data, 47 patients (45%) died or reported a severe decrease of greater than 25% in HRQL at day 28/ICU discharge. Older age was associated with an increased risk of death or severe reduction in HRQL (odds ratio, 1.08; CI, 1.01-1.16).

CONCLUSIONS

Children with ARDS are at risk for deterioration in HRQL and FSS that persists up to 9 months after ARDS. Almost half of children with ARDS experience a poor outcome including death or severe reduction in HRQL at day 28/ICU discharge.

Individual illness dynamics: An analysis of children with sepsis admitted to the pediatric intensive care unit

Illness dynamics and patterns of recovery may be essential features in understanding the critical illness course. We propose a method to characterize individual illness dynamics in patients who experienced sepsis in the pediatric intensive care unit. We defined illness states based on illness severity scores generated from a multi-variable prediction model. For each patient, we calculated transition probabilities to characterize movement among illness states. We calculated the Shannon entropy of the transition probabilities. Using the entropy parameter, we determined phenotypes of illness dynamics based on hierarchical clustering. We also examined the association between individual entropy scores and a composite variable of negative outcomes. Entropy-based clustering identified four illness dynamic phenotypes in a cohort of 164 intensive care unit admissions where at least one sepsis event occurred. Compared to the low-risk phenotype, the high-risk phenotype was defined by the highest entropy values and had the most ill patients as defined by a composite variable of negative outcomes. Entropy was significantly associated with the negative outcome composite variable in a regression analysis. Information-theoretical approaches to characterize illness trajectories offer a novel way of assessing the complexity of a course of illness. Characterizing illness dynamics with entropy offers additional information in conjunction with static assessments of illness severity. Additional attention is needed to test and incorporate novel measures representing the dynamics of illness.

Diagnosis of neonatal sepsis: the past, present and future

Sepsis remains a significant cause of neonatal mortality and morbidity, especially in low- and middle-income countries. Neonatal sepsis presents with nonspecific signs and symptoms that necessitate tests to confirm the diagnosis. Early and accurate diagnosis of infection will improve clinical outcomes and decrease the overuse of antibiotics. Current diagnostic methods rely on conventional culture methods, which is time-consuming, and may delay critical therapeutic decisions. Nonculture-based techniques including molecular methods and mass spectrometry may overcome some of the limitations seen with culture-based techniques. Biomarkers including hematological indices, cell adhesion molecules, interleukins, and acute-phase reactants have been used for the diagnosis of neonatal sepsis. In this review, we examine past and current microbiological techniques, hematological indices, and inflammatory biomarkers that may aid sepsis diagnosis. The search for an ideal biomarker that has adequate diagnostic accuracy early in sepsis is still ongoing. We discuss promising strategies for the future that are being developed and tested that may help us diagnose sepsis early and improve clinical outcomes. IMPACT: Reviews the clinical relevance of currently available diagnostic tests for sepsis. Summarizes the diagnostic accuracy of novel biomarkers for neonatal sepsis. Outlines future strategies including the use of omics technology, personalized medicine, and point of care tests.

Pediatric sepsis biomarkers for prognostic and predictive enrichment

Sepsis is a major public health problem in children throughout the world. Given that the treatment guidelines emphasize early recognition, there is interest in developing biomarkers of sepsis, and most attention is focused on diagnostic biomarkers. While there is a need for ongoing discovery and development of diagnostic biomarkers for sepsis, this review will focus on less well-known applications of sepsis biomarkers. Among patients with sepsis, the biomarkers can give information regarding the risk of poor outcome from sepsis, risk of sepsis-related organ dysfunction, and subgroups of patients with sepsis who share underlying biological features potentially amenable to targeted therapeutics. These types of biomarkers, beyond the traditional concept of diagnosis, address the important concepts of prognostic and predictive enrichment, which are key components of bringing the promise of precision medicine to the bedside of children with sepsis.

Chronic Critical Illness and PICS Nutritional Strategies

The nutritional hallmark of chronic critical illness (CCI) after sepsis is persistent inflammation, immunosuppression, and catabolism syndrome (PICS), which results in global resistance to the anabolic effect of nutritional supplements. This ultimately leaves these patients in a downward phenotypic spiral characterized by cachexia with profound weakness, decreased capacity for rehabilitation, and immunosuppression with the propensity for sepsis recidivism. The persistent catabolism is driven by a pathologic low-grade inflammation with the inability to return to homeostasis and by ongoing increased energy expenditure. Better critical care support systems and advances in technology have led to increased intensive care unit (ICU) survival, but CCI due to PICS with poor long-term outcomes has emerged as a frequent phenotype among ICU sepsis survivors. Unfortunately, therapies to mitigate or reverse PICS-CCI are limited, and recent evidence supports that these patients fail to respond to early ICU evidence-based nutrition protocols. A lack of randomized controlled trials has limited strong recommendations for nutrition adjuncts in these patients. However, based on experience in other conditions characterized by a similar phenotype, immunonutrients aimed at counteracting inflammation, immunosuppression, and catabolism may be important for improving outcomes in PICS-CCI patients. This manuscript intends to review several immunonutrients as adjunctive therapies in treating PICS-CCI.

Functional Outcomes and Morbidity in Pediatric Sepsis Survivors: A Tanzanian Experience

Pediatric sepsis remains a significant cause of childhood morbidity and mortality, disproportionately affecting resource-limited settings. As more patients survive, it is paramount that we improve our understanding of post-sepsis morbidity and its impact on functional outcomes. The functional status scale (FSS) is a pediatric validated outcome measure quantifying functional impairment, previously demonstrating decreased function following critical illnesses, including sepsis, in resource-rich settings. However, functional outcomes utilizing the FSS in pediatric sepsis survivors have never been studied in resource-limited settings or in non-critically ill septic children. In a Tanzanian cohort of pediatric sepsis patients, we aimed to evaluate morbidity associated with an acute septic episode using the FSS modified for resource-limited settings. This was a prospective cohort study at an urban referral hospital in Tanzania, including children with sepsis aged 28 days to 14 years old over a 12-month period. The FSS was adapted to the site's available resources. Functional status scale scores were obtained by interviewing guardians both at the time of presentation to determine the child's baseline and at 28-day follow-up. The primary outcome was "decline in functional status," as defined by a change in FSS score of at least 3. In this cohort, 4.3% of the 1,359 surviving children completing 28-day follow-up had a "decline in functional status." Conversely, 13.8% of guardians reported that their child was not yet back to their pre-illness state. Three-quarters of children reported as not fully recovered were not identified via the FSS as having a decline in functional status. In our cohort of pediatric sepsis patients, we identified a low rate of decline in functional status when using the FSS adapted for resource-limited settings. A higher proportion of children were subjectively identified as not being recovered to baseline. This suggests that the FSS has limitations in this population, despite being adapted for resource-limited settings. Next steps include developing and validating a further revised FSS to better capture patients identified as not recovered but missed by the current FSS.

Dynamic Transitions of Pediatric Sepsis: A Markov Chain Analysis

Pediatric sepsis is a heterogeneous disease with varying physiological dynamics associated with recovery, disability, and mortality. Using risk scores generated from a sepsis prediction model to define illness states, we used Markov chain modeling to describe disease dynamics over time by describing how children transition among illness states. We analyzed 18,666 illness state transitions over 157 pediatric intensive care unit admissions in the 3 days following blood cultures for suspected sepsis. We used Shannon entropy to quantify the differences in transition matrices stratified by clinical characteristics. The population-based transition matrix based on the sepsis illness severity scores in the days following a sepsis diagnosis can describe a sepsis illness trajectory. Using the entropy based on Markov chain transition matrices, we found a different structure of dynamic transitions based on ventilator use but not age group. Stochastic modeling of transitions in sepsis illness severity scores can be useful in describing the variation in transitions made by patient and clinical characteristics.

Autonomic Nervous System Dysfunction Is Associated With Re-hospitalization in Pediatric Septic Shock Survivors

Objective: Re-hospitalization after sepsis can lead to impaired quality of life. Predictors of re-hospitalization could help identify sepsis survivors who may benefit from targeted interventions. Our goal was to determine whether low heart rate variability (HRV), a measure of autonomic nervous system dysfunction, is associated with re-hospitalization in pediatric septic shock survivors. Materials and Methods: This was a retrospective, observational cohort study of patients admitted between 6/2012 and 10/2020 at a single institution. Patients admitted to the pediatric intensive care unit with septic shock who had continuous heart rate data available from the bedside monitors and survived their hospitalization were included. HRV was measured using age-normalized z-scores of the integer HRV (HRVi), which is the standard deviation of the heart rate sampled every 1 s over 5 consecutive minutes. The 24-h median HRVi was assessed on two different days: the last 24 h of PICU admission ("last HRVi") and the 24-h period with the lowest median HRVi ("lowest HRVi"). The change between the lowest and last HRVi was termed "delta HRVi." The primary outcome was re-hospitalization within 1 year of discharge, including both emergency department encounters and hospital readmission, with sensitivity analyses at 30 and 90 days. Kruskal-Wallis, logistic regression, and Poisson regression evaluated the association between HRVi and re-hospitalizations and adjusted for potential confounders. Results: Of the 463 patients who met inclusion criteria, 306 (66%) were re-hospitalized, including 270 readmissions (58%). The last HRVi was significantly lower among re-hospitalized patients compared to those who were not (p = 0.02). There was no difference in the lowest HRVi, but patients who were re-hospitalized showed a smaller recovery in their delta HRVi compared to those who were not re-hospitalized (p = 0.02). This association remained significant after adjusting for potential confounders. In the sensitivity analysis, a smaller recovery in delta HRVi was consistently associated with a higher likelihood of re-hospitalization. Conclusion: In pediatric septic shock survivors, a smaller recovery in HRV during the index admission is significantly associated with re-hospitalization. This continuous physiologic measure could potentially be used as a predictor of patients at risk for re-hospitalization and lower health-related quality of life.