Evolution of surfactant protein-D levels in children with ventilator-associated pneumonia

Infection Associated With Invasive Devices in Pediatric Health Care: A Meta-analysis

CONTEXT

Indwelling invasive devices inserted into the body for extended are associated with infections.

OBJECTIVE

This study aimed to estimate infection proportion and rates associated with invasive devices in pediatric healthcare.

DATA SOURCES

Medline, CINAHL, Embase, Web of Science, Scopus, Cochrane CENTRAL, clinical trial registries, and unpublished study databases were searched.

STUDY SELECTION

Cohort studies and trials published from January 2011 to June 2022, including (1) indwelling invasive devices, (2) pediatric participants admitted to a hospital, (3) postinsertion infection complications, and (4) published in English, were included.

DATA EXTRACTION

Meta-analysis of observational studies in epidemiology guidelines for abstracting and assessing data quality and validity were used.

MAIN OUTCOMES AND MEASURES

Device local, organ, and bloodstream infection (BSIs) pooled proportion and incidence rate (IR) per-1000-device-days per device type were reported.

RESULTS

A total of 116 studies (61 554 devices and 3 632 364 device-days) were included. The highest number of studies were central venous access devices associated BSI (CVAD-BSI), which had a pooled proportion of 8% (95% confidence interval [CI], 6-11; 50 studies) and IR of 0.96 per-1000-device-days (95% CI, 0.78-1.14). This was followed by ventilator-associated pneumonia in respiratory devices, which was 19% (95% CI, 14-24) and IR of 14.08 per-1000-device-days (95%CI, 10.57-17.58).

CONCLUSIONS

Although CVAD-BSI and ventilator associated pneumonia are well-documented, there is a scarcity of reporting on tissue and local organ infections. Standard guidelines and compliance initiatives similar to those dedicated to CVADs should be implemented in other devices in the future.

Evaluation of Five Host Inflammatory Biomarkers in Early Diagnosis of Ventilator-Associated Pneumonia in Critically Ill Children: A Prospective Single Center Cohort Study

Background: Early diagnosis of ventilator-associated pneumonia (VAP) remains a challenge due to subjective clinical criteria and the low discriminative power of diagnostic tests. We assessed whether rapid molecular diagnostics in combination with Clinically Pulmonary Index Score (CPIS) scoring, microbiological surveillance and biomarker measurements of PTX-3, SP-D, s-TREM, PTX-3, IL-1β and IL-8 in the blood or lung could improve the accuracy of VAP diagnosis and follow-up in critically ill children. Methods: A prospective pragmatic study in a Pediatric Intensive Care Unit (PICU) was conducted on ventilated critically ill children divided into two groups: high and low suspicion of VAP according to modified Clinically Pulmonary Index Score (mCPIS). Blood and bronchial samples were collected on days 1, 3, 6 and 12 after event onset. Rapid diagnostics were used for pathogen identification and ELISA for PTX-3, SP-D, s-TREM, IL-1β and IL-8 measurements. Results: Among 20 enrolled patients, 12 had a high suspicion (mCPIS > 6), and 8 had a low suspicion of VAP (mCPIS < 6); 65% were male; and 35% had chronic disease. IL-1β levels at day 1 correlated significantly with the number of mechanical ventilation days (r_s = 0.67, p < 0.001) and the PICU stay (r = 0.66; p < 0.002). No significant differences were found in the levels of the other biomarkers between the two groups. Mortality was recorded in two patients with high VAP suspicion. Conclusions: PTX-3, SP-D, s-TREM, IL-1β and IL-8 biomarkers could not discriminate patients with a high or low suspicion of VAP diagnosis.

Increased surfactant protein-D levels in the airways of preterm neonates with sepsis indicated responses to infectious challenges

AIM

Sepsis is multifactorial and potentially devastating for preterm neonates. Changes in surfactant protein-D (SP-D), phosphatidylcholine (PC) and PC molecular species during infection may indicate innate immunity or inflammation during sepsis. We aimed to compare these important pulmonary molecules in ventilated neonates without or with sepsis.

METHODS

Endotracheal aspirates were collected from preterm neonates born at 23-35 weeks and admitted to the neonatal intensive care unit at the John Radcliffe Hospital, Oxford, UK, from October 2000 to March 2002. Samples were collected at one day to 30 days and analysed for SP-D, total PC and PC molecular species concentrations using enzyme-linked immunosorbent assay and mass spectrometry.

RESULTS

We found that 8/54 (14.8%) neonates developed sepsis. SP-D (p < 0.0001), mono- and di-unsaturated PC were significantly increased (p = 0.05), and polyunsaturated PC was significantly decreased (p < 0.01) during sepsis compared to controls. SP-D:PC ratios were significantly increased during sepsis (p < 0.001), and SP-D concentrations were directly related to gestational age in neonates with sepsis (r²  = 0.389, p < 0.01).

CONCLUSION

Increased SP-D levels and changes in PC molecular species during sepsis were consistent with direct or indirect pulmonary inflammatory processes. Very preterm neonates we able to mount an acute inflammatory innate immune response to infectious challenges, despite low levels of surfactant proteins at birth.

Pediatric Ventilator-Associated Events: Analysis of the Pediatric Ventilator-Associated Infection Data

OBJECTIVES

To compare the prevalence of infection applying the proposed pediatric ventilator-associated events criteria versus clinician-diagnosed ventilator-associated infection to subjects in the pediatric ventilator-associated infection study.

DESIGN

Analysis of prospectively collected data from the pediatric ventilator-associated infection study.

SETTING

PICUs of 47 hospitals in the United States, Canada, and Australia.

PATIENTS

Two-hundred twenty-nine children ventilated for greater than 48 hours who had respiratory secretion cultures performed to evaluate for suspected ventilator-associated infection.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Applying the proposed pediatric ventilator-associated event criteria, 15 of 229 subjects in the ventilator-associated infection study qualified as "ventilator-associated condition" and five of 229 (2%) met criteria for "infection-related ventilator-associated complication." This was compared with 89 of 229 (39%) diagnosed as clinical ventilator-associated infection (Kappa = 0.068). Ten of 15 subjects identified as ventilator-associated condition did not meet criteria for infection-related ventilator-associated complication primarily because they did not receive 4 days of antibiotics. Ventilator-associated condition subjects were similar demographically to nonventilator-associated condition subjects and had similar mortality (13% vs 10%), PICU-free days (6.9 ± 7.7; interquartile range, 0-14 vs 9.8 ± 9.6; interquartile range, 0-19; p = 0.25), but fewer ventilator-free days (6.6 ± 9.3; interquartile range, 1-15 vs 12.4 ± 10.7; interquartile range, 0-22; p = 0.04). The clinical ventilator-associated infection diagnosis in the ventilator-associated infection study was associated with fewer PICU-free days but no difference in mortality or ventilator-free days.

CONCLUSIONS

The ventilator-associated event criteria appear to be insensitive to the clinical diagnosis of ventilator-associated infection. Differentiation between ventilator-associated condition and infection-related ventilator-associated complication was primarily determined by the clinician decision to treat with antibiotics rather than clinical signs and symptoms. The utility of the proposed pediatric ventilator-associated event criteria as a surrogate for ventilator-associated infection criteria is unclear.

Ventilator-associated pneumonia in neonates and children: a systematic analysis of diagnostic methods and prevention

AIM

While ventilator-associated pneumonia (VAP) remains frequent in Pediatric ICU, there is no gold standard for diagnosis.

METHODOLOGY

We conducted a systematic PUBMED analysis (January 1990-January 2017) searching original, full-length studies addressing only pediatric patients; for VAP diagnosis, only those comparing different diagnostic methods and for VAP prevention those implementing preventive measures.

RESULTS

Among 367 articles, 17 and 16 were analyzed for diagnosis and prevention, respectively. For diagnosis, 13 studies used CDC criteria; whereas, 14 assessed algorithms: clinical pulmonary index score, ventilator-associated events and biomarkers. Among five randomized trials assessing preventive strategies one found a role of probiotics. Ventilator-care bundles reduced VAP rates.

CONCLUSION

Absence of diagnostic gold standard impedes comparison of current approaches and preventive strategies.

New Biomarkers to Diagnose Ventilator Associated Pneumonia: Pentraxin 3 and Surfactant Protein D

OBJECTIVE

To detect the most effective biomarker to confirm ventilator associated pneumonia (VAP).

METHODS

Fifty patients with VAP suspicious diagnosis and 30 healthy patients were recruited. Suspicion of VAP was established if patients met the modified CPIS score ≥ 6 points. The confirmation of VAP was defined by the quantitative culture of nonbronchoscopic bronchoalveolar lavage (BAL) >10⁵ CFU/ml of pathogenic microorganism. Serum samples for determination of C-reactive protein (CRP), procalcitonin (PCT), pentraxin 3 (PTX3), surfactant protein D (SPD) were collected on suspected VAP.

RESULTS

Twenty seven of 50 patients were accepted as confirmed VAP group whose nonbronchoscopic BAL cultures were positive and rest of them were accepted as unconfirmed VAP group. PTX3, PCT and SPD levels were significantly higher in confirmed VAP group, (P = 0.021, P = 0.007, P < 0.001 respectively). There were no significant differences in CRP levels between the two groups (P = 0.062). The most sensitive marker for diagnosing VAP was SPD (P < 0.001). Receiver operating characteristic (ROC) curve for modified clinical pulmonary infection score (CPIS) to confirm VAP was evaluated (AUC 0.741 ± 0.07, P < 0.001) and the optimal cutoff value was >7 with a sensitivity of 51.85% and a specificity of 91.3%. SPD levels were significantly higher in Acinetobacter baumannii and Pseudomonas aeruginosa infected patients than culture negative patients (P < 0.001).

CONCLUSIONS

The index findings suggest that serum SPD is the most sensitive biomarker in diagnosis of VAP and it can be used as an early and organism specific marker for Acinetobacter baumannii and Pseudomonas aeruginosa.

Future Directions and Molecular Basis of Ventilator Associated Pneumonia

Mechanical ventilation is a lifesaving treatment and has complications such as ventilator associated pneumonia (VAP) that lead to high morbidity and mortality. Moreover VAP is the second most common hospital-acquired infection in pediatric intensive care units. Although it is still not well understood, understanding molecular pathogenesis is essential for preventing and treating pneumonia. A lot of microbes are detected as a causative agent of VAP. The most common isolated VAP pathogens in pediatric patients are Staphylococcus aureus, Pseudomonas aeruginosa, and other gram negative bacteria. All of the bacteria have different pathogenesis due to their different virulence factors and host reactions. This review article focused on mechanisms of VAP with molecular pathogenesis of the causative bacteria one by one from the literature. We hope that we know more about molecular pathogenesis of VAP and we can investigate and focus on the management of the disease in near future.

Pediatric Ventilator-Associated Infections: The Ventilator-Associated INfection Study

OBJECTIVE

Suspected ventilator-associated infection is the most common reason for antibiotics in the PICU. We sought to characterize the clinical variables associated with continuing antibiotics after initial evaluation for suspected ventilator-associated infection and to determine whether clinical variables or antibiotic treatment influenced outcomes.

DESIGN

Prospective, observational cohort study conducted in 47 PICUs in the United States, Canada, and Australia. Two hundred twenty-nine pediatric patients ventilated more than 48 hours undergoing respiratory secretion cultures were enrolled as "suspected ventilator-associated infection" in a prospective cohort study, those receiving antibiotics of less than or equal to 3 days were categorized as "evaluation only," and greater than 3 days as "treated." Demographics, diagnoses, comorbidities, culture results, and clinical data were compared between evaluation only and treated subjects and between subjects with positive versus negative cultures.

SETTING

PICUs in 47 hospitals in the United States, Canada, and Australia.

SUBJECTS

All patients undergoing respiratory secretion cultures during the 6 study periods.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Treated subjects differed from evaluation-only subjects only in frequency of positive cultures (79% vs 36%; p < 0.0001). Subjects with positive cultures were more likely to have chronic lung disease, tracheostomy, and shorter PICU stay, but there were no differences in ventilator days or mortality. Outcomes were similar in subjects with positive or negative cultures irrespective of antibiotic treatment. Immunocompromise and higher Pediatric Logistic Organ Dysfunction scores were the only variables associated with mortality in the overall population, but treated subjects with endotracheal tubes had significantly lower mortality.

CONCLUSIONS

Positive respiratory cultures were the primary determinant of continued antibiotic treatment in children with suspected ventilator-associated infection. Positive cultures were not associated with worse outcomes irrespective of antibiotic treatment although the lower mortality in treated subjects with endotracheal tubes is notable. The necessity of continuing antibiotics for a positive respiratory culture in suspected ventilator-associated infection requires further study.

Biomarkers in Pediatric ARDS: Future Directions

Acute respiratory distress syndrome (ARDS) is common among mechanically ventilated children and accompanies up to 30% of all pediatric intensive care unit deaths. Though ARDS diagnosis is based on clinical criteria, biological markers of acute lung damage have been extensively studied in adults and children. Biomarkers of inflammation, alveolar epithelial and capillary endothelial disruption, disordered coagulation, and associated derangements measured in the circulation and other body fluids, such as bronchoalveolar lavage, have improved our understanding of pathobiology of ARDS. The biochemical signature of ARDS has been increasingly well described in adult populations, and this has led to the identification of molecular phenotypes to augment clinical classifications. However, there is a paucity of data from pediatric ARDS (pARDS) patients. Biomarkers and molecular phenotypes have the potential to identify patients at high risk of poor outcomes, and perhaps inform the development of targeted therapies for specific groups of patients. Additionally, because of the lower incidence of and mortality from ARDS in pediatric patients relative to adults and lack of robust clinical predictors of outcome, there is an ongoing interest in biological markers as surrogate outcome measures. The recent definition of pARDS provides additional impetus for the measurement of established and novel biomarkers in future pediatric studies in order to further characterize this disease process. This chapter will review the currently available literature and discuss potential future directions for investigation into biomarkers in ARDS among children.

How the modified Clinical Pulmonary Infection Score can identify treatment failure and avoid overusing antibiotics in ventilator-associated pneumonia

AIM

Although the modified Clinical Pulmonary Infection Score (CPIS) has been used to guide treatment decisions in adults with ventilator-associated pneumonia (VAP), paediatric studies are lacking. We assessed a modified CPIS tool to define VAP resolution and identify treatment failure at an early stage.

METHODS

We identified 70 mechanically ventilated children with VAP according to the Center for Disease Control criteria. Modified CPIS was initially measured at VAP onset and then three and five days afterwards. Children were defined as low risk or high risk based on a cut-off score of six.

RESULTS

There were 50 high-risk and 20 low-risk patients. Culture results were positive in 64% of the high-risk patients and just 10% of the low-risk patients. Patients on adequate therapy significantly improved their CPIS scores by day three, regardless of the likelihood of VAP. A lack of score improvement demonstrated sensitivity of 100% and specificity of 83% when it came to detecting treatment failure. The area under the receiver operating curve was 0.92.

CONCLUSION

Serial modified CPIS measurements showed that low-risk patients with negative cultures at day three should be considered for a short course of antibiotics. In contrast, high-risk patients with no score improvement were potentially failing their treatment.

Translational research in pediatrics III: bronchoalveolar lavage

The role of flexible bronchoscopy and bronchoalveolar lavage (BAL) for the care of children with airway and pulmonary diseases is well established, with collected BAL fluid most often used clinically for microbiologic pathogen identification and cellular analyses. More recently, powerful analytic research methods have been used to investigate BAL samples to better understand the pathophysiological basis of pediatric respiratory disease. Investigations have focused on the cellular components contained in BAL fluid, such as macrophages, lymphocytes, neutrophils, eosinophils, and mast cells, as well as the noncellular components such as serum molecules, inflammatory proteins, and surfactant. Molecular techniques are frequently used to investigate BAL fluid for the presence of infectious pathologies and for cellular gene expression. Recent advances in proteomics allow identification of multiple protein expression patterns linked to specific respiratory diseases, whereas newer analytic techniques allow for investigations on surfactant quantification and function. These translational research studies on BAL fluid have aided our understanding of pulmonary inflammation and the injury/repair responses in children. We review the ethics and practices for the execution of BAL in children for translational research purposes, with an emphasis on the optimal handling and processing of BAL samples.

The lack of specificity of tracheal aspirates in the diagnosis of pulmonary infection in intubated children

OBJECTIVES

Ventilator-associated pneumonia is the first or second most commonly diagnosed nosocomial infection in the PICU. Centers for Disease Control diagnostic criteria include clinical signs or symptoms in conjunction with a "positive" tracheal aspirate, defined as more than 10 colony-forming units/mL of bacteria on quantitative culture and/or more than 25 polymorphonuclear neutrophils per low-power field on Gram stain. We hypothesized that tracheal aspirate cultures and Gram stains would not correlate with clinical signs and symptoms and would therefore not distinguish between colonization and infection.

DESIGN

Prospective observational study.

SETTING

PICU in an academic tertiary care center.

PATIENTS

Children intubated more than 48 hours.

INTERVENTIONS

Sequential tracheal aspirate quantitative cultures and Gram stains in conjunction with daily collection of concordant clinical signs and symptoms.

MEASUREMENTS AND MAIN RESULTS

Time since intubation correlated strongly (p < 0.001) with the proportion of positive (> 10 colony-forming units/mL) tracheal aspirate quantitative cultures, but Centers for Disease Control-defined clinical signs or symptoms of ventilator-associated pneumonia, either singly or in combination, did not. Use of in-line suction catheters versus new, sterile catheters to obtain tracheal aspirates was associated with significantly greater proportion of positive tracheal aspirate bacterial cultures (p < 0.001). Most subjects had more than 25 polymorphonuclear neutrophils per low-power field on Gram stain; polymorphonuclear neutrophils on Gram stain correlated with positive bacterial culture (p = 0.04). Seventy-seven percent of the bacterial isolates detected in positive quantitative cultures were "pathogens." Antibiotic use at the time tracheal aspirates were obtained was associated with a lower frequency of positive quantitative cultures only with antibiotic regimens that included cefepime.

CONCLUSIONS

Positive bacterial cultures of tracheal aspirates increase rapidly after intubation and usually include bacteria considered to be pathogens. Tracheal aspirate cultures and Gram stains do not appear to distinguish between infection and colonization. Antibiotic regimens that include cefepime decrease the frequency of positive cultures, but the significance of this is unclear.

Value of clinical pulmonary infection score in critically ill children as a surrogate for diagnosis of ventilator-associated pneumonia

RATIONALE

Although the modified clinical pulmonary infection score (mCPIS) has been endorsed by national organizations, only a very few pediatric studies have assessed it for the diagnosis of ventilator-associated pneumonia (VAP).

METHODS

Seventy children were prospectively included if they fulfilled the diagnosis criteria for VAP referenced by the Centers for Disease Control and Prevention. The primary outcome was performance of mCPIS calculated on day 1 to accurately identify VAP as defined by microbiological data.

RESULTS

The data showed that an mCPIS of 6 or higher had a sensitivity of 94%, specificity of 50%, positive predictive value of 64%, negative predictive value of 90%, a positive likelihood ratio of 1.88, and a negative likelihood ratio of 0.11. The area under the receiver operating characteristic curve was 0.70. A positive posttest result increased the disease probability by 15.4%, whereas a negative test result reduced the probability by 38.6%. Patients with an mCPIS of 6 or higher had longer length of mechanical ventilation and pediatric intensive care unit stay compared with patients with an mCPIS lower than 6.

CONCLUSION

The mCPIS had a clinically acceptable performance, and it can be a helpful screening tool for VAP diagnosis. An mCPIS lower than 6 was highly able in distinguishing patients without VAP. Despite its high sensitivity and negative predictive value of this score, further studies are required to assess the use of mCPIS in guiding therapeutic decisions.