Reproducibility of blind protected bronchoalveolar lavage in mechanically ventilated children

Ventilator-Associated Pneumonia in Critically Ill Children: A New Paradigm

Ventilator-associated pneumonia (VAP) is a serious complication of critical illness. Surveillance definitions have undergone revisions for more objective and consistent reporting. The 1 organism-1 disease paradigm for microbial involvement may not adequately apply to many cases of VAP, in which pathogens are introduced to a pre-existing and often complex microbial community that facilitates or hinders the potential pathogen, consequently determining whether progression to VAP occurs. As omics technology is applied to VAP, a paradigm is emerging incorporating simultaneous assessments of microbial populations and their activity, as well as the host response, to personalize prevention and treatment.

Diagnosis of bacterial ventilator-associated pneumonia in children: reproducibility of blind bronchial sampling

OBJECTIVE

To evaluate the reproducibility of blind bronchial sampling in patients with suspected diagnosis of bacterial ventilator-associated pneumonia.

DESIGN

Prospective study.

SETTING

Pediatric intensive care unit of a tertiary care, multidisciplinary, teaching hospital in Northern India.

PATIENTS

All consecutive patients on mechanical ventilation for >48 hrs were evaluated clinically for ventilator-associated pneumonia.

INTERVENTIONS

Children with clinical ventilator-associated pneumonia were subjected to blind bronchial sampling twice.

MEASUREMENTS AND MAIN RESULTS

Sixty-eight blind bronchial sampling samples from 34 patients were analyzed for polymorphonuclear cells, the presence, type, and number of bacteria. Acinetobacter baumannii was the most common organism grown from distal respiratory secretions. For polymorphonuclear cells, the concordance between two blind bronchial samples was 85.3% and kappa coefficient was 0.65. The concordance for the presence and type of bacteria in Gram staining in two samples was 85.3% and kappa coefficient was 0.68. The intraclass coefficients for bacterial index and predominant species index were 0.82 (95% confidence interval 0.65-0.91) and 0.89 (95% confidence interval 0.78-0.94), respectively. The use of prior antibiotics did not adversely affect the reproducibility of blind bronchial sampling. No major complications were recorded during the procedure.

CONCLUSIONS

Blind bronchial sampling of lower respiratory tract secretions in mechanically ventilated patients generates reproducible results of quantitative and qualitative cultures. We suggest that blind bronchial sampling may provide valuable clue to the bacterial etiology in ventilated child with suspected clinical ventilator-associated pneumonia.

Ventilator-associated pneumonia in newborn infants diagnosed with an invasive bronchoalveolar lavage technique: a prospective observational study

OBJECTIVES

To establish the incidence, etiology, risk factors, and outcomes associated with ventilator-associated pneumonia using an invasive sampling technique to avoid contamination.

PATIENTS

Eligible patients were intubated neonates treated with mechanical ventilation who followed the criteria of the Centers for Disease Control and Prevention/National Nosocomial Infection Surveillance. Bronchoalveolar lavage samples were collected using a blind-protected catheter to avoid contamination of upper respiratory microorganisms. Isolation of >10(3) colony-forming unit/mL was required for diagnosis.

MEASUREMENTS AND MAIN RESULTS

In 198 neonates intubated for >48 hrs, a total of 18 episodes of ventilator-associated pneumonia in 16 infants representing a prevalence of 8.1 were diagnosed. The pooled mean ventilator-associated pneumonia rate was 10.9/1,000 ventilator days. The mean age at diagnosis of ventilator-associated pneumonia was 29 ± 15 days after a mean of 21 ± 16 days of mechanical ventilation. Gram-negative bacteria were the most commonly isolated pathogens and Pseudomonas aeruginosa was the most frequent causative agent. Hospital length of stay was significantly longer for ventilator-associated pneumonia patients; however, no significant differences in mortality were found. Univariate analysis comparing patients with and without ventilator-associated pneumonia showed that days of mechanical ventilation, days of oxygen, number of reintubations, number of transfusions, bloodstream infection, and enteral feeding were all significantly associated with ventilator-associated pneumonia. However, in multivariate analysis the unique independent risk factor was days of mechanical ventilation (odds ratio 1.12, confidence interval 95% 1.07-1.17).

CONCLUSIONS

Ventilator-associated pneumonia is a frequent nosocomial infection in newborns. Only duration of mechanical ventilation has been identified as an independent risk factor for ventilator-associated pneumonia. The use of a blind invasive sampling technique seems to diminish sample contamination.

The management of community-acquired pneumonia in infants and children older than 3 months of age: clinical practice guidelines by the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America

Evidenced-based guidelines for management of infants and children with community-acquired pneumonia (CAP) were prepared by an expert panel comprising clinicians and investigators representing community pediatrics, public health, and the pediatric specialties of critical care, emergency medicine, hospital medicine, infectious diseases, pulmonology, and surgery. These guidelines are intended for use by primary care and subspecialty providers responsible for the management of otherwise healthy infants and children with CAP in both outpatient and inpatient settings. Site-of-care management, diagnosis, antimicrobial and adjunctive surgical therapy, and prevention are discussed. Areas that warrant future investigations are also highlighted.

Opportunities for antibiotic reduction in mechanically ventilated children

OBJECTIVE

To identify opportunities to safely reduce antibiotic use in critically ill children with moderately severe respiratory failure.

DESIGN

Prospective observational.

SETTING

Four pediatric intensive care units at three American tertiary care children's hospitals.

PATIENTS

Children aged 2 months to 18 yrs who were mechanically ventilated, had an abnormal chest radiograph, and for whom the attending physicians had initiated antibiotics for presumed bacterial pneumonia.

INTERVENTION

Nonbronchoscopic bronchoalveolar lavage.

METHODS AND MAIN RESULTS

Eligible children were subjected to nonbronchoscopic bronchoalveolar lavage within 12 hrs of initiating antibiotics. The concentration of bacteria in the lavage fluid was determined by quantitative assay, and the diagnosis of pneumonia was confirmed if >10 (4)pathogenic bacteria/mL were cultivated. Twenty-one subjects were enrolled, in whom 20 nonbronchoscopic bronchoalveolar lavage procedures were completed. Six of 20 subjects had nonbronchoscopic bronchoalveolar lavage results confirmatory of bacterial pneumonia, three additional subjects had bacteria isolated at concentrations below levels conventionally used to diagnose bacterial pneumonia, and the remaining 11 demonstrated no growth. Clinical parameters reflective of severity of disease and laboratory parameters reflective of systemic and local inflammation were tested for their association with a positive nonbronchoscopic bronchoalveolar lavage, but none was demonstrated.

CONCLUSIONS

Eleven of 20 mechanically ventilated children treated with antibiotics for presumed infectious pneumonia had undetectable concentrations of bacteria in their lower respiratory tract, and three others had organisms present at low concentrations, suggesting that opportunities exist to reduce antibiotic exposure in this population.

The diagnostic dilemma of ventilator-associated pneumonia in critically ill children

OBJECTIVE

A review of the existing literature on ventilator-associated pneumonia in children with emphasis on problems in diagnosis.

DATA SOURCES

A systematic literature review from 1947 to 2010 using Ovid MEDLINE, PubMed, Cochrane Central Register of Controlled Trials, and ISI Web of Science using key words "ventilator associated pneumonia" and "children." Where pediatric data were lacking, appropriate adult studies were reviewed and similarly referenced.

STUDY SELECTION

Two hundred sixty-two pediatric articles were reviewed and data from 48 studies selected. Data from 61 adult articles were also included in this review.

DATA EXTRACTION AND SYNTHESIS

Ventilator-associated pneumonia is the second most common nosocomial infection and the most common reason for antibiotic use in the pediatric intensive care unit. Attributable mortality is uncertain but ventilator-associated pneumonia is associated with significant morbidity and cost. Diagnosis is problematic in that clinical, radiologic, and microbiologic criteria lack sensitivity and specificity relative to autopsy histopathology and culture. Qualitative tracheal aspirate cultures are commonly used in diagnosis but lack specificity. Quantitative tracheal aspirate cultures have sensitivity (31-69%) and specificity (55-100%) comparable to bronchoalveolar lavage (11-90% and 43-100%, respectively) but concordance for the same bacterial species when compared with autopsy lung culture was better for bronchoalveolar lavage (52-90% vs. 50-76% for quantitative tracheal aspirate). Staphylococcus aureus and Pseudomonas species are the most common organisms, but microbiologic flora change over time and with antibiotic use. Initial antibiotics should offer broad-spectrum coverage but should be narrowed as clinical response and cultures dictate.

CONCLUSIONS

Ventilator-associated pneumonia is an important nosocomial infection in the pediatric intensive care unit. Conclusions regarding epidemiology, treatment, and outcomes are greatly hampered by the inadequacies of current diagnostic methods. We recommend a more rigorous approach to diagnosis by using the Centers for Disease Control and Prevention algorithm. Given that ventilator-associated pneumonia is the most common reason for antibiotic use in the pediatric intensive care unit, more systematic studies are sorely needed.

Health Care–Associated Infection in the Pediatric Intensive Care Unit

•Handwashing is the most important means of preventing nosocomial infection. Each pediatric intensive care unit should develop programs to increase compliance with hand hygiene. •Nonessential invasive devices should be removed. Establish routines that require individual patient evaluation of device use daily. •Antimicrobial stewardship aims to minimize overexposure and unnecessary use of broad-spectrum antibiotics. Antibiotic-resistant bacteria are an increasing concern as a cause of hospital-acquired infection, requiring a multipronged approach to control that includes adherence to isolation procedures, appropriate use of antibiotics, educational interventions, prescribing guidelines, and restriction of the use of some antibiotics. •A comprehensive infection prevention and control program allied with organizational quality and patient safety programs is an essential strategy for minimizing hospital-acquired infections. Critical care teams should establish strong collaborative partnerships with the infection prevention and control service. •Parents and visitors should be made partners of the infection control team to help prevent infection in their children.

Cell profile of BAL fluid in children and adolescents with and without lung disease

The objective of this study was to review the literature on bronchoalveolar lavage fluid cell profiles in healthy children and adolescents, as well as on the use of BAL as a diagnostic and follow-up tool for lung disease patients in this age bracket. To that end, we used the Medline database, compiling studies published between 1989 and 2009 employing the following MeSH descriptors (with Boolean operators) as search terms: bronchoalveolar lavage AND cytology OR cell AND child. In healthy children, the cell profile includes alveolar macrophages (> 80%), lymphocytes (approximately 10%), neutrophils (approximately 2%) and eosinophils (< 1%). The profile varies depending on the disease under study. The number of neutrophils is greater in wheezing children, especially in non-atopic children, as well as in those with pulmonary infectious and inflammatory profiles, including cystic fibrosis and interstitial lung disease. Eosinophil counts are elevated in children/adolescents with asthma and can reach high levels in those with allergic bronchopulmonary aspergillosis or eosinophilic syndromes. In a heterogeneous group of diseases, the number of lymphocytes can increase. Evaluation of the BAL fluid cell profile, when used in conjunction with clinical and imaging findings, has proven to be an essential tool in the investigation of various lung diseases. Less invasive than transbronchial and open lung biopsies, BAL has great clinical value. Further studies adopting standard international protocols should be carried out. Such studies should involve various age groups and settings in order to obtain reference values for BAL fluid cell profiles, which are necessary for a more accurate interpretation of findings in children and adolescents with lung diseases.

Diagnosis of ventilator-associated pneumonia in children in resource-limited setting: a comparative study of bronchoscopic and nonbronchoscopic methods

OBJECTIVES

To compare the available methods for the diagnosis of ventilator-associated pneumonia in intubated pediatric patients and to suggest less costly diagnostic method for developing countries.

DESIGN

Prospective study.

SETTING

Pediatric intensive care unit of a tertiary care, multidisciplinary teaching hospital located in northern India.

PATIENTS

All consecutive patients on mechanical ventilation for >48 hrs were evaluated clinically for ventilator-associated pneumonia.

INTERVENTIONS

Four diagnostic procedures (tracheal aspiration, blind bronchial sampling, blind bronchoalveolar lavage, and bronchoscopic bronchoalveolar lavage) were performed in the same sequence within 12 hrs of clinical suspicion of ventilator-associated pneumonia. The bacterial density > or =104 colony-forming units/mL in a bronchoscopic bronchoalveolar lavage sample was taken as reference standard.

MEASUREMENTS AND MAIN RESULTS

Thirty patients with 40 episodes of ventilator-associated pneumonia were included in the study. Tracheal aspirate at the cutoff of > or =105 colony-forming units/mL was found to have sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 84%, 77%, 87.5%, 73%, and 80%, respectively. For blind bronchial sampling at > or =104 colony-forming units/mL cutoff, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 88%, 82%, 88%, 83%, and 87%, respectively; the most reliable results were obtained with blind bronchoalveolar lavage at the cutoff of > or =103 cfu/mL (sensitivity 96%, specificity 80%, positive predictive value 88%, negative predictive value 92%, and accuracy 90%). The area under the receiver operating characteristic curve of tracheal aspiration, blind bronchial sampling, and blind bronchoalveolar lavage was 0.87 +/- 0.06, 0.89 +/- 0.06, and 0.89 +/- 0.05, respectively. The cost of balloon-tip pressure catheter used for blind bronchoalveolar lavage was INR 1600.00 (US$40) whereas that for blind bronchial sampling was only INR 35.00 (<1 US$).

CONCLUSIONS

Blind bronchoalveolar lavage was the most reliable method followed closely by blind bronchial sampling for the diagnosis of ventilator-associated pneumonia. Considering the difference of the cost in the two procedures, blind bronchial sampling may be the preferred method in the pediatric intensive care unit of a developing country.

Determining cystic fibrosis-affected lung microbiology: comparison of spontaneous and serially induced sputum samples by use of terminal restriction fragment length polymorphism profiling

Sampling of the lower airways of the adult cystic fibrosis (CF) lung has received insufficient detailed consideration, with the importance of sampling strategies for bacteriological outcome not known. Although spontaneously expectorated sputum (SES) samples are often used for diagnostic bacteriological analysis, induced sputum (IS) methods have advantages. This study examined whether significant differences in bacterial content were detected when using a culture-independent, molecular profiling technique to analyze SES or IS samples. Moreover, this work examined what trends relating to bacterial species distributions and reproducibility were found in sequentially induced sputum samples and what implications this has for pathogen detection. Terminal restriction fragment length polymorphism (T-RFLP) analysis was performed on a SES sample and 4 subsequent IS samples taken at 5-min intervals from 10 clinically stable, adult CF patients. This was repeated over 3 sampling days, with variability between samples, induction periods, and sampling days determined. A diverse range of bacterial species, including potentially novel pathogens, was found. No significant difference in bacterial content was observed for either SES or serial IS samples. On average, the analysis of a single sample from any time point resolved approximately 58% of total bacterial diversity achieved by analysis of an SES sample and 4 subsequent IS samples. The reliance on analysis of a single respiratory sample was not sufficient for the detection of recognized CF pathogens in all instances. Close correlation between T-RFLP and microbiological data in the detection of key species indicates the importance of these findings in routine diagnostics for the detection of recognized and novel CF pathogens.

Nosocomial infections in the pediatric intensive care unit: affecting the impact on safety and outcome

OBJECTIVE

To define the most common types of nosocomial infections in critically ill children and to summarize the effect of methods to reduce their prevalence.

DESIGN

Review of published literature.

RESULTS

While in the pediatric intensive care unit, 16% of children develop a nosocomial infection. Processes affecting modifiable factors of care can reduce the prevalence of hospital-acquired infections.

CONCLUSIONS

The occurrence of a nosocomial infection represents failure and is not an acceptable outcome of treating critically ill children. Evidence-based process improvement can lead to significant reductions in hospital-acquired infections in children. Most of the processes and practices discussed are not novel or intriguing but, when performed routinely and appropriately, can lead to reductions in hospital-acquired infections.

High incidence of pulmonary bacterial co-infection in children with severe respiratory syncytial virus (RSV) bronchiolitis

BACKGROUND

Respiratory syncytial virus (RSV) is the most common cause of viral lower respiratory tract infections (LRTI). Viral LRTI is a risk factor for bacterial superinfection, having an escalating incidence with increasing severity of respiratory illness. A study was undertaken to determine the incidence of pulmonary bacterial co-infection in infants and children with severe RSV bronchiolitis, using paediatric intensive care unit (PICU) admission as a surrogate marker of severity, and to study the impact of the co-infection on morbidity and mortality.

METHODS

A prospective microbiological analysis was made of lower airways secretions on all RSV positive bronchiolitis patients on admission to the PICU during three consecutive RSV seasons.

RESULTS

One hundred and sixty five children (median age 1.6 months, IQR 0.5-4.6) admitted to the PICU with RSV bronchiolitis were enrolled in the study. Seventy (42.4%) had lower airway secretions positive for bacteria: 36 (21.8%) were co-infected and 34 (20.6%) had low bacterial growth/possible co-infection. All were mechanically ventilated (median 5.0 days, IQR 3.0-7.3). Those with bacterial co-infection required ventilatory support for longer than those with only RSV (p<0.01). White cell count, neutrophil count, and C-reactive protein did not differentiate between the groups. Seventy four children (45%) received antibiotics prior to intubation. Sex, co-morbidity, origin, prior antibiotics, time on preceding antibiotics, admission oxygen, and ventilation index were not predictive of positive bacterial cultures. There were 12 deaths (6.6%), five of which were related to RSV.

CONCLUSIONS

Up to 40% of children with severe RSV bronchiolitis requiring admission to the PICU were infected with bacteria in their lower airways and were at increased risk for bacterial pneumonia.

Defining pneumonia in critically ill infants and children

OBJECTIVE

To define pneumonia in critically ill children in the intensive care unit setting for surveillance of infection and for the design, conduct, and evaluation of clinical trials in the prevention and therapy of lower respiratory tract infections in this population.

DESIGN

Summary of the literature with review and consensus by experts in the field.

RESULTS

A variety of diagnostic criteria from the medical literature, professional societies, and governmental health agencies and regulators were identified. Very few of these diagnostic criteria have been validated for use in children. We propose definitions for definite, possible, and probable pneumonia that build on identified definitions in the literature and use combinations of symptoms, signs, and laboratory criteria. Gaps in knowledge were identified.

CONCLUSIONS

Although pneumonia is one of the most common diagnoses in critically ill children, there have been few studies validating diagnostic criteria. Definitions for definite, probable, and possible community-acquired pneumonia and nosocomial pneumonia were achieved by consensus of experts based on guidelines from governmental agencies, professional organizations, and published literature. Future research should determine the utility of these definitions in the critically ill child and adapt them accordingly.

Concurrent bacterial infection and prolonged mechanical ventilation in infants with respiratory syncytial virus lower respiratory tract disease

OBJECTIVE

To identify demographic, clinical, and laboratory variables predictive for a concurrent bacterial pulmonary infection in ventilated infants with respiratory syncytial virus (RSV) lower respiratory tract disease (LRTD) and investigate antimicrobial drug use.

DESIGN AND SETTING

Retrospective, observational study in a 14-bed pediatric intensive care unit.

PATIENTS

82 infants younger than 1 year of age with a virologically confirmed RSV LRTD during 1996-2001, of whom 65 were mechanically ventilated.

RESULTS

Microbiological data were available from 38 ventilated infants, 10 of whom had a positive blood culture (n=1) or endotracheal aspirate (n=9) obtained upon admission to the pediatric intensive care unit (PICU). Infants with a positive culture had a lower mean gestational age but were otherwise demographically comparable to those with negative culture results. Infants with a positive culture were ventilated 4 days longer. Indicators for a concurrent bacterial infection were comparable between ventilated and nonventilated infants. Antimicrobial drugs were used in 95.1% of infants (100% of ventilated infants) with a mean duration of 7.8+/-0.3 days. The moment of initiation and duration of antimicrobial drug treatment varied considerably.

CONCLUSIONS

We observed in ventilated infants a low occurrence of concurrent bacterial pulmonary infection, but infants with positive cultures needed prolonged ventilatory support. Improvement in the diagnosis of a pulmonary bacterial infection is warranted to reduce the overuse of antimicrobial drugs among ventilated infants with RSV LRTD and to restrict these drugs to the proper patients.

[Difficulties on diagnosis of ventilator associated pneumonia]

Ventilator associated pneumonia is associated with high morbidity and mortality. It is important a correct diagnosis in way to guide the antibiotic therapy in the most appropriate way. However, its diagnosis is difficult, because clinical and radiologic features are not specific and approaches to standard diagnosis, that allow its confirmation, are very invasive or not very frequent. Protected techniques and quantitative cultures have been trying to outline the problem of the contamination of the samples obtained by routine methods and to allow the distinction between colonization and infection. The author makes a revision on the different methods of diagnosis of this clinical entity.

Ventilator-associated pneumonia in intubated children: comparison of different diagnostic methods

OBJECTIVES

To compare different methods for diagnosis of ventilator-associated pneumonia in intubated children.

DESIGN

Prospective epidemiologic study.

SETTING

Pediatric intensive care unit of a tertiary care university hospital.

PATIENTS

All consecutive pediatric intensive care unit patients <18 yrs of age with suspected ventilator-associated pneumonia.

INTERVENTIONS

For all patients, the following diagnostic methods were compared: 1) clinical data using Centers for Disease Control criteria; 2) blind protected bronchoalveolar lavage, evaluating quantitative cultures, bacterial index of >5, Gram stain, and presence of intracellular bacteria; and 3) nonquantitative cultures of endotracheal secretions. The reference standard used was clinical judgment of three independent experts (Delphi method) who retrospectively established by consensus the presence of ventilator-associated pneumonia based on clinical, microbiological, and radiologic data. Concordance between each diagnostic method and the reference standard was evaluated by concordance percentage and kappa score. Validity was evaluated using sensitivity, specificity, positive predictive value, negative predictive value, and global value.

RESULTS

A total of 30 patients were included in the study. According to the reference standard, ventilator-associated pneumonia occurred in 10 of 30 patients (33%). Bacterial index of >5 in bronchoalveolar secretions showed the best concordance compared with the reference standard (concordance, 83%; kappa, 0.61). Bacterial index of >5 also showed the best validity (sensitivity, 78%; specificity, 86%; positive predictive value, 70%; negative predictive value, 90%; global value, 90%). Intracellular bacteria and Gram stain from bronchoalveolar secretions were very specific (95% and 81%, respectively) but not sensitive (30% and 50%, respectively). Clinical criteria and endotracheal cultures were very sensitive (100% and 90%, respectively) but poorly specific (15% and 40%, respectively).

CONCLUSION

Our data show that the most reliable diagnostic method for ventilator-associated pneumonia is a bacterial index of >5, using blind protected bronchoalveolar lavage. Further studies should evaluate the validity of all these methods according to the gold standard (autopsy).

Aspiración endotraqueal, cepillado y lavado broncoalveolar

The aim of endotracheal aspiration is to eliminate secretions in patients with an artificial airway. All children with mechanical ventilation must undergo this procedure periodically. The frequency of aspiration depends on the type and quantity of the respiratory secretions and on the patient's clinical status. Aspiration should be performed by two people to maintain a greater degree of asepsis and to optimize stability of the airway and ventilation. Closed aspiration systems are available that allow aspiration without the need to disconnect the patient through a single probe that is constantly protected by a plastic sleeve and isolated from external environment. The most important risks of endotracheal aspiration are hypoxemia, mucosal injury, bronchospasm, arrhythmias, perforation of the airway with development of pneumothorax, accidental extubation, and infections. Bronchial brushing with a protected catheter and brochoalveolar lavage are used to analyze pulmonary infections. These techniques can be performed blind or through fibrobronchoscopy. They can also be used for the diagnosis of noninfectious pulmonary diseases such as alveolar proteinosis, alveolar hemorrhage or histiocytosis. Their adverse effects are similar to those of endotracheal aspiration.