A simple method of reducing complications of pediatric nonbronchoscopic bronchoalveolar lavage

MERS-CoV infection is associated with downregulation of genes encoding Th1 and Th2 cytokines/chemokines and elevated inflammatory innate immune response in the lower respiratory tract

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MERS-CoV infection downregulates Th1 and Th2 cytokines and chemokines.

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MERS-CoV infection provokes high levels of IL-1α, IL-1β and IL-8 (CXCL8).

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Inflammatory cytokines/chemokines correlate with MERS-CoV case fatality rate.

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Th1/Th2 downregulation may contribute to severe infection and evolution of ARDS.

MERS-CoV, a highly pathogenic virus in humans, is associated with high morbidity and case fatality. Inflammatory responses have a significant impact on MERS-CoV pathogenesis and disease outcome. However, CD4⁺ T-cell induced immune responses during acute MERS-CoV infection are barely detectable, with potent inhibition of effector T cells and downregulation of antigen presentation. The local pulmonary immune response, particularly the Th1 and Th2-related immune response during acute severe MERS-CoV infection is not fully understood. In this study, we offer the first insights into the pulmonary gene expression profile of Th1 and Th2-related cytokines/chemokines (Th1 & Th2 responses) during acute MERS-CoV infection using RT² Profiler PCR Arrays. We also quantified the expression level of primary inflammatory cytokines/chemokines. Our results showed a downregulation of Th2, inadequate (partial) Th1 immune response and high expression levels of inflammatory cytokines IL-1α and IL-1β and the neutrophil chemoattractant chemokine IL-8 (CXCL8) in the lower respiratory tract of MERS-CoV infected patients. Moreover, we identified a high viral load in all included patients. We also observed a correlation between inflammatory cytokines, Th1, and Th2 downregulation and the case fatality rate. Th1 and Th2 response downregulation, high expression of inflammatory cytokines, and high viral load may contribute to lung inflammation, severe infection, the evolution of pneumonia and ARDS, and a higher case fatality rate. Further study of the molecular mechanisms underlying the Th1 and Th2 regulatory pathways will be vital for active vaccine development and the identification of novel therapeutic strategies.

Safety profile of blind bronchial sampling-A prospective study in pediatric intensive care unit

OBJECTIVE

To study the safety profile of blind bronchial sampling in mechanically ventilated children.

DESIGN

Prospective interventional study.

SETTING

Tertiary level pediatric intensive care unit of a multispecialty hospital.

PATIENTS

Children aged 1 month to 16 years on mechanical ventilator for ≥48 h, were assessed by clinical pulmonary infection score for ventilator-associated pneumonia (VAP).

INTERVENTIONS

Blind bronchial sampling was performed following standard procedural guidelines. The hemodynamic, ventilation parameters, and arterial blood gases done before, and in next 24 h post procedure were recorded and compared.

MEASUREMENTS AND MAIN RESULTS

Among the 40 enrolled children, VAP was suspected at 5.8 ± 3.7 days post intubation with insignificant increase in median (IQR) PELOD score to 15 (11-23) from 13.5 (11-23) (P value 0.29). A statistically significant increase in mean blood pressure (75.5 ± 14.7 to 79.1 ± 14.2, P 0.04) and transient drop in SpO₂ (98.2 ± 2.3 to 92.2 ± 9.2, P < 0.001) were noted with insignificant change in heart rate (128.7 ± 25.6 vs 132.0 ± 30.8, P 0.52), though these variations were clinically not significant. There were no major complications like significant airway bleed, arrhythmia, air leaks, edema, and change in pulmonary infiltrates during the procedure. There were no significant (either clinical or statistical) effects of BBS procedure, whether transient or prolonged, on ventilatory requirements or gas exchange parameters.

CONCLUSIONS

Blind bronchial sampling is a safe procedure in children with no major adverse events related to hemodynamics, oxygenation, and ventilation parameters.

Pneumocystis pneumonia in South African children diagnosed by molecular methods

Background

Pneumocystis pneumonia (PCP) is an important cause of hospitalization and mortality in HIV-infected children. However, the incidence of PCP has been underestimated due to poor sensitivity of diagnostic tests. The use of polymerase chain reaction (PCR) for pneumocystis has enabled more reliable diagnosis. This study describes the incidence, clinical features and outcome of PCP in South African children diagnosed using PCR.

Methods

A prospective study of children hospitalised in South Africa with suspected PCP was done from November 2006 to August 2008. Clinical, laboratory and radiological information were collected. Lower respiratory tract specimens were obtained for PCP immunofluorescence (IF), real- time PCR for pneumocystis, bacterial and mycobacterial culture. Nasopharyngeal aspirates were taken for immunofluorescence (IF), real-time PCR for pneumocystis and PCR for respiratory viruses. A blood specimen for bacterial culture and for cytomegalovirus PCR was taken. Children were followed for the duration of their hospitalisation and the outcome was recorded.

Results

202 children [median (interquartile range, IQR) age 3.2 (2.1– 4.6) months] were enrolled; 124 (61.4%) were HIV infected. PCP was identified in 109 (54%) children using PCR, compared to 43 (21%) using IF and Grocott staining (p < 0.0001). Most PCP cases (88, 81%) occurred in HIV-infected children. All 21 cases (19%) occurring in HIV- negative children had another risk factor for PCP. On logistic regression, predictive factors for PCP were HIV infection, lack of fever, high respiratory rate and low oxygen saturation whilst cotrimoxazole prophylaxis was protective (OR 0.24; 95% CI 0.1 to 0.5; p < 0.002). The case fatality of children with PCP was higher than those without PCP (32.1% versus 17.2%; relative risk 1.87; 95% confidence interval (CI) 1.11 – 3.15). Amongst HIV-infected children, a CD4 less than 15% was the only independent predictor of mortality.

Conclusions

The diagnostic yield for PCP is more than 2.5 times higher on PCR than other detection methods. PCP is a very common cause of severe hypoxic pneumonia and is associated with high mortality in HIV-infected African infants.

Investigation into the effect of closed-system suctioning on the frequency of pediatric ventilator-associated pneumonia in a developing country

OBJECTIVE

To investigate the effect of closed-system vs. open endotracheal suctioning on the frequency of ventilator-associated pneumonia and outcome in a pediatric intensive care unit in a developing country.

DESIGN

Prospective observational and nonrandomized controlled clinical study.

SETTING

A 20-bed pediatric intensive care unit in a tertiary pediatric hospital.

PATIENTS

Infants and children mechanically ventilated for >24 hrs.

INTERVENTION

: Pediatric intensive care unit suctioning systems were alternated monthly. An 8-month interim analysis was planned with a priori efficacy and futility study termination boundaries set at p < .006 and p > .52, respectively.

MEASUREMENTS AND MAIN RESULTS

Demographic, clinical, and laboratory data were prospectively recorded. Ventilator-associated pneumonia was diagnosed using the Clinical Pulmonary Infection Score, and the results were confirmed retrospectively using Centers for Disease Control criteria. A total of 250 patients (median [interquartile range] age of 3.8 [1.2-15.0] months) in 263 pediatric intensive care unit admissions were included. Fifty-nine admissions developed ventilator-associated pneumonia, with a calculated rate of 45.1 infections per 1000 ventilated days. There was no difference in characteristics or outcome between patients on closed-system suctioning (n = 83) and those on open endotracheal suctioning (n = 180). The frequencies of ventilator-associated pneumonia for patients on closed-system suctioning and open endotracheal suctioning were 20.5% and 23.3%, respectively (p = .6), reaching the a priori set limit of futility. Patients who developed ventilator-associated pneumonia spent a median (interquartile range) of 22 (13-37) and 11 (8-16) days in the hospital and pediatric intensive care unit, respectively, compared to 14.5 (10-24) and 6 (4-8) days for those without ventilator-associated pneumonia (p < .001). A 22% proportion of patients who developed ventilator-associated pneumonia died compared to 11.3% of those without ventilator-associated pneumonia (p = .03). Risk factors for ventilator-associated pneumonia identified on multiple logistic regression were duration of mechanical ventilation, transport out of the pediatric intensive care unit, and blood transfusion.

CONCLUSION

Closed-system suctioning did not affect the frequency of ventilator-associated pneumonia or patient outcome in this setting.

Improved detection of Pneumocystis jirovecii in upper and lower respiratory tract specimens from children with suspected pneumocystis pneumonia using real-time PCR: a prospective study

Background

Pneumocystis pneumonia (PCP) is a major cause of hospitalization and mortality in HIV-infected African children. Microbiologic diagnosis relies predominantly on silver or immunofluorescent staining of a lower respiratory tract (LRT) specimens which are difficult to obtain in children. Diagnosis on upper respiratory tract (URT) specimens using PCR has been reported useful in adults, but data in children are limited. The main objectives of the study was (1) to compare the diagnostic yield of PCR with immunofluorescence (IF) and (2) to investigate the usefulness of upper compared to lower respiratory tract samples for diagnosing PCP in children.

Methods

Children hospitalised at an academic hospital with suspected PCP were prospectively enrolled. An upper respiratory sample (nasopharyngeal aspirate, NPA) and a lower respiratory sample (induced sputum, IS or bronchoalveolar lavage, BAL) were submitted for real-time PCR and direct IF for the detection of Pneumocystis jirovecii. A control group of children with viral lower respiratory tract infections were investigated with PCR for PCP.

Results

202 children (median age 3.3 [inter-quartile range, IQR 2.2 - 4.6] months) were enrolled. The overall detection rate by PCR was higher than by IF [180/349 (52%) vs. 26/349 (7%) respectively; p < 0.0001]. PCR detected more infections compared to IF in lower respiratory tract samples [93/166 (56%) vs. 22/166 (13%); p < 0.0001] and in NPAs [87/183 (48%) vs. 4/183 (2%); p < 0.0001]. Detection rates by PCR on upper (87/183; 48%) compared with lower respiratory tract samples (93/166; 56%) were similar (OR, 0.71; 95% CI, 0.46 - 1.11). Only 2/30 (6.6%) controls were PCR positive.

Conclusion

Real-time PCR is more sensitive than IF for the detection of P. jirovecii in children with PCP. NPA samples may be used for diagnostic purposes when PCR is utilised. Wider implementation of PCR on NPA samples is warranted for diagnosing PCP in children.

Pneumocystis pneumonia in South African children with and without human immunodeficiency virus infection in the era of highly active antiretroviral therapy

BACKGROUND

Pneumocystis pneumonia (PCP) is a major cause of hospitalization and mortality in human immunodeficiency virus (HIV)-infected African children.

AIM

The aim of this study was to investigate the incidence and outcome of PCP in South African children living in a high HIV-prevalence area in the context of a free, available antiretroviral therapy program.

METHODS

Sequential children hospitalized with hypoxic pneumonia were prospectively enrolled from November 2006 to August 2008. Sociodemographic, historical, clinical, and outcome data were collected. A nasopharyngeal aspirate and lower respiratory tract sample (induced sputum or bronchoalveolar lavage) were submitted for PCP immunofluorescence. Lower respiratory tract samples were also investigated for bacterial, mycobacterial, and viral pathogens.

RESULTS

A total of 202 children were enrolled; 124 (61.4%) were HIV-infected; 34 (16.8%) were HIV-exposed but uninfected and 44 (21.8%) were HIV-unexposed. Among HIV-exposed children, 70 (44.3%) had participated in the Prevention of Mother to Child Transmission program, but only 18.4% were taking trimethoprim-sulfamethoxazole prophylaxis. PCP occurred in 43 children (21.3%) of whom 33 (76.7%) were HIV-infected. The case fatality of children with PCP was higher than those without PCP (39.5% vs. 21.4%; relative risk, 1.85; 95% confidence interval, 1.15-2.97; P = 0.01).

CONCLUSIONS

PCP is a common cause of hypoxic pneumonia and mortality in HIV-infected South African infants. Underuse of the Prevention of Mother to Child Transmission program and failure to institute trimethoprim-sulfamethoxazole prophylaxis in HIV-exposed children identified through the program are important obstacles to reducing PCP incidence.

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.

Il lavaggio broncoalveolare (BAL) in età pediatrica

Il lavaggio broncoalveolare o BAL, permettendo di ottenere le cellule ed i soluti presenti sulla superficie epiteliale del tratto respiratorio distale, si è dimostrato una metodica di ricerca essenziale per lo studio dei meccanismi eziopatogenetici delle malattie del polmone profondo, come ad esempio lo studio delle interstiziopatie, su cui esiste una vastissima letteratura di dati ottenuti con il BAL. Oltre a questo aspetto di metodica di ricerca, il BAL rappresenta perè anche una procedura diagnostica insostituibile nella pratica clinica quotidiana.

Inflation lung mechanics deteriorates markedly after saline instillation and open endotracheal suctioning in mechanically ventilated healthy piglets

INTRODUCTION

Non-bronchoscopic bronchoalveolar lavage is an alternative to diagnostic bronchoscopy in pediatric patients, as fiberoptic bronchoscopes with aspiration channels are too large for small infants. There are many variations of the method in clinical practice, and saline instillation followed by open endotracheal suctioning is still commonly used. Lung function can deteriorate with these procedures, and we have investigated the effects on lung mechanics and oxygenation in healthy piglets.

METHODS

The lungs of anesthetized and mechanically ventilated piglets were recruited with CPAP 35 cmH2O. Thereafter we instilled 5 ml of saline into the endotracheal tube, followed by three breaths from the ventilator. Saline was retrieved through a suction catheter wedged far distally in the airway. The procedure was followed by a new recruitment maneuver. Complete inspiratory/expiratory pressure - volume loops (PV-loops) were obtained just before and 5 min after saline instillation. Arterial blood gases were collected at equivalent times in 14 similar piglets submitted to exactly the same procedure.

RESULTS

The inspiratory limb of the PV-loops changed markedly, as the lower inflection point was displaced towards higher pressures (P=0.004), and hysteresis measured at 15 and 30 cmH2O increased (P=0.004 and P=0.012, respectively). Although PaO2 decreased significantly (P=0.001), values after saline instillation/suctioning were still in the high normal range, that is, 22.2 +/- 2.6 kPa.

CONCLUSIONS

Opening pressures of the lungs increase markedly after saline instillation/suctioning in healthy piglets. In this situation, adequate recruitment maneuvers and PEEP might prevent lung collapse and deteriorations in arterial oxygenation.