An adolescent with Wolfram syndrome and central sleep apnea

Wolfram syndrome (WS) is a rare autosomal recessive disorder affecting approximately 1:500,000 individuals. The disorder is most commonly caused by mutations in the WFS1 gene, which encodes an endoplasmic reticulum (ER) protein, wolframin, which is thought to protect against ER stress-related apoptosis. The major clinical findings of WS are diabetes mellitus and optic atrophy, both of which usually appear before 16 years of age. Common additional findings include sensorineural hearing impairment, central diabetes insipidus, non-autoimmune hypothyroidism, delayed puberty, neurogenic bladder, cerebellar ataxia, and psychiatric disorders. Central sleep apnea is an uncommon but serious feature of WS. However, the clinical details of this manifestation have not been documented. Herein, we report an adolescent with recently diagnosed WS who demonstrated severe central sleep apnea on polysomnography testing.

Bacterial Surface Detachment during Nebulization with Contaminated Reusable Home Nebulizers

Patients with chronic respiratory diseases use home nebulizers that are often contaminated with pathogenic microbes to deliver aerosolized medications. The conditions under which these microbes leave the surface as bioaerosols during nebulization are not well characterized. The objectives of this study were to (i) determine whether different pathogens detach and disperse from the nebulizer surface during aerosolization and (ii) measure the effects of relative humidity and drying times on bacterial surface detachment and aerosolization. Bacteria were cultured from bioaerosols after Pari LC Plus albuterol nebulization using two different sources, as follows: (i) previously used nebulizers donated by anonymous patients with cystic fibrosis (CF) and (ii) nebulizers inoculated with bacteria isolated from the lungs of CF patients. Fractionated bioaerosols were collected with a Next-Generation Impactor. For a subset of bacteria, surface adherence during rewetting was measured with fluorescence microscopy. Bacteria dispersed from the surface of used CF patient nebulizers during albuterol nebulization. Eighty percent (16/20) of clinical isolates inoculated on the nebulizer in the laboratory formed bioaerosols. Detachment from the plastic surface into the chamber solution predicted bioaerosol production. Increased relative humidity and decreased drying times after inoculation favored bacterial dispersion on aerosols during nebulized therapy. Pathogenic bacteria contaminating nebulizer surfaces detached from the surface as bioaerosols during nebulized therapies, especially under environmental conditions when contaminated nebulizers were dried or stored at high relative humidity. This finding emphasizes the need for appropriate nebulizer cleaning, disinfection, and complete drying during storage and informs environmental conditions that favor bacterial surface detachment during nebulization. IMPORTANCE Studies from around the world have demonstrated that many patients use contaminated nebulizers to deliver medication into their lungs. While it is known that using contaminated medications in a nebulizer can lead to a lung infection, whether bacteria on the surface of a contaminated nebulizer detach as bioaerosols capable of reaching the lung has not been studied. This work demonstrates that a subset of clinical bacteria enter solution from the surface during nebulization and are aerosolized. Environmental conditions of high relative humidity during storage favor dispersion from the surface. We also provide results of an in vitro assay conducted to monitor bacterial surface detachment during multiple cycles of rewetting that correlate with the results of nebulizer/bacterial surface interactions. These studies demonstrate for the first time that pathogenic bacteria on the nebulizer surface pose a risk of bacterial inhalation to patients who use contaminated nebulizers.

Two vs four puffs of albuterol: does dose change bronchodilator response?

Background

Reversible obstruction on spirometry may be used to diagnose asthma. As per 2005 American Thoracic Society (ATS) guidelines, our pulmonary center began using 360 µg (four puffs) of albuterol rather than 180 µg (two puffs) to determine reversibility on spirometry starting in 2009.

Hypothesis

We hypothesized that fewer patients would respond to two puffs of albuterol than four puffs during spirometric testing.

Methods

We retrospectively reviewed records from new asthmatics seen in Pediatric Pulmonary Clinic from March 2002 to April 2014 who performed reproducible spirometry. Patients were divided into two groups based on whether they had received two or four puffs of albuterol for bronchodilator assessment. A positive bronchodilator response was defined as an increase of ≥12% in forced expiratory volume in one second (FEV₁) or ≥25% in forced expiratory flow (FEF_25–75%). Data were expressed as percentages and mean ± standard error of the mean values. Chi-squared test and Student’s t-test were utilized.

Results

Data were collected for 240 patients; 115 patients received two puffs of albuterol and 125 patients received four puffs. There were no significant differences in baseline characteristics between the two groups. There were no differences following two puffs or four puffs in changes in FEV₁ (10.0±1.1% vs 10.5±1.1% predicted) or FEF_25–75% (30.2±2.9% vs 33.5±2.9% predicted). Moreover, there was no difference in ATS-defined bronchodilator response between the two groups.

Conclusion

Based on the mean change in FEV₁ and overall bronchodilator responsiveness, two puffs of albuterol were not inferior to four puffs in the determination of bronchodilator responsiveness in our pediatric asthmatic patients.

Early-life antibiotics attenuate regulatory T cell generation and increase the severity of murine house dust mite-induced asthma

INTRODUCTION

Early-life exposure to antibiotics (ABX) has been linked to increases in asthma severity and prevalence in both children and laboratory animals. We explored the immunologic mechanisms behind this association using a mouse model of house dust mite (HDM)-induced asthma and early-life ABX exposure.

METHODS

Mice were exposed to three short courses of ABX following weaning and experimental asthma was thereafter induced. Airway cell counts and differentials; serum immunoglobulin E (IgE); pulmonary function; lung histopathology; pulmonary regulatory T cells (Tregs); and the fecal microbiome were characterized following ABX exposure and induction of experimental asthma.

RESULTS

Asthma severity was increased in mice exposed to ABX, including: airway eosinophilia, airway hyper-reactivity, serum HDM-specific IgE, and lung histopathology. ABX treatment led to sharp reduction in fecal microbiome diversity, including the loss of pro-regulatory organisms such as Lachnospira. Pulmonary Tregs were reduced with ABX treatment, and this reduction was directly proportional to diminished microbiome diversity.

CONCLUSION

Intermittent exposure to ABX early in life worsened the severity of experimental asthma and reduced pulmonary Tregs; the latter change correlated with decreased microbiome diversity. These data may suggest targets for immunologic or probiotic therapy to counteract the harmful effects of childhood ABX.

Regulation of IgE activity in inhalational tolerance via formation of IgG anti-IgE/IgE immune complexes

Background

Allergic asthma is an inflammatory disorder of the airways that results from inappropriate production of IgE against harmless, environmental antigens. Sequestration of free IgE using humanized IgG anti-IgE is an effective therapy for asthma and other atopic disorders. However, the status of free IgE in subjects who have naturally developed immune tolerance to inhaled antigens has not been well studied.

Methods

C57BL/6 mice were sensitized and challenged with ovalbumin (OVA) for 7 days to induce allergic airway disease (AAD) or 6 weeks to induce a state of local inhalational tolerance (LIT). Serum from AAD or LIT mice, diluted to achieve equivalent levels of total OVA-specific IgE, was used to sensitize rat basophil leukemia cells for allergen-mediated degranulation. Levels of degranulation were measured in relation to serum concentrations of free IgE and IgG anti-IgE/IgE immune complexes.

Results

Serum from AAD animals induced a greater degree of basophil degranulation than serum from LIT animals. These results correlated with higher levels of free IgE in AAD animals, whereas LIT mice demonstrated a significant increase in IgG anti-IgE/IgE immune complexes relative to their diseased counterparts.

Conclusions

Sequestration of free IgE by naturally occurring IgG anti-IgE may aid in the development of immune tolerance against inhaled allergens. The decrease in bioavailability of free IgE may, in turn, contribute to the overall reduction of asthma symptoms via a mechanism that mimics the therapeutic effects of humanized IgG anti-IgE.

IL-15-deficient mice develop enhanced airway allergic responses in a mouse model of allergic airway disease

Interleukin-15 is a pleiotropic cytokine critical for the development of multiple hematopoietic lineages. Mice lacking IL-15 have selective defects in populations of several pro-allergic immune cells including natural killer (NK) cells, NKT cells, and memory CD8+T cells. We therefore hypothesized that IL-15−/− mice will have reduced inflammatory responses during the development of allergic airway disease (AAD). Here we report that IL-15−/− mice developed enhanced allergic responses in an OVA-induced model of AAD. C57BL/6 wild-type (WT) and IL-15−/− mice were sensitized and challenged with ovalbumin (OVA) and the development of AAD was ascertained. In the absence of IL-15, OVA-challenged mice exhibited enhanced bronchial eosinophilic inflammation, elevated IL-13 production, and severe lung histopathology in comparison with WT mice. In addition, increased numbers of CD4+T and B cells in the spleens and broncholaveolar lavage were also observed. Examination of OVA-challenged IL-15R−/− animals revealed a similar phenotype resulting in enhanced airway eosinophilia compared to WT mice. Adoptive transfer of splenic CD8+T cells from OVA-sensitized WT mice suppressed the enhancement of eosinophilia in IL-15−/− animals to levels observed in WT mice, but had no further effects. These data demonstrate that mice with an endogenous IL-15 deficiency are susceptible to the development of severe, enhanced Th2-mediated AAD. Furthermore, the development of disease as well as allergen-specific Th2 responses occurs despite deficiencies in several IL-15-dependent cell types including NK and NKT cells, suggesting that these cells or their subsets are dispensable for the induction of AAD in IL-15-deficient mice.

IL-15-deficient mice develop enhanced allergic responses to airway allergen exposure

BACKGROUND

Interleukin-15 is a pleiotropic cytokine that is critical for the development and survival of multiple haematopoietic lineages. Mice lacking IL-15 have selective defects in populations of several pro-allergic immune cells including natural killer (NK) cells, NKT cells, and memory CD8⁺ T cells. We therefore hypothesized that IL-15^-/- mice will have reduced inflammatory responses during the development of allergic airway disease (AAD).

OBJECTIVE

To determine whether IL-15^-/- mice have attenuated allergic responses in a mouse model of AAD.

METHODS

C57BL/6 wild-type (WT) and IL-15^-/- mice were sensitized and challenged with ovalbumin (OVA), and the development of AAD was ascertained by examining changes in airway inflammatory responses, Th2 responses, and lung histopathology.

RESULTS

Here, we report that IL-15^-/- mice developed enhanced allergic responses in an OVA-induced model of AAD. In the absence of IL-15, OVA-challenged mice exhibited enhanced bronchial eosinophilic inflammation, elevated IL-13 production, and severe lung histopathology in comparison with WT mice. In addition, increased numbers of CD4⁺ T and B cells in the spleens and bronchoalveolar lavage (BAL) were also observed. Examination of OVA-challenged IL-15Rα^-/- animals revealed a similar phenotype resulting in enhanced airway eosinophilia compared to WT mice. Adoptive transfer of splenic CD8⁺ T cells from OVA-sensitized WT mice suppressed the enhancement of eosinophilia in IL-15^-/- animals to levels observed in WT mice, but had no further effects.

CONCLUSION AND CLINICAL RELEVANCE

These data demonstrate that mice with an endogenous IL-15 deficiency are susceptible to the development of severe, enhanced Th2-mediated AAD, which can be regulated by CD8⁺ T cells. Furthermore, the development of disease as well as allergen-specific Th2 responses occurs despite deficiencies in several IL-15-dependent cell types including NK, NKT, and γδ T cells, suggesting that these cells or their subsets are dispensable for the induction of AAD in IL-15-deficient mice.

Cbl-b Deficiency in Mice Results in Exacerbation of Acute and Chronic Stages of Allergic Asthma

Mice sensitized to ovalbumin (OVA) develop allergic airway disease (AAD) with short-term daily OVA aerosol challenge; inflammation resolves with long-term OVA aerosol exposure, resulting in local inhalational tolerance (LIT). Cbl-b is an E3 ubiquitin ligase involved with CD28 signaling; Cbl-b^−/− effector T cells are resistant to regulatory T cell-mediated suppression in vitro and in vivo. The present study utilized Cbl-b^−/− mice to investigate the role of Cbl-b in the development of AAD and LIT. Cbl-b^−/− mice exhibited increased airway inflammation during AAD, which failed to resolve with long-term OVA aerosol exposure. Exacerbation of inflammation in Cbl-b^−/− mice correlated with increased proinflammatory cytokine levels and expansion of effector T cells in the BAL during AAD, but did not result in either a modulation of lymphocyte subsets in systemic tissues or in OVA-specific IgE in serum. These results implicate a role for Cbl-b in the resolution of allergic airway inflammation.

Long-Term Exposure to House Dust Mite Leads to the Suppression of Allergic Airway Disease Despite Persistent Lung Inflammation

BACKGROUND

Allergic asthma is a major cause of worldwide morbidity and results from inadequate immune regulation in response to innocuous, environmental antigens. The need exists to understand the mechanisms that promote nonreactivity to human-relevant allergens such as house dust mite (HDM) in order to develop curative therapies for asthma. The aim of our study was to compare the effects of short-, intermediate- and long-term HDM administration in a murine asthma model and determine the ability of long-term HDM exposure to suppress allergic inflammation.

METHODS

C57BL/6 mice were intranasally instilled with HDM for short-term (2 weeks), intermediate-term (5 weeks) and long-term (11 weeks) periods to induce allergic airway disease (AAD). The severity of AAD was compared across all stages of the model via both immunological and pulmonary parameters.

RESULTS

Short- and intermediate-term HDM exposure stimulated the development of AAD that included eosinophilia in the bronchoalveolar lavage fluid (BALF), pronounced airway hyperreactivity (AHR) and evidence of lung inflammation. Long-term HDM exposure promoted the suppression of AAD, with a loss of BALF eosinophilia and AHR despite persistent mononuclear inflammation in the lungs. Suppression of AAD with long-term HDM exposure was associated with an increase in both Foxp3+ regulatory T cells and IL-10-positive alveolar macrophages at the site of inflammation.

CONCLUSIONS

This model recapitulates the key features of human asthma and may facilitate investigation into the mechanisms that promote immunological tolerance against clinically relevant aeroallergens.

Oral Bromelain Attenuates Inflammation in an Ovalbumin-induced Murine Model of Asthma

Bromelain, a widely used pineapple extract with cysteine protease activity, has been shown to have immunomodulatory effects in a variety of immune system models. The purpose of the present study was to determine the effects of orally administered bromelain in an ovalbumin (OVA)-induced murine model of acute allergic airway disease (AAD). To establish AAD, female C57BL/6J mice were sensitized with intraperitoneal (i.p.) OVA/alum and then challenged with OVA aerosols for 3 days. Mice were gavaged with either (phosphate buffered saline)PBS or 200 mg/kg bromelain in PBS, twice daily for four consecutive days, beginning 1 day prior to OVA aerosol challenge. Airway reactivity and methacholine sensitivity, bronchoalveolar lavage (BAL) cellular differential, Th2 cytokines IL-5 and IL-13, and lung histology were compared between treatment groups. Oral bromelain-treatment of AAD mice demonstrated therapeutic efficacy as evidenced by decreased methacholine sensitivity (P ≤ 0.01), reduction in BAL eosinophils (P ≤ 0.02) and IL-13 concentrations (P ≤ 0.04) as compared with PBS controls. In addition, oral bromelain significantly reduced BAL CD19+ B cells (P ≤ 0.0001) and CD8+ T cells (P ≤ 0.0001) in AAD mice when compared with controls. These results suggest that oral treatment with bromelain had a beneficial therapeutic effect in this murine model of asthma and bromelain may also be effective in human conditions.

Regulatory B cells from hilar lymph nodes of tolerant mice in a murine model of allergic airway disease are CD5+, express TGF-β, and co-localize with CD4+Foxp3+ T cells

In a biphasic, ovalbumin (OVA)-induced murine asthma model where allergic airway disease is followed by resolution and the development of local inhalational tolerance (LIT), transforming growth factor (TGF)-β-expressing CD5(+) B cells were selectively expanded locally in hilar lymph nodes (HLN) of LIT mice. LIT HLN CD5(+) B cells, but not LIT HLN CD5(-) B cells, induced expression of Foxp3 in CD4(+)CD25(-) T cells in vitro. These CD5(+) regulatory B cells (Breg) and CD4(+)Foxp3(+) T cells demonstrated similar increases in expression of chemokine receptors (CXCR4 and CXCR5) and co-localized in HLN B cell zones of LIT mice. The adoptive transfer of LIT HLN CD5(+) B cells, but not LIT HLN CD5(-) B cells, increased the number of CD4(+)Foxp3(+) T cells in the lung and inhibited airway eosinophilia in this OVA model. Thus, Breg in HLNs of LIT mice reside in a CD5(+) TGF-β-producing subpopulation and co-localize with CD4(+)Foxp3(+) T cells.

β2-adrenergic receptor haplotype linked to intubation and mechanical ventilation in children with asthma

BACKGROUND AND AIMS

Children with asthma and respiratory failure comprise a small but significant subset of children with acute asthma. In addition to clinical and historical factors that have been associated with respiratory failure, there may also be genetic factors that predispose some asthmatic children to intubation and mechanical ventilation. However, this has not previously been assessed in this population. We hypothesized that genetic polymorphisms of the β(2)-adrenergic receptor (ADRβ(2)) are associated with intubation and mechanical ventilation in children with asthma.

MATERIALS AND METHODS

We performed genotyping of the ADRβ(2) in a pooled cohort of 104 children admitted to the intensive care unit (ICU) with a severe asthma exacerbation between 2002 and 2008. Genotype of the ADRβ(2) was compared with intubation for respiratory failure.

RESULTS

At amino acid position 16, 33% (n = 34) of children were homozygous for the glycine allele (Gly16Gly), 15% (n = 16) were homozygous for the arginine allele (Arg16Arg), and 52% (n = 54) were heterozygous (Arg16Gly). At amino acid position 27, 54% (n = 56) of children were homozygous for the glutamine allele (Gln27Gln), 8% (n = 8) were homozygous for the glutamic acid allele (Glu27Glu), and 38% (n = 40) were heterozygous (Gln27Glu). The haplotypes at these positions were Arg16Gly-Gln27Gln (29%, n = 30), Arg16Gly-Gln27Glu (22%, n = 23), Gly16Gly-Gln27Glu (16%, n = 17), Arg16Arg-Gln27Gln (16%, n = 17), Gly16Gly-Gln27Gln (9%, n = 9), and Gly16Gly-Glu27Glu (8%, n = 8). Twelve children in this cohort were intubated for respiratory failure. Intubation was not associated with age, obesity, race/ethnicity, or NHBLI asthma classification. However, children with the Arg16Gly-Gln27Gln haplotype were significantly more likely to be intubated and mechanical ventilated (OR = 4.2; 95% CI = 1.2-14.5; p = .036) than children with other haplotypes of the ADRβ(2). When examining the subset of intubated children, those with the Arg16Gly-Gln27Gln haplotype trended towards longer ICU length of stay (329 ± 270 vs. 124 ± 57 hours; p = .09), but this was not statistically significant.

CONCLUSIONS

Children with the Arg16Gly-Gln27Gln haplotype of the ADRβ(2) were four times more likely to be intubated and mechanically ventilated during severe asthma exacerbations. Genetic factors may influence the development of a more severe asthma phenotype during acute exacerbations.

Bromelain limits airway inflammation in an ovalbumin-induced murine model of established asthma

CONTEXT

Allergic asthma continues to increase despite new pharmacological advances for both acute treatment and chronic-disease management. Asthma is a multifactorial disease process with genetic, allergic, infectious, environmental, and dietary origins. Researchers are investigating the benefits of lifestyle changes and alternative asthma treatments, including the ability of bromelain to inhibit inflammation. Bromelain is a commonly used, proteolytically active pineapple extract.

OBJECTIVE

The present study intended to determine the ability of bromelain to reduce the inflammation of preexisting asthma via an ovalbumin (OVA)-induced murine model of allergic airway disease (AAD).

DESIGN

The research team designed a study examining the effects of bromelain in a control group of mice that received phosphate buffered saline (PBS) only and in an intervention group that received bromelain in PBS. Setting The study took place in the Department of Immunology at the University of Connecticut's School of Medicine, Farmington. Intervention The research team sensitized female C57BL/6J mice with intraperitoneal OVA/alum and then challenged them with OVA aerosolization for 10 consecutive days. On day 4, the team began administering daily doses of PBS to the control group (n = 10) and bromelain (6mg/kg) in PBS to the bromelain (intervention) group (n = 10).

OUTCOME MEASURES

The primary measures included bronchoalveolar lavage (BAL) cellular differential, cellular phenotype via flow cytometry, and lung histology. Additional outcomes included testing for serum cytokines and immunoglobulin.

RESULTS

Bromelain treatment of AAD mice (bromelain group) resulted in significant anti-inflammatory activity as indicated by reduced BAL total leukocytes (P < .05), eosinophils (P < .05), and cellular infiltrates via lung pathology (P < .005), as compared to the control group. In addition, bromelain significantly reduced BAL CD4+ and CD8+ T cells without affecting cell numbers in the spleen or hilar lymph node. The study found decreased interleukins IL-4, IL-12, IL-17, as well as IFN-α in the serum of bromelain-treated animals.

CONCLUSIONS

The results suggest that bromelain has a therapeutic effect in established AAD, which may translate into an effective adjunctive therapy in patients with similar conditions, such as allergic asthma, who have chosen to initiate treatment after the onset of symptoms.

Pulmonary mechanics following albuterol therapy in mechanically ventilated infants with bronchiolitis

BACKGROUND AND AIMS

Bronchiolitis is a common cause of critical illness in infants. Inhaled β(2)-agonist bronchodilators are frequently used as part of treatment, despite unproven effectiveness. The purpose of this study was to describe the physiologic response to these medications in infants intubated and mechanically ventilated for bronchiolitis.

MATERIALS AND METHODS

We conducted a prospective trial of albuterol treatment in infants intubated and mechanically ventilated for bronchiolitis. Before and for 30 minutes following inhaled albuterol treatment, sequential assessments of pulmonary mechanics were determined using the interrupter technique on repeated consecutive breaths.

RESULTS

Fifty-four infants were enrolled. The median age was 44 days (25-75%; interquartile range (IQR) 29-74 days), mean hospital length of stay (LOS) was 18.3 ± 13.3 days, mean ICU LOS was 11.3 ± 6.4 days, and mean duration of mechanical ventilation was 8.5 ± 3.5 days. Fifty percent (n = 27) of the infants were male, 81% (n = 44) had public insurance, 80% (n = 41) were Caucasian, and 39% (n = 21) were Hispanic. Fourteen of the 54 (26%) had reduction in respiratory system resistance (Rrs) that was more than 30% below baseline, and were defined as responders to albuterol. Response to albuterol was not associated with demographic factors or hospitalization outcomes such as LOS or duration of mechanical ventilation. However, increased Rrs, prematurity, and non-Hispanic ethnicity were associated with increased LOS.

CONCLUSIONS

In this population of mechanically ventilated infants with bronchiolitis, relatively few had a reduction in pulmonary resistance in response to inhaled albuterol therapy. This response was not associated with improvements in outcomes.

Phenotypic changes to the endogenous antigen-specific CD8+ T cell response correlates with the development and resolution of allergic airway disease

The role of CD8(+) T cells in the pathogenesis of asthma remains controversial, as both pro- and anti-inflammatory functions have been suggested. This study was designed to examine the endogenous CD8(+) T cell response in a biphasic ovalbumin (OVA)-induced model of allergic airway disease (AAD) and its subsequent resolution with the development of local inhalational tolerance (LIT). We observed increases in OVA-specific CD8(+) T cell numbers in the local lung compartments (bronchoalveolar lavage, lung tissue, hilar lymph node) at AAD and LIT; systemic compartments (spleen, inguinal lymph node) displayed no such increases in CD8(+) T cell numbers. OVA-specific CD8(+) T cells appeared to exhibit plasticity both phenotypically and functionally. They possessed pro-inflammatory characteristics at AAD, with high phenotypic expression of CD11a and increased functional expression of granzyme B and interferon-γ. In contrast, at LIT they showed increased phenotypic expression of the inhibitory marker NKG2A and functionally did not produce granzyme B or interferon-γ. In addition, in a discontinuous model the OVA-specific CD8(+) T cells could be recalled on re-exposure to OVA, demonstrating memory. Finally, confocal microscopy results showed that OVA-specific CD8(+) T cells at AAD are associated with B cell aggregates in lung tissue. These B cell aggregates resembled tertiary ectopic lymphoid tissue and may thus provide a local environment for the salient cellular interactions that contribute to the development of LIT.

Beta-adrenergic receptor polymorphisms associated with length of ICU stay in pediatric status asthmaticus

BACKGROUND

During severe exacerbations, asthmatic children vary significantly in their response to high-dose continuous β(2) -adrenergic receptor (ADRβ(2) ) agonist therapy. Genetic polymorphisms have been identified within the ADRβ(2) that may be functionally relevant, but few studies have been performed in this population. Our hypothesis was that genotypic differences are associated with magnitude of response to ADRβ(2) agonist treatment during severe asthma exacerbations in children.

METHODS

Children aged 2-18 years admitted to the ICU (intensive care unit) with a severe asthma exacerbation between 2006 and 2008 were eligible. Genotyping of the ADRβ(2) was performed.

RESULTS

Eighty-nine children consented and were enrolled. Despite similar clinical asthma scores on admission, children with the Gly(16) Gly genotype at amino acid position 16 had significantly shorter ICU length of stay (LOS) and hospital LOS, compared to children with Arg(16) Arg and Arg(16) Gly genotypes. Children with either the Gln(27) Glu or Glu(27) Glu genotype at amino acid position 27 also had significantly shorter ICU LOS and hospital LOS compared to children with the Gln(27) Gln genotype. The Arg(16) Gly-Gln(27) Gln haplotype was associated with the longest ICU LOS, but this was not statistically different from other haplotypes.

CONCLUSIONS

In this cohort of children with severe asthma exacerbations, ADRβ(2) polymorphisms were associated with responses to therapy. Knowledge of the genetic profile of children with asthma may allow for targeted therapy during acute exacerbations.

Clinical features cannot distinguish allergic from non-allergic asthma in children

OBJECTIVE

Environmental allergens are a major trigger of asthma, but not all asthmatics are allergic. This study was designed to review clinical characteristics in children with allergic and non-allergic asthma, based on responsiveness to allergy skin tests, in order to identify a combination of features that could distinguish allergic from non-allergic asthma in children.

METHODS

Medical records of 321 children who had allergy skin testing were reviewed, and demographic and clinical data were compared between allergic and non-allergic patients.

RESULTS

Approximately two-thirds of the asthmatic children had at least one positive skin test. These allergic patients were more likely to have a history of eczema or Medicaid insurance, but these findings had poor predictive value. There was no difference between allergic patients and non-allergic patients in terms of family history of atopy or asthma, home tobacco smoke exposure, age of onset of asthma, gender, rate of obesity, or asthma severity. Among the allergic asthma patients, neither the number of positive skin tests nor specific individual allergic sensitivities correlated with age of onset of asthma or asthma severity.

CONCLUSIONS

This study failed to identify any combination of features that could reliably distinguish allergic from non-allergic asthma in children. Thus, all children with asthma should undergo allergy testing in order to identify potential allergic triggers in allergic patients and to avoid the institution of unnecessary environmental control measures in non-allergic patients.

Factors associated with the development of severe asthma exacerbations in children

BACKGROUND

Asthma exacerbations are one of the most common causes of hospitalization in children and account for approximately 10,000 intensive care unit (ICU) admissions per year in the United States. Despite the prevalence of this disease in children, the factors associated with the development of these severe exacerbations are largely unknown.

METHODS

A retrospective case-control study was conducted involving all eligible children admitted to the hospital with asthma for a 1-year period. Potential associated factors and outcomes of children admitted to the ICU with a severe exacerbation (cases) were compared to those of children with acute asthma admitted to the ward (controls).

RESULTS

A total of 188 children were hospitalized with asthma during the study period, 57 (30%) of whom required admission to the ICU. There were no differences in age, gender, or race between cases and controls. Children admitted to the ICU were significantly more likely to have an allergy or irritant-triggered exacerbation than children admitted to the ward (OR 3.9; 95% CI 1.9-8.2; p = .0003). Additionally, children in the ICU had a significantly shorter duration of illness before being admitted to the hospital compared to those admitted to the ward (1.7 ± 2.3 vs. 3.4 ± 4.8 days; p = .002).

CONCLUSIONS

In this retrospective review, severe asthma exacerbations in children are associated with a more rapid onset of symptoms and are more likely to be associated with allergens or irritants, supporting the importance of atopy in this population.

Identifying an at-risk population of children with recurrent near-fatal asthma exacerbations

BACKGROUND

Children are frequently admitted to hospitals for treatment of severe asthma exacerbations. Anecdotally, a cohort of these children are thought to have multiple readmissions to the intensive care unit (ICU), yet this group of children has not been characterized. The purpose of this study was to examine the factors related to recurrent ICU admissions in children with asthma.

METHODS

The authors conducted a retrospective study of all children admitted to the pediatric ICU for asthma between April 1997 and December 2007. Children with more than one ICU admission were defined as having recurrent near-fatal asthma exacerbations.

RESULTS

During this period, 306 children with asthma were admitted to the ICU on 350 occasions; 269 children had only one ICU admission and 33 children (11%) had two or more ICU admissions. To predict who might require readmission, the authors compared the first hospitalization of all children. When compared with children admitted to the ICU only once, children admitted to the ICU more than once were more likely to be overweight (odds ratio [OR] 2.3; 95% confidence interval [CI] 1.1, 4.9), to have public insurance (OR 3.6; 95% CI 1.5, 8.5), and less likely to be Caucasian (OR 0.34; 95% CI 0.14, 0.86). There was no difference in Nation Heart, Lung and Blood Institute (NHLBI) asthma classification, admission illness severity, durations of therapy, or length of stay (LOS) that might identify those who would require readmission. To determine the effect of readmission analysis on subsequent hospitalization, the authors used multiple logistic regression to identify factors associated with increased LOS in all hospitalizations of the subset of children with recurrent near-fatal asthma exacerbations. In this analysis, LOS was most closely associated with admission severity of illness (p = .002), but not with number of hospitalizations.

CONCLUSIONS

In this single hospital cohort, there were identifiable factors in children admitted to the ICU that are associated with an increased risk of developing recurrent near-fatal asthma exacerbations. Specifically, overweight children with public insurance were more likely and Caucasian children less likely to be readmitted to the ICU for asthma. These children may represent a group to which specific interventions should be targeted prospectively to prevent readmission.

Reassessment of Disease Severity in Patients Following Severe Acute Exacerbations of Asthma

Patients with asthma may have severe exacerbations. The impact of severe acute exacerbation on patient outcome has not been studied, however. The purpose of this study was to examine the long-term outcome of severe exacerbation of asthma on baseline disease severity in children. Data were collected retrospectively from all children with asthma older than 5 years who were admitted to the intensive care unit (ICU) with an acute exacerbation and were subsequently followed as outpatients. Patients were divided into 4 severity groups (intermittent, mild persistent, moderate persistent, and severe persistent) based on the severity of asthma prior to ICU admission, at the time of admission, and at 12-month follow-up. Thirty-nine patients were followed for 12 months after ICU admission. Pulmonology consultation was more likely to be obtained in patients with moderate and severe asthma at baseline as compared with those with intermittent or mild asthma ( P = .004). On follow-up, 59% had a change in classification of their asthma severity. Changes in asthma severity were more likely to occur at the time of ICU admission rather than at 12-month follow-up. There was no difference in the gender, race, age, or body mass index at the time of ICU admission between the group who had a change in asthma severity and the group with no change in severity. There was no difference in Modified Pulmonary Index Score, duration of hospitalization, or length of stay in the ICU between the 2 groups. Prior inhaled steroid dose was lower in patients who had a change in severity as compared with those who had not ( P = .018). Children with mild asthma were frequently reclassified to a more severe asthma category after an acute life-threatening episode of asthma. It is likely that this reclassification was due to underestimation of disease severity prior to the ICU admission, but the severe acute event itself may have contributed to increased severity classification.

Beta2-adrenergic receptor polymorphisms affect response to treatment in children with severe asthma exacerbations

BACKGROUND

beta(2)-adrenergic receptor (AR) agonists are the mainstay of treatment for severe asthma exacerbations, one of the most common causes of critical illness in children. Genotypic differences in the beta(2)-AR gene, particularly at amino acid positions 16 and 27, have been shown to affect the response to beta(2)-AR agonist therapy. Our hypothesis is that genotypic differences contribute to patient response to beta(2)-AR agonist treatment during severe asthma exacerbations in children.

METHODS

Children admitted to the hospital ICU for a severe asthma exacerbation between 2002 and 2005 were located, and genetic samples were obtained from saliva. Children hospitalized during this period were treated with a protocol that titrated beta(2)-AR therapy (first nebulized, then IV) according to a validated clinical asthma score.

RESULTS

Thirty-seven children hospitalized during the study period were enrolled into the study. At amino acid position 16 in the beta(2)-AR gene, 13 children were homozygous for the glycine (Gly) allele (Gly/Gly), 8 were homozygous for the arginine (Arg) allele (Arg/Arg), and 16 were heterozygous (Arg/Gly). Despite similar clinical asthma scores on hospital admission, the children with the Gly/Gly genotype had significantly shorter hospital ICU length of stay and duration of continuously nebulized albuterol therapy and were significantly less likely to require IV beta(2)-AR therapy than those with Arg/Arg or Arg/Gly genotypes. No association existed among polymorphisms at amino acid position 27 and response to beta(2)-AR therapy.

CONCLUSIONS

In this cohort of children with severe asthma exacerbations, children whose genotypes were homozygous for Gly at amino acid position 16 of the beta(2)-AR gene had a more rapid response to beta(2)-AR agonist treatment. The beta(2)-AR genotype appears to influence the response to therapy in this population.

Severe exacerbations in children with mild asthma: characterizing a pediatric phenotype

BACKGROUND

NHLBI guidelines classify asthma in children as intermittent, mild persistent, moderate persistent, and severe persistent asthma based on baseline symptoms and pulmonary function. However, this may not capture the spectrum of asthma in children, since even mild baseline disease can have significant effects on quality of life. Our objective was to describe a population of children with mild asthma admitted to the ICU with severe exacerbations.

METHODS

We examined data from all children with asthma who were admitted to the ICU with an acute exacerbation between April 1997, and December 2006. Children were defined as having mild asthma if their disease was classified as intermittent or mild persistent according to NHLBI criteria.

RESULTS

Of the 298 children admitted to the ICU with asthma, 164 (55%) were classified as having mild baseline asthma. Compared with children with more severe baseline asthma, mild asthmatic children were younger and less likely to have been previously admitted to the hospital for asthma. Other demographics, including admission severity of illness, gender, and prevalence of overweight, were similar in the two groups. There were no differences between the groups in ICU length of stay, hospital length of stay or types of therapies received. Thirteen children with mild asthma were intubated, although less frequently than those with more severe disease.

CONCLUSIONS

Children with mild asthma have severe exacerbations. This suggests that chronic asthma severity does not necessarily predict asthma phenotypes during acute exacerbations.

Regulatory role of B cells in a murine model of allergic airway disease

Mice sensitized to OVA and subjected to acute OVA aerosol exposures develop allergic airway disease (AAD). However, chronic continuous Ag exposure results in resolution of AAD and the development of local inhalational tolerance (LIT). Because we have previously observed the persistence of B cells in the bronchoalveolar lavage (BAL) and hilar lymph nodes (HLN) at the resolution stage of this model, we investigated the role of B cells in the modulation of AAD. Although B cell-deficient mice developed LIT, adoptive transfer of HLN B cells from LIT mice to OVA-sensitized recipients resulted in attenuated AAD following subsequent OVA aerosol exposure, as determined by reduced BAL leukocytosis and eosinophilia, decreased tissue inflammation, and absent methacholine hyper-responsiveness. In similar adoptive transfer studies, HLN B cells from AAD mice were without effect. The protection transferred by LIT HLN B cells was Ag specific and was associated with accumulation of Foxp3(+) T regulatory cells regionally in BAL and HLN, but not systemically in the spleen. Fluorescent labeling of LIT HLN B cells before adoptive transfer demonstrated that these cells had the capacity to migrate to local inflammatory sites. In vitro assessment demonstrated that the LIT HLN B cells exerted this regulatory effect via TGF-beta induced conversion of CD4(+)CD25(-) T effector cells into functionally suppressive CD4(+)CD25(+)Foxp3(+) T regulatory cells. These findings illustrated a novel regulatory role for regional B cells in AAD and suggested a possible contributory role of B cells, along with other cell types, in the establishment of LIT.

Slow-responders to IV beta2-adrenergic agonist therapy: defining a novel phenotype in pediatric asthma

OBJECTIVES

While aerosolized administration of beta(2)-adrenergic receptor (beta(2)-AR) agonists is the mainstay of treatment for pediatric asthma exacerbations, the efficacy of intravenous (IV) delivery is controversial. Failure to demonstrate improved outcomes with IV beta(2)-AR agonists may be due to phenotypic differences within this patient population. Our hypothesis is that children who respond more slowly to IV beta(2)-AR agonist therapy comprise a distinct phenotype.

METHODS

Retrospective chart review of all children admitted to the ICU for status asthmaticus who were treated with IV terbutaline between December 2002 and September 2006.

RESULTS

Seventy-eight children were treated with IV terbutaline according to guidelines that adjusted the dose by clinical asthma score. After examining the histogram of duration of terbutaline infusions, a 48-hr cutoff was chosen to define responsiveness. Thirty-eight (49%) children were slow-responders by this definition. There were no significant differences in baseline asthma severity or severity on admission between the slow-responders and responders. Slow-responders required significantly higher total doses of IV terbutaline, higher maximum administration rates, and had longer ICU and hospital length of stay.

CONCLUSION

There were significant differences in outcomes between the responders and slow-responders without differences in acute or chronic illness severity. Other factors may have lead to slower response to IV beta(2)-agonist therapy.

Subcutaneous late phase responses are augmented during local inhalational tolerance in a murine asthma model

Acute exposure of sensitized mice to antigen elicits allergic airway disease (AAD) characterized by Th2 cytokine-dependent pulmonary eosinophilia, methacholine hyperresponsiveness and antigen-specific IgE elevation. However, chronic exposure induces a local inhalational tolerance (LIT), with resolution of the airway responses but persistent systemic IgE production. To further determine if systemic immunologic responses were maintained during LIT, we assessed subcutaneous late phase responses to ovalbumin in this model. Sensitized and AAD mice developed small subcutaneous responses to ovalbumin, with footpad thickness increasing to 113.7 and 113.6% of baseline, respectively. In comparison, LIT mice developed marked foot swelling (141.6%). Histologic examination confirmed increased inflammation in the chronic animals, with a significant contribution by eosinophils. Thus, the resolution of airway inflammatory responses with chronic antigen inhalation is a localized response, not associated with loss of systemic responses to antigen.

Effect of a short course of prednisolone in infants with oxygen-dependent bronchopulmonary dysplasia

OBJECTIVE

The purpose of this work was to determine whether oral prednisolone is effective in weaning infants with bronchopulmonary dysplasia, after 36 weeks' postmenstrual age, off supplemental oxygen and to identify factors associated with successful weaning.

METHODS

Data were abstracted from a standardized prospectively collected database at the John Dempsey Hospital NICU. Logistic regression and receiver operating curve analyses were used.

RESULTS

Of 385 infants, 131 (34%) received oral prednisolone and 254 (66%) did not. There was no significant difference in race, gender, birth weight, or gestational age between the groups receiving and not receiving oral prednisolone. Infants in the oral prednisolone group were more likely to have received previous dexamethasone therapy, had longer duration of mechanical ventilation, had longer length of hospital stay, and were more likely to be discharged from the hospital on oxygen. Of those in the oral prednisolone group, 63% responded to treatment. Pulmonary acuity score and PCO2 were the only parameters that remained significant on multiple logistic regression analyses. The oral prednisolone-responsive group had a lower pulmonary acuity score compared with the oral prednisolone-nonresponsive group. A pulmonary acuity score value of < or = 0.5 had a sensitivity of 20% and specificity of 97.4%, with positive and negative predictive values of 94.1% and 42.1%, respectively. Capillary PCO2 values were significantly lower in the oral prednisolone-responsive group compared with the oral prednisolone-nonresponsive group. In predicting a successful response to oral prednisolone, a capillary PCO2 value of < 48.5 mmHg had a sensitivity of 50% and specificity of 89.7%, with positive and negative predictive values of 89.1% and 51.8%, respectively.

CONCLUSIONS

Oral prednisolone therapy is effective in weaning off supplemental oxygen in a postterm infant with oxygen-dependent bronchopulmonary dysplasia who has a pulmonary acuity score of < 0.5 and PCO2 of < 48.5 mmHg. In addition, if a single course of prednisolone fails, there is no clear benefit of using multiple courses.

Accumulation of regulatory T cells in local draining lymph nodes of the lung correlates with spontaneous resolution of chronic asthma in a murine model

BACKGROUND

Mice sensitized to ovalbumin develop allergic airway disease (AAD) with short-term aerosol challenge; however, airway inflammation resolves with long-term aerosol challenge, referred to as local inhalational tolerance (LIT).

METHODS

We sought to determine if resolution of airway inflammation correlated with increases in lymphocyte subsets in local lung compartments, including putative regulatory T cells.

RESULTS

At the AAD stage, total numbers of T and B lymphocytes in bronchoalveolar lavage (BAL) were significantly increased above controls; however, at LIT, T and B lymphocytes were significantly reduced compared to AAD. In the lung tissue, the only alteration was a significant increase in CD4+ CD25+ T cells at AAD. In the hilar lymph node (HLN), CD4+ and CD4+ CD25+ T cells were significantly increased at AAD and LIT. In addition, CD8+ T cells were significantly elevated in the HLN at LIT, and CD19+ B cells were significantly increased at AAD. Adoptive transfer of HLN lymphocytes to lymphopenic mice confirmed that AAD lymphocytes could induce airway inflammation in response to aerosol challenge, whereas LIT lymphocytes were unable to do so. Depletion of CD4+ CD25+ T cells in vivo resulted in exacerbation of inflammation at AAD and LIT. CD4+ CD25+ T cells in the HLN also displayed suppressive activity in vitro. Additionally, T cells expressing Foxp3 were increased in the BAL and HLN during LIT.

CONCLUSIONS

These results indicate that lymphocytes with regulatory functions are increased and sustained in local lung compartments at LIT and that their appearance correlates with the resolution of lung inflammation.

Maternal transmission of resistance to development of allergic airway disease

Parental phenotype is known to influence the inheritance of atopic diseases, such as allergic asthma, with a maternal history being a more significant risk factor for progeny than paternal history. We hypothesized that recall Th1- or Th2-type immune responses during pregnancy would result in transfer of maternal factors that would differentially impact development of immune responsiveness in offspring. Following weaning, susceptibility and severity of allergic airway disease (a murine model of human asthma) was evaluated in progeny, disease being elicited by immunization with OVA-Al(OH)(3) and challenge with aerosolized OVA. We found that progeny of mothers with Th1-biased immunity to OVA subjected to recall aerosol challenge during pregnancy had reduced levels of Ag-specific IgE and airway eosinophilia compared with progeny of mothers with Th2-biased immunity to OVA or naive mothers. Interestingly, progeny of mothers with Th1-type immunity to a heterologous albumin, BSA, were not protected from developing OVA-induced allergic airway disease. These findings demonstrated that maternal transfer of protection from development of allergic airway disease to offspring in this model of maternal Th1-type immunity was Ag specific.

Regional increases of CD103+ Tregs corresponds with resolution of murine allergic airway disease (39.10)

Mice sensitized to ovalbumin (OVA) develop allergic airway disease (AAD) with short-term OVA aerosol challenge (7 days); however, airway inflammation resolves and local inhalational tolerance (LIT) results with long-term continuous aerosol challenge (42 days). We have previously seen that regulatory T cell (Treg) populations that are CD4+CD25+Foxp3+ increase locally in the lung at AAD and expand further at LIT. A recent role for CD4+CD25+Foxp3+ CD103+ Tregs (CD103+Tregs) has been defined in mucosal models of inflammation; this subset of Treg cells has been demonstrated to have greater functionality in suppressing inflammation. The current study was designed to determine if the numbers of CD103+Treg cells in HLN correlate with the development of LIT. HLN and inguinal lymph nodes (ILN) were harvested from groups (n=6) of naive, sensitized, AAD and LIT mice. Flow cytometric analysis on the cells isolated from HLN and ILN demonstrated a significant (p&lt;.001) increase in the numbers and percentages of CD103+ Treg in HLN at LIT (7x103+ 4 HLN; 2x103+0.5 ILN ) compared to AAD (2x103+ 1 HLN; 1x103+0.5 ILN ). There was no significant increase of CD103+Treg in HLN between naïve, sensitized and AAD mice. The increase of CD103+ Tregs was seen regionally in HLN but not in ILN. In summary, the data suggests a novel in vivo role for CD103+Tregs in the subsequent resolution of a Th2 driven inflammatory response.

Funded by NIH/AIRO1 HL-43573

Endotracheal intubation and pediatric status asthmaticus: site of original care affects treatment

OBJECTIVES

Status asthmaticus is a common cause of admission to a pediatric intensive care unit (PICU). Children unresponsive to medical therapies may require endotracheal intubation; however, this treatment carries significant risk, and thresholds for intubation vary. Our hypothesis was that children who sought care at community hospitals received less aggressive treatment and more frequent intubation than children who sought care at a children's hospital.

DESIGN

Retrospective cohort study.

SETTING

A university-affiliated children's hospital PICU.

PATIENTS

We retrospectively examined data from all children older than 2 yrs admitted to the PICU with status asthmaticus between April 1997 and July 2005.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 251 children admitted to the PICU with status asthmaticus, 130 initially presented to the emergency department of a children's hospital and 116 presented to the emergency department of a community hospital. Despite similar illness severity, children presenting to a community hospital were significantly more likely to be intubated than those presenting to a children's hospital (17% vs. 5%; p = .004). In addition, those children intubated at community hospitals were intubated sooner after presentation (2.4 +/- 5.2 vs. 7.5 +/- 5.8 hrs; p = .009), had shorter durations of intubation (71 +/- 73 vs. 151 +/- 81 hrs; p = .02), and had shorter PICU length of stays (129 +/- 82 vs. 230 +/- 84 hrs; p = .01).

CONCLUSIONS

Children with status asthmaticus are more likely to be intubated, and intubated sooner, at a community hospital. The shorter duration of intubation suggests that some children may not have been intubated had they presented to a children's hospital or received more aggressive therapy at their community hospital.

Chronic inhaled corticosteroids do not affect the course of acute severe asthma exacerbations in children

Chronic therapy with inhaled corticosteroids (ICS) suppresses airway inflammation and increases airway responsiveness to beta(2)-adrenergic receptor agonists. We hypothesized that the chronic use of ICS would be associated with shorter duration of hospitalization in severely ill children with status asthmaticus. An 8-year retrospective chart review was conducted of all children admitted to the ICU with status asthmaticus. During the study period, 241 children were admitted, and 44% reported the use of chronic ICS. ICS use was associated with increased baseline asthma severity, previous hospitalization for asthma, and public insurance status. However, ICS use had no effect on hospital or ICU length of stay, type, and duration of treatments received, or the rate of recovery determined by a standard severity of illness scoring system. In the subsets of patients including children with persistent asthma and those who received intravenous terbutaline, there was also no improvement in outcomes with the use of chronic ICS showing that the chronic use of ICS did not improve response to beta(2)-adrenergic receptor agonists in severely ill children with status asthmaticus. Although useful as a preventive therapy, the chronic use of ICS does not appear to affect the course of severe acute asthma exacerbations in pediatric patients once hospitalized.

Childhood obesity increases duration of therapy during severe asthma exacerbations

OBJECTIVES

Childhood obesity contributes to a wide array of medical conditions, including asthma. There is also increasing evidence in adult patients admitted to the intensive care unit (ICU) that obesity contributes to increased morbidity and to a prolonged length of stay. We hypothesized that obesity is associated with the need for increased duration of therapy in children admitted to the ICU with status asthmaticus.

DESIGN

Retrospective cohort study.

SETTING

A tertiary pediatric ICU in a university-affiliated children's hospital.

PATIENTS

We retrospectively examined data from all children older than 2 yrs admitted to the ICU with status asthmaticus between April 1997 and June 2004. Children were classified as normal weight (<95% weight-for-age percentile) or obese (>95% weight-for-age).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 209 children admitted to the ICU with asthma, 45 (22%) were obese. Compared with children of normal weight, the obese children were older (9.7 +/- 4.4 vs. 8.0 +/- 4.3 yrs, p = .02), more likely to be female (60% vs. 37%, p < .01), and more likely to have been admitted to the ICU previously (40% vs. 20%, p = .01). The obese children also had a statistically significant difference in race (more likely to be Hispanic) and in baseline asthma classification (more likely to have persistent asthma). Despite similar severity of illness at ICU admission, obese children had a significantly longer ICU length of stay (116 +/- 125 hrs vs. 69 +/- 57 hrs, p = .02) and hospital length of stay (9.8 +/- 7.0 vs. 6.5 +/- 3.4 days, p < .01). Obese children also received longer courses of supplemental oxygen, continuous albuterol, and intravenous steroids.

CONCLUSIONS

Childhood obesity significantly affects the health of children with asthma. Obese children with status asthmaticus recovered more slowly from an acute exacerbation, even after adjustment for baseline asthma severity and admission severity of illness.

Noninvasive positive pressure ventilation for the treatment of status asthmaticus in children

BACKGROUND

Noninvasive positive pressure ventilation (NPPV) has been used safely and effectively to improve gas exchange and to treat respiratory failure in a variety of disease states. Although this technique has some benefits in the treatment of status asthmaticus in adults, the use of NPPV in pediatric patients with asthma has not been described.

OBJECTIVE

To describe the use of NPPV in the treatment of pediatric status asthmaticus.

METHODS

Retrospective review of children admitted to the intensive care unit with asthma who received NPPV as part of their treatment between October 2002 and April 2004. Before and after initiation of NPPV, data were collected regarding degree of respiratory dysfunction.

RESULTS

Of seventy-nine children admitted to the intensive care unit during the study period for treatment of status asthmaticus, 5 children (mean +/- SD age, 9.6 +/- 4.2 years) were treated with NPPV. Four of the 5 children were morbidly obese, with a mean +/- SD body mass index of 32 +/- 5. There was a statistically significant improvement in respiratory rate (43 +/- 20 vs 31 +/- 12/min, P = .03) and Modified Pulmonary Index Score (13.4 +/- 1.8 vs 11.4 +/- 1.5, P = .03) after initiation of NPPV. The mean +/- SD duration of therapy was 33.2 +/- 23.9 hours, and children tolerated this therapy well, requiring little or no anxiolytics.

CONCLUSIONS

NPPV was well tolerated in this series of children with status asthmaticus and can improve subjective and objective measures of respiratory dysfunction. NPPV may be a useful adjunct in the treatment of status asthmaticus in children.

Protocol-based titration of intravenous terbutaline decreases length of stay in pediatric status asthmaticus

Although frequently used to treat status asthmaticus in children, intravenous (IV) terbutaline has not been shown to decrease hospital length of stay (LOS). We theorized that this lack of demonstrable benefit resulted from variations in dosing and titration, rather than the drug per se, and that intensive care unit (ICU) LOS would be shortened by the administration of terbutaline according to a protocol incorporating a quantitative assessment of severity of illness. We prospectively treated 20 consecutive children with status asthmaticus with IV terbutaline according to a protocol that titrated the dose based on a clinical asthma score, the Modified Pulmonary Index Score (MPIS). Data were compared to a historic cohort of the previous 20 consecutive ICU patients with status asthmaticus who were treated with IV terbutaline prior to initiation of the protocol. Patients who received terbutaline by standardized protocol had significantly shorter ICU LOS (3.5 +/- 1.1 vs. 5.0 +/- 2.0 days, P = 0.01), shorter hospital LOS (5.5 +/- 1.3 vs. 8.3 +/- 2.7 days, P < 0.01), and reduced hospital charges ($19,298 +/- $10,516 vs. $26,528 +/- $12,328, P = 0.04). The method of administration of IV terbutaline significantly influenced ICU length of stay and hospital charges.

Tolerance induced by chronic inhaled antigen in a murine asthma model is not mediated by endotoxin

Ovalbumin (OVA)-sensitized wildtype (WT) and endotoxin-resistant (ER) mice developed similar degrees of airways eosinophilia and serum OVA-specific IgE levels after acute aerosolized OVA challenge. WT mice demonstrated methacholine hyperreactivity, whereas ER mice showed no change in responsiveness. With chronic aerosolized OVA challenge, both WT and ER mice developed local tolerance, with resolution of airway eosinophilia but persistence of anti-OVA IgE in serum. Thus, the development of local tolerance with chronic aerosol exposure to OVA is independent of any potential effects of endotoxin in the OVA aerosol solution.

Interleukin-10 does not mediate inhalational tolerance in a chronic model of ovalbumin-induced allergic airway disease

OBJECTIVE

IL-10 is a potent anti-inflammatory cytokine, and IL-10-producing regulatory T cells are effective inhibitors of murine asthmatic responses. This study determined whether IL-10-dependent mechanisms mediated the local inhalational tolerance seen with chronic inhalational exposure to antigen.

METHODS

Wildtype and IL-10(-/-) mice were sensitized with ovalbumin (OVA) and then challenged with daily OVA inhalations for 10 days or 6 weeks.

RESULTS

The 10-day animals developed allergic airway disease, characterized by BAL eosinophilia, histologic airway inflammation and mucus secretion, methacholine hyperresponsiveness, and OVA-specific IgE production. These changes were more pronounced in IL-10(-/-) mice. The 6-week IL-10(-/-) and wildtype animals both developed inhalational tolerance, with resolution of airway inflammation but persistence of OVA-specific IgE production.

CONCLUSION

IL-10 may have anti-inflammatory effects in the acute stage of murine allergic airways disease, but the cytokine does not mediate the development of local inhalational tolerance with chronic antigen exposure.

Bromelain exerts anti-inflammatory effects in an ovalbumin-induced murine model of allergic airway disease

OBJECTIVE

Bromelain, a clinically used pineapple extract and natural product, has reported anti-inflammatory and immunomodulatory activities. The purpose of this study was to determine the effect of bromelain treatment in an ovalbumin (OVA)-induced murine model of allergic airway disease (AAD).

METHODS

To establish AAD, mice were sensitized with intraperitoneal (i.p.) OVA/alum and challenged with daily OVA aerosols. Mice were treated i.p. with either saline, 2 or 6 mg/kg bromelain, twice daily for four consecutive days. Bronchoalveolar lavage leukocytes and cytokines, lung histology, airway hyperresponsiveness, and lymphocyte populations via flow cytometry were compared between groups.

RESULTS

Bromelain treatment of AAD mice resulted in reduced total BAL leukocytes, eosinophils, CD4+ and CD8+ T lymphocytes, CD4+/CD8+ T cell ratio, and IL-13.

CONCLUSION

Bromelain attenuated development of AAD while altering CD4+ to CD8+ T lymphocyte populations. The reduction in AAD outcomes suggests that bromelain may have similar effects in the treatment of human asthma and hypersensitivity disorders.

The influence of pulmonary function testing on the management of asthma in children

OBJECTIVE

To assess how often in a single encounter that pulmonary function tests (PFTs) influenced management decisions in children with asthma, beyond what was obtained from history and physical examination alone.

STUDY DESIGN

Children with asthma (n = 367, age 4 to 18 years) performed spirometry before clinical evaluation. Physicians and nurse practitioners in the outpatient pulmonary office evaluated the children and made initial treatment recommendations before reviewing the spirometry results. Any changes based on the test results were documented.

RESULTS

Spirometry was abnormal in 45% of the visits, related to underlying asthma severity but not to clinical findings. PFT results changed management decisions in 15% of visits. This frequency was not affected by the patient's age, disease severity, symptom control, or exam findings. When spirometry did not change treatment decisions, the provider was more likely to maintain therapy (58%) than to increase (17%) or decrease (24%) therapy. In contrast, when spirometry did change treatment decisions, the provider was more likely to increase therapy (75%) than to maintain (20%) or decrease (5%) therapy.

CONCLUSION

Without PFTs, providers often overestimated the degree of asthma control. This incorrect assessment could have resulted in suboptimal therapy.

A modified pulmonary index score with predictive value for pediatric asthma exacerbations

BACKGROUND

Several clinical asthma scores have been derived from combinations of physical findings in pediatric asthmatic patients.

OBJECTIVE

To test the reproducibility and validity of one such score, the Modified Pulmonary Index Score (MPIS), and to evaluate its predictive value in children hospitalized for asthma.

METHODS

In the MPIS, 6 categories are evaluated: oxygen saturation, accessory muscle use, inspiratory to expiratory flow ratio, degree of wheezing, heart rate, and respiratory rate. For each of these 6 measurements or observations, a score of 0 to 3 is assigned. To evaluate the reproducibility of the MPIS, inpatients with status asthmaticus were examined by an attending physician, nurse, and respiratory therapist who were blinded to the other observers' scores. To evaluate the validity of the MPIS as a scale of severity of illness in asthmatic patients, the score at admission was compared with selected outcomes in the same patients.

RESULTS

A total of 30 patients participated in this study (mean +/- SD age, 7.6 +/- 5.5 years). Our finding revealed that the MPIS is highly reproducible with a high degree of interrater reliability across caregiver groups (physician to nurse: r = 0.98; 95% confidence interval [CI], >0.96; physician to respiratory therapist: r = 0.95; 95% CI, >0.92; nurse to respiratory therapist: r = 0.94; 95% CI, >0.90). The admission MPIS positively correlated with intensive care unit admission (P < .001), days of continuous albuterol therapy (P = .002), days of supplemental oxygen (P = .002), and length of hospital stay (P = .004).

CONCLUSIONS

The MPIS is a highly reproducible and valid indicator of severity of illness in children with asthma. To our knowledge, this is the first pediatric clinical asthma score demonstrated to be reproducible across groups of health care professionals who treat pediatric patients with asthma.