Risk Factor For Asthma Exacerbations Research Articles

Chronic Rhinosinusitis in Allergic Asthmatic Patients: Radiography Versus Low-Dose Computed Tomography Evaluation

Objective. Chronic rhinosinusitis (CRS) is a risk factor for asthma exacerbations and is associated with greater clinical severity. Discrepancies may exist between CRS clinical diagnosis and data from paranasal sinus (PS) X-ray or computed tomography (CT) scans. The objective was to compare PS involvement using low-dose CT and plain X-ray in allergic asthmatic patients with rhinitis. Methods. Patients underwent PS radiography in the frontal and mentonian positions and low-dose CT consisting of six to eight coronal scans performed on the central region of the sphenoidal, ethmoidal, maxillary, and frontal sinuses. Possible results for each sinus were a normal aspect or the presence of mucosal thickening, opacification, and/or air-fluid level. Results. Eighty-five (93.4%) of 91 study patients had radiological changes on radiography or CT. In only six (6.6%) were both tests normal. The maxillary was the most involved sinus by both methods. Simultaneous PS abnormalities were observed in 40.5% on X-ray and 56.7% on CT. For the frontal, ethmoidal, and sphenoidal sinuses, the proportion of normal results differed significantly between X-ray and CT: 80.2% versus 89%, 76.9% versus 63.7% and 96.7% versus 70.3%, respectively (p <.05). Agreement was over 70% for the maxillary and frontal sinuses. CT also provided a better diagnosis of air-fluid level changes than X-ray. Conclusions. Low-dose CT significantly showed larger number of normal PS results and diagnosed more severe PS lesions. As the determination of true sinus severity lesion impacts in asthma control, low-dose CT may replace PS plain X-ray and conventional CT to support better clinical decisions.

Viral respiratory tract infections and asthma: The course ahead

Inquiries into the relationships between viral respiratory tract illnesses and the inception and exacerbation of asthma are being facilitated by recent advances in research approaches and technology. In this article we identify important knowledge gaps and future research questions, and we discuss how new investigational tools, including improved respiratory tract virus detection techniques, will permit current and future researchers to define these relationships and the host, virus, developmental, and environmental mechanisms that regulate them. A better understanding of these processes should facilitate the development of improved strategies for the prevention and treatment of virus-induced wheezing illnesses and asthma exacerbations and, possibly, the ultimate goal of discovering effective approaches for the primary prevention of asthma.

Fatores de risco para visitas à emergência por exacerbações de asma em pacientes de um programa de controle da asma e rinite alérgica em Feira de Santana, BA

To determine the risk factors for ER visits due to asthma exacerbations in patients monitored at a referral center. Prospective cohort study of 253 outpatients (children and adults) with asthma who were monitored for 12 months at the Referral Center of the Program for the Control of Asthma and Allergic Rhinitis in the city of Feira de Santana, Brazil. Exacerbations were common, and 36.5% of the patients sought ER treatment within the twelve-month period. The risk factors for asthma exacerbations were being over 20 years of age (OR = 1.34: (95% CI: 1.06-1.70), residing in an urban area (OR = 1.19; 95% CI: 1.06-1.33); having a low level of education (OR = 1.53: 95% CI: 1.00-2.39); having severe asthma (OR = 1.65; 95% CI: 1.24-2.18); and having chronic rhinitis (OR = 2.20; 95% CI: 1.00-4.80). In this cohort, having chronic rhinitis, having asthma that is more severe and having a low level of education were the main risk factors for ER visits due to asthma exacerbations. These results are similar to those reported for asthma patients who are receiving no regular treatment.

Obstructive Sleep Apnea Syndrome and Asthma: What Are the Links?

Recent data suggest that obstructive sleep apnea syndrome (OSAS) is an independent risk factor for asthma exacerbations. Neuromechanical reflex bronchoconstriction, gastroesophageal reflux, inflammation (local and systemic), and the indirect effect on dyspnea of OSAS-induced cardiac dysfunction have been suggested as mechanisms that lead to worsening asthma control in patients with concomitant OSAS. Vascular endothelial growth factor-induced airway angiogenesis, leptin-related airway changes, and OSAS-induced weight gain also may play a common mechanistic role linking both disorders. Several studies have confirmed that asthmatic patients are more prone to develop OSAS symptoms than are members of the general population. The common asthmatic features that promote OSAS symptoms are nasal obstruction, a decrease in pharyngeal cross sectional area, and an increase in upper airway collapsibility. Clarifying the nature of the relationship between OSAS and asthma is a critical area with important therapeutic implications.

Update in Asthma 2006

Asthma-related investigations reported in 2006 ranged from the characterization of clinical asthma and airway obstruction (1–4), to human biologic studies (5, 6) and the use of animal models to better understand pathobiologic mechanisms at a cellular and molecular level (7–19). The concept of “risk” has been featured prominently, with articles identifying factors that increase the risk of developing asthma (20–24) as well as those aimed at identifying risk factors for asthma exacerbations and adverse outcomes (25–29). Studies have continued to explore the utility of noninvasive biomarkers (exhaled nitric oxide, exhaled breath condensate) to identify (30, 31), modify (32), and treat disease while increasing understanding of pathophysiologic mechanisms in asthma (33, 34). Clinical trials have sought to optimize treatment with established asthma drugs (35–37) and to evaluate novel modalities to fill voids in our current armory of asthma medications (38–40). Overall, this year has been an interesting journey, particularly in clinical asthma research, challenging accepted concepts in asthma therapy, and urging clinicians to expand their assessment of patients to identify and modify patient risk in addition to traditional measures of asthma control (41).

Efficacy of HEPA-CPZ Air Cleaners on Unscheduled Asthma Visits and Asthma Symptoms in ETS-Exposed Children with Asthma

WM1-O-05 Background: Environmental tobacco smoke (ETS) is a risk factor for asthma exacerbations, but it is unknown if reducing ETS will reduce unscheduled asthma visits or asthma symptoms, especially for older children. There is also uncertainty about the efficacy of high-efficiency particle arresting (HEPA) air cleaners on asthma exacerbations and symptoms. Objective: To test the efficacy of HEPA-CPZ (HEPA with activated carbon, potassium permanganate, and Zeolite filter inserts) air cleaners on unscheduled asthma visits and asthma symptoms for children with asthma who were exposed to ETS. Participants: We enrolled 225 children who were 6 to 12 years of age, had doctor-diagnosed asthma, and were reportedly exposed to >5 cigarettes per day. Study Design: We used a randomized, double-blind, placebo-controlled study design. Children in the Experimental Group received 2 active HEPA-CPZ air cleaners in their home, whereas children in the Control Group received 2 inactivated (placebo) air cleaners. We used the AAP's Child Health Asthma Survey, a validated survey to measure asthma symptoms. Results: Of the 225 children in the trial, 110 (49%) were randomly assigned to the experimental group and 115 (51%) were assigned to the control group. The mean age of children was 8.5 years; 62% were male. Children were exposed to a mean of 14.5 cigarettes per day. Of the 225 enrolled children, 215 (95%) participated in the 12-month follow-up study. At 12 months, there was a significant reduction in unscheduled asthma visits (clinic, emergency visits, and hospitalizations) in the experimental group compared with the control group. Adjusting for baseline visits, the number of unscheduled visits for asthma decreased by 87% from baseline to 12-month follow-up in the experimental group compared with a 35% decrease in the control group (P = 0.043). In contrast, there was no significant difference in exhaled nitric oxide, asthma symptoms (shortness of breath, chest tightness, wheeze, or difficulty sleeping), air nicotine, airborne particulates, serum cotinine, or hair cotinine by group assignment. Conclusions: HEPA-CPZ air cleaners led to a significant reduction in unscheduled asthma visits. In contrast, there was no reduction in ETS exposure, asthma symptoms, or exhaled nitric oxide by group assignment. Although these results hold some promise for using HEPA air cleaners to reduce unscheduled asthma visits, further study is needed before portable HEPA air cleaners can routinely be recommended to reduce indoor air pollutants or asthma exacerbations.

Infections, Immunity &amp; their Effects on Asthma

Infections, Immunity &amp; their Effects on Asthma

LPS binding protein is important in the airway response to inhaled endotoxin

Background Inhaled endotoxin is a risk factor for asthma exacerbation, and endotoxin inhalation by itself recapitulates many of the classical features of asthma in mice, including reversible airflow obstruction and inflammation, airways hyperresponsiveness, and airway remodeling. Objective Our objective was to determine the importance of LPS binding protein (LBP) in the response to inhaled LPS. Methods We challenged LBP-deficient mice (C57BL/6 LBP−/−) and C57BL/6 mice with inhaled endotoxin for 4 hours, 5 days, or 4 weeks, followed by 3 days of recovery. Results LBP in the lung was significantly increased in LPS-exposed C57BL/6 mice from all 3 groups. Only LPS-exposed C57BL/6 mice had significantly enhanced airway responsiveness to inhaled methacholine. Total lavage cells in LPS-exposed C57BL/6 LBP−/− mice were significantly reduced compared with those seen in LPS-exposed C57BL/6 mice; however, the percentage of PMNs was similarly increased in both the C57BL/6 and C57BL/6 LBP−/− mice. TNF-α, IL-1β, and IL-6 protein concentrations in whole-lung lavage fluid from C57BL/6 LBP−/− mice were also significantly reduced when compared with those seen in C57BL/6 mice. In C57BL/6 LBP−/− mice submucosal cell proliferation was significantly reduced in the 1-week group when compared with that seen in similarly exposed C57BL/6 mice. The 4-week exposed C57BL/6 mice had significantly thickened airway submucosa and significantly increased lavaged TGF-β 1 protein compared with that seen in C57BL/6 LBP−/− mice. Conclusions These findings indicate that LBP is one of the critical molecules regulating the acute and chronic airway response to inhaled LPS.

PEDIATRICIAN SELF-EFFICACY FOR COUNSELING PARENTS OF ASTHMATIC CHILDREN TO QUIT SMOKING

Cabana MD, Rand C, Slish K, et al. Pediatrics . 2004;113:78–81 Although environmental tobacco smoke is a known risk factor for asthma exacerbations among children, pediatricians infrequently advise parents who smoke to discontinue smoking. It has been shown that high physician self-efficacy or self-confidence in the counseling of parents regarding smoking discontinuation is related to increased physician screening and counseling on this issue. It is unclear, however, which factors are associated with high physician self-efficacy …

Risk factors for asthma exacerbations: Is asthma severity a predictor?

Risk factors for asthma exacerbations: Is asthma severity a predictor?

Cloning and Molecular Characterization of a cDNA from Blomia tropicalis Homologous to Dust Mite Group 3 Allergens (Trypsin-Like Proteases)

Background: Exposure to the house dust mite Blomia tropicalis is increasingly being implicated as a major risk factor for asthma exacerbations in sensitized individuals. The objective of this study is to clone and characterize B. tropicalis allergens in order to better define their role in allergic asthma. Methods: A λgt22A cDNA library was constructed from B. tropicalis mRNA and screened using specific DNA probes. A full-length cDNA (Bt2-3) was isolated, subcloned, and sequenced. Results: Sequence analysis showed that clone Bt2-3 encodes the full-length serine protease preproenzyme from B. tropicalis. The predicted Bt2-3 protein consists of a 15-amino-acid signal peptide, a 20-amino-acid propeptide and a mature protein of 231 amino residues. BLAST analysis of the deduced amino acid sequence showed high homology (48–54%) between clone Bt2-3 and serine proteases (group 3 allergens) from domestic dust mites. Both the serine active site (DACQGDSGGPVA; amino acids 214–225) and the histidine active site (LTAAHC; amino acids 71–76) of serine proteases were highly conserved. The estimated molecular weight of the preproenzyme is 27.5 kD and its theoretical pI is 8.7. The mature protein contains a putative tyrosine kinase phosphorylation site (amino acids 24–31) and several N-myristoylation sites. Sequence alignment shows that the serine protease active sites are highly conserved among the clinically important mite species, including B. tropicalis. Conclusion: We report the cloning and molecular characterization of a B. tropicalis cDNA clone encoding a trypsin-like protease, with a possible major role as an allergen. Expression and further characterization of the recombinant product will help determine the role of proteolytic enzymes in the pathophysiology of allergic asthma.

Asthma in adventure travelers: a prospective study evaluating the occurrence and risk factors for acute exacerbations.

Exacerbation of asthma during travel to remote regions may lead to devastating consequences. The course of asthma in travelers and the risk factors for disease exacerbation during travel have not been studied. We screened 5835 consecutive travelers and identified 203 patients with asthma. Before travel, all enrollees were assessed for presumed risk factors for asthma exacerbation by means of an interview and an exercise test combined with spirometry. After travel, data regarding travel characteristics and asthma severity were recorded by means of a structured telephone interview. The 203 enrollees visited 56 countries for a median duration of 13 weeks, 147 were engaged in high-altitude trekking, and 88 had asthma attacks. Among these, 40 reported worsening asthma during travel, 32 experienced the worst asthma attack ever, and 11 reported a life-threatening asthma attack. Two independent risk factors for attacks during travel were identified: frequent use (> or = 3 times weekly) of inhaled bronchodilators before travel (relative risk [RR], 3.35; 95% confidence interval [CI], 1.75-6.39) and participation in intensive physical exertion during treks (RR, 2.04; 95% CI, 1.04-3.98). When both risk factors were present, the RR for asthma attacks increased to 5.52 (95% CI, 2.81-10.84). Asthma frequently worsens during travel and should not be ignored as a potentially life-threatening condition requiring pretravel consideration. Asthmatic travelers who frequently use inhaled bronchodilators before travel or participate in intensive trekking during travel are at increased risk to develop asthma attacks. Therapy should be intensified to achieve better disease control; intensive trekking should be discouraged.

Avoidance of allergens and air pollutants in respiratory allergy

Avoidance of allergens and air pollutants in respiratory allergy

Behavioral and environmental factors associated with acute exacerbation of asthma.

The relapse rate following treatment for acute asthma is high. While previous studies have evaluated the utility of pulmonary function measurements to identify patients likely to relapse, the results are conflicting. The purpose of this study was to evaluate other correctable, risk factors that may be associated with relapse. Two hundred twenty-three patients treated in the emergency department during 1994, including those either admitted or discharged. Patient interviews to identify behavioral and environmental risk factors for asthma exacerbation. Telephone contact and medical record review to determine incidence of relapse. Two hundred twenty-three patients were enrolled of whom follow-up data were available for 152 (68%). Twenty-one percent of the patients relapsed within 14 days. Relapse was associated with the lack of an identifiable primary care physician and inability to obtain discharge medications. There was no relationship between relapse and the use of a spacer, hypoallergenic pillow or mattress cover, cigarette smoking, the presence of pets in the home, or weekly carpet cleaning. Even following hospitalization for acute asthma, there is a significant relapse rate. Improving patients' access to primary care physicians and to appropriate medications may decrease the relapse rate. Although a significant portion of patients have behavioral and environmental risk factors for asthma exacerbation including cigarette smoking and failure to maintain a hypoallergenic environment, these factors are not associated with short-term relapse.

Washing the clothes of cat owners is a simple method to prevent cat allergen dispersal

Washing the clothes of cat owners is a simple method to prevent cat allergen dispersal