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Biomedical subjects

H S Nelson

Publications and source records attributed to H S Nelson.

At least 19 recordsLinked to original sources
PubMed2001

Comparison of fluticasone propionate-salmeterol combination therapy and montelukast in patients who are symptomatic on short-acting beta(2)-agonists alone.

The objective of this study was to determine whether initial maintenance therapy for the treatment of inflammation and bronchoconstriction associated with persistent asthma is more effective with a combination product (100 microg of fluticasone propionate and 50 microg of salmeterol [FSC]) administered twice daily through the Diskus device (GlaxoWellcome, Research Triangle Park, NC) or with montelukast at 10 mg once daily. A 12-wk, randomized, double-blind, double-dummy, multicenter study was conducted with 423 patients 15 yr of age and older with asthma and who were symptomatic while receiving short-acting beta(2)-agonists alone. At end point, FSC resulted in significantly greater increases in morning predose FEV(1) (0.54 +/- 0.03 vs. 0.27 +/- 0.03 L), morning peak expiratory flow (PEF) (89.9 +/- 6.7 vs. 34.2 +/- 4.7 L/min), evening PEF (69.9 +/- 5.8 vs. 31.1 +/- 4.5 L/min), the percentage of symptom-free days (48.9 +/- 2.9 vs. 21.7 +/- 2.5%), the percentage of rescue-free days (53.0 +/- 2.8 vs. 26.2 +/- 2.5%), and the percentage of nights with no awakenings (23.0 +/- 2.5 vs. 15.5+/-2.4%) compared with montelukast (p < or = 0.001, all comparisons). FSC significantly reduced asthma symptom scores (-1.0 +/- 0.1 vs. -0.6 +/- 0.1), rescue albuterol use (-3.3 +/- 0.2 vs. -1.9 +/- 0.2 puffs/d), and the number of exacerbations (0 vs. 11) compared with montelukast (p < 0.001). Both treatments were well tolerated. In summary, treatment of the two main components of asthma (inflammation and bronchoconstriction) with fluticasone propionate and salmeterol in a combination product was a more effective initial maintenance treatment strategy than treatment with montelukast, a single-mediator antagonist.

Acetates↗
PubMed2001

Comparison of inhaled salmeterol and oral zafirlukast in asthmatic patients using concomitant inhaled corticosteroids.

CONTEXT: For asthmatic patients who remain symptomatic on inhaled corticosteroids, augmenting the therapy with additional long-term control medication is advocated. Long-acting beta2-adrenergic agonists and leukotriene modifiers are 2 therapeutic alternatives in the long-term controller class. OBJECTIVE: To compare the addition of a long-acting beta2-adrenergic agonist to the addition of an oral leukotriene modifier for asthma therapy in patients who remain symptomatic on inhaled corticosteroids. DESIGN: Double-blind, double-dummy, parallel-group, multicenter clinical studies. SETTING: 54 outpatient clinical centers. PATIENTS: 429 male and female patients with asthma 12 years of age and older who were symptomatic while taking inhaled corticosteroids. INTERVENTIONS: Salmeterol xinafoate 42 mcg via metered dose inhaler twice daily or oral zafirlukast 20 mg twice daily. MAIN OUTCOME MEASURES: Pulmonary function, asthma symptoms, supplemental albuterol use, asthma quality of life scores, and adverse events. RESULTS: Inhaled salmeterol provided significantly greater improvement in pulmonary function as well as significantly greater relief of both daytime and nighttime asthma symptoms compared with oral zafirlukast in patients concurrently treated with inhaled corticosteroids. The use of supplemental albuterol was reduced to a greater extent with salmeterol compared with zafirlukast. Patients treated with salmeterol showed significantly greater improvement in Asthma Quality of Life Questionnaire (AQLQ) scores and were satisfied with how fast, how long, and how well the medication worked compared with patients in the zafirlukast group. Both treatments were well tolerated and demonstrated similar safety profiles. CONCLUSIONS: In patients with moderate to severe persistent asthma not sufficiently controlled with inhaled corticosteroids alone, the combination of inhaled salmeterol and inhaled corticosteroids is superior to the combination of oral zafirlukast and inhaled corticosteroids as stepwise therapy.

Administration, Inhalation↗
PubMed2001

Characterization of aerosol output from various nebulizer/compressor combinations.

OBJECTIVES: Different commercially available nebulizers and compressors are available. However, the optimal combination for drug delivery is unknown. METHODS: Flow rates of five different compressors (n = 3/compressor) tested alone and in combination with five different commercial nebulizers (n = 9 of each brand of nebulizer) were evaluated. Thereafter, the performances of the different nebulizers were evaluated using 2.5 mg albuterol solution (0.5 mL) added to 2.5 mL saline at flow rates of 2, 3, 4, and 5 L/minute using a laser particle analyzer. Volume median diameter and percentage of particles in the respirable range (1-5 microm) were calculated from this data. Time for nebulization (in seconds) and residual volume (in milliliters) were also recorded. RESULTS: The mean flow rates for the compressors evaluated without a nebulizer attached ranged from 6.6 L/minute (LifeCare Freedom-neb; LifeCare International, Lafayette, CO) to 12.2 L/minute (DeVilbiss Pulmo-Aide; DeVilbiss Health Care, Somerset, PA). Flow rates for the nebulizer/compressor combinations ranged from 2.08 L/minute (Pari LC Jet Proneb; Pari Respiratory Equipment, Richmond, VA) to 5.42 L/minute (Puritan Bennett Raindrop; Puritan Bennett, Lenexa, KS/Omron Compare; Omron, Health Care,Vernon Hills, IL). Using the repeated measure ANOVA model, the interaction between flow rate and device was significant (P < 0.001) for both percentage of particles in the respirable range and log volume median diameter. It was observed that the percentage of particles in the respirable range for the Pari LC Jet did not increase across flow rates in contrast to the other 4 nebulizers. All comparisons to the Pari LC Jet at 2 L/minute were significant. CONCLUSIONS: Marked variability exists in the flow rates among different commercially available compressors used for home nebulization of inhaled pulmonary medications. Different nebulizer/compressor combinations have markedly different performance characteristics which could result in different efficacy and safety profiles of the medications being administered via these devices. We recommend that this type of information be used as a starting point for selecting different nebulizer/compressor combinations. Further clinical evaluation is warranted.

Aerosols↗
PubMed2001

Suppression of hypothalamic-pituitary-adrenal axis activity with inhaled flunisolide and fluticasone propionate in adult asthma patients.

BACKGROUND: Suppression of the hypothalamic-pituitary-adrenal (HPA) axis, a potential systemic effect of inhaled corticosteroid therapy, can be quantified by monitoring serum, urinary, and salivary cortisol levels. OBJECTIVES: 1) Compare the effects on HPA axis of the inhaled corticosteroids flunisolide and fluticasone propionate versus placebo and oral prednisone. 2) Estimate dose-potency ratio for HPA-axis suppression. METHODS: Multicenter, randomized, placebo-controlled, open-label, 21-day trial. Active regimens were flunisolide 500 and 1,000 microg, twice daily; fluticasone propionate 110, 220, 330, and 440 microg, twice daily; and prednisone, 7.5 mg daily. Enrolled patients were nonsmokers, 18 to 50 years of age, with persistent mild-to-moderate asthma and had not used oral, nasal, or inhaled corticosteroids for 6 months before study. Main outcome measures were area under serum cortisol concentration curve for 22 hours (AUC(0-22h)); 24-hour urinary cortisol level; and 8 AM salivary cortisol level. RESULTS: One hundred fifty-three patients were randomly assigned to active treatment or placebo; 125 patients completed the study and were at least 80% compliant with their regimens. Both fluticasone propionate and flunisolide caused dose-dependent suppression of HPA axis, which was statistically greater for fluticasone propionate (P = 0.0003). Dose-potency ratio showed 4.4 times more serum-cortisol suppression/microgram increase in dose with fluticasone propionate than with flunisolide. Diurnal pattern of serum cortisol suppression was persistent with fluticasone propionate and "remitting" with flunisolide. Salivary and urinary cortisol data were qualitatively similar to serum cortisol results. CONCLUSIONS: Fluticasone caused significantly more suppression of HPA axis than flunisolide. Flunisolide may provide a safe option for patients with asthma requiring long-term inhaled corticosteroid therapy.

Administration, Inhalation↗
PubMed2001

Advair: combination treatment with fluticasone propionate/salmeterol in the treatment of asthma.

Several classes of medications are available for the treatment of asthma, and often they must be taken concurrently to achieve asthma control. Based on the understanding of asthma as an inflammatory disease, the National Heart Lung and Blood Institute guidelines provide a stepwise approach to pharmacologic therapy. Corticosteroid therapy, principally inhaled corticosteroid (ICS) therapy, is considered the most effective anti-inflammatory treatment. In cases of moderate-to-severe persistent asthma, the addition of a second long-term control medication to ICS therapy is one recommended treatment option. A combination-product inhaler (Advair, Seretide) was developed to treat both the inflammatory and bronchoconstrictive components of asthma by delivering a dose of the ICS, fluticasone propionate, and a dose of the long-acting beta2-adrenergic (LABA) bronchodilator, salmeterol. The Advair Diskus is available in 3 strengths of fluticasone propionate (100, 250, and 500 microg) and a fixed dose (50 microg) of salmeterol. Combination treatment with both ICS and LABA provides greater asthma control than increasing the ICS dose alone, while at the same time reducing the frequency and perhaps the severity of exacerbations. Furthermore, salmeterol added to ICS therapy provides superior asthma control compared with the addition of leukotriene modifiers or theophylline. The superior control is likely a consequence of the complementary actions of the drugs when taken together, including the activation of the glucocorticoid receptor by salmeterol. By combining anti-inflammatory treatment with a long-acting beta2-agonist in a single inhaler (1 inhalation twice daily), physicians can provide coverage for both the inflammatory and bronchoconstrictive aspects of asthma without introducing any new or unexpected adverse consequences. The most common drug-related adverse events were those known to be attributable to the constituent medications (ICS therapy and/or LABA therapy). Although the benefits of combined ICS plus LABA therapy can be achieved with separate inhalers, the convenience of the combination product may improve patient adherence and may therefore reduce the morbidity of asthma.

Administration, Inhalation↗
PubMed2001

Efficacy of soluble IL-4 receptor for the treatment of adults with asthma.

BACKGROUND: IL-4 mediates important proinflammatory functions in asthma, including induction of the IgE isotype switch, increased expression of vascular cell adhesion molecule 1 and promotion of eosinophil transmigration across the endothelium, stimulation of mucus production, and T(H)2 lymphocyte differentiation, leading to release of IL-4, IL-5, IL-9, and IL-13. OBJECTIVE: The current study evaluated the therapeutic potential of inhaled recombinant human soluble interleukin-4 receptor (IL-4R) as an IL-4 antagonist. METHODS: This study was a randomized, double-blind, placebo-controlled study in 62 subjects involving 12 once weekly nebulizations of 0.75, 1.5, or 3.0 mg of IL-4R or placebo. During screening, subjects documented dependence on inhaled corticosteroids by an exacerbation in asthma induced by one or two 50% dose reductions at 2-week intervals. After restabilization for 2 weeks on the dose above which their asthma flared, inhaled steroids were discontinued, patients were randomized, and study medication was started on day 0. RESULTS: IL-4R was well tolerated. Efficacy was demonstrated by a decline in FEV(1) observed in the placebo group (-0.4 L and -13% predicted), which did not occur in the group receiving 3.0 mg of IL-4R (-0.1 L and -2% predicted; P =.05 over the 3-month treatment period). Daily patient-measured morning FEV(1) also demonstrated a significant decline in the placebo group (-0.5 L and -18% predicted), which did not occur in the group receiving 3.0 mg of IL-4R (-0.1 L and -4% predicted; P =.02 over the 3-month treatment period). The efficacy of IL-4R was further confirmed by the absence of increase in asthma symptom scores in the group receiving 3.0 mg of IL-4R (Delta 0.1) compared with that seen in the placebo group (Delta 1.4 over 1 month; P =.07). Study discontinuation for asthma exacerbation was not significantly different between groups (placebo, 56%; 3.0 mg of IL-4R, 47%; P = not significant). CONCLUSION: These promising data suggest that IL-4R is safe and effective in the treatment of moderate persistent asthma.

Adult↗
PubMed2001

The importance of allergens in the development of asthma and the persistence of symptoms.

The importance of allergies and allergens in the development and persistence of asthma is suggested by 3 lines of evidence. First, a number of epidemiologic studies demonstrate that sensitization to indoor allergens and the spores of the outdoor seasonal fungus Alternaria is a risk factor for the development of asthma in both children and adults. Sensitivity to pollens, on the other hand, rarely constitutes a risk for asthma but does constitute a risk for seasonal allergic rhinitis. Second, several studies, again in both children and adults, have demonstrated that, in persons sensitive to indoor allergens, the severity of asthma symptoms will vary with the level of exposure. Third, the elimination of exposure to house-dust mites has produced a remarkable reversal of asthma in sensitive children and adults. Not only have symptoms and pulmonary function improved, but there has also been evidence of a reduction in airway inflammation and hyperresponsiveness. Taken together, these studies make a strong argument for the importance of allergy and allergen exposure as aggravating factors in asthma in both children and adults and reinforce the importance of the identification and treatment of these allergen sensitivities. (J Allergy Clin Immunol 2000;105:S628-32.)

Adult↗
PubMed2001

Onset and persistence of childhood asthma: predictors from infancy.

OBJECTIVE: In a prospective study of children with a family history of asthma, asthma onset by 3 years of age was found previously to be positively associated with variables from the first year of life, including elevated total immunoglobulin E (IgE), frequent respiratory infections, and parenting difficulties. We followed this cohort of genetically at-risk children to investigate the relationship between factors assessed in infancy and asthma, allergy, and psychological status at school age. METHODS: A cohort of 150 children who were at risk for developing asthma were identified prenatally on the basis of the mothers' having asthma. For 28 children, the father had asthma as well, putting them at bilateral genetic risk. Families primarily were middle and upper middle class Caucasians. Parents came to the clinic during the third trimester of pregnancy for assessments of medical and psychosocial functioning. A home visit took place when the infant was 3 weeks old, when parenting risk was assessed before the onset of any asthma symptoms. Parenting difficulties included problems with infant caregiving as well as components of maternal functioning, such as postpartum depression and inadequate marital support. Blood was drawn for serum IgE at 6 months of age. Parents and offspring subsequently came to the clinic multiple times, with the last clinic visit during the child's sixth year. Follow-up at age 6 involved a clinic visit for allergy and psychosocial evaluations, consisting of interviews and a behavior questionnaire. Seventy-seven children received the allergy and psychosocial evaluation, 26 received the psychosocial evaluation in the clinic, and 30 families received telephone interviews and mailed in questionnaires. Additional monitoring of families by telephone and mail was maintained over the next 2 years, until the children were 8, to ensure accurate characterization of the course of illness. Comprehensive medical records were obtained and reviewed for all health care contacts. Children were designated as having asthma when there was documentation in medical records of physician-diagnosed asthma, observed wheezing, and/or prescription of asthma medications during the time period when the child was between 6 and 8 years of age. Parental reports of the occurrence of asthma corroborated the medical record data. RESULTS: Data regarding asthma status were available for 145 children through 8 years of age. Forty (28%) of the children manifested asthma between 6 and 8 years of age. Among variables previously reported to predict asthma onset by age 3, 3 proved to have significant univariate relationships with asthma between ages 6 and 8: elevated IgE levels measured when the children were 6 months of age, global ratings of parenting difficulties measured when infants were 3 weeks old, and higher numbers of respiratory infections in the first year of life. Among these offspring of mothers with asthma, paternal asthma showed a significant association with asthma between ages 6 and 8. Eczema in the first year was not significantly related to later asthma. Multiple logistic regression showed that the model that best predicted asthma at ages 6 to 8 from infancy variables included 2 main effects. The adjusted odds ratio for 6-month IgE was 2.15 (1.51, 3.05) and for parenting difficulties was 2.07 (1.15, 3.71). Although socioeconomic status (SES) was not associated with asthma at ages 6 to 8, families of lower SES were more likely to be rated as having parenting difficulties early in the child's life. The mothers of lower SES breastfed for a shorter period of time and were more likely to smoke during their infant's first year. There were more respiratory infections during the first year of life among infants whose mother was rated as having more parenting difficulties. Mothers who reported smoking breastfed their infants for a shorter length of time. Male gender was significantly associated with higher IgE levels when infants were 6 months of age. Laboratory testing was completed for 77 children at age 6. Total serum IgE levels were significantly higher for the children with asthma between ages 6 and 8. Skin-prick testing showed that the children with asthma had significantly more positive skin test reactions than did the children without asthma. Psychosocial interview data at 6 years of age were available for 103 families, and behavioral questionnaires were available for 133 families. On the basis of 6-year interviews, children with asthma were rated as being at greater psychological risk than were the children without asthma. Mothers' Child Behavior Checklist (CBCL) ratings of their children's behavior indicated higher internalizing scores for the children with asthma as compared with the children without asthma. Like the 6-month IgE, 6-year IgE was higher for boys. IgE levels measured at 6 months of age were significantly correlated with 6-year IgE levels. Parenting difficulties measured at 3 weeks were significantly correlated with 6-year measures of maternal depression, CBCL Internalizing score, and Child Psychological Risk (CPR) score. There also were significant correlations among the psychosocial variables assessed when the children were 6 years of age; maternal depression was significantly associated with child CBCL Internalizing score and CPR score, and the last 2 also were significantly correlated. Multiple logistic regression showed that 2 concurrently measured variables entered the model showing the strongest associations with asthma at ages 6 to 8. The adjusted odds ratio for CPR score was 3.21 (1.29-7.96) and for 6-year IgE was 1.71 (1.04-2.80). CONCLUSIONS: This study of the natural history of childhood asthma focused on the development of asthma into the school-age years in a genetically at-risk group of children. The relationships between biological and psychosocial variables in the first year and school-age asthma support the formulation of asthma as beginning early in life, with the developing immune system interacting with environmental influences. The data provide support for the possible contribution of psychosocial factors to asthma onset and persistence into childhood.

Adult↗
PubMed2000

Effectiveness of specific immunotherapy in the treatment of asthma: a meta-analysis of prospective, randomized, double-blind, placebo-controlled studies.

BACKGROUND: Despite decades of positive experience with specific immunotherapy (SIT) in the treatment of asthma, outcomes associated with SIT have not been evaluated. OBJECTIVE: This meta-analysis was conducted to compare the effects of SIT plus medical treatment with those of SIT without medical treatment in patients with asthma. METHODS: All studies of SIT in patients with asthma published in English between the years 1966 and 1998 were identified through a MEDLINE search. All prospective, randomized, double-blind, placebo-controlled studies of SIT identified by the search were included in the meta-analysis. One author (R.N.R.) extracted data from these studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model. RESULTS: Data were extracted from 24 identified studies of the clinical effectiveness of SIT in the treatment of asthma, involving 962 asthmatic patients with documented allergy. Immunotherapy was judged effective in 17 (71%) of the 24 studies, ineffective in 4 (17%), and equivocal in 3 (12%) (chi2 = 15.25, df = 2, P = 0.0005). Symptoms of asthma were more likely to improve in patients who received SIT than in patients who received placebo (OR 2.76, 95% CI 2.22 to 3.42). Results also favored the immunotherapy group for improvement in pulmonary function (OR 2.87, 95% CI 1.82 to 4.52), protection against bronchial challenge (OR 1.81, 95% CI 1.32 to 2.49), and reduced need for medications (OR 2.00, 95% CI 1.46 to 2.72). CONCLUSION: The findings of this meta-analysis support the conclusion that SIT is effective in a population of patients with allergen-triggered asthma.

Adolescent↗
PubMed2000

Effectiveness of specific immunotherapy in the treatment of allergic rhinitis: an analysis of randomized, prospective, single- or double-blind, placebo-controlled studies.

BACKGROUND: The effectiveness of specific immunotherapy (SIT) in the treatment of allergic rhinitis has been supported by empirical evidence and clinical experience. OBJECTIVE: This report is an analysis of multiple studies involving patients with documented allergic rhinitis. METHODS: All studies of the effectiveness of SIT in the treatment of allergic rhinitis published in English between the years 1966 and 1996 were identified through a MEDLINE search. All prospective, single- or double-blind, placebo-controlled studies were included in the analysis. One author (R.N.R.) extracted data from the studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model for a variety of clinical measures in studies that permitted the extraction of numbers of patients with positive and negative outcomes. RESULTS: Data were extracted from 16 studies of the clinical effectiveness of SIT in the treatment of allergic rhinitis, involving 759 patients (546 adults, 53 children, 160 all ages). In 15 (94%) of the studies, investigators concluded that SIT was effective. In the remaining study (the only one conducted in children), investigators concluded that SIT was not effective. Symptoms of allergic rhinitis were more likely to improve in patients receiving SIT than in the comparison patients (OR 1.81, 95% CI 1.48 to 2.23). Symptom-medication scores were significantly lower in patients receiving SIT than in the comparison patients in all studies using such measures (P < 0.05). CONCLUSION: Results of this analysis support the conclusion that SIT is effective in the treatment of allergic rhinitis.

Adolescent↗
PubMed2000

Effectiveness of specific immunotherapy in the treatment of hymenoptera venom hypersensitivity: a meta-analysis.

BACKGROUND: For most people, Hymenoptera stings produce a transient, local inflammatory reaction (pain, redness, swelling). However, for those who are allergic to components of this venom, the reactions can be severe, frightening, and sometimes fatal. Specific immunotherapy (SIT) has been the only means of desensitizing patients who have experienced a systemic reaction to this venom. OBJECTIVE: This meta-analysis was conducted to compare the effects of SIT in the treatment of Hymenoptera venom hypersensitivity. METHODS: All studies of SIT in the treatment of Hymenoptera venom hypersensitivity published in English between the years 1966 and 1996 were identified through a MEDLINE search. Because of the ethical difficulties involved in designing a double-blind, placebo-controlled study in this patient population, most of the studies were open and not placebo-controlled. One author (R.N.R.) extracted data from the studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model. RESULTS: Data were extracted from 8 studies involving 453 patients; 1 study was conducted in adults (n = 20), 2 in children (n = 188), and 5 in all ages (n = 245). The symptoms of Hymenoptera venom hypersensitivity were prevented in 80 (79%) of the 101 patients receiving SIT versus 49 (36%) of 136 comparison patients. The symptoms were not prevented in 21 (21%) of the patients receiving SIT versus 87 (64%) of the comparison patients (OR 2.20, 95% CI 1.72 to 2.81). CONCLUSION: The findings of this meta-analysis support the conclusion that SIT is effective in the treatment of Hymenoptera venom hypersensitivity.

Adolescent↗
PubMed2000

Fexofenadine HCl is safe and effective for treatment of chronic idiopathic urticaria.

BACKGROUND: Fexofenadine is a nonsedating antihistamine approved for treatment of seasonal allergic rhinitis. OBJECTIVE: This dose-finding study assessed the safety and efficacy of fexofenadine in chronic idiopathic urticaria. METHODS: The 4-week, double-blind, randomized, placebo-controlled study included patients diagnosed with chronic urticaria who had moderate to severe pruritus. Patients received twice daily oral doses of placebo or fexofenadine HCl (20, 60, 120, or 240 mg) at 7 AM and 7 PM. Patients recorded scores for pruritus severity and number of wheals (over the previous 12 hours) in a daily diary. Efficacy variables included mean daily changes from baseline in pruritus severity, number of wheals, and interference with sleep and daily activities due to urticaria. RESULTS: Patients (N = 418) from 37 investigative sites were included. All four fexofenadine HCl doses were statistically superior to placebo (P < or = .0115) for reducing pruritus and number of wheals scores over the 4-week treatment period. There were greater reductions in urticaria symptoms in the 60 mg fexofenadine HCl group than in the 20 mg group, while similar reductions were observed in the 60, 120, and 240 mg dose groups. Additionally, patients receiving fexofenadine experienced significantly less interference with sleep and daily activities than patients receiving placebo (P < or = .0014). Adverse events occurred with similar incidence in all treatment groups, with no dose-related increases in any event. CONCLUSIONS: Fexofenadine HCl significantly reduced pruritus severity, number of wheals, and interference with sleep and normal daily activities in patients with chronic urticaria compared with placebo. Twice-daily doses of 60 mg or greater were most effective.

Adolescent↗
PubMed2000

Comparison of three commercial ultrasonic nebulizers.

BACKGROUND: The clinical acceptance of the initial ultrasonic nebulizers was impeded by their production of significant quantities of droplets larger than the respirable range that could have resulted in poor pulmonary deposition of nebulized medications. Subsequent modifications in the design of ultrasonic nebulizers have occurred. Overall nebulizer performance characteristics of the newer ultrasonic devices have not been evaluated. OBJECTIVE: Three commercially available ultrasonic nebulizers (DeVilbiss-Pulmosonic, Omron-Microair, Rhône Poulenc-Rorer-Fisoneb) were studied to compare the aerosol output characteristics. METHODS: The parameters studied were total volume output (TVO), time to nebulize total output (TTO), percent of droplets with volume diameters in the respirable range (PDVRR, 1 to 5 microm), albuterol concentration during nebulization, and the total drug delivered. All nebulizers were filled with 2.5 mL of saline and 0.5 mL of albuterol nebulizer solution. Three units from each manufacturer, each from a different lot, were evaluated in duplicate. RESULTS: The nebulizer with the largest volume output was the Omron (mean 2.94 mL), which also demonstrated the longest nebulization time (mean 10.3 min). The DeVilbiss and Rhône Poulenc-Rorer units delivered smaller volumes (mean 2.5 mL, 2.4 mL, respectively) but nebulized more rapidly (mean 2.21 min, 3.54 min, respectively). The Omron nebulizer generated the highest PDVRR with a mean of 38%. The DeVilbiss had a mean PDVRR of 16% and the Rhône Poulenc-Rorer a mean PDVRR of 21%. The majority of droplets from all three machines had a volume diameter smaller than the respirable range, ie, in the 0.5 to 1.0 microm range (Omron-60%, DeVilbiss-83%, Rhône Poulenc-Rorer-79%). For all three nebulizers there appeared to be no concentrating or diluting effect during nebulization implying that equal quantities of albuterol and diluent were delivered. The Rhône Poulenc-Rorer units demonstrated the greatest unit-to-unit variability with respect to TVO while the Omron units demonstrated the greatest unit to unit variability with respect to TTO. CONCLUSION: We conclude that several improvements in the design of ultrasonic nebulizers have resulted in the reduction of the size of the droplets generated. Our evaluation of the three commercially available ultrasonic nebulizers revealed that the majority of droplets generated were within or below the respirable range. There was no concentrating or diluting effect during nebulization for all three nebulizers. The output characteristics of the three devices differ and this will effect the delivery time as well as amount of drug delivered to the lungs.

Aerosols↗
PubMed2000

The importance of allergens in the development of asthma and the persistence of symptoms.

The importance of allergies and allergens in the development and persistence of asthma is suggested by 3 lines of evidence. First, a number of epidemiologic studies demonstrate that sensitization to indoor allergens and the spores of the outdoor seasonal fungus Alternaria is a risk factor for the development of asthma in both children and adults. Sensitivity to pollens, on the other hand, rarely constitutes a risk for asthma but does constitute a risk for seasonal allergic rhinitis. Second, several studies, again in both children and adults, have demonstrated that, in persons sensitive to indoor allergens, the severity of asthma symptoms will vary with the level of exposure. Third, the elimination of exposure to house-dust mites has produced a remarkable reversal of asthma in sensitive children and adults. Not only have symptoms and pulmonary function improved, but there has also been evidence of a reduction in airway inflammation and hyperresponsiveness. Taken together, these studies make a strong argument for the importance of allergy and allergen exposure as aggravating factors in asthma in both children and adults and reinforce the importance of the identification and treatment of these allergen sensitivities.

Adult↗
PubMed2000

Quantitative IgE antibody assays in allergic diseases.

During the past several years, immunoassays for specific IgE antibodies have been refined to permit reporting results in mass units. Thus quantitative immunoassays for IgE antibodies may be an adjunct to skin tests. In cases of food allergy among children with atopic dermatitis, cutoff values for IgE antibody concentrations to egg, milk, peanut, and fish have been derived to provide 95% positive and 90% negative predictive values. Food-specific IgE antibody determinations can also be used to predict which food allergies are resolving spontaneously. Elevated egg-specific IgE antibody levels in infancy are associated with significantly increased risk for development of inhalant allergies later in childhood. In cases of inhalant allergy, specific IgE antibody levels correlate closely with results of inhalation challenge studies in cat-sensitive persons. Also, mite-specific IgE antibody levels correlate significantly with the mite allergen contents of reservoir dust in the homes of mite-sensitive persons. Immunoassays for quantitation of specific IgE antibodies may be used to document allergen sensitization over time and to evaluate the risk of reaction on allergen exposure. However, immunoassays and skin tests are not entirely interchangeable, and neither will replace the other in appropriate circumstances.

Antibodies, Anti-Idiotypic↗