Actualización de la prueba de provocación bronquial con ejercicio (PPBE) / Update of the bronchial provocation test with exercise

The bronchial challenge test with exercise aims to demonstrate the presence of exercise-induced bronchial hyperreactivity, characteristic of bronchial asthma. Its realization is well standardized, requiring special environmental conditions, preparation and submaximum effort of the patient. The response is measured by spirometry, and it is considered a positive exercise test a drop in the expired volume at the first second (FEV1) of 10%. This article describes the elements necessary to facilitate this exam, according to national and international standards and guidelines.

La prueba de provocación bronquial con ejercicio tiene como objetivo demostrar la presencia de hiperreactividad bronquial inducida por ejercicio, característica del asma bronquial. Su realización está bien estandarizada, requiriendo de condiciones ambientales especiales, preparación y esfuerzo submáximo del paciente. La respuesta se mide mediante espirometría, y se considera una prueba de provocación con ejercicio positivo, a una caída del volumen espirado al primer segundo (VEF1) del 10%. En este artículo se describen los elementos necesarios para facilitar la realización de este examen, acorde a normas y guías nacionales e internacionales.

Actualización en la prueba de provocación bronquial con metacolina en el niño / Update in the bronchial challenge test with methacholine in children

This document updates the recommendations of the bronchial challenge test with methacholine in children. It is based primarily on the recommendations contained in the guide on the technical standard of the bronchial challenge test for methacholine from the European Society of Respiratory Diseases. The main change is the recommendation to use PD20 (methacholine dose that causes a 20% drop in FEV1) instead of PC20 (methacholine concentration that causes a 20% drop in FEV1), which allows for comparable results when different devices and different protocols are used.

Este documento actualiza las recomendaciones de la prueba de provocación bronquial con metacolina en niños. Se basa fundamentalmente en las recomendaciones contenidas en la guía sobre el estándar técnico de la prueba de provocación bronquial de metacolina de la Sociedad Europea de Enfermedades Respiratorias. El principal cambio es la recomendación de utilizar la PD20 (dosis de metacolina que provoca una caída de 20% del VEF1) en vez de PC20 (concentración de metacolina que provoca una caída del 20% en el VEF1), lo cual permite tener resultados comparables cuando se usan diferentes dispositivos y diferentes protocolos.

Effects of Diet-Induced Mild Obesity on Airway Hyperreactivity and Lung Inflammation in Mice

PURPOSE: Obesity has been suggested to be linked to asthma. However, it is not yet known whether obesity directly leads to airway hyperreactivity (AHR) or obesity-induced airway inflammation associated with asthma. We investigated obesity-related changes in adipokines, AHR, and lung inflammation in a murine model of asthma and obesity. MATERIALS AND METHODS: We developed mouse models of chronic asthma via ovalbumin (OVA)-challenge and of obesity by feeding a high-fat diet, and then performed the methacholine bronchial provocation test, and real-time PCR for leptin, leptin receptor, adiponectin, adiponectin receptor (adipor1 and 2), vascular endothelial growth factor (VEGF), transforming growth factor (TGF) beta, and tumor necrosis factor (TNF) alpha in lung tissue. We also measured cell counts in bronchoalveolar lavage fluid. RESULTS: Both obese and lean mice chronically exposed to OVA developed eosinophilic lung inflammation and AHR to methacholine. However, obese mice without OVA challenge did not develop AHR or eosinophilic inflammation in lung tissue. In obese mice, lung mRNA expressions of leptin, leptin receptor, VEGF, TGF, and TNF were enhanced, and adipor1 and 2 expressions were decreased compared to mice in the control group. On the other hand, there were no differences between obese mice with or without OVA challenge. CONCLUSION: Diet-induced mild obesity may not augment AHR or eosinophilic lung inflammation in asthma.

Exhaled nitric oxide, bronchial hyperresponsiveness and spirometric parameters in patients with allergic rhinitis during pollen season

Allergic rhinitis and asthma share common epidemiological features and inflammatory processes. The aim of the present study was to document the influence of natural allergen exposure in exhaled NO [eNO] and in spirometric parameters of patients with seasonal allergic rhinitis[SAR] and to investigate the differences among subjects with positive versus negative bronchial provocation to metacholine [BP[Mch]]. Twenty-six non-smoking patients [13F/13M; mean age 28.4ys] with a documented history of SAR, 15 healthy, non-atopic [6F/9M; mean age 37.1ys] and 6 non-symptomatic atopic subjects [3F/3M; mean age 36.5ys] were studied. At the first visit during pollen season each subject filled symptom-score card, underwent eNO and nasal NO [nNO] measurements and spirometry. BP[Mch] was performed within the next 10 days. At the second visit out of pollen season, all measurements but BP[Mch] were repeated. Control subjects underwent eNO and nNO measurements. eNO was significantly increased during pollen season in BP[Mch] positive vs BP[Mch] negative [46.22 +/- 32.60 vs 17.81 +/- 12.67, p=0.014] and vs non-atopic controls [11.40 +/- 5.84, p<0.001] as well as atopic controls [13.56 +/- 5.34, p=0.001]. No difference was detected out of pollen season in both patients' groups. nNO values were increased only in BP[Mch] [+] group compared to both control groups in pollen season [vs non-atopies p=0.002, vs atopies p=0.002] and only vs non-atopies out of season, p=0.004. Regression analysis has shown that the difference in FEF 25-75 values [off season-in season] is a predictor of positive BP[Mch]. eNO is markedly increased in BP[Mch] patients with allergic rhinitis while mid-expiratory flow may represent an early marker of lower airway involvement in respiratory allergy

Avaliação espirométrica e da hiper-responsividade brônquica de crianças e adolescentes com asma atópica persistente moderada submetidos a natação / Effects of swimming on spirometric parameters and bronchial hyperresponsiveness in children and adolescents with moderate persistent atopic asthma

OBJETIVO: Investigar os benefícios a médio prazo de um programa de natação em escolares e adolescentes com asma atópica persistente moderada (AAPM). MÉTODOS: Realizou-se um estudo randomizado e prospectivo com crianças e adolescentes (7-18 anos de idade) com AAPM no Hospital de Clínicas da Universidade Estadual de Campinas (UNICAMP), Campinas (SP). Após um período de run in de um mês, 61 pacientes (34 femininos) foram randomizados em dois grupos: grupo natação (GN) (n = 30) e grupo controle (GC) (n = 31) e foram acompanhados durante 3 meses. Os dois grupos receberam fluticasona (pó) inalada (250 mcg, 2 vezes ao dia) diariamente e salbutamol inalado, quando necessário. O programa de natação consistiu em um total de 24 aulas, duas vezes por semana, por 3 meses. O GN e o GC realizaram espirometria, teste de broncoprovocação com metacolina (provocative concentration of methacholine causing a 20 por cento fall in FEV1, PC20 de metacolina), antes e após os 3 meses de estudo. Pressão inspiratória máxima (PImax) e pressão expiratória máxima (PEmax) foram realizadas somente no GN. RESULTADOS: Observou-se que o GN apresentou aumento significativo da PC20 de metacolina (inicial 0,31±0,25 e final 0,63±0,78; p = 0,008), pressão inspiratória máxima (inicial 67,08±17,13 cm H2O e final 79,46±18,66; p < 0,001), pressão expiratória máxima (inicial 71,69±20,01 cm H2O e final 78,92±21,45 cm H2O; p < 0,001). CONCLUSÃO: Crianças e adolescentes com AAPM que se submeteram a um programa de natação apresentaram diminuição estatisticamente significativa da hiper-responsividade brônquica, com aumento dos valores da PC20 de metacolina, quando comparados aos com AAPM que não realizaram natação. O GN também apresentou melhora no componente da força elástica do tórax.

OBJECTIVE: To investigate the medium-term benefits of a swimming program in schoolchildren and adolescents with moderate persistent atopic asthma (MPAA). METHODS: A randomized, prospective study of children and adolescents (age 7-18 years) with MPAA was carried out at the Hospital de Clínicas of Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil. After a 1-month run-in period, 61 patients (34 female) were randomized into two groups, a swimming group (n = 30) and a control group (n = 31), and followed for 3 months. Both patient groups received inhaled fluticasone (dry powder, 250 mcg twice a day) and salbutamol as needed. The swim training program consisted of two weekly classes over a 3-month period for a total of 24 sessions. Both groups underwent spirometric assessment and methacholine challenge test - provocative concentration of methacholine causing a 20 percent fall in FEV1 (PC20) - before and after the study period. Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were measured only in the swimming group. RESULTS: Significant increases in PC20 (pre-training, 0.31±0.25; post-training, 0.63±0.78; p = 0.008), MIP (pre-training, 67.08±17.13 cm H2O; post-training 79.46±18.66; p < 0.001), and MEP (pre-training, 71.69±20.01 cm H2O; post-training, 78.92±21.45 cm H2O; p < 0.001) were found in the swimming group. CONCLUSION: Children and adolescents with MPAA subjected to a swim training program experienced a significant decrease in bronchial hyperresponsiveness, as determined by increased PC20 values, when compared with asthmatic controls who did not undergo swim training. Participants in the swimming group also showed improvement in elastic recoil of the chest wall.

Oscilometría de impulso (IOS) en niños / Impulse oscillometry in children

Este artículo tiene como propósito revisar aspectos fisiológicos, técnicos y clínicos de la oscilometría de impulso aplicada en pediatría; ya que en la actualidad tiene un rol importante en el estudio de la mecánica respiratoria. Es una interesante aproximación al diagnóstico funcional del sistema respiratorio por su fácil realización; en cuanto no necesita de la cooperación activa del paciente, se obtienen resultados comprensibles del sitio y magnitud de la alteración, puede complementar las pruebas de provocación, pesquizar precozmente la respuesta broncodilatadora y participar en el seguimiento de enfermedades crónicas.

Airway Responsiveness to Inhaled Aspirin is Influenced by Airway Hyperresponsiveness in Asthmatic Patients

BACKGROUND/AIMS: Many patients with aspirin-induced asthma have severe methacholine airway hyperresponsiveness (AHR), suggesting a relationship between aspirin and methacholine in airway response. This study was performed to determine whether methacholine AHR affects the response of asthmatics to inhaled aspirin. METHODS: The clinical records of 207 asthmatic patients who underwent inhalation challenges with both aspirin and methacholine were reviewed retrospectively. An oral aspirin challenge was performed in patients with a negative inhalation response. The bronchial reactivity index (BRindex) was calculated from the percent decrease in lung function divided by the last dose of the stimulus. RESULTS: Forty-one (20.9%) and 14 (7.1%) patients showed a positive response to aspirin following an inhalation and oral challenge, respectively. Only 24.3 and 14.3% of the responders had a history of aspirin intolerance, respectively. The methacholine BRindex was significantly higher in the inhalation responders (1.46 +/- 0.02) than in the oral responders (1.36 +/- 0.03, p < 0.01) and in non-responders (n = 141, 1.37 +/- 0.01, p < 0.001). The aspirin BRindex was significantly correlated with the methacholine BRindex (r = 0.270, p < 0.001). Three of four patients who received the oral challenge, despite a positive inhalation test, showed negative responses to the oral challenge. Two of these patients had severe AHR. CONCLUSIONS: A considerable number of asthmatic patients with no history of aspirin intolerance responded to the inhalation aspirin challenge. The airway response to aspirin was significantly correlated with methacholine-AHR, and a false-positive response to aspirin inhalation test seemed to occur primarily in patients with severe AHR.

Protector mechanisms of the association between gastroesophageal reflux disease and asthma: experimental study in rats / Mecanismos protetores: doença do refluxo gastroesofágico e asma: estudo experimental em ratos

BACKGROUND: It is well known the association between gastroesophageal reflux disease and asthma. The hyperreactivity of the airways is a characteristic of an asthmatic. Many studies associate the increase of the airways reactivity with gastroesophageal reflux disease. AIM: In this study we have evaluated the effect of the intraluminal exposition to gastric juice of trachea on the reactivity to methacholine from rats submitted to a pulmonary allergic inflammation. METHODS: Group of rats were sensitized and challenged with ovalbumin. After 24 hours the animals were sacrificed, and their tracheae were removed to be cultured with gastric juice. The gastric juice was obtained from a donor rat. Subsequently the segments were placed into plastic plates with RPMI-1640 for incubation, under suitable atmosphere and time. After the period of incubation the segments were put into chambers for the analysis of the contractile response to methacholine. RESULTS: We observed reduction in the contractile response of trachea cultured with gastric juice from allergic rats. This result was confirmed by the pharmacological treatments with compound 48/80 and dissodium cromoglicate (mast cells blockade), L-NAME (nitric oxide inhibitor, NO), capsaicin (neuropeptides depletion) and indomethacin (ciclooxigenase inhibitor). CONCLUSIONS: Our results highlight to the existence of a complex interaction between pulmonary allergy and gastric juice in the airways. The involvement of the non-adrenergic non-cholinergic system, NO, prostanoids and mast cells are directly related to this interaction. We suggest that the reduced contractile response observed in vitro may represent a protector mechanism of the airways. Despite its presence in the human body it can not be observed due to the predominant effects of excitatory the non-adrenergic non-cholinergic system.

RACIONAL: É bem estabelecida a relação entre a doença do refluxo gastroesofágico e a asma. A hiperreatividade das vias aéreas é uma das características que o indivíduo asmático desenvolve e diversos estudos associam o aumento da reatividade das vias aéreas com o refluxo gastroesofágico. OBJETIVO: Avaliar a reatividade à metacolina de traquéia exposta intraluminalmente ao suco gástrico de ratos submetidos a inflamação alérgica pulmonar. MÉTODOS: Grupos de ratos foram sensibilizados e broncoprovocados com ovoalbumina. Após 24 horas, os animais foram sacrificados e a traquéia removida para preenchimento de seu lúmen com suco gástrico obtido de um animal doador. A seguir, os segmentos foram colocados em placas plásticas com RPMI-1640 e mantidos em estufa por 3 horas em condições ambientais adequadas. Após o tempo de incubação, os fragmentos foram montados em cubas de vidro para órgão isolado para registro isométrico de contração, através da construção de curvas concentração-efeito à metacolina. RESULTADOS: Observou-se redução da resposta contrátil em traquéia exposta ao suco gástrico proveniente de ratos alérgicos. Os tratamentos farmacológicos com composto 48/80 e cromoglicato de sódio (bloqueio de mastócitos), L-NAME (inibidor de óxido nítrico, NO), capsaicina (depleção de neuropeptídios) e indometacina (inibidor da ciclooxigenase) corroboraram esta observação. CONCLUSÕES: Os resultados apontam para a existência de complexa interação entre a alergia pulmonar e o suco gástrico nas vias aéreas, com o envolvimento do sistema não-adrenérgico não-colinérgico, NO, prostanóides e mastócitos. À luz das evidências in vivo sobre a hiperreatividade das vias aéreas na associação asma e refluxo gastroesofágico, sugere-se que a reduzida resposta contrátil detectada in vitro pode representar um mecanismo protetor das vias aéreas. A despeito de sua presença, esta redução pode não ser observada in vivo devido à proeminência dos efeitos do sistema não-adrenérgico ...

Asthma: where is it going?: [review]

Asthma is characterized by reversible airway obstruction, airway hyperresponsiveness, and airway inflammation. Although our understanding of its pathophysiological mechanisms continues to evolve, the relative contributions of airway hyperresponsiveness and inflammation are still debated. The first mechanism identified as important for asthma was bronchial hyperresponsiveness. In a second step, asthma was recognized also as an inflammatory disease, with chronic inflammation inducing structural changes or remodeling. However, persistence of airway dysfunction despite inflammatory control is observed in chronic severe asthma of both adults and children. More recently, a potential role for epithelial-mesenchymal communication or transition is emerging, with epithelial injury often resulting in a self-sustaining phenotype of wound repair modulation by activation/reactivation of the epithelial-mesenchymal trophic unit, suggesting that chronic asthma can be more than an inflammatory disease. It is noteworthy that the gene-environmental interactions critical for the development of a full asthma phenotype involve processes similar to those occurring in branching morphogenesis. In addition, a central role for airway smooth muscle in the pathogenesis of the disease has been explored, highlighting its secretory function as well as different intrinsic properties compared to normal subjects. These new concepts can potentially shed light on the mechanisms underlying some asthma phenotypes and improve our understanding of the disease in terms of the therapeutic strategies to be applied. How we understand asthma and its mechanisms along time will be the focus of this overview.

Acute Effects of Asian Dust Events on Respiratory Symptoms and Peak Expiratory Flow in Children with Mild Asthma

The aim of this study was to investigate the possible adverse effects of Asian dust events on respiratory health in asthmatic children. Fifty-two children with mild asthma were studied for eight consecutive weeks in the spring of 2004 (March 8 to May 2). During the study period, five Asian dust days were identified; we included a lag period of two days following each of the events. Subjects recorded their respiratory symptom diaries and peak expiratory flow (PEF) twice daily during the study period; and they underwent methacholine bronchial challenge tests. The subjects reported a significantly higher frequency of respiratory symptoms during the Asian dust days than during the control days. They showed significantly more reduced morning and evening PEF values, and more increased PEF variability (10.1%+/-3.5% vs. 5.5%+/-2.2%) during the Asian dust days than during the control days. Methacholine PC20 was not significantly different between before and after the study period (geometric mean: 2.82 mg/mL vs. 3.16 mg/mL). These results suggest that the short-term Asian dust events might be associated with increased acute respiratory symptoms and changes in PEF outcomes. However, there might be little long-term influence on airway hyperresponsiveness in children with mild asthma.

Blockade of airway inflammation and hyper-responsiveness by an angiopoietin-1 variant, COMP-Ang1

Inflammation of the asthmatic airway is usually accompanied by increased vascular permeability and plasma exudation. Angiopoietin-1 (Ang1) has potential therapeutic applications in preventing vascular leakage. Recently, we developed a soluble, stable, and potent Ang1 variant, COMP-Ang1. COMP-Ang1 is more potent than native Ang1 in phosphorylating the tyrosine kinase with immunoglobulin and epidermal growth factor homology domain 2 receptor in lung endothelial cells. We have used a mouse model for allergic airway disease to determine effects of COMP-Ang1 on allergen-induced bronchial inflammation and airway hyper-responsiveness. These mice develop the following typical pathophysiological features of allergic airway disease in the lungs: increased numbers of inflammatory cells of the airways, airway hyper-responsiveness, increased levels of Th2 cell cytokines (IL-4, IL-5, and IL-13), adhesion molecules (intercellular adhesion molecule-1 and vascular cell adhesion molecule-1), and chemokines (eotaxin and RANTES), and increased vascular permeability. Intravenous administration of COMP-Ang1 reduced bronchial inflammation and airway hyper-responsiveness. In addition, the increased plasma extravasation in allergic airway disease was significantly reduced by the administration of COMP-Ang1. These results suggest that COMP-Ang1 attenuates airway inflammation and hyper-responsiveness, prevents vascular leakage, and may be used as a therapeutic agent in allergic airway disease.

Bronchial hyperresponsiveness and analysis of induced sputum cells in Crohn's disease

With the aim of investigating the presence of latent inflammatory process in the lungs of patients with Crohn's disease, 15 patients with Crohn's disease were evaluated by spirometry, the methacholine challenge test, induced sputum, and skin tests for inhaled antigens. Serum IgE, erythrocyte sedimentation rate and hematocrit were also determined. The patients were compared with 20 healthy controls by the Mann-Whitney and Fisher exact tests. Their respiratory physical examination was normal. None had a personal or family history of clinical atopy. None had a previous history of pulmonary disease, smoking or toxic bronchopulmonary exposure. None had sinusitis, migraine, diabetes mellitus, or cardiac failure. Four (26.6 percent) of the patients with Crohn's disease had a positive methacholine challenge test whereas none of the 20 controls had a positive methacholine test (P = 0.026, Fisher exact test). Patients with Crohn's disease had a higher level of lymphocytes in induced sputum than controls (mean 14.59 percent, range 3.2-50 vs 5.46 percent, 0-26.92 percent, respectively; P = 0.011, Mann-Whitney test). Patients with Crohn's disease and a positive methacholine challenge test had an even higher percentage of lymphocytes in induced sputum compared with patients with Crohn's disease and a negative methacholine test (mean 24.88 percent, range 12.87-50 vs 10.48 percent, 3.2-21.69 percent; P = 0.047, Mann-Whitney test). The simultaneous findings of bronchopulmonary lymphocytosis and bronchial hyperresponsiveness in patients with Crohn's disease were not reported up to now. These results suggest that patients with Crohn's disease present a subclinical inflammatory process despite the absence of pulmonary symptoms.

Sympathetic hyperactivity in patients of bronchial asthma.

The bronchoconstricting and bronchodilating divisions of the autonomic nervous system control airway caliber of lungs. Parasympathetic hyperactivity in asthmatics eventuates in broncho-constriction. Sympathetic activity increases to combat this but fails to control bronchoconstriction due to negligible innervations of the airway smooth muscles although it causes vasoconstriction of blood vessels. In this study the effects of autonomic function test for sympathetic division were seen on selected patients and controls. Our results indicate sympathetic hyperactivity or an increased alpha-adrenergic input in asthmatics.

The relationship between tobacco smoke & bronchial asthma.

Bronchial asthma is a common disease and an important cause of morbidity among both children and adults. Tobacco smoking, both active and passive i.e., exposure to environmental tobacco smoke (ETS) has got important effects on asthma. Smoking by adults causes bronchial irritation and precipitates acute episodes. It also increases bronchial responsiveness and causes airway sensitization to several occupational allergens. Smoking may also increase the disease severity. Continued smoking by adult asthmatics is the likely cause of irreversibility of airway obstruction and development of chronic obstructive pulmonary disease. ETS exposure affects asthma in a similar fashion. Parental smoking is commonly associated with increased asthma symptoms, respiratory infections, acute episodes and frequent hospitalization of children. Bronchial responsiveness and airway sensitization may also increase. Childhood exposure to smoking is also considered as a risk factor for the development of asthma. Similarly, in utero exposure to maternal smoking may be independently responsible for early onset asthma. ETS exposure in adult asthmatics from smoking by spouses, siblings or colleagues is equally troublesome. There is increased morbidity and poorer asthma control. Asthmatic symptoms sharply decline after the ETS exposure is reduced.

Effects of immunotherapy on pulmonary functions and airway hyper-reactivity in patients with allergic asthma to house dust mites

This study was designed to investigate the effects of immunotherapy with an extract of house dust mites on 20 asthmatic palients allergic to house dust mites during 12 months period. The results of this study showed that there is statistically significant improvement in the pulmonary function parameters including FVC, FEV[1], FEV[1]/ FVC% and PEFR, and also there was statistically significant reduction in airway hyperreactivity to methacholine after completion the course of immunotherapy, these finding suggest that in well selected asthmatic patients allergic to house dust mites only, the immunotherapy is effective in improving pulmonary functions and reducing airway hyperreactivity in these patients

Asthmatic Airway Inflammation is More Closely Related to Airway Hyperresponsiveness to Hypertonic Saline than to Methacholine

BACKGROUND: Airway hyperresponsiveness (AHR) to direct stimuli, such as methacholine (MCh), is observed not only in asthma but other diseases. AHR to indirect stimuli is suggested to be more specific for asthma. The purpose of this study was to determine whether asthmatic airway inflammation is more closely related to AHR to hypertonic saline (HS), an indirect stimulus, than to MCh. METHODS: Sixty-four consecutive adult patients with suspected asthma (45 asthma and 19 non-asthma) performed a combined bronchial challenge and sputum induction with 4.5% saline, and MCh challenge on the next day. RESULTS: Both HS-PD15 and MCh-PC20 were significantly lower in asthma patients than in non-asthma patients. However, the sensitivity/ specificity for asthma was 48.9%/100%, respectively, in the HS test and 82.2%/ 84.2%, respectively, in the MCh test. There was a significant relationship between HS-PD15 and MCh-PC20 and only 52.9% of patients with MCh-PC20 4 mg/mL. There were significant correlations between both HS-PD15 and MCh-PC20 and FEV1, or sputum eosinophils, but FEV1 was more closely related to MCh-PC20 (r=0.478, p < 0.01) than to HS-PD15 (r=0.278, p < 0.05), and sputum eosinophils were more closely related to HS-PD15 (r=-0.324, p < 0.01) than to MCh-PC20 (r=-0.317, p < 0.05). Moreover, the IL-5 level (r=-0.285, p < 0.05) and IFN-gamma/IL-5 ratio (r=0.293, p < 0.05) in sputum were significantly related to HS-PD15, but not to MCh-PC20. CONCLUSION: HS-AHR may reflect allergic asthmatic airway inflammation more closely than MCh-AHR.

Effect of intraesophageal acid instillation on airway reactivity in patients with asthma.

OBJECTIVE: To study the change in airway reactivity due to presence of acid in lower esophagus and its reversibility by antacid. METHOD: In this double blind study 12 subjects with asthma and gastroesophageal reflux received acid (N/10 hydrochloric acid) and antacid (mixture of magnesium trisilicate and aluminum hydroxide) perfusion in lower esophagus via a nasogastric tube. The four combinations were antacid-antacid (control), antacid-acid, acid-antacid and acid-acid. Airway reactivity (Histamine PD20) was recorded after each perfusion. RESULTS: Histamine PD20 significantly decreased (airway reactivity increased) (p < 0.05) with all three combinations containing acid as compared to control. No significant difference in airway reactivity was observed if the antacid was given before or after the acid. CONCLUSION: Presence of acid in lower esophagus can increase airway reactivity. This effect lasts longer than the presence of acid in esophagus itself.

Effect of esophageal and gastric distention on bronchial hyper-responsiveness in patients with bronchial asthma.

OBJECTIVE: Over-eating is said to aggravate asthma though the mechanism is still unclear. We tried to study the mechanism by causing distention in oesophagus and stomach. METHODS: Fifteen patients with nocturnal asthma were studied in a random cross-over design. The esophagus and stomach of the subjects were distended with a balloon. The effect of the distention on the airways was measured by taking forced expiratory volume one second (FEV1), forced vital capacity (FVC) and bronchial hyper-responsiveness (BHR). RESULTS: Distention of stomach caused significant reduction in FEV1 on FEV1/FVC ratio but similar distention of esophagus did not. Histamine PD20 was decreased by 0.43 (SEM 0.28) doubling dose with gastric distention. However, with oesophageal distention no significant change was observed in PD20. CONCLUSION: It can be concluded that gastric distention leads to broncho-constriction as measured by FEV1, FEV1/FVC ratio along with increase in BHR probably by inducing airway inflammation. Therefore asthmatic patients should be advised to avoid large meals.

Procedimiento para realizar pruebas broncodinámicas con alergenos inhalados / Proccedings to bronchodynamics tests with inhalated allergens

El asma es una de las enfermedades crónicas más frecuentes de los niños. Se caracteriza por hiperreactividad de las vías aéreas a estímulos inespecíficos (metacolina e histamina) y específicos (alergenos). Las pruebas broncodinámicas determinan la broncolabilidad del niño asmático y ayudan a establecer el diagnóstico funcional. Deben realizarse con extractos antigénicos de alta calidad, acuosos liofilizados y estandarizados; se puede utilizar un circuito abierto o cerrado y un dosímetro, la dosis inicial del alergeno es más baja que con la que se obtuvo la reactividad cutánea positiva, realizando incrementos sucesivos hasta que el VEF-1 descienda 15 por ciento o más. La seguridad del paciente es fundamental, por eso las pruebas debe realizarlas personal especialmente adiestrado.