RESUMO
PURPOSE: We quantified the magnitude of exercise-induced bronchodilation in adult asthmatics under conditions of narrowed and dilated airways. We then assessed the effect of the bronchodilation on ventilatory capacity and the extent of ventilatory limitation during exercise. METHODS: Eleven asthmatics completed three exercise bouts on a cycle ergometer. Exercise was preceded by no treatment (trialCON), inhaled ß2 agonist (trialBD), or a eucapnic voluntary hyperpnea challenge (trialBC). Maximal expiratory flow-volume maneuvers (MEFV) were performed before and within 40 s of exercise cessation. Exercise tidal flow-volume loops were placed within the preexercise and postexercise MEFV curve and used to determine expiratory flow limitation and maximum ventilatory capacity (VËECap). RESULTS: Preexercise airway function was different among the trials (forced expiratory volume 1 s during trialCON, trialBD, and trialBC = 3.3 ± 0.8 L, 3.8 ± 0.8 L, and 2.9 ± 0.8 L, respectively; P < 0.05). Maximal expired airflow increased with exercise during all three trials, but the increase was greatest during trialBC (delta forced expiratory volume 1 s during trialCON, trialBD, and trialBC = +12.2% ± 13.1%, +5.2% ± 5.7%, +28.1% ± 15.7%). Thus, the extent of expiratory flow limitation decreased, and VËECap increased, when the postexercise MEFV curve was used. During trialCON and trialBC, actual exercise ventilation exceeded VËECap calculated with the preexercise MEFV curve in seven and nine subjects, respectively. CONCLUSIONS: These findings demonstrate the critical importance of exercise bronchodilation in the asthmatic with narrowed airways. Of clinical relevance, the results also highlight the importance of assessing airway function during or immediately after exercise in asthmatic persons; otherwise, mechanical limitations to exercise ventilation will be overestimated.
Assuntos
Antiasmáticos/uso terapêutico , Asma/tratamento farmacológico , Asma/fisiopatologia , Brônquios/fisiologia , Exercício Físico/fisiologia , Ventilação Pulmonar/fisiologia , Adolescente , Adulto , Brônquios/fisiopatologia , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Testes de Função Respiratória , Resultado do Tratamento , Adulto JovemRESUMO
PURPOSE: Hepatopulmonary syndrome (HPS) is defined as an arterial oxygenation defect induced by intrapulmonary vascular dilatations associated with hepatic disease. This study aimed to assess the prevalence of type 1 and 2 pulmonary vascular abnormalities on chest computed tomography (CT) in patients with cirrhosis and HPS and to characterize intra- and interobserver reliability. MATERIALS AND METHODS: Two thoracic radiologists retrospectively evaluated chest CT scans from 38 cirrhosis patients with HPS. They classified the pulmonary vascular abnormalities as type 1 (multiple dilated distal pulmonary arteries), type 2(nodular dilatation or individual pulmonary arterial malformation), or absence of abnormality. Furthermore, they measured the diameters of the central pulmonary arteries and subsegmental pulmonary arteries and bronchi. We analyzed the prevalence, intraobserver reliability, and interobserver reliability of abnormal CT findings related to HPS, and the correlation of these findings with partial arterial oxygen pressure (PaO2). RESULTS: The overall prevalence of pulmonary vascular abnormalities was 28.9% (95% confidence intervals: 15.4%, 45.9%). Moreover, 26.3% of patients had type 1 abnormality (13.4%, 43.1%) and 2.6% of patients had type 2 abnormality (0.0%, 13.8%). The intraobserver reliability kappa value was 0.666 (0.40, 0.91) and the interobserver kappa value was 0.443 (0.12, 0.77). There was no correlation between pulmonary vascular abnormalities on CT and PaO2 values. CONCLUSIONS: The prevalence of pulmonary vascular abnormalities on chest CT of patients with cirrhosis and HPS is low and not correlated with PaO2. These findings question the usefulness of chest CT for the evaluation of patients with cirrhosis and HPS.
Assuntos
Síndrome Hepatopulmonar/diagnóstico , Tórax/diagnóstico por imagem , Doenças Vasculares/diagnóstico , Adulto , Idoso , Brônquios/fisiologia , Feminino , Síndrome Hepatopulmonar/complicações , Humanos , Cirrose Hepática/complicações , Cirrose Hepática/diagnóstico , Masculino , Pessoa de Meia-Idade , Prevalência , Veias Pulmonares/anormalidades , Estudos Retrospectivos , Tomografia Computadorizada por Raios X , Doenças Vasculares/epidemiologiaRESUMO
Airway function study includes a variety of tests involving various sub-specialties of medicine and related professions. We describe the methods that assess: 1) upper airway (nose to larynx): rhinomanometry, acoustic rhinometry and nasopharingolaryngoscopy, 2) central airways (trachea and main bronchi): bronchoscopy, imaging study and Flow / Volume curve, 3) distal or peripheral airway: spirometry, bronchodilator response assessment, airway hyper responsiveness and measurement of airway resistance (plethysmography, interrupted resistence and impulse oscillometry).
El estudio de la función de la vía aérea abarca una gran variedad de exámenes que implican a diversas subespecialidades de la medicina y profesiones relacionadas. Se describen los métodos que evalúan: 1) vía aérea superior (nariz hasta laringe): rinomanometría, rinometría acústica y nasofarigolaringoscopía, 2) vía aérea central (tráquea y bronquios mayores): bronconcoscopia, estudio de imágenes y curva flujo/volumen, 3) vía aérea distalo periférica: espirometría, evaluación de respuesta a broncodilatador y de hiperreactividad bronquial y medición de la resistencia de la vía aérea (pletismografía, resistencia interrumpida y oscilometría de impulso).
Assuntos
Humanos , Criança , Técnicas de Diagnóstico do Sistema Respiratório , Fenômenos Fisiológicos Respiratórios , Broncoscopia , Brônquios/fisiologia , Doenças Respiratórias/diagnóstico , Volume Expiratório Forçado , Faringe/fisiologia , Laringoscopia , Nariz/fisiologia , Rinometria Acústica , Espirometria , Traqueia/fisiologiaRESUMO
The bronchial tree of most mammalian lungs is a good example of an efficient distribution system whose geometry and dimensions of branched structures are important factors in determining the efficiency of respiration. Small and flying endothermic animals have high-energy requirements, requiring morphological and physiological adaptations to reduce energy loss. Here we show that Tadarida brasiliensis, a nocturnal small bat whose energy requirements are exacerbated by this small size and by their frequent exposure to high altitude, has a different morphology in the proximal airway, sustained by a wider trachea and better scaling factors, than other non-flying mammals. This design allows a great decrease of the volume specific resistance of the proximal airway and in consequence a very low entropy production during breathing, approximately 1/18 of that expected for a non-flying mammals of similar body size.
Assuntos
Brônquios/anatomia & histologia , Brônquios/fisiologia , Quirópteros/anatomia & histologia , Quirópteros/fisiologia , Entropia , Modelos Biológicos , Altitude , Animais , Arvicolinae , Tamanho Corporal/fisiologia , Metabolismo Energético/fisiologia , Coelhos , Ratos , RespiraçãoRESUMO
Immune cell airway infiltration and the bronchovascular remodeling process have shown to be promising in the understanding of bronchiolitis obliterans (BO) pathogenesis. In this study we sought to validate the importance of immune cells, whether diffusely distributed or forming lymphoid follicles, collagen density, and vascular factors. Eight weeks after a single nitric acid (NA) nasal instillation, lung changes were characterized by lumen distortion, epithelial layer folding, reduction or total obliteration of terminal bronchiole (TB) lumen, and wall thickness increase. The morphologic changes in the TB and TA (terminal artery) lumen coincide with the measurement difference in the three groups. The TB diameter and lumen were significantly decreased in BO when compared with non-BO lungs (0.76 +/- 0.05 microm vs. 0.81 +/- 0.05 microm and 12,286.13 +/- 378.83 microm vs. 18,182.27 +/- 5,593.98 microm, p = 0.05 and p = 0.01, respectively). Equally significant was the increase in TB thickness in BO when compared with the non-BO group (201.72 +/- 35.75 microm vs. 149.75 +/- 40.61 microm, p = 0.007). The morphologic changes in immune cells seen in TB, TA, and bronchus-associated lymphoid tissue (BALT) also coincide with the quantification differences observed in the three groups. We concluded that immune cell infiltration and collagen/vascular remodeling are related to the spectrum of histologic changes in a BO nasal-induced model in mice and may be an appropriate target for prospective studies of human bronchiolitis.
Assuntos
Brônquios/efeitos dos fármacos , Brônquios/imunologia , Bronquiolite Obliterante/imunologia , Modelos Animais de Doenças , Ácido Nítrico/administração & dosagem , Administração Intranasal , Animais , Linfócitos B/imunologia , Brônquios/irrigação sanguínea , Brônquios/fisiologia , Bronquiolite Obliterante/patologia , Colágeno/fisiologia , Feminino , Imuno-Histoquímica , Instilação de Medicamentos , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Neutrófilos/imunologia , Linfócitos T/imunologiaRESUMO
This paper focuses on the estimation of tube wall compliance using reflection analysis of acoustic pulses. The wall compliance of a rubber latex tube was found theoretically using an acoustical transmission line model. Wall compliance was also obtained experimentally from acoustical and mechanical measurements. The acoustically estimated, mechanically estimated, and simulated wall compliances were CwEXP=6.55x10(-7) cm5/dyne, CwMech=6.89x10(-7) cm5/dyne and CwSim=5.18x10(-7) cm5/dyne respectively. The methods developed and the preliminary results obtained from this research could serve as the groundwork for the development of a device that determines the pathological condition of compliant biological conduits such as the airways.
Assuntos
Acústica , Resistência das Vias Respiratórias/fisiologia , Algoritmos , Brônquios/fisiologia , Modelos Biológicos , Radiometria/métodos , Simulação por Computador , Elasticidade , Doses de Radiação , Estresse MecânicoRESUMO
BACKGROUND: Dopamine exerts inhibitory and excitatory effects on different systems. Its effect on human bronchial tone is controversial. It has been reported that dopamine has no acute effect on human airways from normal subjects or those with asthma background. However, inhaled or infused dopamine decreased histamine-induced bronchoconstriction in both normal and asthmatic subjects. METHODS: We examined the possible modulating effect of dopamine on bronchial diameter by administering inhaled dopamine and the DA(2) dopaminergic blocker metoclopramide (MTC) to subjects with various degrees of bronchial tone. We examined 50 volunteers. Arterial blood pressure and heart rate were determined in each subject. By means of spirometry, we measured forced vital capacity (FVC), forced expiratory volume in the first second (FEV(1)), maximal forced expiratory flow (FEF(max)), and forced expiratory flow at 50% of vital capacity (FEF(50)), before and after each treatment. By inhalation with a nebulizer, we administered the following: a) dopamine (0.5 microg/kg/min) to 10 healthy subjects, 10 subjects with asthma without acute bronchospasm (AWAB), and nine subjects with acute asthma attack (AAA), and b) intravenous (i.v.) metoclopramide (7 microg/kg/min) was administered to 10 healthy subjects and 11 subjects with AWAB. For ethical reasons, MTC was not used in subjects with acute asthma attack. Non-parametric Wilcoxon test for paired samples, ANOVA test, and Bonferroni multiple comparison test were performed. Inhaled dopamine increased FEV(1) and FVC, FEF(max), and FEF(50) in the AAA group, but there were no modifications in the healthy group or in the AWAB group. Metoclopramide did not induce changes in respiratory parameters in healthy individuals or in those with AWAB. CONCLUSIONS: Inhaled dopamine is able to induce bronchodilatation when the bronchial tone is already increased by acute asthma attack but did not modify the resting bronchial tone in normal subjects or in asthmatics without acute bronchospasm. Additionally, DA(2) blockade with metoclopramide did not modify resting bronchial tone. Dopamine exerts a modulatory effect on the bronchial tone of human airways depending on the degree of preexisting tone.
Assuntos
Brônquios/fisiologia , Dopamina/fisiologia , Tono Muscular/fisiologia , Músculo Liso Vascular/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Metoclopramida/administração & dosagemRESUMO
Adult male guinea pigs from both sexes were anaesthetized with pentobarbital (40mg/Kg). After tracheotomy the lungs were perfused with Krebs-Henseleit solution at 37 degrees C in a non recirculated system composed of a perfusion pump, a transducer to measure pressure and another one to measure bronchial resistance. In all groups studied histamine injections were made at the doses of 50, 100, 200 and 400 microg/ml as a bolus. Propranolol (1 microg/ml) added to the perfusate, promoted a remarkable increase in perfusion pressure (p<0.001) and a significant augmentation in bronchoconstriction (p<0.05). When indometacin (10 microg/ml) was added to the perfusate, a great increase in histamine induced bronchoconstriction was observed, that was followed by a remarkable increase in perfusion pressure. Methylene blue at the dose of 8.25 microg/ml increased bronchorreativity as well as the perfusion pressure significantly. L-arginine (3.5 microg/ml) added to the perfusate, did not promote reactivity. The addition of L-arginine plus NADPH (1 microg/ml), promoted a significant decrease in bronchoconstriction (p<0.01). In both cases, perfusion pressure increased when compared to controls. Nitroarginine (2.5 microg/ml) greatly increased perfusion pressure with no change in bronchoconstriction. Therefore, we conclude that nitric oxide (NO) is a very important modulator for keeping the low perfusion pressure and bronchodilation of the isolated perfused guinea pig lung.
Assuntos
Pulmão/fisiologia , Óxido Nítrico/fisiologia , Antagonistas Adrenérgicos beta/farmacologia , Resistência das Vias Respiratórias/fisiologia , Animais , Anti-Inflamatórios não Esteroides/farmacologia , Pressão Sanguínea , Brônquios/fisiologia , Broncoconstrição/fisiologia , Feminino , Cobaias , Técnicas In Vitro , Indometacina/farmacologia , Masculino , Músculo Liso Vascular/fisiologia , NADP/fisiologia , Perfusão , Propranolol/farmacologiaRESUMO
Respiration and metabolism change dramatically over the course of the development of vertebrates. In mammals these changes may be ascribed to organogenesis and differentiation of structures involved in gas exchange and transport and the increase in size. Since young as well as mature individuals must be well-designed if the species is to survive, the physiological changes during the development should be matched with geometrical or structural adjustments of the respiratory system. The aim of this study was to evaluate changes in the fractal geometry of the bronchial tree during the postnatal development of the rat. The average fractal dimension of the bronchial tree of the rats was 1.587, but that of juveniles was larger than that of the adults. We found a significant negative correlation between age and fractal dimension. This correlation could be considered be misleading because of the difficulty of separating age/body size effects. Nevertheless, because fractal dimensions of the bronchial tree of rabbits and humans are known to be similar, 1.58 and 1.57 respectively, the body size effect may be nil. To our knowledge, this is the first report of ontogenetic changes in the fractal dimension of the bronchial tree in mammals.
Assuntos
Brônquios/anatomia & histologia , Fractais , Animais , Brônquios/fisiologia , Feminino , Masculino , RatosRESUMO
In the guinea pig bronchus with epithelium, pre-contracted with histamine, bradykinin (BK), lysyl-BK, prostaglandin E2 (PGE2), cromakalim and S-nitroso-N-acetylpenicillamine each caused graded relaxation with mean EC50s of 34 nM, 11 nM, 0.1 nM, 0.3 microM and 3.4 microM, respectively. The addition of NO synthase inhibitors N(W)-nitro-L-arginine (L-NOARG), N(G)-monomethyl-L-arginine or 7-nitroindazole reduced BK-induced relaxation by 41+/-6%, 59+/-4% and 51+/-2%, respectively. The inhibition of BK response caused by L-NOARG was completely reversed by L-, but not by D-arginine. Methylene blue and 6-(phenylamino)-5,8-quinolinedione (LY 83583) inhibited the BK response by 88+/-5% and 64+/-4%, while 1H-[1,2,4]oxadiazolo[4,3-a]quinolaxin- -one (ODQ) had no effect. However, ODQ almost abolished SNAP-induced relaxation. Indomethacin and the cyclo-oxygenase 2 (COX-2) inhibitor 5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulfonyl)phenyl-2(5H)-furanon e (DFU) caused graded inhibtion of BK responses with mean IC50s of 60 nM and 0.6 nM, respectively. Addition of tetraethylammonium (TEA), charybdotoxin (ChTx), or iberotoxin (IbTx) inhibited BK-induced relaxation by 76+/-4%, 30+/-4% and 99+/-1%, respectively, but the relaxations of PGE2 and cromakalim were unaffected. In contrast, 4-aminopyridine, apamin or glibenclamide did not affect BK-induced relaxation. These results indicate that BK-induced epithelium-dependent relaxation in the guinea pig bronchus is partially mediated by release of NO or by NO-related substances, involving an activation of both cyclo-oxygenase 1 (COX-1) and COX-2 enzymes, through a cyclic guanosine monophosphate (cGMP)-independent mechanism. Furthermore, BK-induced relaxation involves an activation of high-conductance Ca(2+)-activated K+ channels highly sensitive to IbTx, and to a lesser extent to ChTx and TEA.