Characterization of oleic acid-induced acute respiratory distress syndrome model in rat.

Animal studies using oleic acid (OA) model to produce acute respiratory distress syndrome (ARDS) have been inconsistent. Therefore, the present study was undertaken to establish an acute model of ARDS in rats using OA and to characterize its effect on cardio-respiratory parameters and lethality. The trachea, jugular vein and femoral artery of anesthetized adult rats were cannulated. A dose of OA (30-90 µL; iv) was injected in each animal and changes in respiratory frequency (RF), heart rate (HR) and mean arterial pressure (MAP) were recorded. Minute ventilation and PaO2/FiO2 (P/F) ratio were also determined. At the end, lungs were excised for determination of pulmonary water content and histological examination. At all doses of OA, there was immediate decrease followed by increase in RF, however at 75 and 90 µL of OA, RF decreased abruptly and the animals died by 63 ± 8.2 min and 19 ± 6.3 min; respectively. In all the groups, HR and MAP changes followed the respiratory changes. The minute ventilation increased in a dose-dependent manner while the values of P/F ratio decreased correspondingly. Pulmonary edema was induced at all doses. Histological examination of the lung showed alveolar damage, microvascular congestion, microvascular injury, infiltration of inflammatory cells, pulmonary edema and necrosis in a dose-dependent manner. With these results, OA can be used to induce different grades of ARDS in rats and OA doses of 50, 60 and 75 µL resemble mild, moderate and severe forms of ARDS respectively. Hence, OA model serves as a useful tool to study the pathophysiology of ARDS.

Effect of chronic ethanol exposure on rat ventilatory responses to hypoxia and hypercapnia

OBJECTIVE: The effect of chronic ethanol exposure on chemoreflexes has not been extensively studied in experimental animals. Therefore, this study tested the hypothesis that known ethanol-induced autonomic, neuroendocrine and cardiovascular changes coincide with increased chemoreflex sensitivity, as indicated by increased ventilatory responses to hypoxia and hypercapnia. METHODS: Male Wistar rats were subjected to increasing ethanol concentrations in their drinking water (first week: 5% v/v, second week: 10% v/v, third and fourth weeks: 20% v/v). At the end of each week of ethanol exposure, ventilatory parameters were measured under basal conditions and in response to hypoxia (evaluation of peripheral chemoreflex sensitivity) and hypercapnia (evaluation of central chemoreflex sensitivity). RESULTS: Decreased respiratory frequency was observed in rats exposed to ethanol from the first until the fourth week, whereas minute ventilation remained unchanged. Moreover, we observed an increased tidal volume in the second through the fourth week of exposure. The minute ventilation responses to hypoxia were attenuated in the first through the third week but remained unchanged during the last week. The respiratory frequency responses to hypoxia in ethanol-exposed rats were attenuated in the second through the third week but remained unchanged in the first and fourth weeks. There was no significant change in tidal volume responses to hypoxia. With regard to hypercapnic responses, no significant changes in ventilatory parameters were observed. CONCLUSIONS: Our data are consistent with the notion that chronic ethanol exposure does not increase peripheral or central chemoreflex sensitivity. .

Características funcionais pulmonares e uso de broncodilatador em pacientes com fibrose cística / Pulmonary function parameters and use of bronchodilators in patients with cystic fibrosis

OBJETIVO: Analisar as características funcionais pulmonares, a resposta farmacodinâmica a um broncodilatador e sua prescrição em pacientes com diagnóstico de fibrose cística (FC). MÉTODOS: Estudo de coorte retrospectivo de pacientes (6-18 anos) com diagnóstico de FC acompanhados em um centro de referência, capazes de realizar testes de função pulmonar (TFP) entre 2008 e 2010. Foram analisados CVF, VEF1 e FEF25-75%, em percentual do previsto, antes e após prova broncodilatadora (pré-BD e pós-BD, respectivamente) de 312 TFP. Foram realizadas ANOVA para medidas repetidas e comparações múltiplas. RESULTADOS: Foram incluídos no estudo 56 pacientes. Desses, 37 e 19, respectivamente, tinham resultados de TFP entre 2008 e 2010 e apenas em 2009-2010, formando dois grupos. No grupo com TFP nos três anos estudados, houve redução significativa em VEF1 pós-BD em 2008-2010 (p = 0,028) e 2009-2010 (p = 0,036) e em FEF25-75% pré-BD e pós-BD em todas as comparações múltiplas (2008 vs. 2009; 2008 vs. 2010; e 2009 vs. 2010). No grupo com TFP apenas em 2009-2010, não houve diferenças significativas em nenhuma das comparações das variáveis estudadas. Dos 312 TFP, somente 24 (7,7%) apresentaram resposta significativa ao broncodilatador e pertenciam a pacientes sem prescrição de broncodilatador durante o período estudado. CONCLUSÕES: Houve perda funcional, com indicação de doença pulmonar progressiva, nos pacientes com FC estudados. Houve maiores alterações no FEF25-75%, sugerindo o comprometimento inicial de vias aéreas menores.

OBJECTIVE: To analyze pulmonary function parameters and pharmacodynamic response to a bronchodilator, as well as the prescription of bronchodilators, in cystic fibrosis (CF) patients. METHODS: This was a retrospective cohort study involving patients 6-18 years of age, diagnosed with CF, and followed at a referral center between 2008 and 2010. We evaluated only those patients who were able to perform pulmonary function tests (PFTs). We analyzed FVC, FEV1, and FEF25-75%, expressed as percentages of the predicted values, prior to and after bronchodilator tests (pre-BD and post-BD, respectively), in 312 PFTs. Repeated measures ANOVA and multiple comparisons were used. RESULTS: The study included 56 patients, divided into two groups: those whose PFT results spanned the 2008-2010 period (n = 37); and those whose PFT results spanned only the 2009-2010 period (n = 19). In the 2008-2010 group, there were significant reductions in post-BD FEV1 between 2008 and 2010 (p = 0.028) and between 2009 and 2010 (p = 0.036), as was also the case for pre-BD and post-BD FEF25-75% in all multiple comparisons (2008 vs. 2009; 2008 vs. 2010; and 2009 vs. 2010). In the 2009-2010 group, there were no significant differences between any of the years for any of the variables studied. Among the 312 PFTs, significant responses to the bronchodilator occurred in only 24 (7.7%), all of which were from patients for whom no bronchodilator had been prescribed during the study period. CONCLUSIONS: In the CF patients studied, there was loss of pulmonary function, indicating progressive lung disease, over time. The changes were greater for FEF25-75% than for the other variables, which suggests the initial involvement of small airways.

Cyclosporin A reduces airway mucus secretion and mucociliary clearance in rats

PURPOSE: To assay the effects of cyclosporin A on mucus secretion from goblet cells and on mucociliary transport in situ in rats. METHODS: Twenty-one male Wistar rats were assigned to 3 groups: control (n = 5), saline (n = 8), and cyclosporin A (n = 8). After 30 days of drug therapy, the rats were killed, and the lungs were removed from the thoracic cavity. Mucus samples were collected, and the transport rate was evaluated in vitro using a bullfrog palate model. Mucociliary transport was timed in situ by direct view of particles trapped on the mucus moving across the respiratory tract. Finally, the amount of stored mucins in the goblet cells of the respiratory epithelium was measured. RESULTS: Drug dosage measurements showed that cyclosporine blood concentration at the moment the rats were killed was 1246.57 ± 563.88 ng/mL. The in vitro transport rate was significantly lower (P < .001) in the cyclosporin A-treated group. Also, the in-situ mucociliary transport rate was decreased in all cyclosporin A-treated animals when compared to the saline group (P = .02). Mucus quantity measurements showed a significant decrease on both acid (P = .01) and neutral (P = .02) mucus production from goblet cells in the animals submitted to cyclosporin A therapy. The correlation between the percentage of total mucus and in vitro transport rate was positive and significant (r = 0.706, P < .001), as was the correlation between the percentage of total mucus and the in situ mucociliary transport rate (r = 0.688, P = .001). CONCLUSION: This study shows that cyclosporin A plays an important role in the impairment of the mucociliary clearance in rats by reducing both acid and neutral mucus production from goblet cells and causing a decrease in the mucociliary transport velocity.

OBJETIVO: Avaliar os efeitos da ciclosporina A sobre a produção de muco das células caliciformes e sobre o transporte mucociliar in situ de ratos. MÉTODOS: Vinte e um ratos machos Wistar foram distribuídos em três grupos: Controle (n=5), Salina (n=8) e Ciclosporina A (n=8). Após 30 dias de terapia, os ratos foram mortos e os pulmões removidos da cavidade torácica. Amostras de muco foram coletadas e a medida da transportabilidade in vitro foi realizada através de um modelo de palato de rã. A velocidade do transporte mucociliar foi medida através da observação direta do deslocamento de partículas aderidas ao muco do epitélio ciliado brônquico. Por fim, efetuamos a quantificação das mucinas estocadas nas células caliciformes do epitélio respiratório. RESULTADOS: O valor médio da concentração sangüínea da ciclosporina no momento do sacrifício dos ratos foi de 1.246,57 ± 563,88 ng/ml. A transportabilidade do muco in vitro foi estatisticamente menor (p < 0.001) no grupo tratado com ciclosporina. Da mesma forma, houve um decréscimo na velocidade de transporte mucociliar nos animais imunossuprimidos em relação aos que receberam o placebo (p = 0.02). Houve diminuição significativa na quantidade de muco ácido (p = 0,01) e neutro (p = 0,02) produzidos pelas células caliciformes nos animais tratados com ciclosporina. A correlação entre a porcentagem de muco e a transportabilidade in vitro foi positiva e significante (r = 0.706, p < 0.001), assim como entre a porcentagem do muco e o transporte mucociliar in situ (r = 0.688, p = 0.001). CONCLUSÃO: O presente estudo mostra que a ciclosporina A age no sistema mucociliar causando um sério prejuízo através da redução na produção de muco ácido e neutro pelas células caliciformes como também a diminuição da velocidade de transporte mucociliar in situ e a transportabilidade do muco in vitro.

Influencia del reclutamiento alveolar sobre los efectos del surfactante exogeno / Influence of pulmonary recruitment on exogenous surfactant effects

Se investigaron los efectos producidos por una maniobra de insuflación sostenida previa a la administraciónde surfactante exógeno y los producidos por diferentes patrones ventilatorios sobre la respuesta al mismo. Se estudiaron 20 ratas albinas adultas a las que se les produjo una injuria pulmonar por repetidos lavados con solución fisiológica. Se evaluó el pH, PaO2, PaCO2, la presión arterial sistólica, la compliance toracopulmonar y la histología. Los animales se dividieron en 2 grupos según se les hubiera aplicado o no insuflación sostenida para evaluar el efecto inmediato de la misma. Posteriormente los grupos citados fueron subdivididos en función de la capacidad residual funcional (CRF) aplicada, quedando conformados 4 grupos experimentales. El grupo 1 recibió previo al surfactante una insuflación sostenida de 30 cm H2O durante 15 segundos y se ventiló posteriormente con presión al final de la espiración (PEEP) de10 cm H2O. El grupo 2, no recibió insuflación sostenida y se ventiló con PEEP 10 cm H2O. El grupo 3, recibió insuflación sostenida y se ventiló con PEEP 4 cm H2O y el grupo 4, sin insuflación sostenida se ventiló con PEEP 4 cm H2O. Los efectos inmediatos del surfactante no fueron modificados por la aplicación previa de insuflación sostenida. Se verificó durante el transcurso de la experiencia un aumento de la PaO2 asociada al aumento de la capacidad residual funcional (Grupo1 p=0.0001; Grupo2 p= 0.0001), e independiente de la insuflación sostenida. El uso de insuflación sostenida previo a la administración de surfactante sumado a la ventilación con capacidad residual funcional alta se asoció con infiltración de polimorfonucleares debajo del epitelio bronquiolar (p = 0.008). Nuestros resultados no avalan el uso de insuflación sostenida previo a la administración de surfactante exógeno.

Effect of intratesticular injection of xylazine/ketamine combination on canine castration

This study was performed to compare the effect of intratesticular (IT) injection of xylazine/ketamine combination for canine castration with those of intramuscular (IM) or intravenous (IV) injection. Xylazine and ketamine was administered simultaneously via intratesticularly (IT group), intramuscularly (IM group) or intravenously (IV group) at doses of 2 and 10 mg/kg, respectively. Pain response at the time of injection, mean induction time, mean arousal time, mean walking time and cardiopulmonary function during anesthesia were monitored after the xylazine and ketamine administration. In IV and IM groups, heart rates were significantly decreased 30 and 45 min after xylazine and ketamine administration, respectively (p < 0.05). Respiratory rates were significantly decreased in the IV group (p < 0.05). In the IT group, there was no significant changes in heart and respiratory rates. The occurrence of cardiac arrhythmias was less severe in IT group compared with those in IM and IV groups. The route of administration did not affect rectal temperature. Mean induction time was significantly (p < 0.05) longer in IT group than in IM and IV groups. On the contrary, mean arousal time and mean walking time were shortened in IT group. Clinical signs related to pain response at the time of injection and vomiting were less observed in IT group than in IM group, and head shaking was less shown in IT group than in IM and IV groups during recovery period. These results indicated that intratesticular injection of xylazine/ketamine for castration has several advantages such as less inhibition of cardiopulmonary function and fast recovery from anesthesia without severe complications, and would be an effective anesthetic method for castration in small animal practice.

Efeitos na funçäo pulmonar após utilizaçäo de surfactante pulmonar exógeno na síndrome do desconforto respiratório agudo na criança / Effects in the pilmonary function before single dose of exogenous pulmonary surfactant in children with acute respiratory distress syndrome

A s­ndrome do desconforto respiratorio agudo (SDRA) , uma lesao pulmonar de causa multifatorial em que o sistema surfactante se apresenta alterado por causa da sua inativacao e comprometimento da composicao e metabolismo. A utilizacao do surfactante pulmonar exogeno , uma opcao terapeutica que visa manter a estabilidade alveolar, propiciando, dessa forma, a melhora da complacencia pulmonar (aumentando a capacidade residual funcional), da oxigenacao e da mecŸnica respiratøria. Os autores relatam o estudo realizado com a utilizacao de uma dose de surfactante pulmonar exogeno em dois pacientes pedi tricos com SDRA submetidos a ventilacao pulmonar mecanica. Avaliam os pacientes com gasometria arterial e venosa pre e pos-utilizacao de surfactante, sendo observada melhora na oxigenacao, reducao do shunt intrapulmonar, melhora da ventilacao imediatamente apos a instilacao da preparacao na canula orotraqueal e retorno a situacao pre-administracao apos 240 minutos, no caso 1, e apos 120 minutos, no caso 2. Concluem que ainda sao necessarios varios estudos cl­nicos prospectivos e randomizados para avaliar, de forma eficaz, essa modalidade terapeutica na SDRA.

Efecto agudo del lorazepam sobre los musculos respiratorios en los pacientes con EPOC estable / Acute effect of lorazepam on respiratory muscles in stable patients with chronic obstructive pulmonary disease

Con el objetivo de aclarar los efectos de las benzodiacepinas sobre los músculos respiratorios en pacientes con sobrecarga crónica de los mismos debida a enfermedad pulmonar obstructiva crónica (EPOC), se estudiaron 9 pacientes estables con EPOC avanzado (volumen espiratorio forzado en 1 segundo - FEV 1- 0,91 + 0,31 litros), en quienes, antes y 1 hora después de la administración de lorazepam 1,5 a 2 mg por vía sublingual, se evaluaron la capacidad vital forzada (FVC), FEV 1, ventilación voluntaria máxima (MVV), presión arterial de oxígeno (PaO2), presión arterial de anhídrido carbónico (PaCO2), volumen corriente (Vt), frecuencia respiratória (f), ventilación por minuto (Ve), tiempo inspiratorio/tiempo total (Ti/Ttot), flujo inspiratorio medio (Vi), presiones bucales máximas: máxima presión inspiratoria (MIP) y máxima presión espiratoria (MEP), presión pleural máxima (Pplmax), presiones transdiafragmáticas durante diferentes maniobras (Pdi) y mediciones de la fuerza y resistencia de los músculos esqueléticos. Tras la administración del lorazepam no se encontraron cambios en la espirometría (FVC, FEV1, ni FEV1/FVC), aunque sí existió una reducción del 20 por ciento en la Ve, debida a una minución en el Vt, que se acompañó de un pequeño pero significativo incremento en la PaCO2. La fuerza y resistencia de los músculos esqueléticos disminuyó significativamente (22 y 50 por ciento respectivamente), al igual que la MIP, MEP, MVV, Ppl y Pdi, que mostraron también reducciones significativas. Se concluye que una dosis única de lorazepam por vía sublingual, a la par que disminuye la ventilación, reduce la fuerza y la resistencia de la musculatura respiratoria en pacientes con EPOC en situación estable.

Delta pico flujo espiratorio, hiperreactividad bronquial y proteína catiónica del eosinófilo en asmáticos tratados con diferentes dosis de budesonida / Delta peak flow expiratoryhyperreactivity bronchial and cationic protein of the eosinophil in asthmatic treatmentwith different dose of Budesonide

Objetivo: Determinar la acción de distintas dosis de budesonida (BUD) sobre la evolución clínica del asma, la hiperreactividad bronquial (HRB) al aire frío y la proteína catiónica eosinofílica (PCE) sérica en un grupo de pacientes asmáticos atópicos, versus un grupo control tratado sólo con ß2 a demanda. Material y métodos: Se estudiaron 30 pacientes (p) con asma moderada persistente, edad X=25,5 años. Se les determinó: espirometría basal, HRB con aire frío, niveles séricos de PCE (valores normales: 2,6 a 16 mg/l) y monitoreo del pico flujo espiratorio (PFE) matinal y vespertino durante los distintos regímenes terapéuticos. Se los dividió en dos grupos: grupo 1 (23 p): se los medicó con BUD 800 mg/día durante 3 semanas; y grupo 2 (7 p): recibieron solamente ß2 a demanda por 3 semanas. al cabo de las mismas se volvieron a evaluar los mismos parámetros a los fines de determinar diferencias entre los dos tratamientos. Seguidamente al grupo 1 se redujo la dosis de BUD a 400 mg/día durante 2 semanas y a 200 mg/día otras dos semanas, evaluando HRB y valores de delta PEF (PEF) al final de cada tratamiento. Resultados: 1 a) La HRB al aire frío disminuyó en el grupo 1 (BUD) de una PD inicial X=16,4 a una PD X=7,62 luego de 3 semanas de tratamiento con 800 mg/d, mientras que en el grupo 2 (ß2) la PD inicial fue de X=15,8 y la PD final de X=15 (diferencia BUD vs. ß2: p<0,005). 1 b) El promedio semanal de  PFE diarios mayores al 10 por ciento en el grupo 1 fue de X=2,91 al inicio y de X=2 luego de las 3 semanas, mientras que en el grupo 2 subió de X=2,91 al inicio a X=5 al final del tratamiento (p<0,005). 1 c) La PCE sérica en el grupo 1 fue de X=32,5 µg/l al inicio y de X=23 µg/l al final, disminuyendo en 16/23 pacientes, mientras en el grupo 2 fue de X=28 µg/l al inicio y de X=21,2 µg/l al final de las 3 semanas (p<0,18). 2 a) En el grupo 1, la HRB durante el tratamiento con 400 µg/día bajó de una PD X=7,62 a una PD X=3,57 (p<0,005), aumentado nuevamente a una PD X=4,67 al disminuir la dosis a 200 µg/día. 2 b) Los  PEF mayores al 10 por ciento, durante el tratamiento con 400 µg/día bajaron de un X=2 a un X=1,74, volviendo a aumentar a X=2,2 con 200 µg/día. Conclusiones: Al disminuir la dosis del fármaco, este efecto se mantiene hasta una dosis de 400 µg/día, disminuyendo al utilizar 200 µg/día.

Effect of inhaled corticosteroids on bronchial hyperresponsiveness in patients with mild asthma.

We studied the effect of inhaled budesonide on bronchial hyperresponsiveness (BHR) in twenty mild asthmatic patients. The study was conducted as a randomized, double-blind, placebo-controlled study. Before entering the study, the patients performed methacholine inhalation challenge (MIC) using a reservoir method to assess BHR. Then, they were randomly allocated to receive budesonide turbuhaler (200 micrograms/dose) or placebo turbuhaler two inhalations, twice daily for eight weeks. During the study, each patient recorded daily asthma score and daily number of puffs of beta 2 agonist and they were assessed at weeks 4 and 8. At the end of the treatment, MIC was repeated again. Patients receiving budesonide showed a significant improvement in airway responsiveness compared with those receiving placebo (p < 0.05). They also showed a significant improvement in asthma severity score and a significant decrease in beta 2 agonist bronchodilator use. This study also suggested that inhaled corticosteroids may be the primary treatment in patients, even with mild asthmatic and well-controlled symptoms.

Categorisation of ventilatory pattern of response to bronchodilator therapy in airflow limitation.

Improvement in lung function studies following bronchodilator inhalation leads to different pattern of response in ventilatory parameters which are helpful in categorizing the patients into groups for correct interpretation of bronchodilator response and assessment of prognosis of the disease.

Nebulized salbutamol (Asmasal) in Thai children with asthma: comparison of three doses.

Eleven moderate-to-severe asthmatic children 5-11 years of age who were in stable condition were given (randomly, double-blind) nebulized salbutamol sulfate (Asmasal) inhalation therapy at doses of 0.1, 0.2 and 0.3 mg/kg body weight on separated days. All three doses of nebulized solution resulted in clinical improvement and improvement of lung function (FEV1, FVC, PEFR and FEF25-75%). A dose of 0.3 mg/kg produced greatest improvement and longest duration of improvement in FEV1 and PEFR, but the change was statistically significant only in PEFR at 60 minutes (p < 0.05). Five children experienced mild tremors. There were no significant changes in heart rate or blood pressure at any dose. It is concluded that a nebulized solution of salbutamol sulfate at a dose of 0.1-0.3 mg/kg is useful for treatment of asthma in Thai children, with very mild side effects.

Correlación entre VEF1 y FEM en pacientes con asma bronquial / Analysis of lineal correlation betwen FEV1 and MEF after using bronchodilators in bronchial asthma

Se analiza la correlación lineal entre los valores basales del volumen espiratorio forzado al primer segundo (VEF1) medido por medio de la espirometría cronometrada y el flujo espiratorio máximo (FEM) con el flujómetro, analogamente los incrementos en valores absolutos de la misma variable 30 y 60 minutos despues del uso de un broncodilatador en aerosol dosificado. El estudio fue practicado en una muestra de 24 asmáticos. El valor de r (coeficiente de correlación) entre los valores basales de VEF1 y FEM fue 0,54 con p igual a 0.002. De manera similar en el analisis de correlación practicado con los incrementos de las mismas variables a los 30 y 60 minutos de aplicada la sustancia activa se obtuvo r igual a 0.65 con p igual a 0.00015 y p igual a 0.00016 respectivamente. Como ha sido demostrado, existe una buena correlación entre las mediciones obtenidas con estos instrumentos. Se recomienda extender el uso del flujometro en nuestro medio

Rendimiento del atleta que hace ejercicio en aire contaminado con ozono / Performance of athletes exercising in ozone polluted air

Se examinó la literatura sobre le rendimiento del que se ejercita en aire con ozono. La acción de ozono está mediada por receptores muscarinicos y otros de naturaleza desconocida lcalizados, aparentemente, sobre el epitelio respiratorio de transporte gaseoso. Por su acción sobre dichos receptores se reduce la fase inspiratoria de la ventilación pulmonar en un efecto asociado con la aparición de dolor y aumenta la resistencia al paso del aire. Si el ejercicio eleva la ventilación a 90 o más litros por minuto, la concentración efectiva de ozono aumenta hasta potenciar su efecto en la inspiración y la resistencia. La reducción potenciada de la fase inspiratoria y el dolor asociado con ella (a) antagonizan fuertemente el esfuerzo ventilatorio del que se ejercita y (b) reducen la capacidad de responder al aumento en resistencia con inspiraciones aumentadas. De este modo aparece una caída importante en el remdimeinto

Correçäo isovolume dos fluxos respiratórios: sua utilidade no estudo da resposta broncodilatadora / Isovolume correction of respiratory flows: its usefulness in study of bronchodilatador responce

Com a finalidade de estudar a utilidade da correçäo isovolume dos fluxos expiratórios obtidos na curva fluxo-volume para a interpretaçäo da resposta broncodilatadora, foram estudados 50 pacientes obstrutivos (VEF1/CVF < 70%), 32 homens e 18 mulheres, com idade média de 51,7 + ou - 15,9 anos. Os valores basais do grupo foram: VEF1 (L) = 1,61 + ou - 0,60; VEF1/CVF (%) = 52 + ou - 12; Vmax 50 (L/S) = 0,98 + ou - 0,55; Vmax 25 (L/s) = 0,31 + 0,19. Como broncodilatador foi usado salbutamol spray 300 mcg. Após 15 minutos, o Vmax 50 e o Vmax 25 passaram respectivamente para 1,33 + ou - 0,85 (p <0,001) e 0,42 + ou - 0,29 (p <0,001). Quando feita a correçäo isovolume, esses valores passaram a: Vmax 50 = 1,64 + ou - 0,96 (p <0,001) e Vmax 25 = 0,64 + ou - 0,43 (p <0,001). Sete exames (14%) näo puderam sofrer correçäo isovolume, porque a CVF após o broncodilatador era menor ou igual à verificada no exame basal. Os limites de resposta broncodilatadora positiva considerados foram: 20% para Vmax 50 e 25% para Vmax 25. Dos 43 pacientes (86%) em que foi possível realizar a correçäo, 18 mostraram resposta negativa, considerando-se os limites acima. Após correçäo isovolume desses 18 casos, houve resposta broncodilatadora positiva em 11, se considerado o Vmax 50, e 13, se considerado o Vmax 25. Foram as seguintes as variaçöes percentuais em relaçäo aos valores iniciais (delta % inicial): Vmax 50 = + 34% sem correçäo e 69% com correçäo; Vamx 25 = + 33% sem correçäo e 106% com correçäo. Conclui-se que a correçäo isovolume dos fluxos expiratórios é útil na interpretaçäo da resposta broncodilatadora