ABSTRACT
OBJETIVO: Investigar os efeitos da obstrução de vias aéreas nas variações das propriedades resistivas e elásticas do sistema respiratório de asmáticos adultos mediadas pelo uso de salbutamol. MÉTODOS: Foram analisados 24 indivíduos controles e 69 asmáticos, todos não tabagistas, divididos em três grupos segundo o nível de obstrução de vias aéreas (leve, moderada e acentuada). Cada grupo foi dividido em dois subgrupos de acordo com a resposta broncodilatadora: resposta broncodilatadora positiva (RB+) ou negativa (RB-). A espirometria foi utilizada para a avaliação da obstrução, e a técnica de oscilações forçadas, para a análise das propriedades resistivas e elásticas, sendo realizadas antes e após a utilização de 300 µg de salbutamol. RESULTADOS: A resistência no intercepto (R0) apresentou maior redução nos grupos com maior obstrução. Essa redução foi mais evidente nos subgrupos RB+ do que nos RB- (p < 0,02 e p < 0,03, respectivamente). Houve diferença significativa entre o grupo controle e a o subgrupo com obstrução acentuada RB+ (p < 0,002). As reduções na elastância dinâmica (Edyn) se acentuaram significativamente com a obstrução, tanto para os subgrupos RB- (p < 0,03), quanto para os RB+ (p < 0,003). As reduções da Edyn foram significativamente maiores nos subgrupos com obstrução moderada RB- (p < 0,008) e com obstrução acentuada RB+ (p < 0,0005) do que no grupo controle. CONCLUSÕES: Em asmáticos, o aumento da obstrução de vias aéreas resulta na elevação das variações em R0 e Edyn com o uso de salbutamol. Pacientes com RB+ apresentam variações mais elevadas que indivíduos com RB-.
OBJECTIVE: To investigate the effects of airway obstruction on albuterol-mediated variations in the resistive and elastic properties of the respiratory system of adult patients with asthma. METHODS: This study comprised 24 healthy controls and 69 patients with asthma, all of whom were nonsmokers. The patients were divided into three groups according to the severity of airway obstruction (mild, moderate or severe). Each of the three groups was divided into two subgroups according to the bronchodilator response (BR): positive (BR+) or negative (BR-). Airway obstruction was determined by means of spirometry, and the resistive and elastic properties were determined by means of the forced oscillation technique. These measurements were conducted before and after albuterol use (300 µg). RESULTS: The resistance at the intercept (R0) presented greater reductions in the groups with higher obstruction. This reduction was more evident in the BR+ subgroups than in the BR- subgroups (p < 0.02 and p < 0.03, respectively). There was a significant difference between the control group and the BR+ subgroup with severe obstruction (p < 0.002). The reductions in dynamic elastance (Edyn) were significantly greater in proportion to the degree of obstruction, in the BR- subgroups (p < 0.03), and in the BR+ subgroups (p < 0.003). The reductions in Edyn were significantly greater in the BR- subgroup with moderate obstruction (p < 0.008) and in the BR+ subgroup with severe obstruction (p < 0.0005) than in the control group. CONCLUSIONS: In patients with asthma, increased airway obstruction results in greater reductions in R0 and Edyn after albuterol use. These reductions are greater among BR+ patients than among BR- patients.
Subject(s)
Adolescent , Adult , Aged , Female , Humans , Male , Middle Aged , Young Adult , Airway Obstruction/drug therapy , Airway Resistance/drug effects , Albuterol/therapeutic use , Asthma/drug therapy , Bronchodilator Agents/therapeutic use , Respiratory System/drug effects , Analysis of Variance , Airway Obstruction/physiopathology , Airway Resistance/physiology , Case-Control Studies , Dose-Response Relationship, Drug , Respiratory System/physiopathology , Spirometry , Young AdultABSTRACT
INTRODUCTION: The within-breath analysis of respiratory mechanics by the monofrequency Forced Oscillation Technique (mFOT) is of great interest in both physiopathology studies and the diagnosis of respiratory diseases. However, there are limited data on the use of this technique in the analysis of asthma. This study evaluates within-breath mechanics of asthmatic individuals and the contribution of the mFOT in the asthma diagnosis. METHODS: Twenty-two healthy and twenty-two asthmatic subjects, including patients with mild (n=8), moderate (n=8), and severe (n=6) obstruction, were studied. Forced Oscillation Technique data were interpreted using the mean respiratory impedance (Zt), the impedance during inspiration (Zi), expiration (Ze), at the beginning of inspiration (Zii), and at expiration (Zie). The peakto-peak impedance (Zpp) was also calculated by the subtraction of Zii from Zie. Receiver operating characteristic curves were used to determine the sensitivity (Se) and specificity (Sp) of m Forced Oscillation Technique parameters in identifying asthma. RESULTS: Respiratory impedance values were significantly higher in asthmatics: Zt (p<0.001), Zi (p<0.001), Ze (p<0.001), Zii (p<0.001), Zie (p<0.001), and Zpp (p<0.003). The best parameters for detecting asthma were Zi, Zii, and Zie (Se=90.9%, Sp=90.9%), followed by Zt and Ze. These results are in close agreement with recently published theories and pathophysiological fundamentals. CONCLUSIONS: mFOT permits a non-invasive and detailed analysis in different phases of the respiratory cycle, providing parameters that are adequate for the diagnosis of asthma with high accuracy. These results confirm the high clinical and scientific potential of this methodology in the evaluation of asthmatic patients.
Subject(s)
Female , Humans , Male , Middle Aged , Airway Resistance/physiology , Asthma/diagnosis , Forced Expiratory Volume/physiology , Oscillometry/methods , Respiratory Mechanics/physiology , Asthma/physiopathology , Case-Control Studies , ROC Curve , Sensitivity and Specificity , Spirometry , Time FactorsABSTRACT
Introdução: O Flutter® VRP1 é um dispositivo que combina pressão positiva expiratória e oscilações de alta freqüência com objetivo de manter as vias aéreas pérvias. Apesar de sua utilização rotineira na prática da fisioterapia, seu efeito na mecânicarespiratória é escasso na literatura. O presente estudo investigou o efeito, a curto prazo, do uso deste dispositvo em indivíduos saudáveis e em pacientes portadores de Doença Pulmonar Obstrutiva Crônica (DPOC), asma e bronquiectasia. Metodologia: Os pacientes foram submetidos à utilização do Flutter® VRP1 por um período de 5 a 10 minutos. Para análise da mecânica respiratória, a técnica de oscilações forçadas (FOT) e a espirometria foram realizadas antes e imediatamente após o uso do dispositivo. Resultados: O uso do Flutter® VRP1 não resultou em alterações significativas nos parâmetros avaliados pela FOT nos grupos estudados. Considerando-se a espirometria, a única variável que apresentou diferença significativa (p<0,05) foi VEF1 (L) no grupo controle. Conclusão: Com o protocolo utilizado, nos grupos de indivíduos saudáveis e de portadores de DPOC, asma e bronquiectasia, o uso do Flutter® VRP1 não introduziu modificações, a curto prazo, na mecânica respiratória.
Introduction: The Flutter® VRP1 is a device that combines expiratory positive airway pressure with high frequency oscillations to keep airway clean. In spite of the widely clinical use, the effect analyze of this device in the respiratory mechanics of obstructive patients is little. The aim of the present study was to investigate the short-term effect of the use of the Flutter® VRP1 in healthy subjects and patients with Pulmonary Disease, Chronic Obstructive (COPD), asthma and bronchiectasis.Methodology: The patients were submitted to a protocol where the Flutter® VRP1 was used for a period of 5 to 10 minutes. Changes in pulmonary mechanics were analyzed by the forced oscillations technique (FOT) and spirometry, which were performed before and immediately after the use of the device. Results: The use of Flutter® VRP1 didnt result in significant alterations in the evaluated parameters of FOT in the studied groups. Considering spirometry, the only variable that presented significant difference (p <0.05) was VEF1 (L) in healthy group. Conclusion: With the used protocol, in the studied populationof healthy subjects and patients with COPD, asthma and bronchiectasis, the use of the Flutter® VRP1 do not introduced shortterm modifications in respiratory mechanics.