Detection of changes in respiratory mechanics due to increasing degrees of airway obstruction in asthma by the forced oscillation technique

Cavalcanti, Juliana Veiga; Lopes, Agnaldo José; Jansen, José Manoel; Melo, Pedro Lopes de

doi:10.1016/j.rmed.2006.03.009

Cited by 110 publications

(108 citation statements)

References 43 publications

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“…45 The R RS by the impulse oscillometry system and the FOT agree well at higher frequencies (25 Hz). 45 The FOT has been used in many applications, including differentiating healthy from obstructed patients in COPD and asthma; detecting bronchoconstriction, which occurs at lower doses of methacholine for impulse oscillometry system resistance than for FEV 1 46 ; and measuring the severity of obstruction in asthma and COPD 47,48 (Fig. 7).…”

Section: Measurement Of Airway Resistance By the Forced Oscillation Tmentioning

confidence: 99%

What Does Airway Resistance Tell Us About Lung Function?

2012

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SummarySpirometry is considered the primary method to detect the air flow limitation associated with obstructive lung disease. However, air flow limitation is the end-result of many factors that contribute to obstructive lung disease. One of these factors is increased airway resistance. Airway resistance is traditionally measured by relating air flow and driving pressure using body plethysmography, thus deriving airway resistance (R aw ), specific airway resistance (sR aw ), and specific airway conductance (sG aw ). Other methods to measure airway resistance include the forced oscillation technique (FOT), which allows calculation of respiratory system resistance (R RS ) and reactance (X RS ), and the interrupter technique, which allows calculation of interrupter resistance (R int ). An advantage of these other methods is that they may be easier to perform than spirometry, making them particularly suited to patients who cannot perform spirometry, such as young children, patients with neuromuscular disorders, or patients on mechanical ventilation. Since spirometry also requires a deep inhalation, which can alter airway resistance, these alternative methods may provide more sensitive measures of airway resistance. Furthermore, the FOT provides unique information about lung mechanics that is not available from analysis using spirometry, body plethysmography, or the interrupter technique. However, it is unclear whether any of these measures of airway resistance contribute clinically important information to the traditional measures derived from spirometry (FEV 1 , FVC, and FEV 1 /FVC). The purpose of this paper is to review the physiology and methodology of these measures of airway resistance, and then focus on their clinical utility in relation to each other and to spirometry.

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Section: Measurement Of Airway Resistance By the Forced Oscillation Tmentioning

confidence: 99%

What Does Airway Resistance Tell Us About Lung Function?

2012

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“…This method is particularly attractive in children as it requires only passive cooperation from the subject, who breathes quietly at tidal volume during the test. A predominant increase of Rrs at low frequencies (,10-15 Hz) called frequency dependence has been shown to reflect obstruction in distal airways in various obstructive lung diseases, including asthma [87][88][89][90][91]. Low frequency Rrs were increased in asthmatic children with mild airway obstruction (FEV1 .80% pred and FEF25-75% ,80% pred) [92].…”

Section: Pulmonary Resistance Measurementsmentioning

confidence: 99%

Update on the roles of distal airways in asthma

Burgel¹,

Blic²,

Chanez³

et al. 2009

Eur Respir Rev

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The present review is the summary of an expert workshop that took place in Vence (France) in 2007 on the role of distal airways in asthma. The evidence showing inflammation and remodelling in distal airways, and their possible involvement in asthma control and natural history, was reviewed. The usefulness and limitations of various techniques used for assessing distal airways were also evaluated, including pulmonary function tests and imaging. Finally, the available data studying the benefit of treatment better targeting distal airways in asthma was examined. It was concluded that both proximal and distal airways were involved in asthma and that distal airways were the major determinant of airflow obstruction. Inflammation in distal airways appeared more intense in severe and uncontrolled asthma. Distal airways were poorly attained by conventional aerosol of asthma medications owing to their granulometry, being composed of 3-5 mm particles. Both proximal and distal airways might be targeted either by delivering medications systemically or by aerosol of extra-fine particles. Extra-fine aerosols of long-acting b-agonists, inhaled corticosteroids or inhaled corticosteroid/long-acting b-agonist combinations have been shown in short-term studies to be not inferior to non-extra-fine aerosols of comparators. However, available studies have not yet demonstrated that extra-fine inhaled medications offer increased benefit compared with usual aerosols in asthmatic patients.

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“…Using linear regression of the Rrs curve, carried out in the 4-16 Hz frequency range, we obtained the resistance at the intercept (R 0 ). (2,10,17) Based on the Xrs curve, the dynamic compliance (Cdyn) of the respiratory system at the 4-Hz frequency was calculated as follows (17,19) : Cdyn = −2ω × f × Xrs, 4 Hz The analysis of R 0 and Cdyn was performed using the values for the variation between prebronchodilator and postbronchodilator measurements in the different groups (control, mild, moderate and severe) and subgroups (BR+ and BR−).…”

Section: Resultsmentioning

confidence: 99%

“…The instrument used for evaluating respiratory impedance, as well as the protocol for performing the FOT tests, has previously been described. (10,17) A 300-µg dose of inhaled albuterol, (18) divided into three inhalations of 100 µg at 1-min intervals, was used for the bronchodilator test. The bronchodilator response was measured 20 min after the last inhalation and was considered positive when the increase in FEV 1 and FVC was ≥ 12% or 200 mL.…”

mentioning

confidence: 99%

Efeito da obstrução de vias aéreas nas variações das propriedades resistivas e elásticas do sistema respiratório de asmáticos, mediadas pelo uso de salbutamol

et al. 2009

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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−). These measurements were conducted before and after albuterol use (300 µg). Airway obstruction was determined by means of spirometry, and the resistive and elastic properties were determined by means of the forced oscillation technique. Results: The resistance at the intercept (R 0 ) 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 R 0 and Edyn after albuterol use. These reductions are greater among BR+ patients than among BR− patients.Keywords: Asthma; Bronchodilator agents; Respiratory mechanics; Spirometry; Albuterol. ResumoObjetivo: 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 (R 0 ) 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 reduçõe...

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Detection of changes in respiratory mechanics due to increasing degrees of airway obstruction in asthma by the forced oscillation technique

Cited by 110 publications

References 43 publications

What Does Airway Resistance Tell Us About Lung Function?

What Does Airway Resistance Tell Us About Lung Function?

Update on the roles of distal airways in asthma

Efeito da obstrução de vias aéreas nas variações das propriedades resistivas e elásticas do sistema respiratório de asmáticos, mediadas pelo uso de salbutamol

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