Expression of bronchodilator response: comparison of four indices

Joint Indian Chest Society-National College of Chest Physicians (India) guidelines for spirometry

Although a simple and useful pulmonary function test, spirometry remains underutilized in India. The Indian Chest Society and National College of Chest Physicians (India) jointly supported an expert group to provide recommendations for spirometry in India. Based on a scientific grading of available published evidence, as well as other international recommendations, we propose a consensus statement for planning, performing and interpreting spirometry in a systematic manner across all levels of healthcare in India. We stress the use of standard equipment, and the need for quality control, to optimize testing. Important technical requirements for patient selection, and proper conduct of the vital capacity maneuver, are outlined. A brief algorithm to interpret and report spirometric data using minimal and most important variables is presented. The use of statistically valid lower limits of normality during interpretation is emphasized, and a listing of Indian reference equations is provided for this purpose. Other important issues such as peak expiratory flow, bronchodilator reversibility testing, and technician training are also discussed. We hope that this document will improve use of spirometry in a standardized fashion across diverse settings in India.

Determining the time to maximal bronchodilator response in asthmatic children

BACKGROUND

The interval between bronchodilator administration and post-bronchodilator lung function testing is critical for accurate interpretation of the bronchodilator response. The time course of this response in children is not well documented. We aimed to document the time taken to achieve maximal lung function following salbutamol inhalation.

METHODS

Eighteen asthmatic children between 7 and 18 years of age with a history of bronchodilator responsiveness were recruited. Spirometry was performed before and at 0, 10, 15, 20, 40, 60, and 90 minutes after salbutamol inhalation 600 microg (Ventolin; GlaxoSmithKline) via a spacer (Volumatic; GlaxoSmithKline).

RESULTS

Spirometric indices significantly increased after salbutamol inhalation (p < 0.001). The group median time to maximal response in forced expiratory volume in 1 second (FEV(1)) was 17.5 (10-60: 10th-90th centiles) minutes after salbutamol. The magnitude of group response in FEV(1) was significantly higher at 15 and 20 minutes than at 0 and 10 minutes post-salbutamol inhalation (repeat measures analysis of variance [ANOVA] on ranks; p < 0.05).

CONCLUSION

We conclude that a minimal interval of 20 minutes, before re-testing spirometry, is required to document the maximal response to bronchodilators in the majority of asthmatic children.

[Which definition to use when defining reversibility of airway obstruction?]

INTRODUCTION

There is no clear consensus about what constitutes reversibility of airway obstruction. European Respiratory Society (ERS): Increase in FEV1 and/or FVC>12% of their theoretical value and>0.2l. British Thoracic Society: FEV1>15% of initial value and FEV1>0.2l. Global Initiative for Chronic Obstructive Lung Disease: Increase in FEV1>12% and>0.2l. Australia and New Zealand Thoracic Society: Increase in FEV1 >15%. American Thoracic Society/ERS: Increase in FEV1>12% and>0.2l or increase in FVC>12% and 0.2l. Our principal objective was to determine the percentage of patients with COPD (n=62) who were significant responders to the reversibility test according to the 5 recommendations.

METHODS

Plethysmography was performed before and 15 minutes after inhalation of 400 micrograms of a short acting bronchodilator (BD). COPD is defined as a FEV1/FVC post BD<0.7.

RESULTS

The percentage of responders varied from 24% to 50% depending on the recommendations used.

CONCLUSION

Reversibility of airway obstruction is recommendation dependent.

[Which definition to use when defining airflow obstruction?]

INTRODUCTION

There is no clear consensus as to what constitutes an obstructive ventilatory defect (OVD). According to the American Thoracic Society and European Respiratory Society, it is defined as being when the ratio of the forced expiratory volume (FEV1) and the slow expiratory vital capacity (VC) is below the lower limit of normal (LLN). According to the Global initiative for chronic Obstructive Lung Disease and the British Thoracic Society, it is an FEV1/forced expiratory vital capacity (FVC)<0.70 and an FEV1<80%. In addition, in daily practice, the OVD is diagnosed by a "Fixed ratio" FEV1/FVC<0.70 or<LLN. The aim of this study is to determine, according to the different recommendations, the percentage of subjects having an OVD among them addressed for suspicion of chronic obstructive pulmonary disease.

METHODS

A medical questionnaire was administered and anthropometric data were collected. The expiratory flows and pulmonary volumes were measured by a body plethysmograph.

RESULTS

121 (81%) subjects among the 150 examined were included. The percentage of subjects having an OVD was 56.1% (FEV1/VC<LLN), 54.1% (FEV1/FVC<0.70), 48.7% (FEV1/FVC<0.70 and FEV1<80%), and 47.8% (FEV1/FVC<LLN).

CONCLUSION

The prevalence of obstructive ventilatory defect in a population depends on the definition chosen.

Determinants of bronchodilator responsiveness in patients with controlled asthma

Short-term bronchodilator responsiveness to an inhaled ss 2 adrenergic agonist was assessed by changes in forced expiratory volume in 1 second (FEV(1)) in nonsmoking adults with controlled asthma (mild disease, 20 patients; moderate disease, 20 patients; severe disease, 18 patients). Responsiveness correlated significantly with age and with percent of predicted FEV(1) (%FEV(1)) except in patients with severe asthma, who showed significantly less responsiveness than others. Thus, responsiveness is closely associated with degree of airflow limitation in patients with controlled asthma and is significantly influenced by severity of disease and by aging.

Characterisation of patients with frequent exacerbation of asthma

BACKGROUND

Exacerbation is one of the most significant problems in patients with asthma. Although subpopulation of patients is more susceptible to exacerbations than others, which clinical features characterise susceptibility to exacerbation are not well understood.

METHODS

Consecutive non-smoking adult patients with asthma who had multiple exacerbations (ME) despite regular maintenance treatment were compared with those who had at most single exacerbation as control during the previous 1 year. Exacerbation of asthma is defined initiations or escalations of systemic corticosteroid as part of the management for aggravated asthma condition.

RESULTS

Patients with ME (n=32, male: 6, mean age: 46.7 years) were characterised by intensive current maintenance treatment (dose of inhaled corticosteroid; 1037.5+/-452.8 vs 621.6+/-257.3 microg, P=0.0005, proportion of oral corticosteroid users; 28.1% vs 2.7%, P=0.008), severe episodes of exacerbation (asthma-related hospitalisations; 71.9% vs 23.4%, P=0.0002, arrival on ambulance; 37.5% vs 8.1%, P=0.008), concomitant chronic sinusitis (34.4% vs 10.8%, P=0.038) and intolerance to non-steroidal anti-inflammatory drugs (NSAIDs) (34.4% vs 5.4%, P=0.006) in comparison with controls (n=37, male:11, mean age:44.4). Pulmonary function in patients with ME was characterised by persistent airflow limitation and reduced reversibility.

CONCLUSION

Patients with ME are at increased risk for severe exacerbation despite more intensive maintenance anti-inflammatory treatment. Persistent irreversible airflow limitation and complications of chronic sinusitis and/or NSAIDs intolerance are characteristics to this subpopulation.

Lung function in patients with chronic airflow obstruction due to tuberculous destroyed lung

Lung function in cases of chronic airflow obstruction (CAO) due to tuberculous destroyed lung, which is still common in Korea, has not been objectively investigated. We evaluated lung functions and postbronchodilator responses in 21 CAO patients with a forced expiratory volume in 1 s (FEV1) of 30-65% of the predicted value, and compared some of these results with those of age-, sex- and FEV1% predicted-matched patients with chronic obstructive pulmonary disease (COPD). In addition, we analyzed the lung functions of CAO patients with respect to wheezing. The forced vital capacity (FVC) (P < 0.05) and postbronchodilator FEV1 of CAO patients were lower than those of COPD patients (P < 0.05). When a positive bronchodilator response was defined as an absolute change of FEV1 (FEV1 delta(abs)) of more than 0.2 l (P < 0.05) and a percentage of initial FEV1 (FEV1 delta%init) of more than 12%, the positive rates in CAO patients were lower than in COPD patients (P < 0.05). Among the CAO patients, patients with wheezing showed lower forced expiratory flow 25%-75% (FEF(25-75%)) (P < 0.05) and higher airway resistance than those without wheezing (P < 0.05). CAO patients with wheezing were more responsive to bronchodilator than those without wheezing. Although the pathophysiology of CAO differs from that of COPD, bronchodilator therapy could be useful for treating CAO, especially in cases presenting with wheezing.