COPD-X | C4. Assessing acute response to bronchodilators

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C: Confirm diagnosis

C4. Assessing acute response to bronchodilators

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C4. Assessing acute response to bronchodilators

The response to bronchodilators is determined to:

assign a level of severity of airflow obstruction (post- bronchodilator); and
help confirm or exclude asthma.

The details for this assessment are outlined in Box 7.

The change in FEV₁ after an acute bronchodilator reversibility test indicates the degree of reversibility of airflow limitation. This is often expressed as a percentage of the baseline measurement (eg, 12% increase). An increase in FEV₁ of more than 12% and 200mL is greater than average day-to-day variability and is unlikely to occur by chance.(Sourk and Nugent, 1983),(Pellegrino et al., 2005) However, this degree of reversibility is not diagnostic of asthma and is frequently seen in patients with COPD (eg, the FEV₁ increases from 0.8L to 1.0L when the predicted value is, say, 3.5L). The diagnosis of asthma relies on an appropriate history and complete, or at least substantial, reversibility of airflow limitation (see also below).

Box 7: Assessment of acute response to inhaled beta-agonist at diagnosis

Preparation

Patients should be clinically stable and free of respiratory infection.
Withhold inhaled short-acting bronchodilators in the previous six hours, long-acting beta-agonists in the previous 12 hours, or sustained-release theophyllines in the previous 24 hours.

Spirometry

Measure baseline spirometry (pre-bronchodilator). An FEV₁ <80% predicted and FEV₁/FVC ratio <0.70 shows airflow limitation.
Give the bronchodilator by metered dose inhaler (MDI) through a spacer device or by nebuliser.
Give short-acting beta-agonist, at a dose selected to be high on the doseresponse curve (eg, 200400mcg salbutamol from MDI and spacer).

Repeat spirometry 1530 minutes after bronchodilator is given and calculate reversibility.

FEV₁=forced expiratory flow in one second.
FVC=forced vital capacity.

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COPD-X Plan - Version 2.30 - December 2011

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Top COPD-X Areas

C: Confirm diagnosis

O: Optimise function

X: Manage eXacerbations

P: Prevent deterioration

O1. Inhaled bronchodilators

D: Develop support network and self-management

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