Which index of peak expiratory flow is most useful in the management of stable asthma?

Abstract

Calculation of diurnal peak expiratory flow (PEF) variability using values before and after bronchodilator is no longer possible for many asthmatic patients because they now use beta-agonists "as needed" for symptoms rather than regularly. This study assesses the usefulness of a number of alternative PEF indices as markers of airway liability in subjects with stable, although not necessarily well-controlled, asthma. Forty-six adult subjects completed a questionnaire about symptoms and treatment in the previous 3 mo. Spirometric function and airway hyperresponsiveness (AHR) were assessed; AHR was expressed as dose response ratio (DRR) (maximal percent fall in FEV1 divided by final dose of histamine). Subjects recorded PEF morning and evening, before and after bronchodilator (if used) for 2 wk. Nine different PEF indices were calculated. Diurnal variability (amplitude percent maximum) without bronchodilator was significantly less than diurnal variability with bronchodilator. Normal indices of PEF lability were found in 42% of subjects with reduced maximal midexpiratory flow (MMEF). Most of the PEF indices correlated strongly with DRR, and less strongly with symptom score and airway obstruction. Minimum morning prebronchodilator PEF over a week (expressed as percent recent best or percent predicted) is recommended as the best PEF index of airway lability in patients with stable asthma because it correlates strongly with AHR, patients are more likely to comply with a once-daily reading, the calculation is simple, and regular use of a beta-agonist is not required.

Targeting pCO2 in Asthma: Pilot Evaluation of a Capnometry-Assisted Breathing Training

“…Thus, improvement through training extended beyond patients' perception of their disease to a somatic outcome measure central to the pathophysiology of asthma. Although the relationship between PEF variability and airway hyperresponsiveness has been debated (Douma, Kerstjens, Roos, et al, 2000;Reddel, Salome, Peat, et al, 1995), such findings are compatible with prior findings of a negative correlation between pCO 2 and hyperresponsiveness to methacholine challenge (Osborne et al, 2000). It is likely that additional benefits of an adjunctive breathing training will be less apparent in basal lung function (or only be visible in more direct measures of airway obstruction) than in a reduction of fluctuations in symptoms.…”

Effect of asthma severity on symptom perception in childhood asthma

“…We used morning PEF since Reddel et al (12) showed that the minimum morning prebronchodilator PEF over a week was the most useful index in the management of asthma. In addition, morning measurements of PEF had a smaller number of missing points in our series.…”

Changes in peak expiratory flow indices as a proxy for changes in bronchial hyperresponsiveness

“…Cross-sectional studies showed that diurnal variability correlated well with BHR [7,19]. REDDEL et al [8] recommended minimum pre-BD PEFa.m. (%recent best) as the most useful index, because it strongly correlates with BHR in patients with stable asthma and does not require the use of BDs.…”

“…Increased PEF variation is thought by many experts to reflect the degree of bronchial hyperresponsiveness (BHR) [6]. Several cross-sectional studies have indeed shown moderate-to-strong correlations between PEF indices and BHR [2,7,8]. However, if serial PEF measurements are to be used in patients to reflect BHR in order to monitor asthma severity, the measure of PEF variation should correlate with changes in BHR within patients longitudinally, instead of between patients cross-sectionally.…”

“…Mean PEF variation over the day expressed as percentage of the maximum, the mean, and the personal best are but a few of the expressions encountered [8]. In this study, the longitudinal relationship between these and other PEF indices and BHR were investigated in a 2-yr study including the effects of different treatment regimens, i.e.…”