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Can peak expiratory flow measurements estimate small airway function in asthmatic children?
S Goldberg1, C Springer, A Avital
1Institute of Pulmonology, Hadassah University Hospital, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Insights
Peak expiratory flow (PEF) is a useful asthma management tool but has low sensitivity for detecting small airways dysfunction. Multiple PEF measurements improve its correlation with forced expired flow at 50% of vital capacity (FEF(50)) in children with asthma.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Asthma Management
Background:
- Asthma management guidelines recommend peak expiratory flow (PEF) measurements.
- Small airways dysfunction is a key feature of asthma.
- PEF correlates with FEV(1) but not consistently with FEF(50).
Purpose of the Study:
- To assess the utility of PEF as a predictor of small airways status.
- To evaluate PEF's correlation with forced expired flow at 50% of vital capacity (FEF(50)).
Main Methods:
- Analysis of PEF and FEF(50) association in 111 asthmatic children.
- Children were categorized based on FEV(1) values.
- Single and multiple PEF measurements were analyzed.
Main Results:
- A significant overall correlation was found between PEF and FEF(50) (r = 0.49).
- However, 41.6% of patients showed >20% discrepancy between actual and calculated FEF(50).
- PEF demonstrated high specificity but low sensitivity for detecting FEF(50) status, performing better in severe asthma cases and with multiple measurements.
Conclusions:
- PEF is valuable but insufficient for a complete assessment of small airways function due to low sensitivity.
- PEF is best used at home alongside regular clinic spirometry.
- Individual regression analysis of PEF may enhance its role in monitoring small airways changes.
Background:
Asthma is characterized in part by small airways dysfunction. Peak expiratory flow (PEF) measurement has been suggested by all international guidelines as an important tool in asthma management. The correlation between PEF and FEV(1) but not with forced expired flow at 50% of vital capacity (FEF(50)) is well-established.
Study Objective:
To determine the value of PEF measurement as a predictor of small airways status as expressed by FEF(50).
Design:
Analysis of the association between PEF and FEF(50) in single and multiple determinations.
Patients:
One hundred eleven asthmatic children (mean age, 11.8 years), grouped in the following way according to FEV(1) values: within normal range (n = 46); mildly reduced FEV(1) (n = 44); and moderately/severely reduced FEV(1) (n = 21).
Results:
Overall, FEF(50) and PEF were significantly correlated (r = 0.49; p < 0.0001). However, in 41.6% of the patients, the actual FEF(50) differed by > 20% from the calculated FEF(50). PEF has a high specificity (82.4%) but a poor sensitivity (51.7%) to detect FEF(50) status. PEF was better able to reflect abnormal FEF(50) in the patients with more severe asthma and to reflect normal FEF(50) values in the healthier patients. In patients with multiple measurements (n = 40), the correlation between FEF(50) and PEF was significantly better than that derived from a single determination (multiple measurements r = 0.77; single measurement, r = 0.49).
Conclusions:
Although PEF is an important tool in the management of asthmatic patients, it does not yield a complete picture because it is not sensitive in detecting small airways function. It is best used at home along with regular spirometry measurements at the clinic. PEF may serve as a better index of changes in small airways function once an individual regression is determined.