The Science Journal of the American Association for Respiratory Care

2005 OPEN FORUM Abstracts

VARIATIONS OF PEAK FLOW RATES AMONG HEALTHY SUBJECTS USING DIFFERENT BRANDS OF PEAK FLOW METERS

Daniel Gregory Gassaway BS, RRT-NPS Durham Technical Community College Durham, North Carolina

Background: Many different brands of peak flow meters are available for consumer use. While each meter must pass quality standards before marketing, variations in values from different products are frequently noted. We conducted this study to ascertain the magnitude of differences between peak flow values obtained using different peak flow meters. In addition, we compared actual peak flow values with accepted predictions.

Method:
Fourteen respiratory care students who were not experiencing acute asthma attacks tested themselves during a three hour class period with five different brands of peak flow meters. (Personal Best, Assess, Pocket, Respiradyne, Wrights) We charted the highest of three values for each device. Using the students' sex, height and age, predicted normal values were obtained from an accepted table (Knudson 1983).

Results:
We observed differences between the highest and lowest recorded values ranging from 30 lpm to 293 lpm (mean difference 122 lpm) among the different devices on the same subject. We observed differences ranging from 6 lpm to 256 lpm (mean difference 94 lpm) between predicted and observed values, with all students performing above the predicted value.

Conclusion:
Patients presenting for peak flow evaluations in outpatient clinics, emergency rooms, health fairs, inpatient settings and summer camps often come into the test with preconceived notions of what their values should be based on past experiences and published normal values. Patients and clinicians are often pleasantly surprised or disappointed when their measured values deviate from expectations.Peak flow values are often used in making treatment decisions. This study shows that the same subject can have wide variations in peak flow values on the same day from different measurement devices. Many of our subjects also showed wide deviations from predicted normal values. Based on these findings, assessment of peak flow values should be only one component of a thorough respiratory assessment. Consistency in use of a specific device and a correlation of that device with laboratory spirometry findings would be recommended.

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