Correlation of a unique "Los Angeles" phonospirometry technique with peak expiratory flows in children with asthma.

Background: Measurement of peak expiratory flow (PEF) is recommended as part of the assessment of patients with asthma. However, there are multiple barriers in the use of PEF, even for older pediatric patients.

Objective: Phonospirometry, as measured by the Los Angeles (LA) technique, was assessed and compared with standard PEF measurements in patients with asymptomatic and symptomatic asthma.

Methods: A convenience sample of patients with asthma aged 8-17 years was enrolled from visits in the Allergy/Immunology Clinic and in the Emergency Department of Children's Hospital Los Angeles. The phonospirometry technique was demonstrated, and the length of time the patient repeated the syllable "lah" continuously with the same breath was measured. After a brief interval of time to recover, the patient performed conventional PEF measurement.

Results: Using the first observation for each patient in our study, the Pearson correlation coefficient between phonospirometry and PEF was r = 0.67, p = .0016 for asymptomatic asthma patients and r = 0.77, p < .0001 for symptomatic asthma patients. Analysis of the first and last measurements of the symptomatic asthma patients who had multiple measurements revealed a Pearson correlation coefficient between phonospirometry and PEF at first measurement r = 0.69, p = .0008 and at the last measurement r = 0.76, p < .0001.

Conclusions: Using the LA technique, phonospirometry was shown to have a linear correlation with PEF in pediatric patients with asymptomatic and symptomatic asthma. It is simple and easily reproducible, as well as cross-cultural. This novel technique shows promise to aid the assessment of patients with acute asthma exacerbations.