Los Angeles phonospirometry technique: Creating a normogram that correlates with peak expiratory flow measurements in children

Objective: Measurement of peak expiratory flow (PEF) is recommended in the assessment of patients with asthma. However, the use of PEF involves multiple barriers, which have limited its use. Phonospirometry, as assessed by a novel Los Angeles phonospirometry technique, has shown good correlation to standard PEF measurements in a pilot study on symptomatic patients with asthma. We sought to develop a normogram for phonospirometry, and to validate the PEF normogram. Methods: A convenience sample of asymptomatic children ages 3-17 years old was approached for participation in the Emergency Department. Sample size calculations determined that at least 30 children per age group (n = 450) were needed. Children were asked to perform PEF measurements and phonospirometry, measured as the length of time (in s) the child was able to chant "lalala" in a single breath. Results: 510 children were enrolled. Spearman's rho between PEF and phonospirometry was 0.722. Phonospirometry correlated with both age and height, with a spearman rho of 0.697 and 0.696, respectively. This was slightly lower than the correlation of PEF with age and height with spearman rhos of 0.877 and 0.902, respectively. A normogram was developed for phonospirometry based on age and height. Conclusions: This study determined normal value ranges for the Los Angeles phonospirometry technique for age and height, and also showed that the technique has good correlation with PEF. This technique may be used to assess a pediatric patient with an acute asthma exacerbation.