Airflow measures are useful to document vocal function resulting from glottal insufficiency (Vaca et al, 2015). With COVID-19, the ability to obtain these measures was compromised. If other measures could be obtained from patients safely and shown to predict airflow, documentation of glottal insufficiency could be performed with minimal risk of spreading COVID-19.
Three other measures documenting glottal insufficiency were studied: s/z ratio, cepstral peak prominence smoothed for vowels (CPPSa), and Glottal Function Index (GFI).
Three populations with glottal insufficiency were included: 156 patients with unilateral vocal fold paresis/paralysis; 45 patients with bilateral vocal fold paresis; and 46 patients with presbylarynges. Excluded were subjects with reported respiratory impairment (Asnaashari et al, 2012) and/or prolonged /s/ productions below the normal limit ( < 15 l/sec). The longest productions of /s/ and /z/, CPPSa, GFI ratings and airflow obtained from repeated /pi/ syllables at conversational pitch and loudness from the initial clinic visit were recorded from electronic medical records onto a password-protected database. Spearman-ranked rhos were calculated.
Results were: positive statistically significant correlation between flow and s/z ratio (rs(245) = 0.29, p = .00001); negative statistically significant correlation between flow and CPPSa (rs(245) = -0.16, p = .014); and positive statistically significant correlation between flow and GFI (rs(245) = 0.14, p = .03). All three measures correlated with flow, indicating that these additional measurers are useful in confirming glottal insufficiency. Predicting flow using additional measures is a valid determinant of glottal insufficiency.