Subglottic Pressure and Laryngeal Efficiency in Patients with Laryngeal Carcinoma

Subglottic pressures and laryngeal efficiencies were measured in 12 normal subjects and 19 patients with laryngeal carcinoma. In this study, the PS-77 ph o natory equipment was used to measure airflow, pitch, intensity levels and subglottic pressure during phonation. Measurements were taken by a miniature pressure transducer through the glottis. These parameters were entered into a PI-201 computer analyzing system. Subjects were requested to phonate the maximum sustained comfortable pitch and intensity level, and to change the intensity levels from lower to louder as far as they could. During sustained ph o nation, subglottic pressure showed a mean value of 10.2 cm H₂O in normal subjects and 29.2 cmH₂O in patients with laryngeal carcinoma. The mean value of laryngeal efficiency was 1.47±1.79×10^-4 in normal subjects and 1.05±1.82×10^-4 in carcinoma patients. When changing the intensity levels of their voices, parameters such as subglottic pressure, laryngeal resistance, subglottic power and efficiency were increased linearly with the increasing intensity level in normal subjects, but in patients with laryngeal carcinoma, laryngeal efficiency demonstrated lower values and was less changed with increasing intensity levels compared to those of normal subjects.