The indirect measurement of laryngeal and tracheal resistance.

We used a body-plethysmograph to determine air-way resistances in 485 cases of laryngeal and tracheal stenoses. We decided in 143 cases to intervene after observing resistance exceeding 60 mm H2O/l and sec. A vocal chord was lateral fixated in 49 patients suffering bilateral recurrent paralysis. Optimal results were obtained at a postoperative resistance level of 30 mm H2O/l and sec (standard value: 14.77+/-6.53--n = 387). The patients could carry out work of medium intensity and had a steady voice. We performed tracheal interventions in 94 cases of tracheal stenoses. A mean, post-operative resistance of 29.9 mm H2O/l and sec, with a tracheal diameter of 7--8 mm was attained. In practice, only a few patients found the remaining obstruction a hindrance during work of maximal intensity. No recurrences were observed after treatment. Airway resistances exceeding 150 mm H2O/l and sec were found in 13 new admissions and 73 times in those undergoing therapy. In these cases asphyxiation threatens. These patients have to be tracheotomized or intubated immediately.