Indirect measurement of laryngeal and tracheal resistance.

We used a body plethysmograph to determine airway resistances in 485 cases of laryngeal and tracheal stenoses. 143 cases who had resistances exceeding 60 mm H2O/l.a.sec underwent surgery. A vocal cord was laterally fixed in 49 patients suffering from bilateral recurrent paralysis. Optimal results were obtained at a postoperative resistance level of 30 mm H2O/l.a.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 postoperative resistance of 29.9 mm HWO/l.a.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 resistance exceeding 150 mm H2O/l.a.sec were found in 13 new admissions and 73 times in those undergoing therapy. In these cases asphyxiation threatens. These patients must be tracheotomized or intubated immediatly.