Nasal model and lung model machine for intranasal stent with filters efficacy evaluation.

Nasal model and lung model machine simulated human respiratory situation with cyclical air flow rate of 2 1/min. They were used to evaluate filtration efficacy of filters in an intranasal stent for laser smoke particles in the Otolaryngology Department, Ramathibodi Hospital from February to June 1998. The filters were three layers of half face mask outer filters. Each of five sets or 10 intranasal stents with filters or Whatman filters was attached at both inlet ends of the nasal model. A Whatman filter collected the maximum particle amount from 10 shots, 10 W and 0.2 s of single pulse mode carbon dioxide laser evaporative field for 5 min which was the same amount passed through filters of the intranasal stent. A high power optical microscope was used to count particle retention in each filter. The mean filtration efficacy of filters in the intranasal stent was 94.4 per cent when compared with that of the Whatman filter. A personal respiratory protective device could be applied in the human nasal vestibule to prevent polydisperse suspended particulate matter in a highly air-polluted area. The nasal model with lung model machine should be tested under different concentrations of laser smoke particles or at the main roadside.