Detection of particles within the nasal airways during respiration.

This study introduces a new experimental setup for particle detection within the nasal airways and describes intranasal deposition of particles at various regions of the nasal cavity and the nasopharynx. During respiration of an aerosol of starch particles the nondeposited particles in the air were detected in 11 volunteers by a transnasally placed suction probe at numerous sites of the nasal cavity and nasopharynx. Another, identical suction probe measured the initial number of inhaled particles at the nostril. The two suction probes were connected to two identical laser particle counters and allowed calculation of particle deposition. Particles 1-3 microm in size were deposited to about 60% within the entire nasal cavity, whereas most of the particles 4-30 microm in size were deposited within the entire nasal cavity. Between 80% and 90% of the particles retained in the nasal cavity were deposited at the anterior nasal segment. Studies on deposition of various drugs within the nasal cavity using this experimental set-up are conceivable.