Comparison of subjective perception with objective measurement of olfaction.

OBJECTIVE: To see if nasal peak inspiratory flow rate and subjective sense of smell had any correlation with olfactory thresholds. STUDY DESIGN AND SETTING: A cohort study of 186 normal volunteers was recruited from among staff and visitors at a university hospital. Olfactory thresholds were detected for each subject (103 with eucalyptol and 83 with phenethyl alcohol), along with nasal peak inspiratory flow (PIFR). Subjective sense of smell, along with nasal symptoms, mood, and alertness, were recorded on visual analogue scores. RESULTS: Subjective perception of smell had no correlation with olfactory thresholds detected (P = 0.4057) and the other subjective measures also had no correlation. There was a significant relationship of PIFR to thresholds in the group tested with phenethyl alcohol (P = 0.002). CONCLUSION: As with the sensation of nasal patency, the self-assessment of a subject's sense of smell has poor correlation with their actual olfactory ability. SIGNIFICANCE: A patient's history cannot be relied upon when determining their olfactory ability and formal testing should be performed. EBM RATING: A-1b.

Effect of device inhalational resistance on the three-dimensional configuration of the upper airway.

Entrainment and de-aggregation of aerosol particles from dry powder inhalers (DPIs) is achieved by a forceful inhalation from the device by the patient and by the airflow resistance built into the device. The aerodynamic shear stress imposed by the upper airway also plays an important role in the de-aggregation process. In this study the effect of device airflow resistance on the upper airway shape is determined. Seven healthy subjects inhaled via a test inhaler of different resistances (0.2 x 10(5) to 2.2 x 10(5) N(0.5).s.m(-4)) while the upper airway was imaged using magnetic resonance imaging. Decreasing the test inhaler resistance led to an increase in the cross-sectional areas of the upper airway at the oral cavity, oropharynx and larynx, while the cross-sectional areas of the upper trachea remained rather constant. The mean volume of the upper airway also increased from 72 (22) cm3 (mean (SD)) to 101 (25) cm3 by decreasing device airflow resistance from 2.2 x 10(5) to 0.2 x 10(5) N(0.5).s.m(-4). In conclusion, this study shows a significant variation in the shape of the upper airway during inhalation via devices with different resistances. This may aid understanding of drug deposition in the lungs from DPIs.