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Nasal response to inhaled histamine measured by acoustic rhinometry in infants
S Kano1, O F Pedersen, P D Sly
1Division of Clinical Sciences, Western Australia Research Institute for Child Health, Perth.
Insights
Inhaled histamine aerosols significantly alter nasal passage geometry in infants, reducing nasal cavity volume and minimum cross-sectional area. Acoustic rhinometry is a valuable tool for assessing these nasal responses in young children.
Area of Science:
- Pediatric Respiratory Medicine
- Otolaryngology
- Allergy and Immunology
Background:
- Aerosolized histamine challenges are standard for assessing bronchial hyperresponsiveness in infants.
- Nasal responses to inhaled substances in infants are less understood.
- Acoustic rhinometry offers a non-invasive method to evaluate nasal cavity dimensions.
Purpose of the Study:
- To investigate the effects of inhaled histamine on nasal passage geometry in infants.
- To assess the utility of acoustic rhinometry in measuring histamine-induced nasal changes.
- To explore potential dose-response relationships and correlations with lung function.
Main Methods:
- Acoustic rhinometry was used to measure nasal cavity volume (V04), minimum cross-sectional area (Amin), and distance to minimum area (Dmin) in 17 infants.
- Nasal geometry and lung function (VmaxFRC) were measured before and after histamine aerosol challenge.
- Histamine dose was varied to assess dose-response effects.
Main Results:
- Histamine aerosols significantly decreased V04 by 17% and Amin by 13% (P < 0.001).
- A small but significant increase in Dmin was observed on the right side, suggesting mucosal swelling.
- A dose-response relationship was noted for V04, but no correlation was found between nasal changes and VmaxFRC.
Conclusions:
- Inhaled histamine aerosol impacts nasal cavity geometry in infants.
- Acoustic rhinometry is a promising technique for evaluating nasal responses to histamine in pediatric populations.
- Further research is warranted to fully elucidate histamine's effects on the infant nasal airway.
Abstract:
Aerosolized histamine, delivered via a face mask, is commonly used to evaluate bronchial responsiveness in infants. To investigate nasal response to inhaled histamine we have measured nasal passage geometry in 32 infants by the use of acoustic reflections. Satisfactory data were obtained from only 17 infants (12 males, 5 females, 6.6 +/- 4.4 months), because of awakening prior to completing the study in the remaining 15 infants. Acoustic rhinometry provided nasal cavity volume at 4 cm from the entrance of the nostril (V04), the minimum cross-sectional area (Amin), and the distance from the nostril to Amin (Dmin). Nasal geometry and lung function (maximum expiratory functional residual capacity [VmaxFRC] were measured before and immediately after a histamine challenge test using rapid thoratic compression. The histamine aerosols decreased both VO4 and Amin significantly by a mean of 17% and 13%, respectively (P < 0.001). There was a small, but significant increase (mean = 0.19 cm) of Dmin in the right side only, indicating a posterior dislocation of the narrowest site with swelling of the mucous membrane. In general, we found a dose-response relationship in grouped data, with a greater fall in VO4 with increasing dose of histamine, but there was no correlation between percent fall in VO4 and VmaxFRC. This pilot study suggests that histamine aerosol affects nasal cavity geometry and that of acoustic rhinometry in infants and children warrants further investigation.