10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Characterization of Airspace Dimension Assessment with Nanoparticles (AiDA) on a Large Population and Relation to Anthropometry and Lung Function Parameters
JONAS JAKOBSSON, H Laura Aaltonen, Hanna Nicklasson, Sandra Diaz, Per Wollmer, Jakob Löndahl, Lund University
Abstract Number: 824 Working Group: Aerosols in Medicine
Abstract Introduction Airspace Dimension Assessment (AiDA) is a technique to assess airspace dimensions in the distal lung by measuring the recovery of inhaled nanoparticles (Löndahl et al. 2016, Jakobsson et al. 2016). It has previously been shown that the average diffusion distances, corresponding to effective airspace dimensions, can be inferred by measuring the half-life time of inhaled nanoparticles (Löndahl et al. 2016). It has also been suggested that estimated particle recovery after a hypothetical measurement without breath-hold (called the intercept) may hold additional information about individual lung features related to the conducting airways.
The aim of this work was to investigate the characteristics of the AiDA technique and the relation of the AiDA parameters to anthropometry and lung function parameters in a large population of mostly healthy subjects.
Method Nineteen healthy subjects performed measurements of recovery of inhaled nanoparticles for breath-holding times between 5 and 20 s and volumetric sample depths between approx. 200 and 5000 mL. A simplified protocol, measuring recovery at a fixed (1300 mL) sample depth and breath-holding times between 5 and 10 s was performed by a larger group (n = 668). The measurements were performed with monodisperse 50 nm polystyrene nanospheres.
All subjects underwent a detailed investigation of lung function, including measurement of vital capacity (VC), forced expiratory volume in 1 s (FEV1), lung diffusing capacity for carbon monoxide (DL,CO) and forced oscillation technique (FOT), which gives information about respiratory resistance and reactance. The larger group also underwent a computed tomography (CT) scan of the lungs, to detect and quantify respiratory disease.
Characteristics of the derived airspace dimensions and the intercept (zero breath-hold recovery) were analysed in detail for the smaller group. Statistical analysis comparing AiDA to anthropometry and clinical lung function parameters was performed for the larger group to elucidate the AiDA parameters relation to established clinical techniques.
Results The data from the smaller group showed that the derived airspace dimensions showed reasonable agreement with lung models based on histological measurements. The dimensions are root mean square (RMS) diameters of the airspaces and therefore larger than a normal arithmetic mean. The data also showed that both the airspace dimension and intercept were highly reproducible with sufficient sensitivity to reflect individual lung morphology.
The statistical analysis showed that the airspace dimensions correlated mainly with age, DL,CO and FEV1/VC while the intercept correlated mainly with height, VC, FEV1 and FOT. Importantly, airspace dimensions and intercept did not correlate strongly (n.s. for n = 19), (p =.02, r = -.09 for n = 668). Significant differences were detected between smokers (n = 101) and non-smokers (n = 570) (p < 0.00011 for intercept, p < 0.0068 for airspace dimensions) and between subjects with emphysema (n = 58, assessed with CT) and healthy subjects (n = 604), (p < 0.0023, p < 0.0000000002) for intercept and airspace dimensions, respectively.
Conclusion The results show that the AiDA-derived airspace dimension and intercept convey independent information about individual lung properties. They further suggest that AiDA may have sensitivity to lung abnormalities (such as caused by smoking and respiratory disease); however studies including more subjects with respiratory disease are needed to evaluate the clinical value of the technique.
This work was supported by Swedish Research Council, Vinnova, EU EuroNanoMed, The Swedish Heart and Lung Foundation and the Crafoord foundation.
[1] Löndahl, J., J. Jakobsson, D. Broday, H. Aaltonen and P. Wollmer (2016). Int J of Nanomed 2017; 12: 41–51. [2] Jakobsson, J., J. Hedlund, J. Kumlin, P. Wollmer and J. Löndahl (2016). Sci Rep 6: 36147.