A new paradigm in respiratory hygiene: increasing the cohesivity of airway secretions to improve cough interaction and reduce aerosol dispersion

Abstract

BackgroundInfectious respiratory diseases are transmitted to non-infected subjects when an infected person expels pathogenic microorganisms to the surrounding environment when coughing or sneezing. When the airway mucus layer interacts with high-speed airflow, droplets are expelled as aerosol; their concentration and size distribution may each play an important role in disease transmission. Our goal is to reduce the aerosolizability of respiratory secretions while interfering only minimally with normal mucus clearance using agents capable of increasing crosslinking in the mucin glycoprotein network.MethodsWe exposed mucus simulants (MS) to airflow in a simulated cough machine (SCM). The MS ranged from non-viscous, non-elastic substances (water) to MS of varying degrees of viscosity and elasticity. Mucociliary clearance of the MS was assessed on the frog palate, elasticity in the Filancemeter and the aerosol pattern in a "bulls-eye" target. The sample loaded was weighed before and after each cough maneuver. We tested two mucomodulators: sodium tetraborate (XL"B") and calcium chloride (XL "C").ResultsMucociliary transport was close to normal speed in viscoelastic samples compared to non-elastic, non-viscous or viscous-only samples. Spinnability ranged from 2.5 ± 0.6 to 50.9 ± 6.9 cm, and the amount of MS expelled from the SCM increased from 47 % to 96 % adding 1.5 μL to 150 μL of XL "B". Concurrently, particles were inversely reduced to almost disappear from the aerosolization pattern.ConclusionThe aerosolizability of MS was modified by increasing its cohesivity, thereby reducing the number of particles expelled from the SCM while interfering minimally with its clearance on the frog palate. An unexpected finding is that MS crosslinking increased "expectoration".

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“…Sputum appearance is most likely a surrogate for viscosity and other rheological, or flow, properties of respiratory secretions. These properties have long been suspected as determinants of infectiousness (17), and experimental data using mucus stimulants suggest that aerosolization is inversely associated with "cohesivity" (18).…”

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“…Promotes particle aggregation and increases particle size 128 Pre-exposure to saline in the airways Increases particle size and reduces particle number 100,129…”

“…Induces changes to mucus composition and increases particle size and number 71,129 Current research gaps Improved understanding of the behaviour of particles in the transmission of aerosolised disease has the capacity to stimulate the update of current infection control precautions.…”

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“…Airborne infection research requires intense multidisciplinary efforts, but it can substantially increase our understanding of the variability and control of airborne transmission of tuberculosis through the simultaneous study of source patients, the environment, bacillary strains, and susceptible hosts. The research infrastructure of Escombe et al [3] could be used to study the efficacy of interventions proposed to decrease production of infectious aerosols from individual patients [18,19] or the efficacy of environmental measures, such as UV germicidal irradiation or air ionization, as their preliminary data suggest are effective [20]. Escombe et al [3,20] could resolve the questions of differential infectiousness associated with HIV infection or with multidrug-resistant or XDR tuberculosis by using the same laboratory system to study subjects with and without these characteristics.…”