Shear thinning effect on liquid foam distribution in heterogeneously constricted in vitro airway models

Exploring pulmonary distribution of intratracheally instilled liquid foams in excised porcine lungs

“…The effective dynamic viscosity of the foamed polysorbate solution was 70.4±0.9 cP as measured by pressure drop across a tube (see Methods). We note that the effective viscosity of the foamed polysorbate solution was rather similar to that of the Tacholiquin foam reported previously when measured using the same tube diameter and flow rate ( Fishler et al., 2022 ).

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“…Our findings highlight the mechanistic potential of foams to improve pulmonary distribution of liquid instillations by increasing the dose volume and reducing gravitational biases. Foam delivery may also prove superior to liquid instillations in targeting diseased lung regions due to the increased pressures that may open for example atelectatic regions, or in combination with the shear thinning properties of the foam that may give it an advantage in targeting heterogeneously constricted airways, as we have previously shown using in vitro airway models ( Fishler et al., 2022 ). Together with these in vitro experiments, our present results lay a promising ground for further investigation, most notably in preclinical in vivo animal experiments.…”

“…Recalling that foams display shear thinning properties such that their effective viscosity may change within constricted airways ( Fishler et al., 2022 ), it is important to note that within healthy conducting airways the shear rates lies within a relatively narrow interval (∼700 to ∼1100 1/s for human conductive airways ventilated at 25 lit/min when approximating the shear rate as ( Finlay et al., 2012 )) Such that the measured effective viscosity represents fairly well the viscosity across all conductive lung generations.…”

“…Motivated by the drawbacks of existing pulmonary delivery modalities, we have recently shown in vitro how intratracheal administration of liquid foams could hold an advantage over inhalation therapy for drug delivery locally past obstructed or constricted airways due to their shear thinning properties ( Fishler et al., 2022 ). Here, we explore for the first time the potency of liquid foams to yield more homogenous pulmonary distributions compared with liquid instillations at the whole-lung level.…”