The effect of discontinuing hypertonic saline or dornase alfa on mucociliary clearance in elexacaftor/tezacaftor/ivacaftor treated people with cystic fibrosis: The SIMPLIFY-MCC Study.

Many people with CF (pwCF) desire a reduction in inhaled treatment burden after initiation of elexacaftor/tezacaftor/ivacaftor. The randomized, open-label SIMPLIFY study showed that discontinuing hypertonic saline (HS) or dornase alfa (DA) was non-inferior to continuation of each treatment with respect to change in lung function over a 6-week period. In this SIMPLIFY substudy, we used gamma scintigraphy to determine whether discontinuation of either HS or DA was associated with deterioration in the rate of in vivo mucociliary clearance (MCC) in participants ≥12 years of age. While no significant differences in MCC endpoints were associated with HS discontinuation, significant improvement in whole and peripheral lung MCC was observed after discontinuing DA. These results suggest that pwCF on ETI with mild lung disease do not experience a subclinical deterioration in MCC that could later impact health outcomes after discontinuing HS, and in fact may benefit from improved MCC after stopping DA treatment.

Effect of elexacaftor/tezacaftor/ivacaftor on mucus and mucociliary clearance in cystic fibrosis.

BACKGROUND: The cystic fibrosis transmembrane conductance regulator (CFTR) modulator elexacaftor/tezacaftor/ivacaftor (E/T/I) is highly effective clinically for those with at least one F508del-CFTR allele. The effects of E/T/I on mucociliary clearance (MCC) and sputum properties are unknown. We, therefore, sought to characterize the effects of E/T/I on in vivo MCC and sputum characteristics hypothesized to impact mucus transport. METHODS: Forty-four participants ≥12 years of age were enrolled into this prospective, observational trial prior to initiation of E/T/I and had baseline measurement of MCC and characterization of induced sputum and exhaled breath condensate (EBC) samples. Study procedures were repeated after 1 month of E/T/I treatment. RESULTS: Average age was 27.7 years with baseline forced expiratory volume in 1 second (FEV1) of 78.2 % predicted. 52 % of subjects had previously been treated with a 2-drug CFTR modulator combination. The average whole lung MCC rate measured over 60 min (WLAveClr60) significantly improved from baseline to post-E/T/I (14.8 vs. 22.8 %; p = 0.0002), as did other MCC indices. Sputum% solids also improved (modeled mean 3.4 vs. 2.2 %; p<0.0001), whereas non-significant reductions in sputum macrorheology (G', G") were observed. No meaningful changes in exhaled breath condensate endpoints (sialic acid:urea ratio, pH) were observed. CONCLUSIONS: E/T/I improved the hydration of respiratory secretions (% solids) and markedly accelerated MCC. These data confirm the link between CFTR function, mucus solid content, and MCC and help to define the utility of MCC and mucus-related bioassays in future efforts to restore CFTR function in all people with CF.

Preclinical Studies of the Nebulized Delivery of Liposomal Amphotericin B.

Background: Intravenous liposomal amphotericin B (L-AMB) has accompanying side effects that may be diminished when administering an inhaled form. Delivery systems for inhaled or aerosolized L-AMB vary, and there has not been a recent comparison of available systems to date. Methods: We compared three differently designed nebulizer delivery systems for the inhaled delivery of L-AMB to determine the best combination of efficient lung dosing and treatment time. Aerosol size was measured using a Malvern Mastersizer, and five separate nebulizers were tested. For drug output measurements, a Harvard Lung was used, and aerosol was collected using HEPA filters. Results: Overall aerosol size characteristics were similar for all devices with volume median diameters in the 4-5 µm range. The highest inhaled dose was delivered by the AeroEclipse. The Aerogen and the AeroEclipse had similar predicted pulmonary doses, and the AeroEclipse had the highest pulmonary delivery rates. Conclusion: The AeroEclipse nebulizer may provide more efficient delivery in a shorter amount of time; however, human studies are warranted to assess the safety, tolerability, and efficacy of inhaled delivery of L-AMB from this system.

Effect of a Surfactant Additive on Drug Transport and Distribution Uniformity After Aerosol Delivery to Ex Vivo Lungs.

Background: Inhaled drug delivery can be limited by heterogeneous dose distribution. An additive that would disperse drug over the internal surfaces of the lung after aerosol deposition could improve dosing uniformity and increase the treated area. Our previous studies demonstrated that surfactant additives can produce surface tension-driven (Marangoni) flows that effectively dispersed aerosol-delivered drugs over mucus surfaces. Here we sought to determine whether the addition of a surfactant would increase transport of an aerosol between lung regions and also improve dosing uniformity in human lungs. Methods: We compared the deposition and postdeposition dispersion of surfactant (10 mg/mL dipalmitoylphosphatidylcholine; DPPC) and saline-based liquid aerosols, admixed with Technetium 99m (Tc99m) diethylenetriaminepentaacetic acid, using gamma scintigraphy. Deposition images were obtained ex vivo in eight pairs of ventilated human lungs. The trachea was intubated and the mainstem bronchi were alternately clamped so that saline was delivered to one lung and then DPPC to the other (sides alternated). The lungs were continually imaged for 15 minutes during delivery. We assessed transport of the deposited aerosol by quantifying the percentage of Tc99m in each of four lung quadrants over time. We quantified dose uniformity within each lung quadrant by measuring the coefficient of variation (CV = standard deviation of the pixel associated radioactive counts/mean of the counts within each quadrant). Results: There was no change in the percentage of Tc99m in each quadrant over time, indicating no improvement in transport with the addition of the surfactant. The addition of surfactant was associated with a statistically significant decrease in CV in the lower inner lung quadrant at each of the three time points, indicating an improvement in dosing uniformity. Conclusion: These preliminary results indicate the possible utility of adding surfactant to aerosols to improve drug distribution uniformity to lower inner lung regions.

Effect of lumacaftor-ivacaftor on mucociliary clearance and clinical outcomes in cystic fibrosis: Results from the PROSPECT MCC sub-study.

CFTR function is required for normal mucociliary clearance (MCC) and cough-assisted clearance (CC). Lumacaftor-ivacaftor is approved for use in people with cystic fibrosis (CF) carrying two copies of F508del-CFTR. In this observational study performed at four study sites, we characterized the effect of lumacaftor-ivacaftor on mucociliary and cough clearance and related this to other clinical and research endpoints after one month of treatment. Twenty-five adolescents and adults were enrolled. No effect on whole lung MCC was observed, but CC was significantly increased. Sweat chloride improved by 18 mEq/L in this group, indicating a modest restoration of CFTR activity, but no demonstrable change in FEV1 or lung clearance index was observed. We speculate that the modest effect of lumacaftor-ivacaftor on CFTR function was insufficient to yield an improvement in MCC.

Nasal epithelial cell culture fluorescence recovery after photobleaching predicts cystic fibrosis therapeutic response.

Background: Human nasal epithelial (HNE) cells can be sampled noninvasively and cultured to provide a model of the airway epithelium that reflects cystic fibrosis (CF) pathophysiology. We hypothesised that in vitro measures of HNE cell physiology would correlate directly with in vivo measures of lung physiology and therapeutic response, providing a framework for using HNE cells for therapeutic development and precision medicine. Methods: We sampled nasal cells from participants with CF (CF group, n=26), healthy controls (HC group, n=14) and single CF transmembrane conductance regulator (CFTR) mutation carrier parents of the CF group (CR group, n=16). Participants underwent lung physiology and sweat chloride testing, and nuclear imaging-based measurement of mucociliary clearance (MCC) and small-molecule absorption (ABS). CF participants completed a second imaging day that included hypertonic saline (HS) inhalation to assess therapeutic response in terms of MCC. HNE measurements included Ussing chamber electrophysiology, small-molecule and liquid absorption rates, and particle diffusion rates through the HNE airway surface liquid (ASL) measured using fluorescence recovery after photobleaching (FRAP). Results: Long FRAP diffusion times were associated with increased MCC response to HS in CF. This implies a strong relationship between inherent factors affecting ASL mucin concentration and therapeutic response to a hydrating therapy. MCC decreased with age in the CR group, which had a larger range of ages than the other two groups. Likely this indicates a general age-related effect that may be accentuated in this group. Measures of lung ABS correlated with sweat chloride in both the HC and CF groups, indicating that CFTR function drives this measure of paracellular small-molecule probe absorption. Conclusions: Our results demonstrate the utility of HNE cultures for assessing therapeutic response for hydrating therapies. In vitro measurements of FRAP were particularly useful for predicting response and for characterising important properties of ASL mucus that were ultimately reflected in lung physiology.

Mucociliary Clearance Scans Show Infants Undergoing Congenital Cardiac Surgery Have Poor Airway Clearance Function.

Background: Infants undergoing congenital cardiac surgery with cardiopulmonary bypass are at high risk for respiratory complications. As impaired airway mucociliary clearance (MCC) can potentially contribute to pulmonary morbidity, our study objective was to measure airway clearance in infants undergoing congenital cardiac surgery and examine correlation with clinical covariables that may impair airway clearance function. Materials and Methods: Airway clearance in infants was measured over 30 min using inhaled nebulized Technetium 99m sulfur colloid administered either via a nasal cannula or the endotracheal tube in intubated infants. This was conducted bedside with a portable gamma camera. No difficulty was encountered in positioning the gamma camera over the patient, and neither the camera nor the MCC scan interfered with routine medical care or caused any adverse events. Patient and perioperative variables were examined relative to the MCC measurements. Results: We prospectively enrolled 57 infants undergoing congenital cardiac surgery and conducted a single MCC scan per patient. MCC data from 42 patients were analyzable, including five pre-operative, 15 (40.5%) in the immediate post-operative period (days 1-2), and 22 (59.5%) were later post-operative (≥3 days). Pre-operative MCC was inversely proportional to days requiring post-operative mechanical ventilation (p = 0.006) and non-invasive positive pressure ventilation (p = 0.017). MCC was higher at later post-operative days (p = 0.002) with immediate post-operative MCC being lower (3%; 0-13%) than either pre-operative (21%; 4-25%) (p = 0.091) or later post-operative MCC (18%; 0-29%) (p = 0.054). Among the infants with low post-operative MCC, significantly more were pre-mature [5/19 (26%) vs. 0/18 (0%); p = 0.046], were intubated [14/19 (75%) vs. only 7/18 (39%); p = 0.033] and were receiving higher FiO2 (40%, 27-47% vs. 26%, 21-37%; p = 0.015). Conclusions: This is the first study to show that infants undergoing congenital cardiac surgery have impaired MCC. MCC appeared lowest in the immediate post-operative period. Worse MCC was associated with pre-maturity, mechanical ventilation, or receiving higher FiO2. These findings suggest MCC scans should be further explored for informing clinical decision making to improve post-surgical respiratory outcomes. The possible therapeutic benefit of airway clearance maneuvers for infants with poor MCC function should also be investigated.

Mucociliary Clearance Differs in Mild Asthma by Levels of Type 2 Inflammation.

BACKGROUND: Although mucus plugging is a well-reported feature of asthma, whether asthma and type 2 inflammation affect mucociliary clearance (MCC) is unknown. RESEARCH QUESTION: Does type 2 inflammation influence mucus clearance rates in patients with mild asthma who are not receiving corticosteroids? STUDY DESIGN AND METHODS: The clearance rates of inhaled radiolabeled particles were compared between patients with mild asthma with low (n = 17) and high (n = 18) levels of T2 inflammation. Fraction exhaled nitric oxide (Feno) was used to prospectively segregate subjects into T2 Lo (Feno < 25 ppb) and T2 Hi (Feno > 35 ppb) cohorts. Bronchial brush samples were collected with fiber-optic bronchoscopy, and quantitative polymerase chain reaction was performed to measure expression of genes associated with T2 asthma. MCC rate comparisons were also made with a historical group of healthy control subjects (HCs, n = 12). RESULTS: The T2 Lo cohort demonstrated increased MCC when compared with both T2 Hi and historic HCs. MCC within the T2 Hi group varied significantly, with some subjects having low or zero clearance. MCC decreased with increasing expression of several markers of T2 airway inflammation (CCL26, NOS2, and POSTN) and with Feno. MUC5AC and FOXJ1 expression was similar between the T2Lo and T2Hi cohorts. INTERPRETATION: Increasing T2 inflammation was associated with decreasing MCC. High rates of MCC in T2 Lo subjects may indicate a compensatory mechanism present in mild disease but lost with high levels of inflammation. Future studies are required to better understand mechanisms and whether impairments in MCC in more severe asthma drive worse clinical outcomes.

Measurements of deposited aerosol dose in infants and small children.

Pediatric patients are very dependent on inhaled aerosol medications. There are significant differences in how these aerosols deposit in the lungs of children vs. adults that may affect the efficacy of the therapies. Inefficient aerosol delivery to children, caused by factors such as high mouth and throat deposition during oral inhalation, significant losses within adjunct devices such as masks, and high rates of nasal deposition during cannula delivery, can lead to dosing that is difficult to control. Here we discuss the methods, such as deposition scintigraphy, that are used to assess inhaled dose in vivo and review previous studies where these techniques have been applied to measure dosing in children. This includes studies of nebulizers and metered dose inhalers and delivery through adjuncts such as facemasks and nasal cannulas. We discuss the factors that can lead to inefficient inhaled drug delivery and high levels of mouth and throat deposition in children. Finally, we propose areas of innovation to improve inhaled drug delivery to this population. There is a need for child-specific technologies for inhaled drug delivery. This includes the use of smart devices that can guide pediatric breathing patterns and better engage children during treatments, the use of smaller aerosols which are less likely to deposit in the upper airways after inhalation, and the design of better nasal cannula interfaces for aerosol delivery to infants.

Droplet and Aerosol Generation With Mastoidectomy During the COVID-19 Pandemic: Assessment of Baseline Risk and Mitigation Measures With a High-performance Cascade Impactor.

HYPOTHESIS: Aerosols are generated during mastoidectomy and mitigation strategies may effectively reduce aerosol spread. BACKGROUND: An objective understanding of aerosol generation and the effectiveness of mitigation strategies can inform interventions to reduce aerosol risk from mastoidectomy and other open surgeries involving drilling. METHODS: Cadaveric and fluorescent three-dimensional printed temporal bone models were drilled under variable conditions and mitigation methods. Aerosol production was measured with a cascade impactor set to detect particle sizes under 14.1 µm. Field contamination was determined with examination under UV light. RESULTS: Drilling of cadaveric bones and three-dimensional models resulted in strongly positive aerosol production, measuring positive in all eight impactor stages for the cadaver trials. This occurred regardless of using coarse or cutting burs, irrigation, a handheld suction, or an additional parked suction. The only mitigation factor that led to a completely negative aerosol result in all eight stages was placing an additional microscope drape to surround the field. Bone dust was scattered in all directions from the drill, including on the microscope, the surgeon, and visually suspended in the air for all but the drape trial. CONCLUSIONS: Aerosols are generated with drilling the mastoid. Using an additional microscope drape to cover the surgical field was an effective mitigation strategy to prevent fine aerosol dispersion while drilling.

Aerosol and Droplet Risk of Common Otolaryngology Clinic Procedures.

OBJECTIVES: Define aerosol and droplet risks associated with routine otolaryngology clinic procedures during the COVID-19 era. METHODS: Clinical procedures were simulated in cadaveric heads whose oral and nasal cavities were coated with fluorescent tracer (vitamin B2) and breathing was manually simulated through retrograde intubation. A cascade impactor placed adjacent to the nares collected generated particles with aerodynamic diameters ≤14.1 µm. The 3D printed models and syringes were used to simulate middle and external ear suctioning as well as open suctioning, respectively. Provider's personal protective equipment (PPE) and procedural field contamination were also recorded for all trials using vitamin B2 fluorescent tracer. RESULTS: The positive controls of nebulized vitamin B2 produced aerosol particles ≤3.30 µm and endonasal drilling of a 3D model generated particles ≤14.1 µm. As compared with positive controls, aerosols and small droplets with aerodynamic diameter ≤14.1 µm were not detected during rigid nasal endoscopy, flexible fiberoptic laryngoscopy, and rigid nasal suction of cadavers with simulated breathing. There was minimal to no field contamination in all 3 scenarios. Middle and external ear suctioning and open container suctioning did not result in any detectable droplet contamination. The clinic suction unit contained all fluorescent material without surrounding environmental contamination. CONCLUSION: While patients' coughing and sneezing may create a baseline risk for providers, this study demonstrates that nasal endoscopy, flexible laryngoscopy, and suctioning inherently do not pose an additional risk in terms of aerosol and small droplet generation. An overarching generalization cannot be made about endoscopy or suctioning being an aerosol generating procedure. LEVEL OF EVIDENCE: 3.

Droplet and Aerosol Generation With Endonasal Surgery: Methods to Mitigate Risk During the COVID-19 Pandemic.

OBJECTIVE: To define the aerosol and droplet risks associated with endonasal drilling and to identify mitigation strategies. STUDY DESIGN: Simulation series with fluorescent 3-dimensional (3D) printed sinonasal models and deidentified cadaveric heads. SETTINGS: Dedicated surgical laboratory. SUBJECTS AND METHODS: Cadaveric specimens irrigated with fluorescent tracer and fluorescent 3D-printed models were drilled. A cascade impactor was used to collect aerosols and small droplets of various aerodynamic diameters under 15 µm. Large droplet generation was measured by evaluating the field for fluorescent debris. Aerosol plumes through the nares were generated via nebulizer, and mitigation measures, including suction and SPIWay devices, nasal sheaths, were evaluated regarding reduction of aerosol escape from the nose. RESULTS: The drilling of cadaveric specimens without flexible suction generated aerosols ≤3.30 µm, and drilling of 3D sinonasal models consistently produced aerosols ≤14.1 µm. Mitigation with SPIWay or diameter-restricted SPIWay produced same results. There was minimal field contamination in the cadaveric models, 0% to 2.77% field tarp area, regardless of drill burr type or drilling location; cutting burr drilling without suction in the 3D model yielded the worst contamination field (36.1%), followed by coarse diamond drilling without suction (19.4%). The simple placement of a flexible suction instrument in the nasal cavity or nasopharynx led to complete elimination of all aerosols ≤14.1 µm, as evaluated by a cascade impactor positioned immediately at the nares. CONCLUSION: Given the findings regarding aerosol risk reduction, we strongly recommend that physicians use a suction instrument in the nasal cavity or nasopharynx during endonasal surgery in the COVID-19 era.

Novel Use of Vitamin B2 as a Fluorescent Tracer in Aerosol and Droplet Contamination Models in Otolaryngology.

OBJECTIVE: During the COVID-19 era, a reliable method for tracing aerosols and droplets generated during otolaryngology procedures is needed to accurately assess contamination risk and to develop mitigation measures. Prior studies have not investigated the reliability of different fluorescent tracers for the purpose of studying aerosols and small droplets. Objectives include (1) comparing vitamin B2, fluorescein, and a commercial fluorescent green dye in terms of particle dispersion pattern, suspension into aerosols and small droplets, and fluorescence in aerosolized form and (2) determining the utility of vitamin B2 as a fluorescent tracer coating the aerodigestive tract mucosa in otolaryngology contamination models. METHODS: Vitamin B2, fluorescein, and a commercial fluorescent dye were aerosolized using a nebulizer and passed through the nasal cavity from the trachea in a retrograde-intubated cadaveric head. In another scenario, vitamin B2 was irrigated to coat the nasal cavity and nasopharyngeal mucosa of a cadaveric head for assessment of aerosol and droplet generation from endonasal drilling. A cascade impactor was used to collect aerosols and small droplets ≤14.1 µm based on average aerodynamic diameter, and the collection chambers were visualized under UV light. RESULTS: When vitamin B2 was nebulized, aerosols ≤5.4 µm were generated and the collected particles were fluorescent. When fluorescein and the commercial water tracer dye were nebulized, aerosols ≤8.61 µm and ≤2.08 µm respectively were generated, but the collected aerosols did not appear visibly fluorescent. Endonasal drilling in the nasopharynx coated with vitamin B2 irrigation yielded aerosols ≤3.30 µm that were fluorescent under UV light. CONCLUSION: Vitamin B2's reliability as a fluorescent tracer when suspended in aerosols and small droplets ≤14.1 µm and known mucosal safety profile make it an ideal compound compared to fluorescein and commercial water-based fluorescent dyes for use as a safe fluorescent tracer in healthcare contamination models especially with human subjects.

Reducing Aerosol-Related Risk of Transmission in the Era of COVID-19: An Interim Guidance Endorsed by the International Society of Aerosols in Medicine.

National and international guidelines recommend droplet/airborne transmission and contact precautions for those caring for coronavirus disease 2019 (COVID-19) patients in ambulatory and acute care settings. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, an acute respiratory infectious agent, is primarily transmitted between people through respiratory droplets and contact routes. A recognized key to transmission of COVID-19, and droplet infections generally, is the dispersion of bioaerosols from the patient. Increased risk of transmission has been associated with aerosol generating procedures that include endotracheal intubation, bronchoscopy, open suctioning, administration of nebulized treatment, manual ventilation before intubation, turning the patient to the prone position, disconnecting the patient from the ventilator, noninvasive positive-pressure ventilation, tracheostomy, and cardiopulmonary resuscitation. The knowledge that COVID-19 subjects can be asymptomatic and still shed virus, producing infectious droplets during breathing, suggests that health care workers (HCWs) should assume every patient is potentially infectious during this pandemic. Taking actions to reduce risk of transmission to HCWs is, therefore, a vital consideration for safe delivery of all medical aerosols. Guidelines for use of personal protective equipment (glove, gowns, masks, shield, and/or powered air purifying respiratory) during high-risk procedures are essential and should be considered for use with lower risk procedures such as administration of uncontaminated medical aerosols. Bioaerosols generated by infected patients are a major source of transmission for SARS CoV-2, and other infectious agents. In contrast, therapeutic aerosols do not add to the risk of disease transmission unless contaminated by patients or HCWs.

A physiologically-motivated model of cystic fibrosis liquid and solute transport dynamics across primary human nasal epithelia.

Cystic fibrosis (CF) disease is caused by mutations affecting the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR), an anion channel expressed in the mucosal side of epithelial tissue. In the airway, dysfunctional CFTR results in a transepithelial osmotic imbalance leading to hyperabsorption of airway surface liquid mucostasis, chronic inflammation, and eventual respiratory failure. Human nasal epithelial cell cultures from healthy and CF donors were used to perform studies of liquid and solute transport dynamics at an air/liquid interface in order to emulate the in vivo airway. Then, these results were used to inform a quantitative systems pharmacology model of airway epithelium describing electrically and chemically driven transcellular ionic transport, contributions of both convective and diffusive paracellular solute transport, and osmotically driven transepithelial water dynamics. Model predictions showed CF cultures, relative to non-CF ones, have increased apical and basolateral water permeabilities, and increase paracellular permeability and transepithelial chemical driving force for a radiolabeled tracer used to track small molecule absorption. These results provide a computational platform to better understand and probe the mechanisms behind the liquid hyperabsorption and small molecule retention profiles observed in the CF airway.

Aerosolization of Second-generation Triazoles: In Vitro Evaluation and Application in Therapy of Invasive Airway Aspergillosis.

BACKGROUND: A lung transplant patient with invasive aspergillosis (IA) manifested symptoms of voriconazole-induced transaminitis with systemic voriconazole and progression of IA after switching to oral posaconazole. With limited options for standard triazole therapy, aerosolized delivery with one of the second-generation triazoles was considered. METHODS: Feasibility for aerosolized delivery was evaluated using cascade impactor and analysis of physicochemical characteristics of voriconazole (10 mg/mL) and posaconazole (6, 12 mg/mL) solutions. RESULTS: Both triazoles showed favorable characteristics for aerosol delivery with mass median aerodynamic diameter, geometric standard deviation, respirable fraction (<5.4 µm) of 2.8 µm, 2.0, 86%; 3.4 µm, 2.4, 78%; and 3.0 µm, 2.3, 79% for voriconazole and 6, 12 mg/mL of posaconazole, respectively. Aspergillus fumigatus isolate from the patient was more susceptible to voriconazole, and hence aerosolized voriconazole was introduced around the third month posttransplant at 40 mg TID for 1 week, 40 mg BID for 1 week, followed by 40 mg daily thereafter, along with IV caspofungin (50 mg/d) and liposomal amphotericin B (300 mg/d). The aerosol regimen was well tolerated by the patient with undetectable trough plasma levels of voriconazole. Bronchoscopy at the fourth month revealed improvement in anastomotic plaques with reduction in bronchoalveolar lavage galactomannan values (7.48-2.15 ng/mL). This consolidated aerosolized and intravenous regimen was maintained until 2.97 years posttransplant. CONCLUSIONS: The intravenous solutions of both second-generation triazoles showed characteristics that were suitable for aerosol delivery. Our report further adds to the therapeutic experience with the use of aerosolized voriconazole for IA in a lung transplant patient.

Flow regime transitions and effects on solute transport in surfactant-driven Marangoni flows.

HYPOTHESIS: Surfactant-driven Marangoni flow on liquid films is predicted to depend on subphase depth and initial surface tension difference between the subphase and deposited surfactant solution drop. Changes in flow behavior will impact transport of soluble species entrained in the Marangoni flow along the surface. In extreme cases, the subphase film may rupture, limiting transport. Understanding this behavior is important for applications in drug delivery, coatings, and oil spill remediation. EXPERIMENTS: A trans-illumination optical technique measured the subphase height profiles and drop content transport after drop deposition when varying initial subphase depth, surfactant concentration, and subphase viscosity. FINDINGS: Three distinct flow regimes were identified depending on the subphase depth and surfactant concentration and mapped onto an operating diagram. These are characterized as a "central depression" bounded by an outwardly traveling ridge, an "annular depression" bounded by a central dome and the traveling ridge, and an "annular dewetting" when the subphase ruptures. Well above the critical micelle concentration, transitions between regimes occur at characteristic ratios of gravitational and initial surface tension gradient stresses; transitions shift when surfactant dilution during spreading weakens the stress before the completion of the spreading event. Drop contents travel with the ridge, but dewetting hinders transport.