Fundamentals of aerosol therapy in critical care

Pulmonary drug delivery devices and nanosystems as potential treatment strategies for acute respiratory distress syndrome (ARDS)

Despite advances in drug delivery technologies, treating acute respiratory distress syndrome (ARDS) is challenging due to pathophysiological barriers such as lung injury, oedema fluid build-up, and lung inflammation. Active pharmaceutical ingredients (API) can be delivered directly to the lung site of action with the use of aerosol-based drug delivery devices, and this circumvents the hepatic first-pass effect and improves the bioavailability of drugs. This review discusses the various challenges and barriers for pulmonary drug delivery, current interventions for delivery, considerations for effective drug delivery, and the use of nanoparticle drug delivery carriers as potential strategies for delivering therapeutics in ARDS. Nanosystems have the added benefit of entrapping drugs, increase pulmonary drug bioavailability, and using biocompatible and biodegradable excipients that can facilitate targeted and/or controlled delivery. These systems provide an alternative to existing conventional systems. An effective way to deliver drugs for the treatment of ARDS can be by using colloidal systems that are aerosolized or inhaled. Drug distribution to the deeper pulmonary tissues is necessary due to the significant endothelial cell destruction that is prevalent in ARDS. The particle size of nanoparticles (<0.5 μm) makes them ideal candidates for treating ARDS as they can reach the alveoli. A look into the various potential benefits and limitations of nanosystems used for other lung disorders is also considered to indicate how they may be useful for the potential treatment of ARDS.

Ciprofloxacin-Loaded Inhalable Formulations against Lower Respiratory Tract Infections: Challenges, Recent Advances, and Future Perspectives

Inhaled ciprofloxacin (CFX) has been investigated as a treatment for lower respiratory tract infections (LRTIs) associated with cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), and bronchiectasis. The challenges in CFX effectiveness for LRTI treatment include poor aqueous solubility and therapy resistance. CFX dry powder for inhalation (DPI) formulations were well-tolerated, showing a remarkable decline in overall bacterial burden compared to a placebo in bronchiectasis patients. Recent research using an inhalable powder combining Pseudomonas phage PEV20 with CFX exhibited a substantial reduction in bacterial density in mouse lungs infected with clinical P. aeruginosa strains and reduced inflammation. Currently, studies suggest that elevated biosynthesis of fatty acids could serve as a potential biomarker for detecting CFX resistance in LRTIs. Furthermore, inhaled CFX has successfully addressed various challenges associated with traditional CFX, including the incapacity to eliminate the pathogen, the recurrence of colonization, and the development of resistance. However, further exploration is needed to address three key unresolved issues: identifying the right patient group, determining the optimal treatment duration, and accurately assessing the risk of antibiotic resistance, with additional multicenter randomized controlled trials suggested to tackle these challenges. Importantly, future investigations will focus on the effectiveness of CFX DPI in bronchiectasis and COPD, aiming to differentiate prognoses between these two conditions. This review underscores the importance of CFX inhalable formulations against LRTIs in preclinical and clinical sectors, their challenges, recent advancements, and future perspectives.

Aerosol drug therapy in critically ill patients (Aero-in-ICU study): A multicentre prospective observational cohort study

BACKGROUND

In recent years, a significant understanding of delivering optimal aerosol therapy and the availability of various drugs and devices have led to an increase in its use in clinical practice. There are only a few studies available regarding their use in critically ill patients from a few parts of the world. We aimed to study the practice pattern of aerosol therapy in critically ill patients from Indian intensive care units (ICUs).

METHODS

After ethical approval, this multi-centric prospective observational study was performed over a study period of four weeks. Newly admitted adult patients considered who had an artificial airway and/or ventilation (including non-invasive). Patients were followed up for the next 14 days or until ICU discharge/death (whichever came first) for details of each aerosol therapy, including ongoing respiratory support, drug type, and aerosol-generating device.

RESULTS

From the nine participating centers across India, 218 patients were enrolled. Of 218 enrolled patients, 72.48% received 4884 aerosols with 30.91 ± 27.15 (95%CI: 26.6-35.1) aerosols per patient over 1108 patient days. Approximately 62.7% during IMV, 30.2% during NIV, 2.3% in spontaneously breathing patients with an artificial airway during weaning, and 4.7% were given without an artificial airway after weaning or decannulation. In 59%, a single drug was used, and bronchodilators were the most frequent. The jet nebulizer was the most common, followed by the ultrasonic and vibrating mesh aerosol generator. The ventilator setting was changed in only 6.6% of the aerosol sessions with IMV and none with NIV.

CONCLUSION

Aerosol therapy is frequently used with a wide variation in practices; bronchodilators are the most commonly used drugs, and jet nebulizers are the most widely used.

A novel therapeutic outlook: Classification, applications and challenges of inhalable micron/nanoparticle drug delivery systems in lung cancer (Review)

Lung cancer represents a marked global public health concern. Despite existing treatment modalities, the average 5‑year survival rate for patients with patients with lung cancer is only ~20%. As there are numerous adverse effects of systemic administration routes, there is an urgent need to develop a novel therapeutic strategy tailored specifically for patients with lung cancer. Non‑invasive aerosol inhalation, as a route of drug administration, holds unique advantages in the context of respiratory diseases. Nanoscale materials have extensive applications in the field of biomedical research in recent years. The present study provides a comprehensive review of the classification, applications summarized according to existing clinical treatment modalities for lung cancer and challenges associated with inhalable micron/nanoparticle drug delivery systems (DDSs) in lung cancer. Achieving localized treatment of lung cancer preclinical models through inhalation is deemed feasible. However, further research is required to substantiate the efficacy and long‑term safety of inhalable micron/nanoparticle DDSs in the clinical management of lung cancer.

Discrete fast Fourier transform-assisted ultraviolet-infrared dual resonance spectroscopy for aerosol detection and identification

Aerosol decrease is considered as one of the most important environmental challenges. The current study introduces a novel analytical method for accurate and precise detection and identification of different aerosols. The designed array-based spectroscopic method is based on "discrete fast Fourier transform"-assisted dual resonance ultraviolet-infrared spectroscopy for reliable quantitative/qualitative analysis of aerosols like fug, smog, silica-based micro-/nanoparticles, carbon soot, etc. The detection system is arranged using a slice (5 × 5 cm) of a digital versatile disk as a simple, low-cost, available, and size-controllable wavelength selector (grating) and light reflector with control through a software program. The results show that this method is suitable for real-time detection of different types of chemical agent-modified particles with acceptable sensitivity and selectivity and improved detection limit.

Understanding the nebulisation of antibiotics: the key role of lung microdialysis studies

BACKGROUND

Nebulisation of antibiotics is a promising treatment for ventilator-associated pneumonia (VAP) caused by multidrug-resistant organisms. Ensuring effective antibiotic concentrations at the site of infection in the interstitial space fluid is crucial for clinical outcomes. Current assessment methods, such as epithelial lining fluid and tissue homogenates, have limitations in providing longitudinal pharmacokinetic data.

MAIN BODY

Lung microdialysis, an invasive research technique predominantly used in animals, involves inserting probes into lung parenchyma to measure antibiotic concentrations in interstitial space fluid. Lung microdialysis offers unique advantages, such as continuous sampling, regional assessment of antibiotic lung concentrations and avoidance of bronchial contamination. However, it also has inherent limitations including the cost of probes and assay development, the need for probe calibration and limited applicability to certain antibiotics. As a research tool in VAP, lung microdialysis necessitates specialist techniques and resource-intensive experimental designs involving large animals undergoing prolonged mechanical ventilation. However, its potential impact on advancing our understanding of nebulised antibiotics for VAP is substantial. The technique may enable the investigation of various factors influencing antibiotic lung pharmacokinetics, including drug types, delivery devices, ventilator settings, interfaces and disease conditions. Combining in vivo pharmacokinetics with in vitro pharmacodynamic simulations can become feasible, providing insights to inform nebulised antibiotic dose optimisation regimens. Specifically, it may aid in understanding and optimising the nebulisation of polymyxins, effective against multidrug-resistant Gram-negative bacteria. Furthermore, lung microdialysis holds promise in exploring novel nebulisation therapies, including repurposed antibiotic formulations, bacteriophages and immunomodulators. The technique's potential to monitor dynamic biochemical changes in pneumonia, such as cytokines, metabolites and inflammation/infection markers, opens avenues for developing theranostic tools tailored to critically ill patients with VAP.

CONCLUSION

In summary, lung microdialysis can be a potential transformative tool, offering real-time insights into nebulised antibiotic pharmacokinetics. Its potential to inform optimal dosing regimen development based on precise target site concentrations and contribute to development of theranostic tools positions it as key player in advancing treatment strategies for VAP caused by multidrug-resistant organisms. The establishment of international research networks, exemplified by LUMINA (lung microdialysis applied to nebulised antibiotics), signifies a proactive step towards addressing complexities and promoting multicentre experimental studies in the future.

An in vitro study of the effects of respiratory circuit setup and parameters on aerosol delivery during mechanical ventilation

Introduction

Aerosol therapy is often prescribed concurrently during invasive mechanical ventilation (IMV). This study determines the effects of nebuliser position, circuit humidification source, and most importantly, lung health on the delivery of aerosol in simulated adult and paediatric IMV patients. Furthermore, the influence of closed suction catheters on aerosol delivery is also addressed.

Methods

A vibrating mesh nebuliser was used to deliver Albuterol to simulated adult and paediatric IMV patients with differing states of lung health. Four different nebuliser positions and two types of humidification were analysed. Closed suction catheter mounts, a mainstay in IMV therapy, were incorporated into the circuits. The mean ± SD dose of aerosol (%) was assayed from a filter at the distal end of the endotracheal tube.

Results

Nebuliser placement and circuit humidification source had no effect on the delivered dose (%) in adults, yet both significantly did in the simulated paediatric patients. The use of closed suction catheter mounts significantly reduced the delivered dose (%) in adults but not in paediatric patients. A simulated healthy lung state generated the largest delivered dose (%), irrespective of nebuliser position in the adult. However, different lung health and nebuliser positions yielded higher delivered doses (%) in paediatrics.

Conclusion

Lung health and respiratory circuit composition significantly affect aerosol delivery in both adult and paediatric IMV patients. Nebuliser placement and respiratory circuit humidification source do not affect the delivered dose in adult but do in paediatric IMV patients.

Aerosol Delivery of a Novel Recombinant Modified Superoxide Dismutase Protein Reduces Oxidant Injury and Attenuates Escherichia coli Induced Lung Injury in Rats

Background: Acute respiratory distress syndrome (ARDS) is a life-threatening respiratory failure syndrome with diverse etiologies characterized by increased permeability of alveolar-capillary membranes, pulmonary edema, and acute onset hypoxemia. During the ARDS acute phase, neutrophil infiltration into the alveolar space results in uncontrolled release of reactive oxygen species (ROS) and proteases, overwhelming antioxidant defenses and causing alveolar epithelial and lung endothelial injury. Objectives: To investigate the therapeutic potential of a novel recombinant human Cu-Zn-superoxide dismutase (SOD) fusion protein in protecting against ROS injury and for aerosolized SOD delivery to treat Escherichia coli induced ARDS. Methods: Fusion proteins incorporating human Cu-Zn-SOD (hSOD1), with (pep1-hSOD1-his) and without (hSOD1-his) a fused hyaluronic acid-binding peptide, were expressed in E. coli. Purified proteins were evaluated in in vitro assays with human bronchial epithelial cells and through aerosolized delivery to the lung of an E. coli-induced ARDS rat model. Results: SOD proteins exhibited high SOD activity in vitro and protected bronchial epithelial cells from oxidative damage. hSOD1-his and pep1-hSOD1-his retained SOD activity postnebulization and exhibited no adverse effects in the rat. Pep1-hSOD1-his administered through instillation or nebulization to the lung of an E. coli-induced pneumonia rat improved arterial oxygenation and lactate levels compared to vehicle after 48 hours. Static lung compliance was improved when the pep1-hSOD1-his protein was delivered by instillation. White cell infiltration to the lung was significantly reduced by aerosolized delivery of protein, and reduction of cytokine-induced neutrophil chemoattractant-1, interferon-gamma, and interleukin 6 pro-inflammatory cytokine concentrations in bronchoalveolar lavage was observed. Conclusions: Aerosol delivery of a novel recombinant modified SOD protein reduces oxidant injury and attenuates E. coli induced lung injury in rats. The results provide a strong basis for further investigation of the therapeutic potential of hSOD1 in the treatment of ARDS.

Prospective randomised unblinded comparison of sputum viscosity for three methods of saline nebulisation in mechanically ventilated patients: A pilot study protocol

INTRODUCTION

Heat and moisture exchanger (HME) filters are commonly used as passive circuit humidifiers during mechanical ventilation, however, are only ~80% efficient. As a result, patients that undergo mechanical ventilation in critical care with HME filter circuits will be exposed to partial airway humidification. This is associated with detrimental effects including increased secretion load which has been shown to be an independent predictor of failed extubation. Nebulised normal saline is commonly utilised to supplement circuit humidification in ventilated patients with high secretion loads, although there are no randomised control trials evaluating its use. Novel vibrating mesh nebulisers generate a fine aerosol resulting in deeper lung penetration, potentially offering a more effective means of nebulisation in comparison to jet nebulisers. The primary aim of this study is to compare the viscosity of respiratory secretions after treatment with nebulised normal saline administered via vibrating mesh nebuliser or jet nebuliser.

METHODS AND ANALYSIS

This randomised controlled trial is enrolling 60 mechanically ventilated adult critical care patients breathing on HME filter circuits with high secretion loads. Recruited patients will be randomised to receive nebulised saline via 3 modalities: 1) Continuous vibrating mesh nebuliser; 2) Intermittent vibrating mesh nebuliser or 3) Intermittent jet nebuliser. Over the 72-hr study period, the patients' sputum viscosity (measured using a validated qualitative sputum assessment tool) and physiological parameters will be recorded by an unblinded assessor. A median reduction in secretion viscosity of ≥0.5 on the qualitative sputum assessment score will be deemed as a clinically significant improvement between treatment groups at analysis.

DISCUSSION

At the conclusion of this trial, we will provisionally determine if nebulised normal saline administered via vibrating mesh nebulisation is superior to traditional jet nebulisation in terms of reduced respiratory secretion viscosity in intubated patients. Results from this pilot study will provide information to power a definitive clinical study.

TRIAL REGISTRATION

ClinicalTrails.Gov Registry (NCT05635903).

Aerosol therapy in adult critically ill patients: a consensus statement regarding aerosol administration strategies during various modes of respiratory support

BACKGROUND

Clinical practice of aerosol delivery in conjunction with respiratory support devices for critically ill adult patients remains a topic of controversy due to the complexity of the clinical scenarios and limited clinical evidence.

OBJECTIVES

To reach a consensus for guiding the clinical practice of aerosol delivery in patients receiving respiratory support (invasive and noninvasive) and identifying areas for future research.

METHODS

A modified Delphi method was adopted to achieve a consensus on technical aspects of aerosol delivery for adult critically ill patients receiving various forms of respiratory support, including mechanical ventilation, noninvasive ventilation, and high-flow nasal cannula. A thorough search and review of the literature were conducted, and 17 international participants with considerable research involvement and publications on aerosol therapy, comprised a multi-professional panel that evaluated the evidence, reviewed, revised, and voted on recommendations to establish this consensus.

RESULTS

We present a comprehensive document with 20 statements, reviewing the evidence, efficacy, and safety of delivering inhaled agents to adults needing respiratory support, and providing guidance for healthcare workers. Most recommendations were based on in-vitro or experimental studies (low-level evidence), emphasizing the need for randomized clinical trials. The panel reached a consensus after 3 rounds anonymous questionnaires and 2 online meetings.

CONCLUSIONS

We offer a multinational expert consensus that provides guidance on the optimal aerosol delivery techniques for patients receiving respiratory support in various real-world clinical scenarios.

Impact of gas humidification and nebulizer position under invasive ventilation: preclinical comparative study of regional aerosol deposition

Successful aerosol therapy in mechanically ventilated patients depends on multiple factors. Among these, position of nebulizer in ventilator circuit and humidification of inhaled gases can strongly influence the amount of drug deposited in airways. Indeed, the main objective was to preclinically evaluate impact of gas humidification and nebulizer position during invasive mechanical ventilation on whole lung and regional aerosol deposition and losses. Ex vivo porcine respiratory tracts were ventilated in controlled volumetric mode. Two conditions of relative humidity and temperature of inhaled gases were investigated. For each condition, four different positions of vibrating mesh nebulizer were studied: (i) next to the ventilator, (ii) right before humidifier, (iii) 15 cm to the Y-piece adapter and (iv) right after the Y-piece. Aerosol size distribution were calculated using cascade impactor. Nebulized dose, lung regional deposition and losses were assessed by scintigraphy using 99mtechnetium-labeled diethylene-triamine-penta-acetic acid. Mean nebulized dose was 95% ± 6%. For dry conditions, the mean respiratory tract deposited fractions reached 18% (± 4%) next to ventilator and 53% (± 4%) for proximal position. For humidified conditions, it reached 25% (± 3%) prior humidifier, 57% (± 8%) before Y-piece and 43% (± 11%) after this latter. Optimal nebulizer position is proximal before the Y-piece adapter showing a more than two-fold higher lung dose than positions next to the ventilator. Dry conditions are more likely to cause peripheral deposition of aerosols in the lungs. But gas humidification appears hard to interrupt efficiently and safely in clinical use. Considering the impact of optimized positioning, this study argues to maintain humidification.

Influence of Mechanical Ventilation Modes on the Efficacy of Nebulized Bronchodilators in the Treatment of Intubated Adult Patients with Obstructive Pulmonary Disease

BACKGROUND

Little has been reported in terms of clinical outcomes to confirm the benefits of nebulized bronchodilators during mechanical ventilation (MV). Electrical Impedance Tomography (EIT) could be a valuable method to elucidate this gap.

OBJECTIVE

The purpose of this study is to evaluate the impact of nebulized bronchodilators during invasive MV with EIT by comparing three ventilation modes on the overall and regional lung ventilation and aeration in critically ill patients with obstructive pulmonary disease.

METHOD

A blind clinical trial in which eligible patients underwent nebulization with salbutamol sulfate (5 mg/1 mL) and ipratropium bromide (0.5 mg/2 mL) in the ventilation mode they were receiving. EIT evaluation was performed before and after the intervention. A joint and stratified analysis into ventilation mode groups was performed, with p < 0.05.

RESULTS

Five of nineteen procedures occurred in controlled MV mode, seven in assisted mode and seven in spontaneous mode. In the intra-group analysis, the nebulization increased total ventilation in controlled (p = 0.04 and ⅆ = 2) and spontaneous (p = 0.01 and ⅆ = 1.5) MV modes. There was an increase in the dependent pulmonary region in assisted mode (p = 0.01 and ⅆ = 0.3) and in spontaneous mode (p = 0.02 and ⅆ = 1.6). There was no difference in the intergroup analysis.

CONCLUSIONS

Nebulized bronchodilators reduce the aeration of non-dependent pulmonary regions and increase overall lung ventilation but there was no difference between the ventilation modes. As a limitation, it is important to note that the muscular effort in PSV and A/C PCV modes influences the impedance variation, and consequently the aeration and ventilation values. Thus, future studies are needed to evaluate this effort as well as the time on ventilator, time in UCI and other variables.

In vitro bio-characterization of solid lipid nanoparticles of favipiravir in A549 human lung epithelial cancer cells

Objectives

Lung cancer is a leading cause of mortality worldwide. In lung cancer treatment, nebulized solid lipid nanoparticles may be a viable drug delivery method, helping the drug reach sites of action, and improving its inhalation efficiency and pulmonary deposition. This research focused on evaluating the effectiveness of solid lipid nanoparticles of favipiravir (Fav-SLNps) in facilitating drug delivery to sites of action in lung cancer treatment.

Methods

The hot-evaporation method was used to formulate Fav-SLNps. The in vitro cell viability, anti-cancer effects, and cellular uptake activity were evaluated in A549 human lung adenocarcinoma cells treated with the Fav-SLNp formulation.

Results

The Fav-SLNps were formulated successfully. Importantly, Fav-SLNps at a concentration of 322.6 μg/ml were found to be safe and non-toxic toward A549 cells in vitro. The formulation had potential anti-proliferative properties via increasing the proportions of cells in G2/M and G0/G1 phases to 1.20 and 1.13 times those in untreated cells. Additionally, Fav-SLNp treatment significantly induced necrosis in A549 cells. Furthermore, the use of SLNps in the Fav formulation resulted in a macrophage drug uptake 1.23 times that of the free drug.

Conclusion

Our results confirmed the internalization and anti-cancer activity of the Fav-SLNp formulation in the A549 lung cancer cell line. Our findings suggest that Fav-SLNps could potentially be used as lung cancer treatment to facilitate drug delivery to sites of action in the lungs.

A review of upper airway physiology relevant to the delivery and deposition of inhalation aerosols

Developing effective oral inhaled drug delivery treatment strategies for respiratory diseases necessitates a thorough knowledge of the respiratory system physiology, such as the differences in the airway channel's structure and geometry in health and diseases, their surface properties, and mechanisms that maintain their patency. While respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma and their implications on the lower airways have been the core focus of most of the current research, the role of the upper airway in these diseases is less known, especially in the context of inhaled drug delivery. This is despite the fact that the upper airway is the passageway for inhaled drugs to be delivered to the lower airways, and their replicas are indispensable in current standards, such as the cascade impactor experiments for testing inhaled drug delivery technology. This review provides an overview of upper airway collapsibility and their mechanical properties, the effects of age and gender on upper airway geometry, and surface properties. The review also discusses how COPD and asthma affect the upper airway and the typical inhalation flow characteristics exhibited by the patients with these diseases.

Application of Secondary Electrospray Ionization Coupled with High-Resolution Mass Spectrometry in Chemical Characterization of Thermally Generated Aerosols

Inhalation as a route for administering drugs and dietary supplements has garnered significant attention over the past decade. We performed real-time analyses of aerosols using secondary electrospray ionization (SESI) technology interfaced with high-resolution mass spectrometry (HRMS), primarily developed for exhaled breath analysis with the goal to detect the main aerosol constituents. Several commercially available inhalation devices containing caffeine, melatonin, cannabidiol, and vitamin B12 were tested. Chemical characterization of the aerosols produced by these devices enabled detection of the main constituents and screening for potential contaminants, byproducts, and impurities in the aerosol. In addition, a programmable syringe pump was connected to the SESI-HRMS system to monitor aerosolized active pharmaceutical ingredients (APIs) such as chloroquine, hydroxychloroquine, and azithromycin. This setup allowed us to detect caffeine, melatonin, hydroxychloroquine, chloroquine, and cannabidiol in the produced aerosols. Azithromycin and vitamin B12 in the aerosols could not be detected; however, our instrument setup enabled the detection of vitamin B12 breakdown products that were generated during the aerosolization process. Positive control was realized by liquid chromatography-HRMS analyses. The compounds detected in the aerosol were confirmed by exact mass measurements of the protonated and/or deprotonated species, as well as their respective collision-induced dissociation tandem mass spectra. These results reveal the potential wide application of this technology for the real-time monitoring of aerosolized active pharmaceutical ingredients that can be administered through the inhalation route.

Effects of jet nebulization on ventilator performance with different invasive ventilation modes: A bench study

Background

The effects of jet nebulization on ventilator performance in the volume control mode (VC) and pressure control mode (PC) of ventilation have not been determined.

Objectives

The present study investigated the impact of jet nebulization on ventilator performance in different modes in vitro.

Methods

Two types of jet nebulizer (ventilator-integrated jet nebulizers, external jet nebulizer) and six types of ventilator were connected with a simulated lung to simulate aerosol therapy during mechanical ventilation. The ventilation modes were set to VC and PC, and the driving flows of external jet nebulizer were set at 4 L/min and 8 L/min, respectively. Jet nebulizers were placed between patient airway and Y-piece or at 15 cm from the Y-piece in the inspiratory limb. The effects of jet nebulization were compared with the baseline of triggering performance, control performance, and tidal volume under different experimental conditions.

Results

Ventilator-integrated jet nebulizers had no effect on ventilator performance in different modes (all P &gt; 0.05). However, the effects of external jet nebulizers on ventilator performance varied widely: for triggering performance, all parameters were increased in different modes and nebulization positions (all P &lt; 0.05), including the time from the beginning of the inspiratory effort to the lowest value of airway pressure needed to trigger the ventilator (TPmin), the time to trigger (Ttrig), and the magnitude of airway pressure drop needed to trigger (Ptrig); for control performance, peak inspiratory pressure (Ppeak) and peak inspiratory flow(Pflow) were increased in the VC mode (P &lt; 0.05), but not significantly changed in the PC mode (P &gt; 0.05);the actual tidal volume (VT) and expiratory tidal volume monitored (VTe) were significantly increased (P &lt; 0.05), however, the inspiratory tidal volume monitored (VTi) was not affected by jet nebulization in the VC mode. In the PC mode, there were no significant changes in VT, whereas VTi decreased and VTe increased (P &lt; 0.05). The higher the driving flow of external jet nebulizers, the stronger the impact on ventilator performance (all P &lt; 0.05).

Conclusion

Triggering performance was decreased in both the VC and PC modes when using an external jet nebulizer, while the effects of nebulization on control performance and tidal volume varied significantly.

Insights into the modulation of the interferon response and NAD+ in the context of COVID-19

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in dramatic worldwide mortality. Along with developing vaccines, the medical profession is exploring new strategies to curb this pandemic. A better understanding of the molecular consequences of SARS-CoV-2 cellular infection could lead to more effective and safer treatments. This review discusses the potential underlying impact of SARS-CoV-2 in modulating interferon (IFN) secretion and in causing mitochondrial NAD⁺ depletion that could be directly linked to COVID-19's deadly manifestations. What is known or surmised about an imbalanced innate immune response and mitochondrial dysfunction post-SARS-CoV-2 infection, and the potential benefits of well-timed IFN treatments and NAD⁺ boosting therapies in the context of the COVID-19 pandemic are discussed.

Indian Guidelines on Nebulization Therapy

Inhalational therapy, today, happens to be the mainstay of treatment in obstructive airway diseases (OADs), such as asthma, chronic obstructive pulmonary disease (COPD), and is also in the present, used in a variety of other pulmonary and even non-pulmonary disorders. Hand-held inhalation devices may often be difficult to use, particularly for children, elderly, debilitated or distressed patients. Nebulization therapy emerges as a good option in these cases besides being useful in the home care, emergency room and critical care settings. With so many advancements taking place in nebulizer technology; availability of a plethora of drug formulations for its use, and the widening scope of this therapy; medical practitioners, respiratory therapists, and other health care personnel face the challenge of choosing appropriate inhalation devices and drug formulations, besides their rational application and use in different clinical situations. Adequate maintenance of nebulizer equipment including their disinfection and storage are the other relevant issues requiring guidance. Injudicious and improper use of nebulizers and their poor maintenance can sometimes lead to serious health hazards, nosocomial infections, transmission of infection, and other adverse outcomes. Thus, it is imperative to have a proper national guideline on nebulization practices to bridge the knowledge gaps amongst various health care personnel involved in this practice. It will also serve as an educational and scientific resource for healthcare professionals, as well as promote future research by identifying neglected and ignored areas in this field. Such comprehensive guidelines on this subject have not been available in the country and the only available proper international guidelines were released in 1997 which have not been updated for a noticeably long period of over two decades, though many changes and advancements have taken place in this technology in the recent past. Much of nebulization practices in the present may not be evidence-based and even some of these, the way they are currently used, may be ineffective or even harmful. Recognizing the knowledge deficit and paucity of guidelines on the usage of nebulizers in various settings such as inpatient, out-patient, emergency room, critical care, and domiciliary use in India in a wide variety of indications to standardize nebulization practices and to address many other related issues; National College of Chest Physicians (India), commissioned a National task force consisting of eminent experts in the field of Pulmonary Medicine from different backgrounds and different parts of the country to review the available evidence from the medical literature on the scientific principles and clinical practices of nebulization therapy and to formulate evidence-based guidelines on it. The guideline is based on all possible literature that could be explored with the best available evidence and incorporating expert opinions. To support the guideline with high-quality evidence, a systematic search of the electronic databases was performed to identify the relevant studies, position papers, consensus reports, and recommendations published. Rating of the level of the quality of evidence and the strength of recommendation was done using the GRADE system. Six topics were identified, each given to one group of experts comprising of advisors, chairpersons, convenor and members, and such six groups (A-F) were formed and the consensus recommendations of each group was included as a section in the guidelines (Sections I to VI). The topics included were: A. Introduction, basic principles and technical aspects of nebulization, types of equipment, their choice, use, and maintenance B. Nebulization therapy in obstructive airway diseases C. Nebulization therapy in the intensive care unit D. Use of various drugs (other than bronchodilators and inhaled corticosteroids) by nebulized route and miscellaneous uses of nebulization therapy E. Domiciliary/Home/Maintenance nebulization therapy; public & health care workers education, and F. Nebulization therapy in COVID-19 pandemic and in patients of other contagious viral respiratory infections (included later considering the crisis created due to COVID-19 pandemic). Various issues in different sections have been discussed in the form of questions, followed by point-wise evidence statements based on the existing knowledge, and recommendations have been formulated.

Inhaled Atorvastatin Nanoparticles For Lung Cancer

BACKGROUND

Lung cancer is one of the main causes of mortality globally. This research paper aims at the development of an inhaled nanotechnology for lung cancer to deliver an atorvastatin calcium compound, for lung cancer, capable of reaching the tumor site directly via inhalation.

METHODS

Atorvastatin calcium micellar nanoparticles (ATO-NPs) encapsulated with Pluronic F-127 and polyvinyl alcohol (PVA) were manufactured utilizing the solvent and anti-solvent precipitation technique. The physicochemical features of the formulation were evaluated in terms of their physicochemical characteristics using Fourier transform infrared spectroscopy, differential scanning calorimetry, and dynamic light scattering. Additionally, the Andersen Cascade impactor was used at 15 L/minutes to assist in the aerosols performances of the formulation. The ATO-NPs formula's cell viability was tested in vitro using the A549 non-small cell lung cancer cell type.

RESULTS

Transmission electron microscopy was utilized to determine the ATO-NPs particle morphology, demonstrating a spherical shape with a smooth surface. The fine particle fraction of the aerosol produced was 62.70 ± 1.18%. This finding suggests that atorvastatin micellar nanoparticles are suitable for medication administration by inhalation with a wide particle size dispersion. Moreover, it was found in vitro that concentrations up to 21 µg/mL of the atorvastatin nanoparticles were safe and non-toxic on the cell model.

CONCLUSION

This study found that atorvastatin micellar nanoparticles for inhalation could potentially be used for lung cancer treatment.

Aerosol-Cell Exposure System Applied to Semi-Adherent Cells for Aerosolization of Lung Surfactant and Nanoparticles Followed by High Quality RNA Extraction

Nanoparticle toxicity assessments have moved closer to physiological conditions while trying to avoid the use of animal models. An example of new in vitro exposure techniques developed is the exposure of cultured cells at the air-liquid interface (ALI), particularly in the case of respiratory airways. While the commercially available VITROCELL^® Cloud System has been applied for the delivery of aerosolized substances to adherent cells under ALI conditions, it has not yet been tested on lung surfactant and semi-adherent cells such as alveolar macrophages, which are playing a pivotal role in the nanoparticle-induced immune response.

OBJECTIVES

In this work, we developed a comprehensive methodology for coating semi-adherent lung cells cultured at the ALI with aerosolized surfactant and subsequent dose-controlled exposure to nanoparticles (NPs). This protocol is optimized for subsequent transcriptomic studies.

METHODS

Semi-adherent rat alveolar macrophages NR8383 were grown at the ALI and coated with lung surfactant through nebulization using the VITROCELL^® Cloud 6 System before being exposed to TiO₂ NM105 NPs. After NP exposures, RNA was extracted and its quantity and quality were measured.

RESULTS

The VITROCELL^® Cloud system allowed for uniform and ultrathin coating of cells with aerosolized surfactant mimicking physiological conditions in the lung. While nebulization of 57 μL of 30 mg/mL TiO₂ and 114 μL of 15 mg/mL TiO₂ nanoparticles yielded identical cell delivered dose, the reproducibility of dose as well as the quality of RNA extracted were better for 114 μL.

Depletion and Dysfunction of Dendritic Cells: Understanding SARS-CoV-2 Infection

Uncontrolled severe acute respiratory syndrome-coronavirus (SARS-CoV)-2 infection is closely related to disorders of the innate immune and delayed adaptive immune systems. Dendritic cells (DCs) “bridge” innate immunity and adaptive immunity. DCs have important roles in defending against SARS-CoV-2 infection. In this review, we summarize the latest research concerning the role of DCs in SARS-CoV-2 infection. We focus on the complex interplay between DCs and SARS-CoV-2: pyroptosis-induced activation; activation of the renin–angiotensin–aldosterone system; and activation of dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin. We also discuss the decline in DC number, the impaired antigen-presentation capability, and the reduced production of type-I interferon of DCs in severe SARS-CoV-2 infection. In addition, we discuss the potential mechanisms for pathological activation of DCs to understand the pattern of SARS-CoV-2 infection. Lastly, we provide a brief overview of novel vaccination and immunotherapy strategies based on DC targeting to overcome SARS-CoV-2 infection.

Nanomedicine formulations for respiratory infections by inhalation delivery: Covid-19 and beyond

For respiratory infections treatment and prevention, we analyze for the first time the possibility of providing a broad range medication based on metallic nanoparticles colloids (NpC) delivery by controlled aerosol inhalation. (i) Based on in-vitro data combined with aerosol deposition characteristics in the respiratory system, we calculate the required effective formulations, dosages and delivery parameters for an aerosol inhalation treatment. The goal is to achieve an effective NpC inhibitory concentration (IC) in the target airway surface liquid (ASL); (ii) We evaluate the clinical safety of such dosages, drawing on information from animal testing data and regulatory limits in the USA for such nanoparticles aerosol inhalation safety. Our analysis indicates a wide range of potentially safe and effective dosages that can be clinically explored, targeting the upper respiratory and bronchial tree system. Similar dosages can also provide antibacterial effectiveness for prophylactic treatment in hospital intensive care units to lower the risk of ventilator-associated pneumonia (VAP).

Our calculations are phenomenological, independent of mechanisms. Nevertheless, we highlight a mechanism of action by which any suitably designed NpC, with nanoparticles sized 2–10 nm and having a large negative zeta-potential, preferentially bind to viruses with predominantly positively-charged spike proteins. These will be ineffective against viruses with predominantly negatively-charged spike proteins. Accordingly, the popular silver metal base for NpC serves just as a construction ingredient, and other metal or metal-oxides which can serve to construct the noted nanoparticle properties would be similarly effective.

We suggest that inhalation delivery of the proposed antiviral formulations could be applied as a first-line intervention while respiratory infections are primarily localized to the upper respiratory system and bronchial tree.

Inhaled Pulmonary Vasodilator Therapy in Adult Lung Transplant: A Randomized Clinical Trial

Importance

Inhaled nitric oxide (iNO) is commonly administered for selectively inhaled pulmonary vasodilation and prevention of oxidative injury after lung transplant (LT). Inhaled epoprostenol (iEPO) has been introduced worldwide as a cost-saving alternative to iNO without high-grade evidence for this indication.

Objective

To investigate whether the use of iEPO will lead to similar rates of severe/grade 3 primary graft dysfunction (PGD-3) after adult LT when compared with use of iNO.

Design, Setting, and Participants

This health system-funded, randomized, blinded (to participants, clinicians, data managers, and the statistician), parallel-designed, equivalence clinical trial included 201 adult patients who underwent single or bilateral LT between May 30, 2017, and March 21, 2020. Patients were grouped into 5 strata according to key prognostic clinical features and randomized per stratum to receive either iNO or iEPO at the time of LT via 1:1 treatment allocation.

Interventions

Treatment with iNO or iEPO initiated in the operating room before lung allograft reperfusion and administered continously until cessation criteria met in the intensive care unit (ICU).

Main Outcomes and Measures

The primary outcome was PGD-3 development at 24, 48, or 72 hours after LT. The primary analysis was for equivalence using a two one-sided test (TOST) procedure (90% CI) with a margin of 19% for between-group PGD-3 risk difference. Secondary outcomes included duration of mechanical ventilation, hospital and ICU lengths of stay, incidence and severity of acute kidney injury, postoperative tracheostomy placement, and in-hospital, 30-day, and 90-day mortality rates. An intention-to-treat analysis was performed for the primary and secondary outcomes, supplemented by per-protocol analysis for the primary outcome.

Results

A total of 201 randomized patients met eligibility criteria at the time of LT (129 men [64.2%]). In the intention-to-treat population, 103 patients received iEPO and 98 received iNO. The primary outcome occurred in 46 of 103 patients (44.7%) in the iEPO group and 39 of 98 (39.8%) in the iNO group, leading to a risk difference of 4.9% (TOST 90% CI, -6.4% to 16.2%; P = .02 for equivalence). There were no significant between-group differences for secondary outcomes.

Conclusions and Relevance

Among patients undergoing LT, use of iEPO was associated with similar risks for PGD-3 development and other postoperative outcomes compared with the use of iNO.

Trial Registration

ClinicalTrials.gov identifier: NCT03081052.

Physicochemical Characteristics and In Vitro Toxicity/Anti-SARS-CoV-2 Activity of Favipiravir Solid Lipid Nanoparticles (SLNs)

The rise of coronavirus (COVID-19) cases worldwide has driven the need to discover and develop novel therapeutics with superior efficacy to treat this disease. This study aims to develop an innovative aerosolized nano-formulation of favipiravir (FPV) as an anti-viral agent against coronavirus infection. The local delivery of FPV nanoparticles (NPs) via nebulization ensures that the drug can reach the site of infection, the lungs. Solid lipid NPs of favipiravir (FPV-SLNs) were formulated utilizing the hot-evaporation method. The physicochemical formulation properties were evaluated using dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The aerosol formulation performance was evaluated using an Andersen Cascade Impactor (ACI) at a flow rate of 15 L/min. The FPV-SLN formulation's in vitro anti-viral activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was also evaluated using the SARS-CoV-2 pathogen (hCoV-19/Egypt/NRC-3/2020 isolate). The FPV-SLNs' morphology was defined utilizing transmission electron microscopy, showing an irregular shape. By means of FPV-SLNs' nebulization, a fine particle fraction of 60.2 ± 1.7% was produced with 60.2 ± 1.7%, and this finding suggests that FPV-SLNs were appropriate for inhalation drug delivery with a particle size of 537.6 ± 55.72 nm. Importantly, the FPV-SLNs showed anti-viral activity against SARS-CoV-2 with CC50 and IC50 values of 449.6 and 29.9 µg/mL, respectively. This study suggests that inhaled solid lipid NPs of favipiravir could potentially be used against coronavirus.

In Vitro Evaluation of Aerosol Delivery by Hand-Held Mesh Nebulizers in an Adult Spontaneous Breathing Lung Model

Background: Drug inhalation is common mode of treatment for chronic obstructive pulmonary disease (COPD). The aim of this study was to evaluate the efficiency of aerosol devices in a simulated COPD adult lung model using five commercially available hand-held mesh nebulizers. Materials and Methods: Five nebulizers (PARI VELOX^®, Omron NE-U22, Aeroneb^® Go, APEX PY001, and Pocket Air^®) were tested with a unit dose of 5.0 mg/2.5 mL salbutamol. An in vitro lung model (compliance: 0.06 L/cm H₂O, resistance: 20 cm H₂O/L/sec) was constructed to simulate parameters (tidal volume of 500 mL, respiratory rate of 15 breaths/min, inspiratory time of 1 second) of an adult patient with COPD. A bacterial filter was attached at the bronchi level for drug collection, referring as inhaled mass. After nebulization, the inhaled mass (%), dose remaining on each component (%), particle size characteristics, and nebulizer performances were analyzed. Particle size characteristics were analyzed using an 8-stage Anderson Cascade Impactor. The salbutamol particles deposited were eluted and analyzed using a spectrophotometer at 276 nm. The inhaled mass (%), dose remaining on each component (%), particle size distribution, and nebulizer performance were statistically analyzed using analysis of variance (ANOVA) with Sheffee post hoc tests. Results: Pocket Air and APEX PY001 showed the greatest inhaled mass and the lowest dose in the mouthpiece connection. The largest and smallest mass median aerodynamic diameters were found with Omron NE-U22 and PARI VELOX, respectively. In addition, the output rate and inhaled aerosol rate (IAR) of PARI VELOX were higher than those of other nebulizers. Conclusions: This study showed that the performance of commercially available mesh nebulizers varied. Aerosol particles deposited on different auxiliary equipment directly influenced the output rate and IAR of the mesh nebulizer. Clinical validation of the drug IAR is necessary to avoid overdose and reduce drug wastage.

Cellular Therapy for the Treatment of Paediatric Respiratory Disease

Respiratory disease is the leading cause of death in children under the age of 5 years old. Currently available treatments for paediatric respiratory diseases including bronchopulmonary dysplasia, asthma, cystic fibrosis and interstitial lung disease may ameliorate symptoms but do not offer a cure. Cellular therapy may offer a potential cure for these diseases, preventing disease progression into adulthood. Induced pluripotent stem cells, mesenchymal stromal cells and their secretome have shown great potential in preclinical models of lung disease, targeting the major pathological features of the disease. Current research and clinical trials are focused on the adult population. For cellular therapies to progress from preclinical studies to use in the clinic, optimal cell type dosage and delivery methods need to be established and confirmed. Direct delivery of these therapies to the lung as aerosols would allow for lower doses with a higher target efficiency whilst avoiding potential effect of systemic delivery. There is a clear need for research to progress into the clinic for the treatment of paediatric respiratory disease. Whilst research in the adult population forms a basis for the paediatric population, varying disease pathology and anatomical differences in paediatric patients means a paediatric-centric approach must be taken.

Drug delivery to the pediatric upper airway

Pediatric upper airway disorders are frequently life-threatening and require precise assessment and intervention. Targeting these pathologies remains a challenge for clinicians due to the high complexity of pediatric upper airway anatomy and numerous potential etiologies; the most common treatments include systemic delivery of high dose steroids and antibiotics or complex and invasive surgeries. Furthermore, the majority of innovative airway management technologies are only designed and tested for adults, limiting their widespread implementation in the pediatric population. Here, we provide a comprehensive review of the most recent challenges of managing common pediatric upper airway disorders, describe the limitations of current clinical treatments, and elaborate on how to circumvent those limitations via local controlled drug delivery. Furthermore, we propose future advancements in the field of drug-eluting technologies to improve pediatric upper airway management outcomes.

The Clinical Practice and Best Aerosol Delivery Location in Intubated and Mechanically Ventilated Patients: A Randomized Clinical Trial

This randomized clinical trial (RCT) is aimed at exploring the best nebulizer position for aerosol delivery within the mechanical ventilation (MV) circuitry. This study enrolled 75 intubated and MV patients with respiratory failure and randomly divided them into three groups. The nebulizer position of patients in group A was between the tracheal tube and Y-piece. For group B, the nebulizer was placed at the inspiratory limb near the ventilator water cup (80 cm away from the Y-piece). For group C, the nebulizer was placed between the ventilator inlet and the heated humidifier. An indirect competitive enzyme-linked immunosorbent assay (ELISA) was used to measure salbutamol drug concentrations in serum and urine. The serum and urine salbutamol concentrations of the three groups were the highest in group B, followed by group C, and the lowest in group A. Serum and urine salbutamol concentrations significantly differed among the three groups (P < 0.05). It was found that the drug was statistically significant between group differences for groups B and A (P = 0.001; P = 0.002, respectively) for both serum and urine salbutamol concentrations. There were no significant differences observed among the other groups. It was found that the drug concentrations were the highest when the nebulizer was placed 80 cm away from the Y-piece, while the location between the tracheal tube and the Y-piece with the higher frequency of nebulizer placement was the location with the lowest drug concentration.

Application of aerosol therapy in respiratory diseases in children: A Saudi expert consensus

The Saudi Pediatric Pulmonology Association (SPPA) is a subsidiary of the Saudi Thoracic Society (STS), which consists of a group of Saudi experts with well-respected academic and clinical backgrounds in the fields of asthma and other respiratory diseases. The SPPA Expert Panel realized the need to draw up a clear, simple to understand, and easy to use guidance regarding the application of different aerosol therapies in respiratory diseases in children, due to the high prevalence and high economic burden of these diseases in Saudi Arabia. This statement was developed based on the available literature, new evidence, and experts' practice to come up with such consensuses about the usage of different aerosol therapies for the management of respiratory diseases in children (asthma and nonasthma) in different patient settings, including outpatient, emergency room, intensive care unit, and inpatient settings. For this purpose, SPPA has initiated and formed a national committee which consists of experts from concerned specialties (pediatric pulmonology, pediatric emergency, clinical pharmacology, pediatric respiratory therapy, as well as pediatric and neonatal intensive care). These committee members are from different healthcare sectors in Saudi Arabia (Ministry of Health, Ministry of Defence, Ministry of Education, and private healthcare sector). In addition to that, this committee is representing different regions in Saudi Arabia (Eastern, Central, and Western region). The subject was divided into several topics which were then assigned to at least two experts. The authors searched the literature according to their own strategies without central literature review. To achieve consensus, draft reports and recommendations were reviewed and voted on by the whole panel.

In vitro evaluation of disposable transport ventilators with combination aerosol therapy

Background

The COVID-19 pandemic has highlighted the need for alternative short-term, reliable means to aid in the treatment of patients requiring ventilatory support. Concurrent aerosol drug delivery is often prescribed to such patients. As such, this study examines one such short-term option, the disposable gas-powered transport ventilator to effectively deliver aerosol therapy. Factors such as aerosol generator type, patient breathing pattern, humidification and nebuliser position within the respiratory circuit were also examined.

Methods

Aerosol drug delivery characterisation was undertaken using two different disposable transport ventilators (DTVs). Two different nebuliser types, a closed circuit vibrating mesh nebuliser (VMN) and an open circuit jet nebuliser (JN), at different locations in a respiratory circuit, proximal and distal to an endotracheal tube (ETT), with and without passive humidification, were evaluated in simulated adult and paediatric patients.

Results

Placement of a nebuliser proximal to the ETT (VMN: 25.19%–34.15% and JN: 3.14%–8.92%), and the addition of a heat and moisture exchange filter (VMN: 32.37%–40.43% and JN: 5.60%–9.91%) resulted in the largest potential lung dose in the adult patient model. Irrespective of nebuliser position and humidification in the respiratory circuit, use of the VMN resulted in the largest potential lung dose (%). A similar trend was recorded in the paediatric model data, where the largest potential lung dose was recorded with both nebuliser types placed proximal to the ETT (VMN: 8.12%–10.89% and JN: 2.15%–3.82%). However, the addition of a heat and moisture exchange filter had no statistically significant effect on the potential lung dose (%) a paediatric patient would receive (p>>0.05).

Conclusions

This study demonstrates that transport ventilators, such as DTVs, can be used concurrently with aerosol generators to effectively deliver aerosolised medication in both adult and paediatric patients.

Pharmacodynamics of once- versus twice-daily dosing of nebulized amikacin in an in vitro Hollow-Fiber Infection Model against 3 clinical isolates of Pseudomonas aeruginosa

This study aims to compare the bacterial killing of once- versus twice-daily nebulized amikacin against Pseudomonas aeruginosa and to determine the optimal duration of therapy. Three clinical P. aeruginosa isolates (amikacin MICs 2, 8, and 64 mg/L) were exposed to simulated epithelial lining fluid exposures of nebulized amikacin with dosing regimens of 400 mg and 800 mg once- or twice-daily up to 7-days using the in vitro hollow-fiber infection model. Quantitative cultures were performed. Simulated amikacin dosing regimens of 400 mg twice-daily and 800 mg once-daily achieved ≥2-log reduction in the bacterial burden within the first 24-hours of therapy for all isolates tested. No dosing regimen suppressed the emergence of amikacin resistance. No difference in bacterial killing or regrowth was observed between 3- and 7-days of amikacin. Amikacin doses of 800 mg once-daily for up to 3-days may be considered for future clinical trials.

Comparative lung distribution of radiolabeled tobramycin between nebulized and intravenous administration in a mechanically-ventilated ovine model, an observational study

BACKGROUND

Ventilator-associated pneumonia is common and is treated using nebulized antibiotics. Although adequate pulmonary biodistribution is important for antibiotic effect, there is a lack of data for both intravenous (IV) and nebulized antibiotic administration during mechanical ventilation.

OBJECTIVE

To describe the comparative pulmonary regional distribution of IV and nebulized technetium-99m-labeled tobramycin (^99mTc-tobramycin) 400 mg in a mechanically-ventilated ovine model.

METHODS

The study was performed in a mechanically-ventilated ovine model. ^99mTc-tobramycin 400 mg was obtained using a radiolabeling process. Computed tomography (CT) was performed. Ten sheep were given ^99mTc-tobramycin 400 mg via either an IV (five sheep) or nebulized (five sheep) route. Planar images (dorsal, ventral, left lateral and right lateral) were obtained using a gamma camera. Blood samples were obtained every 15 min for 1 h (4 time points) and lung, liver, both kidney, and urine samples were obtained post-mortem.

RESULTS

Ten sheep were anesthetized and mechanically ventilated. Whole-lung deposition of nebulized ^99mTc-tobramycin 400 mg was significantly lower than with IV (8.8% vs. 57.1%, P<0.001). For both administration routes, there was significantly lower deposition in upper lung zones compared with the rest of the lungs. Dorsal deposition was significantly higher with nebulized ^99mTc-tobramycin 400 mg compared with IV (68.9% vs. 58.9%, P=0.003). Lung concentrations of ^99mTc-tobramycin were higher with IV compared with nebulized administration. There were significantly higher concentrations of ^99mTc-tobramycin in blood, liver and urine with IV administration compared with nebulized.

CONCLUSIONS

Nebulization resulted in lower whole and regional lung deposition of ^99mTc-tobramycin compared with IV administration and appeared to be associated with low blood and extra-pulmonary organ concentrations.

Pulmonary infections complicating ARDS

Pulmonary infection is one of the main complications occurring in patients suffering from acute respiratory distress syndrome (ARDS). Besides traditional risk factors, dysregulation of lung immune defenses and microbiota may play an important role in ARDS patients. Prone positioning does not seem to be associated with a higher risk of pulmonary infection. Although bacteria associated with ventilator-associated pneumonia (VAP) in ARDS patients are similar to those in patients without ARDS, atypical pathogens (Aspergillus, herpes simplex virus and cytomegalovirus) may also be responsible for infection in ARDS patients. Diagnosing pulmonary infection in ARDS patients is challenging, and requires a combination of clinical, biological and microbiological criteria. The role of modern tools (e.g., molecular methods, metagenomic sequencing, etc.) remains to be evaluated in this setting. One of the challenges of antimicrobial treatment is antibiotics diffusion into the lungs. Although targeted delivery of antibiotics using nebulization may be interesting, their place in ARDS patients remains to be explored. The use of extracorporeal membrane oxygenation in the most severe patients is associated with a high rate of infection and raises several challenges, diagnostic issues and pharmacokinetics/pharmacodynamics changes being at the top. Prevention of pulmonary infection is a key issue in ARDS patients, but there is no specific measure for these high-risk patients. Reinforcing preventive measures using bundles seems to be the best option.

The utilization of aerosol therapy in mechanical ventilation patients: a prospective multicenter observational cohort study and a review of the current evidence

Background

Aerosol delivery via mechanical ventilation has been reported to vary significantly among different intensive care units (ICU). The optimal technique for using each aerosol generator may need to be updated with the available evidence.

Methods

A 2-week prospective multicenter observational cohort study was implemented to record aerosol delivery for mechanically ventilated adult patients in Chinese ICUs. Our data included the type of aerosol device and its placement, ventilator type, humidification, and aerosolized medication administered. A guide for the optimal technique for aerosol delivery during mechanical ventilation was summarized after a thorough literature review.

Results

A total of 160 patients (105 males) from 28 ICUs were enrolled, of whom 125 (78.1%) received aerosol therapy via invasive ventilation. Among these 125 patients, 53 received ventilator-integrated jet nebulizer, with 64% (34/53) of them placed the nebulizer close to Y piece in the inspiratory limb. Further, 56 patients used continuous nebulizers, with 84% (47/56) of them placed the nebulizer close to the Y piece in the inspiratory limb. Of the 35 patients who received aerosol therapy via noninvasive ventilation, 30 received single limb ventilators and continuous nebulizers, with 70% (21/30) of them placed between the mask and exhalation port. Only 36% (58/160) of the patients received aerosol treatments consistent with optimal practice.

Conclusions

Aerosol delivery via mechanical ventilation varied between ICUs, and only 36% of the patients received aerosol treatments consistent with optimal practice. ICU clinicians should be educated on the best practices for aerosol therapy, and quality improvement projects aim to improve the quality and outcome of patients with the optimal technique for aerosol delivery during mechanical ventilation are warranted.

Interplay between SARS-CoV-2 and the type I interferon response

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the current COVID-19 pandemic. An unbalanced immune response, characterized by a weak production of type I interferons (IFN-Is) and an exacerbated release of proinflammatory cytokines, contributes to the severe forms of the disease. SARS-CoV-2 is genetically related to SARS-CoV and Middle East respiratory syndrome-related coronavirus (MERS-CoV), which caused outbreaks in 2003 and 2013, respectively. Although IFN treatment gave some encouraging results against SARS-CoV and MERS-CoV in animal models, its potential as a therapeutic against COVID-19 awaits validation. Here, we describe our current knowledge of the complex interplay between SARS-CoV-2 infection and the IFN system, highlighting some of the gaps that need to be filled for a better understanding of the underlying molecular mechanisms. In addition to the conserved IFN evasion strategies that are likely shared with SARS-CoV and MERS-CoV, novel counteraction mechanisms are being discovered in SARS-CoV-2-infected cells. Since the last coronavirus epidemic, we have made considerable progress in understanding the IFN-I response, including its spatiotemporal regulation and the prominent role of plasmacytoid dendritic cells (pDCs), which are the main IFN-I-producing cells. While awaiting the results of the many clinical trials that are evaluating the efficacy of IFN-I alone or in combination with antiviral molecules, we discuss the potential benefits of a well-timed IFN-I treatment and propose strategies to boost pDC-mediated IFN responses during the early stages of viral infection.

Pharmacokinetic Analysis of Epithelial/Endothelial Cell Barriers in Microfluidic Bilayer Devices with an Air-Liquid Interface

As the range of applications of organs-on-chips is broadening, the evaluation of aerosol-based therapies using a lung-on-a-chip model has become an attractive approach. Inhalation therapies are not only minimally invasive but also provide optimal pharmacokinetic conditions for drug absorption. As drug development evolves, it is likely that better screening through use of organs-on-chips can significantly save time and cost. In this work, bio-aerosols of various compounds including insulin were generated using a jet nebulizer. The aerosol flows were driven through microfluidic bilayer devices establishing an air–liquid interface to mimic the blood–air barrier in human small airways. The aerosol flow in the microfluidic devices has been characterized and adjusted to closely match physiological values. The permeability of several compounds, including paracellular and transcellular biomarkers, across epithelial/endothelial cell barriers was measured. Concentration–time plots were established in microfluidic devices with and without cells; the curves were then utilized to extract standard pharmacokinetic parameters such as the area under the curve, maximum concentration, and time to maximum concentration. The cell barrier significantly affected the measured pharmacokinetic parameters, as compound absorption through the barrier decreases with its increasing molecular size. Aerosolizing insulin can lead to the formation of fibrils, prior to its entry to the microfluidic device, with a substantially larger apparent molecular size effectively blocking its paracellular transport. The results demonstrate the advantage of using lung-on-a-chip for drug discovery with applications such as development of novel inhaled therapies.

Future Trends in Nebulized Therapies for Pulmonary Disease

Aerosol therapy is a key modality for drug delivery to the lungs of respiratory disease patients. Aerosol therapy improves therapeutic effects by directly targeting diseased lung regions for rapid onset of action, requiring smaller doses than oral or intravenous delivery and minimizing systemic side effects. In order to optimize treatment of critically ill patients, the efficacy of aerosol therapy depends on lung morphology, breathing patterns, aerosol droplet characteristics, disease, mechanical ventilation, pharmacokinetics, and the pharmacodynamics of cell-drug interactions. While aerosol characteristics are influenced by drug formulations and device mechanisms, most other factors are reliant on individual patient variables. This has led to increased efforts towards more personalized therapeutic approaches to optimize pulmonary drug delivery and improve selection of effective drug types for individual patients. Vibrating mesh nebulizers (VMN) are the dominant device in clinical trials involving mechanical ventilation and emerging drugs. In this review, we consider the use of VMN during mechanical ventilation in intensive care units. We aim to link VMN fundamentals to applications in mechanically ventilated patients and look to the future use of VMN in emerging personalized therapeutic drugs.

Evaluation of health-care providers' knowledge in the science of aerosol drug delivery: Educational sessions are necessary

BACKGROUND:

Aerosolized drugs are widely used to treat and control a variety of pulmonary diseases. However, there is increasing evidence that patients are unable to use their drug delivery device correctly. The failure of aerosolized treatment is usually the result of poorly communicated instructions. The aim of this investigation was to evaluate the knowledge of health-care providers in the science of aerosol drug delivery (ADD) and assess the impact of further education on their knowledge.

MATERIALS AND METHODS:

One hundred and seventeen health-care providers attended a 4-hour educational course on ADD science. The course was conducted from June to August 2018 in Jeddah, Riyadh, and Dammam. Pre-course assessment done with a 12-item multiple-choice questionnaire. Post-course assessment was conducted after the end of course in which participants were asked to rate their knowledge of ADD on a scale of 1–10 (before and after the course).

RESULTS:

Sixty-six health-care providers (physicians, pharmacists, respiratory therapists, and health educators) completed the course. The participants' clinical experience, on average (±standard deviation), was 7.6 ± 7.3 years. Clinical experience favored physicians over other groups. The precourse score for all participants was 3.2 ± 1.9 out of 12 and the postcourse score was 6.97 ± 2.7. There was a significant statistical difference between pre- and postcourse assessment scores (P < 0.05). Differences between the four specialties were insignificant (P = 0.216), without a correlation between clinical experience and preassessment scores (P = 0.202).

CONCLUSION:

The present data indicate that health-care providers' knowledge of ADD is completely inadequate. There is an urgent need to introduce an ADD educational package in the curricula. An annual competency-based evaluation for health-care providers is critical as well.

Lung Pharmacokinetics of Tobramycin by Intravenous and Nebulized Dosing in a Mechanically Ventilated Healthy Ovine Model

BACKGROUND

Nebulized antibiotics may be used to treat ventilator-associated pneumonia. In previous pharmacokinetic studies, lung interstitial space fluid concentrations have never been reported. The aim of the study was to compare intravenous and nebulized tobramycin concentrations in the lung interstitial space fluid, epithelial lining fluid, and plasma in mechanically ventilated sheep with healthy lungs.

METHODS

Ten anesthetized and mechanically ventilated healthy ewes underwent surgical insertion of microdialysis catheters in upper and lower lobes of both lungs and the jugular vein. Five ewes were given intravenous tobramycin 400 mg, and five were given nebulized tobramycin 400 mg. Microdialysis samples were collected every 20 min for 8 h. Bronchoalveolar lavage was performed at 1 and 6 h.

RESULTS

The peak lung interstitial space fluid concentrations were lower with intravenous tobramycin 20.2 mg/l (interquartile range, 12 mg/l, 26.2 mg/l) versus the nebulized route 48.3 mg/l (interquartile range, 8.7 mg/l, 513 mg/l), P = 0.002. For nebulized tobramycin, the median epithelial lining fluid concentrations were higher than the interstitial space fluid concentrations at 1 h (1,637; interquartile range, 650, 1,781, vs. 16 mg/l, interquartile range, 7, 86, P < 0.001) and 6 h (48, interquartile range, 17, 93, vs. 4 mg/l, interquartile range, 2, 9, P < 0.001). For intravenous tobramycin, the median epithelial lining fluid concentrations were lower than the interstitial space fluid concentrations at 1 h (0.19, interquartile range, 0.11, 0.31, vs. 18.5 mg/l, interquartile range, 9.8, 23.4, P < 0.001) and 6 h (0.34, interquartile range, 0.2, 0.48, vs. 3.2 mg/l, interquartile range, 0.9, 4.4, P < 0.001).

CONCLUSIONS

Compared with intravenous tobramycin, nebulized tobramycin achieved higher lung interstitial fluid and epithelial lining fluid concentrations without increasing systemic concentrations.

Aerosol Therapy for Pneumonia in the Intensive Care Unit

Antibiotic aerosolization in patients with ventilator-associated pneumonia (VAP) allows very high concentrations of antimicrobial agents in the respiratory secretions, far more than those achievable using the intravenous route. However, data in critically ill patients with pneumonia are limited. Administration of aerosolized antibiotics might increase the likelihood of clinical resolution, but no significant improvements in important outcomes have been consistently documented. Thus, aerosolized antibiotics should be restricted to the treatment of extensively resistant gram-negative pneumonia. In these cases, the use of a vibrating-mesh nebulizer seems to be more efficient, but specific settings and conditions are required to improve lung delivery.

The effect of aerosolized indomethacin on lung inflammation and injury in a rat model of blunt chest trauma

Background

Acute lung contusion from blunt chest trauma (BCT) is characterized by an intense inflammatory response in the pulmonary parenchyma, which is associated with acute lung injury (ALI), acute respiratory distress syndrome and ventilator-associated pneumonia. We hypothesized that aerosolized indomethacin may reduce pulmonary inflammation and ALI in a rat model of BCT.

Methods

Sprague-Dawley rats were anesthetized and received a tracheotomy for administration of aerosolized medication through a catheter. The BCT procedure involved free-dropping a hollow metal weight (200 g) from a height of 25.5, 38.3 or 51.2 cm onto the right thorax. We administered 1 mg/kg of indomethacin or 1 mL/kg of saline intratracheally 15 minutes after BCT. The sham group had a similar procedure without the exposure to BCT and treatment. Three hours postimpact, we obtained arterial blood gas and analyzed bronchoalveolar lavage for protein concentration, polymorphonuclear leukocytes (PMN) and cytokine levels, and lung tissue samples were taken for histopathological analysis.

Results

The rats’ mean arterial pressure and heart rate dropped immediately postimpact but recovered close to that of the sham group after 30 minutes in both control and treatment groups. Compared to BCT alone, indomethacin significantly reduced the total protein level in the lungs (1.06 ± 0.39 mg/mL v. 3.75 ± 1.95 mg/mL, p = 0.006) and alveolar FD-70 leak (0.23 ± 0.19 μg/mL v. 0.53 ± 0.19 μg/mL, p = 0.02). Indomethacin also significantly attenuated the acute inflammatory response in percent PMN (13.33 ±7.5% v. 28.0 ± 12.96%, p = 0.04). Tumour necrosis factor-α and interleukin-6 decreased in the indomethacin group, but the decreases were not significant compared with other groups.

Conclusion

Aerosolized indomethacin has a protective effect against alveloar tissue permeability and inflammatory response induced by BCT.

Effect of Jet Nebulization on Noninvasive Positive-Pressure Ventilation Administered with Noninvasive or Intensive Care Unit Ventilators: A Bench Study

BACKGROUND

Most of the patients on noninvasive positive pressure ventilation require aerosol inhalation therapy to moisturize the airways or deliver drugs in acute settings. However, the effect of jet nebulization on noninvasive positive pressure ventilation (NPPV) has not been determined.

OBJECTIVES

This study was designed to investigate the impact of jet nebulization on NPPV applied in ventilators.

METHODS

Aerosol therapy during NPPV was conducted in a simulated lung. The jet nebulizer was connected at both the distal and proximal end of the exhalation valve for the noninvasive ventilators, while it was placed both in front of the Y tube proximal to the patient and at 15 cm distance from the Y-tube inspiratory limb distal to the patient for the intensive care unit (ICU) ventilators. Driving flow was set at 4 and 8 L/min, respectively.

RESULTS

TPmin (time from the beginning of the lung simulator's inspiratory effort to the lowest value of airway pressure needed to trigger the ventilator), Ttrig (time to trigger), and Ptrig (the magnitude of airway pressure drop needed to trigger) were not significantly altered by jet nebulization in the noninvasive ventilators, while they were significantly increased in the ICU ventilators. The greater the driving flow, the stronger the impact on TPmin, Ttrig, and Ptrig. The actual tidal volume and control performance were not significantly affected by jet nebulization in either noninvasive or ICU ventilators. The tidal volume monitored was significantly increased at 8 L/min driving flow. The greater the driving flow, the stronger the impact on the tidal volume monitored.

CONCLUSION

The effect of jet nebulization on NPPV was different when compared to invasive ventilation. Jet nebulization only affected the tidal volume monitored in the noninvasive ventilator. Jet nebulization also affected the triggering performance and tidal volume monitored in the ICU ventilator.