Differential Medical Aerosol Device and Interface Selection in Patients during Spontaneous, Conventional Mechanical and Noninvasive Ventilation

Does Valved Holding Chamber Improve Aerosol Lung Deposition with a Jet Nebulizer? A Randomized Crossover Study

Using valved holding chambers (VHC) during aerosol therapy has been reported to improve the inhaled dose with various aerosol devices, including vibrating mesh nebulizers. The aim of this study was to quantify the pulmonary deposition of a jet nebulizer (JN) with and without a VHC, and a mesh nebulizer (MN) with a VHC in a randomized cross-over trial with seven healthy consenting adults. Our hypothesis was that the use of a VHC would improve deposition with the JN. Diethylnitriaminopentacetic acid with technetium (DTPA-Tc99m), with the activity of 1 mC with 0.9% saline solution was nebulized. The radiolabeled aerosol was detected by 2D planar scintigraphy after administration. The pulmonary deposition was greater with a JN with a VHC (4.5%) than a JN alone (3.2%; p = 0.005. However, an MN with a VHC (30.0%) was six-fold greater than a JN or JN with a VHC (p < 0.001). The extrapulmonary deposition was higher in the JN group without a VHC than in the other two modalities (p < 0.001). Deposition in the device was greater with a JN + VHC than an MN+/VHC (p < 0.001). Lower residual drug at the end of the dose was detected with an MN than either JN configuration. The exhaled dose was greater with a JN alone than either an MN or JN with VHC (p < 0.001). In conclusion, the addition of the VHC did not substantially improve the efficiency of aerosol lung deposition over a JN alone.

A bench-to-bedside study about trigger asynchronies induced by the introduction of external gas into the non-invasive mechanical ventilation circuit

Treatments that require the introduction of external gas into the non-invasive ventilation (NIV) circuit, such as aerosol and oxygen therapy, may influence the performance of the ventilator trigger system. The aim of the study was to determine the presence and type of asynchronies induced by external gas in the NIV circuit in a bench model and in a group of patients undergoing chronic NIV. Bench study: Four ventilators (one with two different trigger design types) and three gas sources (continuous flow at 4 and 9 l/min and pulsatile flow at 9 l/min) were selected in an active simulator model. The sensitivity of the trigger, the gas introduction position, the ventilatory pattern and the level of effort were also modified. The same ventilators and gas conditions were used in patients undergoing chronic NIV. Bench: the introduction of external gas caused asynchronies in 35.9% of cases (autotriggering 73%, ineffective effort 27%). Significant differences (p < 0.01) were detected according to the ventilator model and the gas source. In seven patients, the introduction of external gas induced asynchrony in 20.4% of situations (77% autotriggering). As in the bench study, there were differences in the occurrence of asynchronies depending on the ventilator model and gas source used. The introduction of external gas produces alterations in the ventilator trigger. These alterations are variable, and depend on the ventilator design and gas source. This phenomenon makes it advisable to monitor the patient at the start of treatment.

Treating COPD Patients with Inhaled Medications in the Era of COVID-19 and Beyond: Options and Rationales for Patients at Home

COVID-19 has affected millions of patients, caregivers, and clinicians around the world. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads via droplets and close contact from person to person, and there has been an increased concern regarding aerosol drug delivery due to the potential aerosolizing of viral particles. To date, little focus has been given to aerosol drug delivery to patients with COVID-19 treated at home to minimize their hospital utilization. Since most hospitals were stressed with multiple admissions and experienced restricted healthcare resources in the era of COVID-19 pandemic, treating patients with COPD at home became essential to minimize their hospital utilization. However, guidance on how to deliver aerosolized medications safely and effectively to this patient population treated at home is still lacking. In this paper, we provide some strategies and rationales for device and interface selection, delivery technique, and infection control for patients with COPD who are being treated at home in the era of COVID-19 and beyond.

Inhaled bacteriophage therapy in a porcine model of pneumonia caused by Pseudomonas aeruginosa during mechanical ventilation

BACKGROUND AND PURPOSE 255: Pseudomonas aeruginosa is a main cause of ventilator-associated pneumonia (VAP) with drug-resistant bacteria. Bacteriophage therapy has experienced resurgence to compensate for the limited development of novel antibiotics. However, phage therapy is limited to a compassionate use so far, resulting from lack of adequate studies in relevant pharmacological models. We used a pig model of pneumonia caused by P. aeruginosa that recapitulates essential features of human disease to study the antimicrobial efficacy of nebulized-phage therapy.

EXPERIMENTAL APPROACH

(i) Lysis kinetic assays were performed to evaluate in vitro phage antibacterial efficacy against P. aeruginosa and select relevant combinations of lytic phages. (ii) The efficacy of the phage combinations was investigated in vivo (murine model of P. aeruginosa lung infection). (iii) We determined the optimal conditions to ensure efficient phage delivery by aerosol during mechanical ventilation. (iv) Lung antimicrobial efficacy of inhaled-phage therapy was evaluated in pigs, which were anaesthetized, mechanically ventilated and infected with P. aeruginosa.

KEY RESULTS

By selecting an active phage cocktail and optimizing aerosol delivery conditions, we were able to deliver high phage concentrations in the lungs, which resulted in a rapid and marked reduction in P. aeruginosa density (1.5-log reduction, p < .001). No infective phage was detected in the sera and urines throughout the experiment.

CONCLUSION AND IMPLICATIONS

Our findings demonstrated (i) the feasibility of delivering large amounts of active phages by nebulization during mechanical ventilation and (ii) rapid control of in situ infection by inhaled bacteriophage in an experimental model of P. aeruginosa pneumonia with high translational value.

Comparison of Vibrating Mesh and Jet Nebulizers During Noninvasive Ventilation in Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Background: Advances in aerosol technology have improved drug delivery efficiency during noninvasive ventilation (NIV). Clinical evaluation of the efficacy of aerosol therapy during NIV in the treatment of acute exacerbation of chronic obstructive pulmonary disease (COPD) is very limited. The aim of our study was to compare the efficacy of bronchodilators administered through a vibrating mesh nebulizer (VMN) and jet nebulizer (JN) during NIV in patients with acute exacerbation of COPD. Methods: Prospective randomized cross-over study included 30 patients treated with NIV for acute exacerbation of COPD in an acute care hospital. Patients were consented and enrolled after stabilization of acute exacerbation (3-5 days after admission). Subjects were randomly assigned into two treatment arms receiving salbutamol (2.5 mg): with VMN (Aerogen Solo) and JN (Sidestream) positioned between the leak port and the nonvented oronasal mask during bilevel ventilation with a single-limb circuit. Measurements (clinical data, pulmonary function tests [PFTs], and arterial blood gases) were performed at baseline, 1, and 2 hours after treatment. Results: All measured PFT parameters significantly increased in both groups, but numerically results were better after inhalation with VMN than with JN: for forced expiratory volume in 1 second (FEV₁) (mean increase from baseline to 120 minutes-165 ± 64 mL vs. 116 ± 46 mL, p = 0.001) and for forced vital capacity (FVC) (mean increase-394 ± 154 mL vs. 123 ± 57 mL, p < 0.001). There was also a statistically significant reduction in respiratory rate and in Borg dyspnea score after therapy with VMN in comparison with the conventional JN. In both groups, there were improvements in PaCO₂, but with VMN these changes were significantly higher. Conclusion: Bronchodilator administration in patients with acute exacerbation of COPD during NIV with VMN resulted in clinically significant improvements in FVC and in Borg dyspnea score. Additional studies required to determine the impact on clinical outcomes.

Optimal Connection for Tiotropium SMI Delivery through Mechanical Ventilation: An In Vitro Study

We aimed to quantify Soft Mist Inhalers (SMI) delivery to spontaneous breathing model and compare with different adapters via endotracheal tube during mechanical ventilation or by manual resuscitation. A tiotropium SMI was used with a commercial in-line adapter and a T-adapter placed between the Y-adapter and the inspiratory limb of the ventilator circuit during mechanical ventilation. The SMI was actuated at the beginning of inspiration and expiration. In separate experiments, a manual resuscitator with T-adapter was attached to endotracheal tube, collecting filter, and a passive test lung. Drug was eluted from collecting filters with salt-based solvent and analyzed using high-performance liquid chromatography. Results showed the percent of SMI label dose inhaled was 3-fold higher with the commercial in-line adapter with actuation during expiration than when synchronized with inspiration. SMI with T-adapter delivery via ventilator was similar to inhalation (1.20%) or exhalation (1.02%), and both had lower delivery dose than with manual resuscitator (2.80%; p = 0.01). The inhaled dose via endotracheal tube was much lower than inhaled dose with spontaneous breathing (22.08%). In conclusion, the inhaled dose with the commercial adapter was higher with SMI actuated during expiration, but still far less than reported spontaneous inhaled dose.

Recent advances in aerosol devices for the delivery of inhaled medications

Introduction: Aerosolized medications are commonly prescribed for the treatment of patients with pulmonary diseases, and there has been an increased interest in the development of aerosol delivery devices over the years. Technical innovations have advanced device design, novel features such as breath actuation, dose tracking, portability, and feedback mechanism during treatment that improved the performance of aerosol devices, and effectiveness of inhalation therapy.Areas covered: The purpose of this paper is to review recent advances in aerosol devices for delivery of inhaled medications.Expert opinion: Drug formulations and device designs are rapidly evolving to make more consistent dosing across a broad range of inspiratory efforts, to maximize dose and target specific areas of the diseased lung.

An immune cell spray (ICS) formulation allows for the delivery of functional monocyte/macrophages

Macrophages are key cells of the innate immune system and act as tissue resident macrophages (TRMs) in the homeostasis of various tissues. Given their unique functions and therapeutic use as well as the feasibility to derive macrophages in vitro from hematopoietic stem cell (HSC) sources, we propose an “easy-to-use” immune cell spray (ICS) formulation to effectively deliver HSC-derived macrophages. To achieve this aim, we used classical pump spray devices to spray either the human myeloid cell line U937 or primary murine HSC-derived macrophages. For both cell types used, one puff could deliver cells with maintained morphology and functionality. Of note, cells tolerated the spraying process very well with a recovery of more than 90%. In addition, we used osmotic preconditioning to reduce the overall cell size of macrophages. While a 800 mosm hyperosmolar sucrose solution was able to reduce the cell size by 27%, we identified 600 mosm to be effective to reduce the cell size by 15% while maintaining macrophage morphology and functionality. Using an isolated perfused rat lung preparation, the combinatorial use of the ICS with preconditioned and genetically labeled U937 cells allowed the intra-pulmonary delivery of cells, thus paving the way for a new cell delivery platform.

Effect of Nebulizer Location and Spontaneous Breathing on Aerosol Delivery During Airway Pressure Release Ventilation in Bench Testing

BACKGROUND

Airway pressure release ventilation (APRV) maintains a sustained airway pressure over a large proportion of the respiratory cycle, and has a long inspiratory time at high pressure. The purpose of this study was to determine the influence of the APRV with and without spontaneous breathing on albuterol aerosol delivery with a continuous vibrating-mesh nebulizer (VMN) placed at different positions on an adult lung model of invasive mechanical ventilation.

METHODS

An adult lung model was assembled by connecting a ventilator with a dual-limb circuit to an 8-mm inner diameter endotracheal tube (ETT) and collecting filter attached to a test lung with set compliance of 0.1 L/cmH₂O and resistance of 0.5 cmH₂O/(L·s). Four ventilator modes were compared: pressure control ventilation (PCV) with no bias flow, PCV with bias flow of 6 L/min (PCV_BF6), APRV with no spontaneous breaths (APRV), and APRV with spontaneous breath trigger (APRVs). Peak inspiratory pressure, peak end-expiratory pressure, aerosol dose, and nebulization time were similar for all modes. The VMN was placed (1) between Y-piece and inspiratory limb, (2) at the gas outlet of a heated humidifier, and (3) at the gas inlet of a heated humidifier. Albuterol sulfate (5 mg/2.5 mL) was administered with each run and collected on a filter distal to the ETT. Deposited drug was eluted from each filter (purified water) and analyzed by UV spectrophotometry at 276 nm. Analysis of variance [general linear model (GLM) multivariate] was performed using the linear model of multiple variables, significance at p < 0.05.

RESULTS

Albuterol (in micrograms, mean ± standard deviation) delivered was higher with VMN placed at the gas inlet of the humidifier with each mode of ventilation (p < 0.01). APRVs has the highest albuterol delivery followed by PCV, PCV_BF6, and APRV (1706.2 ± 60.9 μg vs. 1490.6 ± 61.1 μg vs. 1182.3 ± 61.4 μg vs. 1153.1 ± 99.7 μg, respectively, p < 0.001). The minute volume was positively correlated with the inhaled albuterol dose.

CONCLUSIONS

Spontaneous breathing increased the albuterol delivery during APRV, compared with APRV alone and PCV modes. Placing the nebulizer proximal to the ventilator was more efficient for all modes tested.

Inhalation Techniques Used in Patients with Respiratory Failure Treated with Noninvasive Mechanical Ventilation

The administration of aerosolized medication is a basic therapy for patients with numerous respiratory tract diseases, including obstructive airway diseases (OADs), cystic fibrosis (CF), and infectious airway diseases. The management and care for patients requiring mechanical ventilation remains one of the greatest challenges for medical practitioners, both in intensive care units (ICUs) and pulmonology wards. Aerosol therapy is often necessary for patients receiving noninvasive ventilation (NIV), which may be stopped for the time of drug delivery and administered through a metered-dose inhaler or nebulizer in the traditional way. However, in most severe cases, this may result in rapid deterioration of the patient's clinical condition. Unfortunately, only limited number of original well-planned studies addressed this problem. Due to inconsistent information coming from small studies, there is a need for more precise data coming from large prospective real life studies on inhalation techniques in patients receiving NIV.

Drug delivery to the lungs: challenges and opportunities

Pulmonary drug delivery is relatively complex because the respiratory tract has evolved defense mechanisms to keep inhaled drug particles out of the lungs and to remove or inactivate them once deposited. In addition to these mechanical, chemical and immunological barriers, pulmonary drug delivery is adversely affected by the behavioral barriers of poor adherence and poor inhaler technique. Strategies to mitigate the effects of these barriers include use of inhaler devices and formulations that deliver drug to the lungs efficiently, appropriate inhaler technique and improved education of patients. Owing to the advantages offered by the pulmonary route, the challenges that the route poses are worth addressing, and if successfully addressed, the pulmonary route offers huge opportunities, often fulfilling unmet clinical needs.

Inhaled colistin monotherapy for respiratory tract infections in adults without cystic fibrosis: a systematic review and meta-analysis

BACKGROUND

Inhaled colistin is becoming increasingly popular against respiratory tract infections caused by multidrug resistant (MDR) Gram-negative bacteria because it may overcome the problems associated with intravenous (IV) administration.

OBJECTIVE

To investigate the effectiveness and safety of inhaled colistin as monotherapy (without concomitant IV administration of colistin) in the treatment of respiratory tract infections caused by MDR or colistin-only susceptible Gram-negative bacteria.

METHODS

PubMed and Scopus databases were searched. A systematic review and meta-analysis were conducted.

RESULTS

Twelve studies (373 patients receiving inhaled colistin for respiratory tract infection) were included. Ten studies evaluated patients with pneumonia (including 8 studies with ventilator-associated pneumonia) and 2 studies evaluated patients with ventilator-associated tracheobronchitis. Patients with infections due to MDR Acinetobacter baumannii and Pseudomonas aeruginosa were mainly studied. Daily dose of inhaled colistin and treatment duration varied in the individual studies. The pooled all-cause mortality was 33.8% (95% CI 24.6% - 43.6%), clinical success was 70.4% (58.5% - 81.1%) and eradication of Gram-negative bacteria was shown in 71.3% (57.6% - 83.2%) of cases.

CONCLUSIONS

Inhaled colistin monotherapy may deserve further consideration as a mode for colistin administration for the treatment of respiratory tract infections caused by MDR A. baumannii and P. aeruginosa.

Inhalation therapy in patients with tracheostomy: a guide to clinicians

INTRODUCTION

Inhalation therapy has become a popular procedure for the treatment of patients with tracheostomy. However, clinicians are faced with many challenges during inhalation therapy because of the many factors affecting aerosol therapy to this patient population, and the lack of literature providing guidance in this area of research. Areas covered: The purpose of this paper is to describe the factors affecting aerosol drug delivery to patients with tracheostomy and to explain how to optimize inhalation therapy through device selection, interface selection and delivery technique in this patient population. Expert commentary: Many factors affect inhalation therapy in this patient population and without understanding the impact of these factors on aerosol drug delivery, clinicians will not be able to provide the treatment properly and patients may not benefit from prescribed medications. In the next 5 years, aerosol medicine will continue to experience tremendous growth with new devices and drug/device combinations. However, these advances will have minimal impact on inhalation therapy in patients with tracheostomy unless we provide guidance and training to clinicians on optimizing aerosol drug delivery to this patient population.

Creation of a protective pulmonary bioshield against inhaled organophosphates using an aerosolized bioscavenger

In addition to the global use of organophosphate (OP) pesticides for agriculture, OP nerve agents and pesticides have been employed on battlefields and by terrorists (e.g., a recent sarin attack in Syria). These occurrences highlight the need for an effective countermeasure against OP exposure. Human butyrylcholinesterase (HuBChE) is a leading candidate, but injection of the high doses required for protection present pharmacokinetic challenges. An aerosolized recombinant form (aer-rHuBChE) that can neutralize inhaled OPs at the portal of entry has been assessed for its efficacy in protecting macaques against respiratory toxicity following inhalation exposure to the pesticide paraoxon (aer-Px). While protection in macaques has been demonstrated using the MicroSprayer® delivery device, administration to humans will likely employ a vibrating mesh nebulizer (VMN). Compared to the 50-70% lung deposition achieved in adult humans with a VMN, deposition in macaques is <5%, an initial major obstacle to demonstrating protection. Such problems have been partly overcome by using a more efficient modified VMN and proportionally higher doses, which together generate an effective rHuBChE pulmonary bioshield and protect against high levels of inhaled Px.