Performance Characterisation of the Airvo2TM Nebuliser Adapter in Combination with the Aerogen SoloTM Vibrating Mesh Nebuliser for in Line Aerosol Therapy during High Flow Nasal Oxygen Therapy

High flow oxygen (HFO) therapy is a well-established treatment in respiratory disease. Concurrent aerosol delivery can greatly expediate their recovery. The aim of this work was to complete a comprehensive characterisation of one such HFO therapy system, the Airvo2TM, used in combination with the Aerogen SoloTM vibrating mesh nebuliser. Representative adult, infant, and paediatric head models were connected to a breathing simulator via a collection filter placed at the level of the trachea. A tracheostomy interface and nasal cannulas were used to deliver the aerosol. Cannula size and gas flow rate were varied across the full operating range recommended by the manufacturer. The tracheal and emitted doses were quantified via UV-spectrophotometry. The aerosol droplet diameter at the exit of the nares and tracheal interface was measured via cascade impaction. High gas flow rates resulted in low emitted and tracheal doses (%). Nasal cannula size had no significant effect on the tracheal dose (%) available in infant and paediatric models. Higher gas flow rates resulted in smaller aerosol droplets at the exit of the nares and tracheostomy interface. Gas flow rate was found to be the primary parameter affecting aerosol delivery. Thus, gas flow rates should be kept low and where possible, delivered using larger nasal cannulas to maximise aerosol delivery.

Bronchodilator Efficacy of High-Flow Nasal Cannula in COPD: Vibrating Mesh Nebulizer Versus Jet Nebulizer

BACKGROUND

Jet nebulizers are commonly used for bronchodilator therapy in COPD. High-flow nasal cannula with vibrating mesh nebulizer (HFNC-VMN) is a recently developed system; however, few studies have compared the efficacy of bronchodilator administration via HFNC-VMN to jet nebulizer in stable COPD. This study aimed to compare the effect of salbutamol administered via HFNC-VMN versus jet nebulizer on airway and lung function in subjects with stable COPD.

METHODS

This randomized non-inferiority crossover physiologic study enrolled subjects with stable COPD. Salbutamol was nebulized via HFNC-VMN or jet nebulizer in random order with a 4-h washout period between crossover sequences. Spirometry, lung volume, and impulse oscillometry were performed at baseline and after each intervention. The primary outcome was change in FEV1 from baseline. Secondary outcomes included changes in other respiratory-related parameters and nebulization time compared between the 2 devices.

RESULTS

Seventeen subjects were enrolled. HFNC-VMN and jet nebulizer both significantly improved FEV1 from baseline (P = .005 and P = .002, respectively). The difference between respiratory resistance at 5 Hz and 20 Hz significantly decreased after HFNC-VMN compared to baseline (P = .02), while no significant change was observed after jet nebulizer (P = .056). Area of reactance and resonant frequency of reactance were both significantly decreased (P = .035 and P = .03, respectively), and respiratory reactance at 5 Hz significantly increased (P = .02) in the HFNC-VMN group compared to baseline indicating improved lung mechanics, with no significant changes with the jet nebulizer. HFNC-VMN had a shorter nebulization time (6 [5-9] min vs 20 [16-22] min, respectively, P < .001).

CONCLUSIONS

Bronchodilator therapy via HFNC-VMN was not inferior to jet nebulizer for subjects with stable COPD and can significantly improve airway oscillometry mechanics and decrease nebulization time compared to jet nebulizer.

In-Line Aerosol Therapy via Nasal Cannula during Adult and Paediatric Normal, Obstructive, and Restrictive Breathing

High-flow nasal oxygen therapy is being increasingly adopted in intensive and home care settings. The concurrent delivery of aerosolised therapeutics allows for the targeted treatment of respiratory illnesses. This study examined in-line aerosol therapy via a nasal cannula to simulated adult and paediatric models with healthy, obstructive and restrictive lung types. The Aerogen Solo vibrating mesh nebuliser was used in combination with the InspiredTM O2FLO high-flow therapy system. Representative adult and paediatric head models were connected to a breathing simulator, which replicated several different states of lung health. The aerosol delivery was quantified at the tracheal level using UV-spectrophotometry. Testing was performed at a range of supplemental gas flow rates applicable to both models. Positive end-expiratory pressure was measured pre-, during and post-nebulisation. The increases in supplemental gas flow rates resulted in a decrease in aerosol delivery, irrespective of lung health. Large tidal volumes and extended inspiratory phases were associated with the greatest aerosol delivery. Gas flow to inspiratory flow ratios of 0.29-0.5 were found to be optimum for aerosol delivery. To enhance aerosol delivery to patients receiving high-flow nasal oxygen therapy, respiratory therapists should keep supplemental gas-flow rates below the inspiratory flow of the patient.

Comparative Study of Inhaled Fluticasone Versus Oral Prednisone in 30 Dogs with Cough and Tracheal Collapse

Coughing is common in dogs with tracheal collapse (TC). The use of inhaled corticosteroids is less widespread than oral ones. This study aims to compare the effects of oral and inhaled corticosteroids in dogs with cough and TC. Thirty dogs were prospectively included and randomized to the prednisone oral group (OG, 14) or fluticasone inhaled group (IG, 16). A clinical score (CS) based on four clinical parameters (respiratory distress, cough episodes, cough frequency, tracheal sensitivity) was monitored at the hospital (enrolment and weeks 2 and 4). Water intake, urination habits, and adherence and tolerance to treatments were monitored weekly. Significant improvements in clinical parameters were identified in both groups throughout the study. Between-group (OG-IG) comparisons revealed no significant differences, indicating equivalent improvement. At the study's endpoint, the IG dogs had a significantly lower CS (5.69 ± 0.79) than OG dogs (6.43 ± 1.02, p < 0.05). Adherence and tolerance were comparable. From weeks 2 to 4, OG dogs were significantly thirstier and urinated more frequently than IG dogs. In conclusion, fluticasone provided good tolerability and efficacy in controlling cough in dogs with TC, and they showed a lower incidence of signs of hypercortisolism compared to prednisone. These data encourage the use of inhaled fluticasone in dogs with cough and TC.

Respiratory Care Management of COPD Exacerbations

A COPD exacerbation is characterized by an increase in symptoms such as dyspnea, cough, and sputum production that worsens over a period of 2 weeks. Exacerbations are common. Respiratory therapists and physicians in an acute care setting often treat these patients. Targeted O₂ therapy improves outcomes and should be titrated to an S_pO2 of 88-92%. Arterial blood gases remain the standard approach to assessing gas exchange in patients with COPD exacerbation. The limitations of arterial blood gas surrogates (pulse oximetry, capnography, transcutaneous monitoring, peripheral venous blood gases) should be appreciated so that they can be used wisely. Inhaled short-acting bronchodilators can be provided by nebulizer (jet or mesh), pressurized metered-dose inhaler (pMDI), pMDI with spacer or valved holding chamber, soft mist inhaler, or dry powder inhaler. The available evidence for the use of heliox for COPD exacerbation is weak. Noninvasive ventilation (NIV) is standard therapy for patients who present with COPD exacerbation and is supported by clinical practice guidelines. Robust high-level evidence with patient important outcomes is lacking for the use of high-flow nasal cannula in patients with COPD exacerbation. Management of auto-PEEP is the priority in mechanically ventilated patients with COPD. This is achieved by reducing airway resistance and decreasing minute ventilation. Trigger asynchrony and cycle asynchrony are addressed to improve patient-ventilator interaction. Patients with COPD should be extubated to NIV. Additional high-level evidence is needed before widespread use of extracorporeal CO₂ removal. Care coordination can improve the effectiveness of care for patients with COPD exacerbation. Evidence-based practices improve outcomes in patients with COPD exacerbation.

Minimizing Aerosol Leakage from Facemasks in the COVID-19 Pandemic

Background: Aerosol therapies with vented facemasks are considered a risk for nosocomial transmission of viruses such as severe acute respiratory syndrome coronavirus 2. The transmission risk can be decreased by minimizing aerosol leakage and filtering the exhaled air. Objective: In this study, we determined which closed facemask designs show the least leakage. Methods: Smoke leakage was quantified during in- and exhalation in a closed system with expiration filter for three infant, six child, and six adult facemasks (three times each mask), using age-appropriate anatomical face models and breathing patterns. To assess leakage, smoke release was recorded and cumulative average pixel intensity (cAPI) was calculated. Results: In the adult group, aircushion edges resulted in less leakage than soft edges (cAPI: 407 ± 250 vs. 774 ± 152) (p = 0.004). The Intersurgical^® Economy 5 mask (cAPI: 146 ± 87) also released less smoke than the Intersurgical^® Clearlite 5 (cAPI: 748 ± 68) mask with the same size, but different geometry and edge type (p-value <0.05). Moreover, mask size had an effect, as there was a difference between Intersurgical^® Economy 4 (cAPI: 708 ± 346) and 5, which have the same geometry but a different size (p-value <0.05). Finally, repositioning masks increased the standard deviations. Mask leakage was not dependent on breathing patterns within the child group. Conclusions: Mask leakage can be minimized by using a closed system with a well-fitting mask that is appropriately positioned. To decrease leakage, and therewith minimize potential viral transmission, selecting a well-fitting mask with an aircushion edge is to be recommended.

Optimal delivery of aerosolized medication to mechanically ventilated pediatric and neonatal patients: A scoping review

Objectives

Delivering aerosolized medication to patients during mechanical ventilation is a common practice in respiratory therapy for adult, pediatric, and neonatal populations. However, aerosol delivery in pediatric populations is inconsistent and challenging, impacting how the drug is delivered. Some factors that influence drug delivery efficiency are directly under the purview of the clinician or therapist administering the drugs. However, excessive variability exists amongst clinicians and therapists working at the same site and between different sites. This review aims to systematically summarize the literature to identify current practice variations, identify common practices, and provide suggestions to guide future research in this area. In addition, this scoping review aims to identify the available evidence and knowledge gaps in the literature regarding the delivery of aerosolized medication to pediatric populations during mechanical ventilation. More specifically, the question that guided our research was: What are the best strategies for optimizing aerosol delivery of medication to pediatric patients, including neonates, while on mechanical ventilation?

Methods

A scoping review, using the Joanna Briggs Institute methodology, was conducted until September 2022 in the CINAHL, EMBASE (Ovid), and Medline (Ovid) databases. Our initial search yielded 248 articles. After screening the titles, abstracts, and full text of the articles according to inclusion and exclusion criteria, five articles were analyzed.

Results

We identified three main topics for discussion: the type of device used for administering aerosolized medication, appropriate mechanical ventilation settings, and optimal placement of the nebulizer delivery system.

Conclusion

Of the three topics we intended to discuss, we only found enough evidence to suggest using mesh nebulizers to increase aerosol deposition. We found conflicting or outdated results for the other two topics. This demonstrates a significant gap in the literature since aerosol medications are routinely administered to mechanically ventilated neonatal and other pediatric patients.

Aerosol release, distribution, and prevention during aerosol therapy: a simulated model for infection control

Aerosol therapy is used to deliver medical therapeutics directly to the airways to treat respiratory conditions. A potential consequence of this form of treatment is the release of fugitive aerosols, both patient derived and medical, into the environment and the subsequent exposure of caregivers and bystanders to potential viral infections. This study examined the release of these fugitive aerosols during a standard aerosol therapy to a simulated adult patient. An aerosol holding chamber and mouthpiece were connected to a representative head model and breathing simulator. A combination of laser and Schlieren imaging was used to non-invasively visualize the release and dispersion of fugitive aerosol particles. Time-varying aerosol particle number concentrations and size distributions were measured with optical particle sizers at clinically relevant positions to the simulated patient. The influence of breathing pattern, normal and distressed, supplemental air flow, at 0.2 and 6 LPM, and the addition of a bacterial filter to the exhalation port of the mouthpiece were assessed. Images showed large quantities of fugitive aerosols emitted from the unfiltered mouthpiece. The images and particle counter data show that the addition of a bacterial filter limited the release of these fugitive aerosols, with the peak fugitive aerosol concentrations decreasing by 47.3-83.3%, depending on distance from the simulated patient. The addition of a bacterial filter to the mouthpiece significantly reduces the levels of fugitive aerosols emitted during a simulated aerosol therapy, p≤ .05, and would greatly aid in reducing healthcare worker and bystander exposure to potentially harmful fugitive aerosols.

[Using the Model of Motivation to Improve the Accuracy of Nurses Conducting Aerosol Therapy in Mechanically Ventilated Patients]

ACKGROUND & PROBLEMS

Aerosol therapy is increasingly used in pulmonary critical care and in patients with respiratory disease. However, improper application of the aerosol delivery device will decrease the therapeutic effect as well as increase the incidence of pulmonary infection. An initial assessment conducted in our intensive care unit found an accuracy rate for nursing staff aerosol-therapy execution of only 55.9%. Possible reasons identified for this low rate included lack of learning experience and resources, lack of related standard operating procedures, lack of related performance assessments, complicated / unfamiliar device assembly procedure, diffuse storage of device components, and a lack of illustrations.

PURPOSE

This project was developed to increase the accuracy rate of performing aerosol therapy to over 90% in our intensive care unit.

METHODS

We designed diverse learning materials using the model of motivation, developed an evaluation system, simplified the assembly of components based on evidence-based research, improved the storage situation, and added reference illustrations.

RESULTS

The accuracy rate in aerosol therapy execution for our nursing staff increased from 55.9% to 95.0% after the intervention.

CONCLUSIONS

This project used the model of motivation to develop the teaching materials. By using diverse teaching methods, including both in-person classes and online interactive quizzes, we realized high learning satisfaction and efficacy. Along with simplifying equipment handling, improving the working environment, enhancing nurses' aerosol therapy techniques, establishing standard operating procedure guidelines, and adding an evaluation system, we standardized the entire procedure for potential promotion to other intensive care units.

Human inhalable antibody fragments neutralizing SARS-CoV-2 variants for COVID-19 therapy

As of December 2021, coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global emergency, and novel therapeutics are urgently needed. Here we describe human single-chain variable fragment (scFv) antibodies (76clAbs) that block an epitope of the SARS-CoV-2 spike protein essential for ACE2-mediated entry into cells. 76clAbs neutralize the Delta variant and other variants being monitored (VBMs) and inhibit spike-mediated pulmonary cell-cell fusion, a critical feature of COVID-19 pathology. In two independent animal models, intranasal administration counteracted the infection. Because of their high efficiency, remarkable stability, resilience to nebulization, and low cost of production, 76clAbs may become a relevant tool for rapid, self-administrable early intervention in SARS-CoV-2-infected subjects independently of their immune status.

Reconciling Oxygen and Aerosol Delivery with a Hood on In Vitro Infant and Paediatric Models

This study aimed to evaluate optimal aerosol and oxygen delivery with a hood on an infant model and a paediatric model. A facemask and a hood with three inlets, with or without a front cover, were used. A small-volume nebuliser with a unit-dose of salbutamol was used for drug delivery and an air entrainment nebuliser was used to deliver oxygen at 35%. Infant and paediatric breathing patterns were mimicked; a bacterial filter was connected to the end of a manikin trachea for aerosol drug collection, and an oxygen analyser was used to measure the oxygen concentration. For the infant model, inhaled drug dose was significantly higher when the nebuliser was placed in the back of the hood and with a front cover. This was verified by complementary computational simulations in a comparable infant-hood model. For the paediatric model, the inhaled dose was greater with a facemask than with a hood. Oxygen delivery with a facemask and a hood with a front cover achieved a set concentration in both models, yet a hood without a front cover delivered oxygen at far lower concentrations than the set concentration.

The Impact of High-Flow Nasal Cannula Device, Nebulizer Type, and Placement on Trans-Nasal Aerosol Drug Delivery: An In Vitro Study

BACKGROUND

Aerosol delivery via high-flow nasal cannula (HFNC) has been increasingly used in recent years. However, the effects of different HFNC devices, nebulizer types, and placement on aerosol deposition remain largely unknown.

METHODS

An adult manikin with anatomically correct upper airway was used with a collection filter placed between the manikin's trachea and a breathing simulator, composed of a dual-chamber model lung driven by a critical care ventilator. Three HFNC device configurations were compared, with vibrating mesh nebulizer and small-volume nebulizer placed at the humidifier (inlet for Optiflow and outlet for Airvo 2) and proximal to the nasal cannula at gas flows of 10, 20, 40 and 60 L/min, in quiet and distressed breathing patterns. Albuterol (2.5 mg) was nebulized for each condition (no. = 3). The drug was eluted from the collection filter and assayed with ultraviolet spectrophotometry (276 nm).

RESULTS

At all settings, except when a nebulizer was placed proximal to the nasal cannula with the Optiflow and when the HFNC flow was set at 60 L/min, the vibrating mesh nebulizer generated a higher inhaled dose than did the small-volume nebulizer (all P < .05). With the exception of distressed breathing at an HFNC flow of 10 L/min, the inhaled dose with the vibrating mesh nebulizer placed at the humidifier was greater than with the vibrating mesh nebulizer placed proximal to the nasal cannula (all P < .05), Optiflow provided a higher inhaled dose than did Airvo 2 with either AirSpiral or 900PT501 circuits with the vibrating mesh nebulizer placed at the humidifier (all P < .05).

CONCLUSIONS

During transnasal aerosol delivery, the vibrating mesh nebulizer generated a higher inhaled dose than did the small-volume nebulizer when the nebulizer was placed at the humidifier. With the vibrating mesh nebulizer placed at the humidifier and an HFNC flow > 10 L/min, the inhaled dose was higher than with the vibrating mesh nebulizer placed proximal to the nasal cannula, and the inhaled dose was higher with Optiflow than with Airvo 2.

Bronchodilator Delivery via High-Flow Nasal Cannula: A Randomized Controlled Trial to Compare the Effects of Gas Flows

(1) Background: Aerosol delivery via high-flow nasal cannula (HFNC) has attracted increasing clinical interest. In vitro studies report that the ratio of HFNC gas flow to patient inspiratory flow (GF:IF) is a key factor in the efficiency of trans-nasal aerosol delivery. (2) Methods: In a randomized controlled trial, patients with a history of COPD or asthma and documented positive responses to inhaled bronchodilators in an outpatient pulmonary function laboratory were recruited. Subjects were randomized to receive inhalation at gas flow ratio settings of: GF:IF = 0.5, GF:IF = 1.0, or GF = 50 L/min. Subjects were assigned to inhale saline (control) followed by salbutamol via HFNC with cumulative doses of 0.5 mg, 1.5 mg, 3.5 mg, and 7.5 mg. Spirometry was performed at baseline and 10-12 min after each inhalation. (3) Results: 75 subjects (49 asthma and 26 COPD) demonstrating bronchodilator response were enrolled. Per the robust ATS/ERS criteria no difference was observed between flows, however using the criteria of post-bronchodilator forced expiratory volume in the first second (FEV₁) reaching the screening post-bronchodilator FEV₁ with salbutamol, a higher percentage of subjects receiving GF:IF = 0.5 met the criteria at a cumulative dose of 1.5 mg than those receiving GF:IF = 1.0, and GF = 50 L/min (64% vs. 29% vs. 27%, respectively, p = 0.011). Similarly at 3.5 mg (88% vs. 54% vs. 46%, respectively, p = 0.005). The effective dose at GF:IF = 0.5 was 1.5 mg while for GF = 50 L/min it was 3.5 mg. (4) Conclusions: During salbutamol delivery via HFNC, cumulative doses of 1.5 mg to 3.5 mg resulted in effective bronchodilation. Applying the robust ATS/ERS criteria no difference was observed between the flows, however using the more sensitive criteria of subjects reaching post screening FEV₁ to salbutamol via HFNC, a higher number of subjects responded to the doses of 0.5 mg and 1.5 mg when HFNC gas flow was set at 50% of patient peak inspiratory flow.

Worldwide Clinical Practice of High-Flow Nasal Cannula and Concomitant Aerosol Therapy in the Adult ICU Setting

BACKGROUND

High-flow nasal cannula (HFNC) oxygen therapy has been broadly used. However, no consensus has been achieved on the practical implementation of HFNC and how to provide aerosol delivery during HFNC therapy in adult patients.

METHODS

An online anonymous questionnaire survey endorsed by 4 academic societies from America, Europe, mainland China, and Taiwan was administered from May to December 2019. Clinicians who had worked in adult ICUs for > 1 year and had used HFNC to treat patients within 30 days were included.

RESULTS

A total of 2,279 participants clicked on the survey link, 1,358 respondents completed the HFNC section of the questionnaire, whereas 1,014 completed the whole survey. Postextubation hypoxemia and moderate hypoxemia were major indications for HFNC. The initial flow was mainly set at 40-50 L/min. Aerosol delivery via HFNC was used by 24% of the participants (248/1,014), 30% (74/248) of whom reported reducing flow during aerosol delivery. For the patients who required aerosol treatment during HFNC therapy, 40% of the participants (403/1,014) reported placing a nebulizer with a mask or mouthpiece while pursuing HFNC whereas 33% (331/1,014) discontinued HFNC to use conventional aerosol devices. A vibrating mesh nebulizer was the most commonly used nebulizer (40%) and was mainly placed at the inlet of the humidifier.

CONCLUSIONS

The clinical utilization of HFNC was variable, as were indications, flow settings, and criteria for adjustment. Many practices associated with concomitant aerosol therapy were not consistent with available evidence for optimal use. More efforts are warranted to close the knowledge gap.

Salbutamol Delivered by Jet Nebulizer: Closed System Design and Impact of a Model Biofilm

BACKGROUND

Aerosol therapy is commonly used by intensivists during invasive mechanical ventilation. More information is needed to optimize outcomes. The first aim of this study was to assess the deposition of salbutamol on components of a closed mechanical ventilation system, both in the presence and absence of biofilm generated by Acinetobacter baumannii. The second aim was to evaluate the deposition of salbutamol, using a single dose and a double dose, delivered via a jet nebulizer placed between the flexible tube and the heat and moisture exchanger.

METHODS

A mechanical ventilator was connected to a standard system, and a jet nebulizer was placed between the heat and moisture exchanger and the flexible tube. Clinical isolates of A. baumanii were used to generate a biofilm layer on the endotracheal tube. Two amounts of salbutamol were delivered via the jet nebulizer. An analytical liquid chromatography tandem mass spectrometry method was developed to evaluate salbutamol deposition.

RESULTS

The presence of a biofilm on the endotracheal tube had no impact on salbutamol deposition (P = .83). There was no difference in surface deposition of salbutamol on component parts of the closed system in a comparison of a single dose and a double dose delivered via a jet nebulizer.

CONCLUSIONS

Our findings indicate that an A. baumannii biofilm had no impact on the extent of salbutamol deposition. Salbutamol deposition was comparatively low and could be delivered without removal of the heat and moisture exchanger.

An in vitro visual study of fugitive aerosols released during aerosol therapy to an invasively ventilated simulated patient

COVID-19 can cause serious respiratory complications resulting in the need for invasive ventilatory support and concurrent aerosol therapy. Aerosol therapy is considered a high risk procedure for the transmission of patient derived infectious aerosol droplets. Critical-care workers are considered to be at a high risk of inhaling such infectious droplets. The objective of this work was to use noninvasive optical methods to visualize the potential release of aerosol droplets during aerosol therapy in a model of an invasively ventilated adult patient. The noninvasive Schlieren imaging technique was used to visualize the movement of air and aerosol. Three different aerosol delivery devices: (i) a pressurized metered dose inhaler (pMDI), (ii) a compressed air driven jet nebulizer (JN), and (iii) a vibrating mesh nebulizer (VMN), were used to deliver an aerosolized therapeutic at two different positions: (i) on the inspiratory limb at the wye and (ii) on the patient side of the wye, between the wye and endotracheal tube, to a simulated intubated adult patient. Irrespective of position, there was a significant release of air and aerosol from the ventilator circuit during aerosol delivery with the pMDI and the compressed air driven JN. There was no such release when aerosol therapy was delivered with a closed-circuit VMN. Selection of aerosol delivery device is a major determining factor in the release of infectious patient derived bioaerosol from an invasively mechanically ventilated patient receiving aerosol therapy.

Inadequate Functioning of Nebulizer System Compressors Used by Individuals With Cystic Fibrosis

BACKGROUND

The treatment of cystic fibrosis involves the use of drugs delivered by nebulizer systems, and adequate functioning of the compressors and nebulizers is essential. We hypothesized that compressors of nebulizer systems used by individuals with cystic fibrosis would not work properly. Therefore, we aimed to assess the performance of the compressors from nebulizer systems used by individuals with cystic fibrosis.

METHODS

This is a cross-sectional study to assess the performance of compressors from nebulizer systems used by subjects with cystic fibrosis registered at the Cystic Fibrosis Patient Association in Minas Gerais, Brazil. Compressors (Proneb Ultra II) brought by the individuals were tested with new nebulizer parts (Pari LC plus) to assess the variables of nebulization efficiency, including residual volume, solution output, and aerosol output rate. Compression performance was assessed by measuring the operating pressure using a PARI PG101 manometer.

RESULTS

The performance of 146 compressors was analyzed. Fifty-seven (39%) of the compressors were ineffective, with operating pressure values well below the manufacturer's technical reference and the compressor time used for a median time of 36 (15 days to 156 months). The systems with low pressure values demonstrated significantly worse results for nebulization efficiency variables, and a significant correlation was found between residual volume (r = -0.5, P < .001), solution output (r = +0.5, P < .001), and aerosol output rate (r = +0.5, P < .001), and operating pressure values.

CONCLUSIONS

A significant number of compressors generate low operating pressure values. These systems showed a compromised efficiency of nebulization, indicating that the pressure generated by the compressor is a critical aspect of treatment efficiency.

Evaluation of Aerosol Therapy during the Escalation of Care in a Model of Adult Cystic Fibrosis

Lung disease is the main cause of morbidity and mortality in cystic fibrosis (CF). CF patients inhale antibiotics regularly as treatment against persistent bacterial infections. The goal of this study was to investigate the effect of clinical intervention on aerosol therapy during the escalation of care using a bench model of adult CF. Droplet size analysis of selected antibiotics was completed in tandem with the delivered aerosol dose (% of total dose) assessments in simulations of various interventions providing oxygen supplementation or ventilatory support. Results highlight the variability of aerosolised dose delivery. In the homecare setting, the vibrating mesh nebuliser (VMN) delivered significantly more than the jet nebuliser (JN) (16.15 ± 0.86% versus 6.51 ± 2.15%). In the hospital setting, using VMN only, significant variability was seen across clinical interventions. In the emergency department, VMN plus mouthpiece (no supplemental oxygen) was seen to deliver (29.02 ± 1.41%) versus low flow nasal therapy (10 L per minute (LPM) oxygen) (1.81 ± 0.47%) and high flow nasal therapy (50 LPM oxygen) (3.36 ± 0.34%). In the ward/intensive care unit, non-invasive ventilation recorded 19.02 ± 0.28%, versus 22.64 ± 1.88% of the dose delivered during invasive mechanical ventilation. These results will have application in the design of intervention-appropriate aerosol therapy strategies and will be of use to researchers developing new therapeutics for application in cystic fibrosis and beyond.

Aerosol delivery via invasive ventilation: a narrative review

In comparison with spontaneously breathing non-intubated subjects, intubated, mechanically ventilated patients encounter various challenges, barriers, and opportunities in receiving medical aerosols. Since the introduction of mechanical ventilation as a part of modern critical care medicine during the middle of the last century, aerosolized drug delivery by jet nebulizers has become a common practice. However, early evidence suggested that aerosol generators differed in their efficacies, and the introduction of newer aerosol technology (metered dose inhalers, ultrasonic nebulizer, vibrating mesh nebulizers, and soft moist inhaler) into the ventilator circuit opened up the possibility of optimizing inhaled aerosol delivery during mechanical ventilation that could meet or exceed the delivery of the same aerosols in spontaneously breathing patients. This narrative review will catalogue the primary variables associated with this process and provide evidence to guide optimal aerosol delivery and dosing during mechanical ventilation. While gaps exist in relation to the appropriate aerosol drug dose, discrepancies in practice, and cost-effectiveness of the administered aerosol drugs, we also present areas for future research and practice. Clinical practice should expand to incorporate these techniques to improve the consistency of drug delivery and provide safer and more effective care for patients.

Metered-dose inhalers versus nebulization for the delivery of albuterol for acute exacerbations of wheezing or asthma in children: A systematic review with meta-analysis

OBJECTIVES

The benefits of metered-dose inhalers with a spacer (MDI+S) have increasingly been recognized as an alternative method of albuterol administration for treating pediatric asthma exacerbations. The aim of this systematic review was to compare the response to albuterol delivered through nebulization (NEB) with albuterol delivered through MDI+S in pediatric patients with asthma exacerbations.

METHODS

We conducted an electronic search in MEDLINE/PubMed, EMBASE, Ovid, and ClinicalTrials. To be included in the review, a study had to a randomized clinical trial comparing albuterol delivered via NEB versus MDI+S; and had to report the rate of hospital admission (primary outcome), or any of the following secondary outcomes: oxygen arterial saturation, heart rate (HR), respiratory rate (RR), the pulmonary index score (PIS), adverse effects, and need for additional treatment.

RESULTS

Fifteen studies (n = 2057) met inclusion criteria. No significant differences were found between the two albuterol delivery methods in terms of hospital admission (relative risk, 0.89; 95% confidence interval [CI], 0.55-1.46; I²  = 32%; p = .65). There was a significant reduction in the PIS score (mean difference [MD], -0.63; 95% CI, -0.91 to -0.35; I²  = 0%; p < .00001), and a significantly smaller increase in HR (better; MD -6.47; 95% CI, -11.69 to -1.25; I²  = 0%; p = .02) when albuterol was delivered through MDI+S than when it was delivered through NEB.

CONCLUSIONS

This review, an update of a previously-published meta-analysis, showed a significant reduction in the PIS and a significantly smaller increase in HR when albuterol was delivered through MDI+S than when it was delivered through NEB.

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 different cleaning methods for feline inhalation chambers after bacterial contamination

OBJECTIVES

Inhalation chambers are commonly used for the delivery of aerosol drugs to cats with respiratory disease. The aim of the study was to identify successful cleaning methods for inhalation devices after standardised bacterial contamination.

METHODS

Spacer devices of two different manufacturers were used: RC Chamber (Cegla Medizintechnik) and Aerokat (Trudell Medical International). The bacterial contamination was performed using Pseudomonas aeruginosa. Previously marked areas of the chamber were contaminated with 50 μl of bacterial solution, containing between 2.2 ×10⁵ and 2.1 ×10⁸ colony-forming units/ml each. After cleaning the devices as recommended by each manufacturer (RC Chamber: special microwave cleaning bag [n = 5] or boiling water with liquid dish detergent for 15 mins [n = 5]; Aerokat: rinsing in a solution of lukewarm water and liquid dish detergent for 15 mins), chambers were air-dried for 24 h and samples for bacterial culture were taken from three defined areas. Sample material was applied on Müller-Hinton agar plates and subsequently incubated for 24 h at 37°C.

RESULTS

Bacterial contamination was not detected in any of the examined inhalation devices using the recommended cleaning methods.

CONCLUSIONS AND RELEVANCE

If inhalation chambers are cleaned following the manufacturers' recommendations, successful bacterial decontamination can be expected.

Feasibility of Aerosol Bronchodilators Delivery Through High-Flow Nasal Cannula in Pediatric Subjects With Respiratory Distress

BACKGROUND

High-flow nasal cannula (HFNC) is commonly used to provide respiratory support to pediatric patients with respiratory failure. Although the use of bronchodilators via HFNC has been described, the feasibility and safety of aerosolized bronchodilator delivery via HFNC are controversial. In this study, we sought to evaluate whether the HFNC system can be used to deliver nebulized bronchodilators at lower gas flow of 2-4 L/min, increase patient comfort, and minimize respiratory therapist (RT) bedside time when compared to traditional interfaces.

METHODS

A retrospective chart review of all pediatric subjects who were admitted to the pediatric ICU in a tertiary care children's hospital and required nebulized bronchodilators between December 2017 and June 2018.

RESULTS

A total of 205 nebulizations were administered to 28 children; 31% of nebulized bronchodilators were given using a nebulization system integrated into the HFNC. Nebulized treatments resulted in an average increase in heart rate of 9.98 (95% CI 3.72-16.2) beats/min when HFNC was used and 0.64 (95% CI -1.65 to 2.93) beats/min when traditional interfaces were used, a difference of 9.34 (95% CI 2.30-16.4) beats/min (P < .001). RT bedside time was significantly longer for HFNC nebulized treatments (P = .031). Subjective level of comfort was not statically different when nebulized bronchodilators were delivered via HFNC or via traditional interfaces. Length of pediatric ICU stay was not statistically different between subjects who received some aerosol nebulized bronchodilators via HFNC versus those who received all bronchodilators through traditional interfaces (P = .11).

CONCLUSIONS

Aerosol bronchodilator delivery using HFNC is feasible at low gas flow (ie, 2-4 L/min). However, the use of HFNC did not improve subjects' comfort, and it increased RT bedside time. Further prospective randomized studies are needed to determine the efficacy and efficiency of aerosol therapy delivered through HFNC and potential patient-oriented outcomes.

Adjunctive Nebulized Antibiotics: What Is Their Place in ICU Infections?

Inhaled antibiotics have been used as adjunctive therapy for patients with pneumonia, primarily caused by multidrug resistant (MDR) pathogens. Most studies have been in ventilated patients, although non-ventilated patients have also been included (but not discussed in this review), and most patients have had nosocomial pneumonia. Aerosolized antibiotics are generally added to systemic therapy, and have shown efficacy, primarily as salvage therapy for failing patients and as adjunctive therapy after an MDR gram-negative has been identified. An advantage to aerosolized antibiotics is that they can achieve high intra-pulmonary concentrations that are potentially effective, even for highly resistant pathogens, and because they are generally not well-absorbed systemically, it is possible to avoid some of the toxicities of systemic therapy. When using inhaled antibiotics, it is essential to choose the appropriate agent and the optimal delivery method. Animal and human studies have shown that aerosolized antibiotics reach higher concentrations in the lung than systemic antibiotics, but that areas of dense pneumonia may not receive as much antibiotic as less affected areas of lung. Optimal delivery in ventilated patients depends on device selection, generally with a preference for vibrating mesh nebulizers and with careful attention to where the device is placed in the ventilator circuit and how the delivery is coordinated with the ventilator cycle. Although some studies have shown a benefit for clinical cure, adjunctive therapy has not led to reduced mortality. In some studies, adjunctive aerosol therapy has reduced the duration of systemic antibiotic therapy, thus serving to promote antimicrobial stewardship. Two recent multicenter, randomized, double-blinded, placebo-controlled trials of adjunctive nebulized antibiotics for VAP patients with suspected MDR gram-negative pneumonia were negative for their primary endpoints. This may have been related to trial design and execution and the lessons learned from these studies need to be incorporated in any future trials. Currently, routine use of adjunctive aerosolized therapy cannot be supported by available data, and this therapy is only recommended to assist in the eradication of highly resistant pathogens and to be used as salvage therapy for patients failing systemic therapy.

High-Flow Nasal Cannula in Pediatric Patients: A Survey of Clinical Practice

BACKGROUND

High-flow nasal cannula (HFNC) use has greatly increased in recent years. In non-neonatal pediatric patients, there are limited data available to guide HFNC use, and clinical practice may vary significantly. The goal of this study was to evaluate current HFNC practice by surveying practicing pediatric respiratory therapists.

METHODS

A survey instrument was posted on the American Association for Respiratory Care's AARConnect online social media platform in March 2017. Paper versions of the survey were also distributed at the annual Children Hospitals Association meeting.

RESULTS

There were 63 responses, of which 98% used HFNC. HFNC was defined as any heated gas delivered by nasal cannula by 49% of respondents, whereas 21% defined HFNC as heated gas delivered via nasal cannula at flow greater than or equal to the patient's inspiratory demand, and 16% defined HFNC as any gas delivered via nasal cannula above predefined thresholds. Initial flow was set per provider orders by 34% of respondents, per respiratory therapist-driven protocol by 28%, per patient weight by 15%, per patient age by 15%; 5% of respondents used other methods. Noninvasive ventilation or CPAP was used by 88% of respondents as the next step for patients who failed HFNC, with 7% opting for intubation and 5% using other interventions. Aerosol therapy was delivered by 75% of respondents during HFNC, with 77% of these respondents delivering aerosol via vibrating mesh nebulizer. During aerosol therapy, 13% of respondents decreased HFNC flow, while 23% removed patients from HFNC.

CONCLUSION

There was no consensus on the definition of HFNC, how to set initial flow, or how to make adjustments. Aerosols were delivered by 75% of respondents, predominantly via a vibrating mesh nebulizer placed on the dry side of the humidifier. The definition of HFNC, how to set flow, and aerosolized medication delivery are areas in which more research is needed.

How Should Aerosols Be Delivered During Invasive Mechanical Ventilation?

The delivery of aerosols to mechanically ventilated patients presents unique challenges and differs from inhaled drug delivery in spontaneously breathing patients in several respects. Successful aerosol delivery during invasive mechanical ventilation requires careful consideration of a host of factors that influence the amount of drug inhaled by the patient. Pressurized metered-dose inhalers and nebulizers (jet, ultrasonic, and vibrating mesh) are the most commonly used aerosol delivery devices in these patients, although other delivery devices, such as dry powder inhalers, soft mist inhalers, and intratracheal nebulizing catheters, could also be adapted for in-line use. Bronchodilators, inhaled corticosteroids, antibiotics, pulmonary surfactant, mucolytics, biologicals, genes, prostanoids, and other agents are administered by inhalation during mechanical ventilation for a variety of indications. The goals of inhalation therapy during mechanical ventilation could be best achieved by (1) assuring drug delivery; (2) optimizing drug deposition in the lung; (3) providing consistent dosing; (4) avoiding inappropriate therapies; (5) achieving reproducible dosing; (6) employing clinically feasible methods; (7) enhancing the safety of inhaled drugs; and (8) controlling costs of aerosol therapy. The techniques of administration of aerosols with various delivery devices during mechanical ventilation are well known, but there continues to be significant variation in clinical practice and guidelines are needed to provide best practices for a wide range of clinical settings encountered in mechanically ventilated patients.

Effect of Heat Moisture Exchanger on Aerosol Drug Delivery and Airway Resistance in Simulated Ventilator-Dependent Adults Using Jet and Mesh Nebulizers

BACKGROUND

Placement of a heat moisture exchanger (HME) between aerosol generator and patient has been associated with greatly reduced drug delivery. The purpose of this study was to evaluate the effect of filtered and nonfiltered HMEs placed between nebulizer and patient on aerosol deposition and airway resistance (Raw) in simulated ventilator-dependent adults.

METHODS

An in vitro lung model was developed to simulate a mechanically ventilated adult (Vt 500 mL, RR 15/min, and PEEP 5 cmH₂O, using two inspiratory flow rates 40 and 50 L/min) using an intubated adult manikin with an endotracheal tube (8 mmID). The bronchi of the manikin were connected to a Y-adapter through a collecting filter (Respirgard II) attached to a test lung through a heated humidifier (37°C producing 100% relative humidity) to simulate exhaled humidity. For treatment conditions, a nonfiltered HME (ThermoFlo™ 6070; ARC Medical) and filtered HMEs (ThermoFlo™ Filter; ARC Medical and PALL Ultipor; Pall Medical) were placed between the ventilator circuit at the endotracheal tube and allowed to acclimate to the exhaled heat and humidity for 30 minutes before aerosol administration. Airway resistance (cmH₂O/L/s) was taken at 0, 10, 20, and 30 minutes after HME placement and after each of four aerosol treatments. Albuterol sulfate (2.5 mg/3 mL) was administered with jet (Misty Max 10; Airlife) and mesh (Aerogen Solo; Aerogen) nebulizers positioned in the inspiratory limb proximal to the Y-adapter. Control consisted of nebulization with no HME. Drug was eluted from filter at the end of the trachea and measured using spectrophotometry (276 nm).

RESULTS

Greater than 60% of the control dose was delivered through the ThermoFlo. No significant difference was found between the first four treatments given by the jet (p = 0.825) and the mesh (p = 0.753) nebulizers. There is a small increase in Raw between pre- and post-four treatments with the jet (p = 0.001) and mesh (p = 0.015) nebulizers. Aerosol delivery through filtered HMEs was similar (<0.5%) across the four treatments. Airway resistance was similar using the ThermoFlo Filter. With the PALL Ultipor, changes in Raw increased with mesh nebulizer after treatment (p = 0.005). Changes in resistance pre- and post-treatment were similar with both filtered HMEs.

CONCLUSION

The ThermoFlo™ nonfilter HME allowed the majority of the control dose to be delivered to the airway. Increases in Raw would likely not be outside of a tolerable range in ventilated patients. In contrast, filtered HMEs should not be placed between nebulizers and patient airways. Further research with other HMEs and materials is warranted.

Systematic Review of Errors in Inhaler Use: Has Patient Technique Improved Over Time?

BACKGROUND

Problems with the use of inhalers by patients were noted shortly after the launch of the metered-dose inhaler (MDI) and persist today. We aimed to assess the most common errors in inhaler use over the past 40 years in patients treated with MDIs or dry powder inhalers (DPIs).

METHODS

A systematic search for articles reporting direct observation of inhaler technique by trained personnel covered the period from 1975 to 2014. Outcomes were the nature and frequencies of the three most common errors; the percentage of patients demonstrating correct, acceptable, or poor technique; and variations in these outcomes over these 40 years and when partitioned into years 1 to 20 and years 21 to 40. Analyses were conducted in accordance with recommendations from Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Strengthening the Reporting of Observational Studies in Epidemiology.

RESULTS

Data were extracted from 144 articles reporting on a total number of 54,354 subjects performing 59,584 observed tests of technique. The most frequent MDI errors were in coordination (45%; 95% CI, 41%-49%), speed and/or depth of inspiration (44%; 40%-47%), and no postinhalation breath-hold (46%; 42%-49%). Frequent DPI errors were incorrect preparation in 29% (26%-33%), no full expiration before inhalation in 46% (42%-50%), and no postinhalation breath-hold in 37% (33%-40%). The overall prevalence of correct technique was 31% (28%-35%); of acceptable, 41% (36%-47%); and of poor, 31% (27%-36%). There were no significant differences between the first and second 20-year periods of scrutiny.

CONCLUSIONS

Incorrect inhaler technique is unacceptably frequent and has not improved over the past 40 years, pointing to an urgent need for new approaches to education and drug delivery.

Intratracheal Administration of Antimicrobial Agents in Mechanically Ventilated Adults: An International Survey on Delivery Practices and Safety

BACKGROUND

Intratracheal antibiotic administration is increasingly used for treating respiratory infections. Limited information is available on delivery devices, techniques, and safety.

METHODS

An online survey on intratracheal administration of anti-infective agents in mechanically ventilated adults was answered by health-care workers from 192 ICUs to assess the most commonly used devices, current delivery practices, and safety issues. We investigated whether ICU usage experience (≥3 y) impacted its performance.

RESULTS

Intratracheal antibiotic administration was a current practice in 87 ICUs (45.3%), with 40 (46%) having experience with the technique (≥3 y). Sixty-six (78.6%) of 84 health-care workers reported avoiding intratracheal antibiotic administration due to an absence of evidence-based guidelines (78.6%). Jet nebulizers were the most commonly used devices for delivery, in 24 less experienced ICUs (27.6%) and in 18 (20.7%) experienced ICUs. Direct tracheal instillation (6; 6.9%) was still considered for drug prescription in 12 ICUs (6.9%). More experience resulted in neither greater adherence to measures improving the drug's delivery efficiency (93 measures in the experienced group; 27.9%) nor a greater adoption of measures to increase safety. Indeed, the expiratory filter was changed after each nebulization in only 2 experienced ICUs (6.9%), whereas 15 (51.7%) changed it daily instead.

CONCLUSIONS

Intratracheal antibiotic administration is a common therapeutic modality in ICUs, but inadequate practices were widely encountered, independent of the level of experience with the technique. This suggests a need to develop standardization to reduce variability and improve safety and efficacy.

Physicochemical aspects and efficiency of albuterol nebulization: comparison of three aerosol types in an in vitro pediatric model

BACKGROUND

Advances in nebulizer design have produced both ultrasonic nebulizers and devices based on a vibrating mesh (vibrating mesh nebulizers), which are expected to enhance the efficiency of aerosol drug therapy. The aim of this study was to compare 4 different nebulizers, of 3 different types, in an in vitro model using albuterol delivery and physical characteristics as benchmarks.

METHODS

The following nebulizers were tested: Sidestream Disposable jet nebulizer, Multisonic Infra Control ultrasonic nebulizer, and the Aerogen Pro and Aerogen Solo vibrating mesh nebulizers. Aerosol duration, temperature, and drug solution osmolality were measured during nebulization. Albuterol delivery was measured by a high-performance liquid chromatography system with fluorometric detection. The droplet size distribution was analyzed with a laser granulometer.

RESULTS

The ultrasonic nebulizer was the fastest device based on the duration of nebulization; the jet nebulizer was the slowest. Solution temperature decreased during nebulization when the jet nebulizer and vibrating mesh nebulizers were used, but it increased with the ultrasonic nebulizer. Osmolality was stable during nebulization with the vibrating mesh nebulizers, but increased with the jet nebulizer and ultrasonic nebulizer, indicating solvent evaporation. Albuterol delivery was 1.6 and 2.3 times higher with the ultrasonic nebulizer and vibrating mesh nebulizers devices, respectively, than with the jet nebulizer. Particle size was significantly higher with the ultrasonic nebulizer.

CONCLUSIONS

The in vitro model was effective for comparing nebulizer types, demonstrating important differences between nebulizer types. The new devices, both the ultrasonic nebulizers and vibrating mesh nebulizers, delivered more aerosolized drug than traditional jet nebulizers.

The science guiding selection of an aerosol delivery device

Aerosol therapy continues to be considered as one of the cornerstones of the profession of respiratory care, even after 60 years. Aerosol therapy serves as a critical intervention for both exacerbations and chronic maintenance for a variety of respiratory care conditions. Aerosol therapy uniquely blends both the art and science of medicine together to produce the practical and necessary clinical outcomes for patients with respiratory diseases. This review was presented as part of the New Horizons Symposium on how to guide the scientific selection of an appropriate aerosol device.

Aerosols for systemic treatment

The development of a new group of drugs (polypeptides) have recently increased the interest of alternative administration to the enteral route because of its proteolytic activity and the catabolism of the "first-pass effect." Aside from the "needle," the administration in the respiratory tract via aerosol is the method with the best efficiency. But several problems prohibited its spreading: (1) the accuracy and the reproducibility of the inhaled dose (range ca. 1:4); (2) the small amount of inhaled drug in relation to the dose in the aerosol delivery system (range ca. 1%-10%); (3) the fear of allergic reactions of the respiratory system; (4) the variability of the drug transport into the systemic circulation. New approaches and data raise hopes in reducing the problems: (1) aerosol delivery systems with defined particle spectrum and storage systems; slow vital capacity inhaling maneuver; (2) delivery systems that nebulizes nearly the total amount of drug; (3) all studies with the inhalation application of insulin, heparin, ergotamin, ribavirin, aminoglycosides, and "cigarette smoke" do not reveal any relevant allergic reaction; (4) many studies were performed in the last 10 years on the influence of substances and especially of diseases on the transport of molecules through the respiratory tract. Only a few of them are relevant (exogen allergic alveolitis, active sarcoidosis, active smoking). Aerosols for (exogen allergic alveolitis, active sarcoidosis, active smoking). Aerosols for systemic drug treatment seems to be a gained alternative to the "syringe."