Aerosol therapy during mechanical ventilation: an international survey

Bronchodilator administration by pressurized inhaler during invasive mechanical ventilation in adults: A scoping review

OBJECTIVE

To identify the administration characteristics and connection methods of bronchodilators by pressurized inhalers to the ventilatory circuit of patients under invasive mechanical ventilation.

METHODS

A scope review was conducted following the PRISMA for Scoping Review, using the PubMed, Embase Elsevier, Cochrane Library, and Lilacs databases without language restrictions, up to July 2023. Eligible sources included reviews and consensuses (based on clinical studies), experimental and observational studies involving adult patients admitted to the intensive care unit and undergoing invasive mechanical ventilation, regardless of the underlying condition, who used bronchodilator drugs contained in pressurized inhalers. Information regarding inhalation technique, pressurized inhalers connection mode to the circuit, and patient care were collected by 2 researchers independently, with discrepancies resolved by a third reviewer. Studies involving bronchodilators combined with other pharmacological classes in the same device, as well as reviews containing preclinical studies, were excluded.

RESULTS

In total, 23 publications were included, comprising 19 clinical trials and 4 non-randomized experimental studies. Salbutamol (albuterol) was the bronchodilator of study in the majority of the articles (n=18), and the spacer device was the most commonly used to connect the pressurized inhaler to the circuit (n=15), followed by an in-line adapter (n=3), and a direct-acting device without chamber (n=3). Concerning the pressurized inhaler placement in the circuit, 18 studies positioned it in the inspiratory limb, and 19 studies synchronized the jet actuation with the start of the inspiratory phase. Agitation of the pressurized inhaler before each actuation, waiting time between actuations, airway suction before administration, and semi-recumbent patient positioning were the most commonly described measures across the studies.

CONCLUSIONS

This review provided insights into the aspects related to inhalation technique in mechanically ventilated patients, as well as the most prevalent findings and the existing gaps in knowledge regarding bronchodilator administration in this context. The evidence indicates the need for further research on this subject.

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.

Nursing Practice of Airway Care Interventions and Prone Positioning in ICU Patients with COVID-19-A Dutch National Survey

Background: Airway care interventions and prone positioning are used in critically ill patients with coronavirus disease 2019 (COVID-19) admitted to the intensive care unit (ICU) to improve oxygenation and facilitate mucus removal. At the onset of the COVID-19 pandemic, the decision-making process regarding the practice of airway care interventions and prone positioning was challenging. Objective: To provide an overview of the practice of airway care interventions and prone positioning during the second wave of the pandemic in the Netherlands. Method: Web-based survey design. Seventy ICU nurses, each representing one intensive care in the Netherlands, were contacted for participation. Potential items were generated based on a literature search and formulated by a multidisciplinary team. Questions were pilot tested for face and construct validity by four intensive care nurses from four different hospitals. Results: The response rate was 53/77 (69%). This survey revealed widespread use of airway care interventions in the Netherlands in COVID-19 patients, despite questionable benefits. Additionally, prone positioning was used in invasively and non-invasively ventilated patients. Conclusions: The use of airway care interventions and prone positioning is time consuming and comes with the production of waste. Further research is needed to assess the effectiveness, workload, and environmental impact of airway care interventions and prone positioning.

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.

Not all nebulizers are created equal: Considerations in choosing a nebulizer for aerosol delivery during mechanical ventilation

INTRODUCTION

Aerosol therapy is commonly prescribed in the mechanically ventilated patient. Jet nebulizers (JN) and vibrating mesh nebulizers (VMN) are the most common nebulizer types, however, despite VMN's well established superior performance, JN use remains the most commonly used of the two. In this review, we describe the key differentiators between nebulizer types and how considered selection of nebulizer type may enable successful therapy and the optimization of drug/device combination products.

AREAS COVERED

Following a review of the published literature up to February 2023, the current state of the art in relation to JN and VMN is discussed under the headings of in vitro performance of nebulizers during mechanical ventilation, respective compatibility with formulations for inhalation, clinical trials making use of VMN during mechanical ventilation, distribution of nebulized aerosol throughout the lung, measuring the respective performance of nebulizers in the patient and non-drug delivery considerations in nebulizer choice.

EXPERT OPINION

Whether for standard care, or the development of drug/device combination products, the choice of nebulizer type should not be made without consideration of the unique needs of the combination of each of drug, disease and patient types, as well as target site for deposition, and healthcare professional and patient safety.

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.

Acinetobacter baumannii among Patients Receiving Glucocorticoid Aerosol Therapy during Invasive Mechanical Ventilation, China

Acinetobacter baumannii is a nosocomial pathogen associated with severe illness and death. Glucocorticoid aerosol is a common inhalation therapy in patients receiving invasive mechanical ventilation. We conducted a prospective cohort study to analyze the association between glucocorticoid aerosol therapy and A. baumannii isolation from ventilator patients in China. Of 497 enrolled patients, 262 (52.7%) received glucocorticoid aerosol, and A. baumannii was isolated from 159 (32.0%). Glucocorticoid aerosol therapy was an independent risk factor for A. baumannii isolation (hazard ratio 1.5, 95% CI 1.02-2.28; p = 0.038). Patients receiving glucocorticoid aerosol had a higher cumulative hazard for A. baumannii isolation and analysis showed that glucocorticoid aerosol therapy increased A. baumannii isolation in most subpopulations. Glucocorticoid aerosol was not a direct risk factor for 30-day mortality, but A. baumannii isolation was independently associated with 30-day mortality in ventilator patients. Physicians should consider potential A. baumannii infection when prescribing glucocorticoid aerosol therapy.

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 > 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 < 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 < 0.05), but not significantly changed in the PC mode (P > 0.05);the actual tidal volume (VT) and expiratory tidal volume monitored (VTe) were significantly increased (P < 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 < 0.05). The higher the driving flow of external jet nebulizers, the stronger the impact on ventilator performance (all P < 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.

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.

Aerosol therapy during mechanical ventilation in intensive care units: A questionnaire-based survey of 2203 ICU medical staff in China

Background

To describe the current status of aerosol therapy during mechanical ventilation (MV) and the practice, knowledge, and beliefs about aerosol therapy in physicians working in the intensive care unit (ICU) in China.

Methods

A physician self-administered questionnaire-based cross-sectional survey was carried out from January 2019 to July 2019. An electronic questionnaire was designed, and physicians who worked regularly in ICUs across several hospitals were contacted through WeChat. Answers to all questions and the general characteristics of physicians who answered the questionnaire were collected and analyzed.

Results

A total of 2203 medical staff who regularly worked in the ICUs completed this questionnaire (9.0% missing data); 87.7% of the participants were doctors. Most respondents claimed that they often administered aerosolization therapy. Ultrasonic atomizer (50.7%) and jet nebulizer (48.6%) were the most commonly used atomization devices. Bronchodilators (65.8%) and steroids (66.3%) were the most frequently aerosolized drugs during MV. During nebulization, ventilator settings were never changed by 32.7% of respondents. Only 49.1% of respondents knew the appropriate place for a nebulizer. Further, 62.7% of respondents using heated humidifiers reported turning them off during nebulization. Specific knowledge about droplet size and nebulization yield was poor. Respondents from tertiary hospitals and those with higher technical title or work experience tended to have better accuracy than those from primary hospitals or with lower technical titles (P < 0.050).

Conclusions

Aerosol therapy was commonly used during MV, and the most frequent drugs were bronchodilators and steroids. Scientific knowledge about the optimal implementation of aerosol therapy during MV seemed deficient.

[Nebulization of emergency medications in the south German rescue service]

BACKGROUND

In German emergency rescue services, inhalation treatment is routinely carried out by qualified health personnel. Standard operating procedures (SOP) for nebulization are neither uniform throughout Germany nor available in all federal states. Standardized recommendations with respect to which nebulizer type should be used are missing. The aerosol output as well as the drug deposition rates of jet and mesh nebulizers, however, differ considerably. Mesh devices can achieve a threefold higher lung deposition. Their use in emergency departments has also been shown to be associated with a better patient outcome when compared to jet nebulizers.

OBJECTIVE

This survey was designed to evaluate the type of nebulizer used in the south German rescue services. Special attention was paid to the influence of existing SOP on the decision to perform nebulization during emergency treatment.

MATERIAL AND METHODS

A total of 4800 emergency paramedics working in Baden-Württemberg, Bavaria and Rhineland-Palatinate received a questionnaire with a total of 17 questions on the implementation of drug nebulization in the daily practice.

RESULTS

Despite the existence of more efficient nebulizer types, the jet nebulizer was by far the most frequently used nebulizer in the south German rescue services. The deposition rates of both the jet and mesh nebulizers were considerably overestimated by most respondents; however, 77.5% of all respondents could not give any information about the deposition rates of the mesh nebulizer. Only two thirds of all respondents carried out nebulization treatment on the basis of SOP. The implementation of SOP, however, was pivotal to the application of nebulization during emergencies. If SOP were in place,76.9% of the responders used aerosol treatment compared to 23.1% when there were none. The perceived safety when using nebulization during emergencies was also significantly higher (p = 0.013) when SOP were implemented.

CONCLUSION

The exclusive use of mesh nebulizers could standardize the treatment of emergency patients in the south German rescue services. The use of mesh devices might possibly improve patient outcomes, even if clinical studies are still lacking. Nebulizer treatment differs between the federal states. A comprehensive implementation of SOP for nebulization treatment might support this process and could increase the application frequency and the perceived safety of nebulization during emergencies. A better training of paramedic personnel could improve the knowledge of aerosols as a treatment option for emergency patients and help to classify the advantages and disadvantages of the different aerosol generators available.

Evaluation of Aerosol Drug Delivery Options during Adult Mechanical Ventilation in the COVID-19 Era

Drug delivery devices used for aerosol therapy during mechanical ventilation to ease the symptoms of respiratory diseases provide beneficial treatment but can also pose challenges. Reflecting the significant changes in global guidance around aerosol usage and lung-protective ventilation strategies, seen in response to the COVID-19 pandemic, for the first time, we describe the drug delivery performance of commonly used devices under these conditions. Here, vibrating mesh nebuliser (VMN), jet nebuliser (JN) and pressurised metered-dose inhaler (pMDI) performance was assessed during simulated adult mechanical ventilation. Both standard test breathing patterns and those representatives of low tidal volume (LTV) ventilation with concurrent active and passive humidification were investigated. Drug delivery using a VMN was significantly greater than that with a JN and pMDI for both standard and LTV ventilation. Humidification type did not affect the delivered dose across all device types for standard ventilation. Significant variability in the pMDI dosing was evident, depending on the timing of actuation and the adapter type used. pMDI actuation synchronised with inspiration resulted in a higher delivered drug dose. The type of adapter used for pMDI actuation influenced drug delivery, with the highest dose observed using the CombiHaler.

Cellular Immunotherapy and the Lung

The new era of cellular immunotherapies has provided state-of-the-art and efficient strategies for the prevention and treatment of cancer and infectious diseases. Cellular immunotherapies are at the forefront of innovative medical care, including adoptive T cell therapies, cancer vaccines, NK cell therapies, and immune checkpoint inhibitors. The focus of this review is on cellular immunotherapies and their application in the lung, as respiratory diseases remain one of the main causes of death worldwide. The ongoing global pandemic has shed a new light on respiratory viruses, with a key area of concern being how to combat and control their infections. The focus of cellular immunotherapies has largely been on treating cancer and has had major successes in the past few years. However, recent preclinical and clinical studies using these immunotherapies for respiratory viral infections demonstrate promising potential. Therefore, in this review we explore the use of multiple cellular immunotherapies in treating viral respiratory infections, along with investigating several routes of administration with an emphasis on inhaled immunotherapies.

Airway Care Interventions for Invasively Ventilated Critically Ill Adults-A Dutch National Survey

Airway care interventions may prevent accumulation of airway secretions and promote their evacuation, but evidence is scarce. Interventions include heated humidification, nebulization of mucolytics and/or bronchodilators, manual hyperinflation and use of mechanical insufflation-exsufflation (MI-E). Our aim is to identify current airway care practices for invasively ventilated patients in intensive care units (ICU) in the Netherlands. A self–administered web-based survey was sent to a single pre–appointed representative of all ICUs in the Netherlands. Response rate was 85% (72 ICUs). We found substantial heterogeneity in the intensity and combinations of airway care interventions used. Most (81%) ICUs reported using heated humidification as a routine prophylactic intervention. All (100%) responding ICUs used nebulized mucolytics and/or bronchodilators; however, only 43% ICUs reported nebulization as a routine prophylactic intervention. Most (81%) ICUs used manual hyperinflation, although only initiated with a clinical indication like difficult oxygenation. Few (22%) ICUs used MI-E for invasively ventilated patients. Use was always based on the indication of insufficient cough strength or as a continuation of home use. In the Netherlands, use of routine prophylactic airway care interventions is common despite evidence of no benefit. There is an urgent need for evidence of the benefit of these interventions to inform evidence-based guidelines.

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.

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.

Inhaled antibiotics during mechanical ventilation-why it will work

Inhaled antibiotics are a common therapy among patients suffering recurrent or chronic pulmonary infections. Their use is less frequent in acutely ill patients despite a strong theoretical rationale and growing evidence of their efficiency, safety and beneficial effect on reducing bacterial resistance emergence. Clinical trials of inhaled antibiotics have shown contradictory results among mechanically ventilated patients. The optimal nebulization setup, not always implemented in all trials, the difficulty to identify the population most likely to benefit and the testing of various therapeutic strategies such as adjunctive versus alternative to systemic antibiotics may explain the disparity in trial results. The present review first presents the reasons why inhaled antibiotics have to be developed and the benefits to be expected of inhaled anti-infectious therapy among mechanically ventilated patients. A second part develops the constraints of aerosolized therapies that one has to be aware of and the simple actions required during nebulization to ensure optimal delivery to the distal lung parenchyma. Positive and negative studies concerning inhaled antibiotics are compared to understand the discrepancies of their findings and conclusions. The last part presents current developments and perspective which will likely turn it into a fully successful therapeutic modality, and makes the link between inhaled antibiotics and inhaled anti-infectious therapy.

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.

Nebuliser Type Influences Both Patient-Derived Bioaerosol Emissions and Ventilation Parameters during Mechanical Ventilation

COVID-19 may lead to serious respiratory complications which may necessitate ventilatory support. There is concern surrounding potential release of patient-derived bioaerosol during nebuliser drug refill, which could impact the health of caregivers. Consequently, mesh nebulisers have been recommended by various clinical practice guidelines. Currently, there is a lack of empirical data describing the potential for release of patient-derived bioaerosol during drug refill. This study examined the release of simulated patient-derived bioaerosol, and the effect on positive end expiratory pressure during nebuliser refill during mechanical ventilation of a simulated patient. During jet nebuliser refill, the positive end expiratory pressure decreased from 4.5 to 0 cm H2O. No loss in pressure was noted during vibrating mesh nebuliser refill. A median particle number concentration of 710 particles cm-3 above ambient was detected when refilling the jet nebuliser in comparison to no increase above ambient detected when using the vibrating mesh nebuliser. The jet nebuliser with the endotracheal tube clamped resulted in 60 particles cm-3 above ambient levels. This study confirms that choice of nebuliser impacts both the potential for patient-derived bioaerosol release and the ability to maintain ventilator circuit pressures and validates the recommended use of mesh nebulisers during mechanical ventilation.

Knowledge and current practices of ICU nurses regarding aerosol therapy for patients treated with invasive mechanical ventilation: a nationwide cross-sectional study

BACKGROUND

Aerosol therapy is a routine operation for intensive care unit (ICU) nurses; however, evidence of the knowledge and current practices of ICU nurses regarding aerosol therapy for patients with invasive mechanical ventilation is insufficient in China.

OBJECTIVE

This study aimed to determine the knowledge and current practices of ICU nurses regarding aerosol therapy for patients with invasive mechanical ventilation in China.

SETTING

A total of 433 hospitals in 92 cities (including 31 capital cities) in 31 provinces in China participated in the study.

METHODS

A questionnaire was used to investigate the knowledge and current practices of ICU nurses regarding aerosol therapy for patients treated with invasive mechanical ventilation, including 42 questions covering five aspects: sociodemographic information, aerosolization devices, atomised drugs, atomisation operation, and atomisation-related knowledge. Descriptive analyses of the distribution of the sample are reported as percentages and medians. Univariate and multivariate analysis was used to detect the factors of the interviewee's atomisation knowledge and practices scores. A STROBE checklist was used to guide the reporting of the research.

RESULTS

Of the 1,995 questionnaires that were returned, 1,978 were analysed. Bronchodilators and glucocorticoids were the most frequently administered drugs. Seventy-four percent of the total respondents reported placing a filter on the expiratory limb during aerosol therapy, and 47% of these reported that the filter was changed once a day. Only 13% of the respondents reported always turning the heating humidifier off during aerosol therapy, and 48% never did. Knowledge about the optimal droplet size or atomisation yield was poor. Work experience in the ICU and frequency of atomisation training were the independent influencing factors for atomisation knowledge and practice scores (F=279.653, P<0.001; F=120.556, P<0.001, respectively).

CONCLUSIONS

The knowledge of ICU nurses about the optimal implementation of aerosol therapy is poor, and the current scientific knowledge about optimal implementation seemed to be applied infrequently. Atomisation-related training should be strengthened, especially for nurses with junior titles and with less work experience.

RELEVANCE TO CLINICAL PRACTICE

Improving the level of ICU nurses' atomization practice ability is helpful to ensure patient safety. In clinical work, atomization expert consensus can be used to carry out relevant training and standardize atomization operation.

An in vitro investigation into the release of fugitive medical aerosols into the environment during manual ventilation

BACKGROUND

During manual resuscitation, nebulizer therapy may be used to deliver therapeutics to patients in respiratory distress. However, the devices used to generate and deliver these medical aerosols have the potential to release these therapeutics into the local environment and expose caregivers to unwanted medical aerosols.

AIM

To quantify the levels of fugitive medical aerosol released into the environment during aerosol drug delivery using a manual resuscitation bag with and without filtration.

METHODS

Time-varying fugitive aerosol concentrations were measured using an aerodynamic particle sizer placed at a position designed to mimic a caregiver. Two nebulizer types were assessed, a vibrating mesh nebulizer and a jet nebulizer. The aerosol dose delivered to the simulated patient lung was also quantified.

FINDINGS

Filtration of the exhalation port of the manual resuscitation bag was seen to reduce fugitive medical aerosols to ambient levels for both nebulizer types. The vibrating mesh nebulizer delivered the greatest quantity of aerosol to the simulated adult patient (18.44 ± 1.03% versus 3.64 ± 0.26% with a jet nebulizer).

CONCLUSIONS

The results highlight the potential for exposure to fugitive medical aerosols released during the delivery of aerosol therapy with a manual resuscitation bag and also the potential for significant variation in patient lung dose depending on nebulizer type.

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.

Inpatient Care during the COVID-19 Pandemic: A Survey of Italian Physicians

BACKGROUND

Coronavirus disease 2019 (COVID-19) is a potentially fatal disease that is of great global public health concern.

OBJECTIVE

We explored the clinical management of inpatients with COVID-19 in Italy.

METHODS

A self-administered survey was sent by email to Italian physicians caring for adult patients with COVID-19. A panel of experts was selected according to their clinical curricula and their responses were analyzed.

RESULTS

A total of 1,215 physicians completed the survey questionnaire (17.4% response rate). Of these, 188 (15.5%) were COVID-19 experts. Chest computed tomography was the most used method to detect and monitor COVID-19 pneumonia. Most of the experts managed acute respiratory failure with CPAP (56.4%), high flow nasal cannula (18.6%), and non-invasive mechanical ventilation (8%), while an intensivist referral for early intubation was requested in 17% of the cases. Hydroxychloroquine was prescribed as an antiviral in 90% of cases, both as monotherapy (11.7%), and combined with protease inhibitors (43.6%) or azithromycin (36.2%). The experts unanimously prescribed low-molecular-weight heparin to patients with severe COVID-19 pneumonia, and half of them (51.6%) used a dose higher than standard. The respiratory burden in patients who survived the acute phase was estimated as relevant in 28.2% of the cases, modest in 39.4%, and negligible in 9%.

CONCLUSIONS

In our survey some major topics, such as the role of non-invasive respiratory support and drug treatments, show disagreement between experts, likely reflecting the absence of high-quality evidence studies. Considering the significant respiratory sequelae reported following COVID-19, proper respiratory and physical therapy programs should be promptly made available.

Mucoactive agents for acute respiratory failure in the critically ill: a systematic review and meta-analysis

PURPOSE

Acute respiratory failure (ARF) is a common cause of admission to intensive care units (ICUs). Mucoactive agents are medications that promote mucus clearance and are frequently administered in patients with ARF, despite a lack of evidence to underpin clinical decision making. The aim of this systematic review was to determine if the use of mucoactive agents in patients with ARF improves clinical outcomes.

METHODS

We searched electronic and grey literature (January 2020). Two reviewers independently screened, selected, extracted data and quality assessed studies. We included trials of adults receiving ventilatory support for ARF and involving at least one mucoactive agent compared with placebo or standard care. Outcomes included duration of mechanical ventilation. Meta-analysis was undertaken using random-effects modelling and certainty of the evidence was assessed using Grades of Recommendation, Assessment, Development and Evaluation.

RESULTS

Thirteen randomised controlled trials were included (1712 patients), investigating four different mucoactive agents. Mucoactive agents showed no effect on duration of mechanical ventilation (seven trials, mean difference (MD) -1.34, 95% CI -2.97 to 0.29, I²=82%, very low certainty) or mortality, hospital stay and ventilator-free days. There was an effect on reducing ICU length of stay in the mucoactive agent groups (10 trials, MD -3.22, 95% CI -5.49 to -0.96, I²=89%, very low certainty).

CONCLUSION

Our findings do not support the use of mucoactive agents in critically ill patients with ARF. The existing evidence is of low quality. High-quality randomised controlled trials are needed to determine the role of specific mucoactive agents in critically ill patients with ARF.

PROSPERO REGISTRATION NUMBER

CRD42018095408.

International Consensus Guidelines for the Optimal Use of the Polymyxins: Endorsed by the American College of Clinical Pharmacy (ACCP), European Society of Clinical Microbiology and Infectious Diseases (ESCMID), Infectious Diseases Society of America (IDSA), International Society for Anti-infective Pharmacology (ISAP), Society of Critical Care Medicine (SCCM), and Society of Infectious Diseases Pharmacists (SIDP)

The polymyxin antibiotics colistin (polymyxin E) and polymyxin B became available in the 1950s and thus did not undergo contemporary drug development procedures. Their clinical use has recently resurged, assuming an important role as salvage therapy for otherwise untreatable gram-negative infections. Since their reintroduction into the clinic, significant confusion remains due to the existence of several different conventions used to describe doses of the polymyxins, differences in their formulations, outdated product information, and uncertainties about susceptibility testing that has led to lack of clarity on how to optimally utilize and dose colistin and polymyxin B. We report consensus therapeutic guidelines for agent selection and dosing of the polymyxin antibiotics for optimal use in adult patients, as endorsed by the American College of Clinical Pharmacy (ACCP), Infectious Diseases Society of America (IDSA), International Society of Anti-Infective Pharmacology (ISAP), Society for Critical Care Medicine (SCCM), and Society of Infectious Diseases Pharmacists (SIDP). The European Society for Clinical Microbiology and Infectious Diseases (ESCMID) endorses this document as a consensus statement. The overall conclusions in the document are endorsed by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). We established a diverse international expert panel to make therapeutic recommendations regarding the pharmacokinetic and pharmacodynamic properties of the drugs and pharmacokinetic targets, polymyxin agent selection, dosing, dosage adjustment and monitoring of colistin and polymyxin B, use of polymyxin-based combination therapy, intrathecal therapy, inhalation therapy, toxicity, and prevention of renal failure. The treatment guidelines provide the first ever consensus recommendations for colistin and polymyxin B therapy that are intended to guide optimal clinical use.

Clinical Use and Barriers of Thoracic Ultrasound: A Survey of Italian Pulmonologists

INTRODUCTION

Thoracic ultrasound is accurate in the diagnosis of a wide range of respiratory diseases. Yet the extent of its use is unknown. Through a national survey, we aimed to explore the clinical use of thoracic ultrasound and the barriers to the diffusion of the technique in Italy.

METHODS

Accademia di Ecografia Toracica (AdET) developed a self-administered survey which was sent by email to Italian pulmonologists via national scientific societies and networks.

RESULTS

Of the 2010 physicians invited, 514 completed the survey (26% response rate). According to 99% of responders, thoracic ultrasound had a relevant clinical role. Seventy-nine percent of the responders used thoracic ultrasound at least once a month. The main settings were: 53% pulmonology ward, 15% outpatient clinic, 15% interventional pulmonology room, 10% internal medicine ward, 4% respiratory intensive care units, and 9% other. Thoracic ultrasound was primarily used: (1) with both diagnostic and interventional aims (72%), (2) as diagnostic imaging (17%), and (3) as guidance for interventional procedures (11%). The main clinical applications were: (1) diagnosis and management of pleural effusion, (2) pneumothorax, (3) pneumonia, (4) cardiac failure, and (5) acute dyspnea. Twenty-one percent of the responders do not use thoracic ultrasound. The main reported bar-riers were: (1) availability of an ultrasound system (52%), (2) lack of protected time and training (22%), and (3) use of the technique by other specialists (15%).

CONCLUSION

Thoracic ultrasound is widely used by Italian pulmonologists and considered a clinically relevant tool. The availability of dedicated ultrasound systems seems to be a major limit of the use of the technique.

Intranasal instillation of distilled water, hypertonic saline and sodium bicarbonate promotes redox imbalance and acute lung inflammation in adult mice

Bronchial obstruction, caused by retained secretions, is often treated by the administration of mucoactive agents including distilled water, saline, hypertonic saline, and sodium bicarbonate. However, the inflammatory effect of these solutions on the lungs remains unclear. This study evaluated the instillation effects of different solutions on oxidative stress and lung inflammatory response in C57BL/6 mice. Fifty C57BL/6 mice were divided into 5 groups: control (CG); distilled water (DWG), hypertonic saline (HSG), saline (SG) and sodium bicarbonate (SBG). CG was exposed to ambient air while DWG, HSG, SG and SBG had 50 μl of respective solutions administered intranasally for 5 consecutive days. Twenty-four hours after the last intranasal instillation, all animals were euthanized for subsequent analysis. All solutions promoted increased recruitment of inflammatory cells to the lung compared to controls. Superoxide dismutase activity was lower in HSG compared to all other groups; catalase activity was reduced in SG, while it increased in SBG and DWG compared to CG. Finally, there was an increase in the inflammatory markers TNF-α, CCL2 and IFN-γ in DWG compared to CG, SG and HSG. In conclusions, the intranasal instillation of different solutions promotes redox imbalance and inflammation on lungs of adult mice.

Use of Colistin in Critically Ill Patients

Due to lack of better therapeutic options, colistin use for extensively drug-resistant Gram-negative organisms was revived in the past two decades, including in patients in intensive-care units (ICU). There are multiple knowledge gaps pertaining to the clinical use and utility of colistin in critically-ill patients, but due to lack of options, it is used in these high risk patients. In this chapter, we critically review the various topics pertaining to colistin use in critically-ill patients, while highlighting the (lack of) controlled evidence supporting common current practices pertaining to colistin use by clinicians.

Practice pattern of aerosol therapy among patients undergoing mechanical ventilation in mainland China: A web-based survey involving 447 hospitals

BACKGROUND AND OBJECTIVE

Aerosol therapies are widely used for mechanically ventilated patients. However, the practice pattern of aerosol therapy in mainland China remains unknown. This study aimed to determine the current practice of aerosol therapy in mainland China.

METHODS

A web-based survey was conducted by the China Union of Respiratory Care (CURC) from August 2018 to January 2019. The survey was disseminated via Email or WeChat to members of CURC. A questionnaire comprising 16 questions related to hospital information and 12 questions related to the practice of aerosol therapy. Latent class analysis was employed to identify the distinct classes of aerosol therapy practice.

MAIN RESULTS

A total of 693 valid questionnaires were returned by respiratory care practitioners from 447 hospitals. Most of the practitioners used aerosol therapy for both invasive mechanical ventilation (90.8%) and non-invasive mechanical ventilation (91.3%). Practitioners from tertiary care centers were more likely to use aerosol therapy compared with those from non-tertiary care centers (91.9% vs. 85.4%, respectively; p = 0.035). The most commonly used drugs for aerosol therapy were bronchodilators (64.8%) followed by mucolytic agents (44.2%), topical corticosteroids (43.4%) and antibiotics (16.5%). The ultrasonic nebulizer (48.3%) was the most commonly used followed by the jet nebulizer (39.2%), the metered dose inhaler (15.4%) and the vibrating mesh nebulizer (14.6%). Six latent classes were identified via latent class analysis. Class 1 was characterized by the aggressive use of aerosol therapy without a standard protocol, while class 3 was characterized by the absence of aerosol therapy.

CONCLUSIONS

Substantial heterogeneity among institutions with regard to the use of aerosol therapy was noted. The implementation of aerosol therapy during mechanical ventilation was inconsistent in light of recent practice guidelines. Additional efforts by the CURC to improve the implementation of aerosol therapy in mainland China are warranted.

Inhaled Antimicrobials for Ventilator-Associated Pneumonia: Practical Aspects

Positive experience with inhaled antibiotics in pulmonary infections of patients with cystic fibrosis has paved the way for their utilization in mechanically ventilated, critically ill patients with lower respiratory tract infections. A successful antibiotic delivery depends upon the size of the generated particle and the elimination of drug impaction in the large airways and the ventilator circuit. Generated droplet size is mainly affected by the type of the nebulizer employed. Currently, jet, ultrasonic, and vibrating mesh nebulizers are marketed; the latter can deliver optimal antibiotic particle size. Promising novel drug-device combinations are able to release drug concentrations of 25- to 300-fold the minimum inhibitory concentration of the targeted pathogens into the pulmonary alveoli. The most important practical steps of nebulization include pre-assessment and preparation of the patient (suctioning, sedation, possible bronchodilation, adjustment of necessary ventilator settings); adherence to the procedure (drug preparation, avoidance of unnecessary tubing connections, interruption of heated humidification, removal of heat-moisture exchanger); inspection of the procedure (check for residual in drug chamber, change of expiratory filter, return sedation, and ventilator settings to previous status); and surveillance of the patient for adverse events (close monitoring of the patient and particularly of peak airway pressure and bronchoconstriction). Practical aspects of nebulization are very important to ensure optimal drug delivery and safe procedure for the patient. Therefore, the development of an operational checklist is a priority for every department adopting this modality.

Effect of On-Demand vs Routine Nebulization of Acetylcysteine With Salbutamol on Ventilator-Free Days in Intensive Care Unit Patients Receiving Invasive Ventilation: A Randomized Clinical Trial

IMPORTANCE

It remains uncertain whether nebulization of mucolytics with bronchodilators should be applied for clinical indication or preventively in intensive care unit (ICU) patients receiving invasive ventilation.

OBJECTIVE

To determine if a strategy that uses nebulization for clinical indication (on-demand) is noninferior to one that uses preventive (routine) nebulization.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial enrolling adult patients expected to need invasive ventilation for more than 24 hours at 7 ICUs in the Netherlands.

INTERVENTIONS

On-demand nebulization of acetylcysteine or salbutamol (based on strict clinical indications, n = 471) or routine nebulization of acetylcysteine with salbutamol (every 6 hours until end of invasive ventilation, n = 473).

MAIN OUTCOMES AND MEASURES

The primary outcome was the number of ventilator-free days at day 28, with a noninferiority margin for a difference between groups of -0.5 days. Secondary outcomes included length of stay, mortality rates, occurrence of pulmonary complications, and adverse events.

RESULTS

Nine hundred twenty-two patients (34% women; median age, 66 (interquartile range [IQR], 54-75 years) were enrolled and completed follow-up. At 28 days, patients in the on-demand group had a median 21 (IQR, 0-26) ventilator-free days, and patients in the routine group had a median 20 (IQR, 0-26) ventilator-free days (1-sided 95% CI, -0.00003 to ∞). There was no significant difference in length of stay or mortality, or in the proportion of patients developing pulmonary complications, between the 2 groups. Adverse events (13.8% vs 29.3%; difference, -15.5% [95% CI, -20.7% to -10.3%]; P < .001) were more frequent with routine nebulization and mainly related to tachyarrhythmia (12.5% vs 25.9%; difference, -13.4% [95% CI, -18.4% to -8.4%]; P < .001) and agitation (0.2% vs 4.3%; difference, -4.1% [95% CI, -5.9% to -2.2%]; P < .001).

CONCLUSIONS AND RELEVANCE

Among ICU patients receiving invasive ventilation who were expected to not be extubated within 24 hours, on-demand compared with routine nebulization of acetylcysteine with salbutamol did not result in an inferior number of ventilator-free days. On-demand nebulization may be a reasonable alternative to routine nebulization.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02159196.

Better airway resistance reduction profile in intubated COPD patients by personalized bronchodilator dosing: A pilot randomized control trial

INTRODUCTION

The optimal dose of inhaled metered-dose bronchodilators for intubated patients with chronic obstructive pulmonary disease (COPD) is unknown. In this study, we proposed a bronchodilator dosing schedule based on an individual's airway resistance (R_aw) and tested its efficacy in reducing R_aw.

METHODS

A total of 51 newly admitted patients with invasively ventilated COPD were randomly assigned to receive personalized or fixed bronchodilator dosing. Personal target R_aw was defined by measuring each individual's R_aw after maximal pharmacologic bronchodilatation. Thereafter, R_aw was measured every 8 h until the 28th day. Patients in the fixed-dosing group received only predetermined doses. Additional doses of bronchodilators were given to patients in the personalized-dosing group when the measured R_aw exceeded their target R_aw.

RESULTS

The median daily doses of salmeterol/fluticasone were 9.2 (personalized-dosing) vs 7.6 (fixed-dosing) puffs (P < 0.001). The relative deviation of R_aw from the personal target was expressed as (measured R_aw - target R_aw)/target R_aw. The experimental group showed a smaller relative R_aw deviation than the control group (0.09 ± 0.10 vs 0.44 ± 0.11, P = 0.02). There were no differences between the two groups in terms of ventilator-free days from day 1 to day 28, number of episodes of nosocomial pneumonia, total number of puffs of rescue bronchodilator, number of drug-related adverse effects or mortality rate at day 180.

CONCLUSION

Personalized dosing of inhaled bronchodilator administered to invasively ventilated COPD patients can produce a better reduction in R_aw. Further studies with larger sample size are required to verify the conclusion of this pilot study.

Vibrating Mesh Nebulisers – Can Greater Drug Delivery to the Airways and Lungs Improve Respiratory Outcomes?

Aerosols are an increasingly important mode of delivery of drugs, particularly bronchodilators, for the treatment of respiratory diseases, notably asthma and chronic obstructive pulmonary disease. The most common type of nebuliser is the jet nebuliser (JN); they have been in use for more than a century but these devices can be cumbersome to use and may sometimes deliver insufficient amounts of drug. A more recent development in aerosol therapy is the vibrating mesh nebuliser (VMN) which is very user friendly and is more efficient than the JNs due to an extremely low residual volume. Scintigraphy images from studies of volunteer subjects using radio-labelled aerosol treatment show that VMN-generated aerosols deliver more drug to patients in a shorter period of time than JN-generated aerosols. Various bench, animal model and small clinical studies have shown that VMNs are more efficient than JNs in drug delivery, potentially improving clinical outcomes. These studies have included various breathing circuits used in mechanical ventilation (MV), non-invasive ventilation, high-flow nasal cannula systems and devices for spontaneously breathing patients. The efficiency of drug delivery was affected by factors including the position of the nebuliser in the circuit and humidity. Some studies have shown potential substantial savings by hospitals in the cost of MV treatments after switching from metered dose inhalers to VMNs. VMNs have also been shown to be effective for the administration of inhaled antibiotics, corticosteroids and other drugs. Larger studies of the effects of VMNs on patient outcomes are needed but they are likely to be an increasingly important means of administering therapies to a burgeoning population with respiratory disease.

In vitro evaluation of aerosol delivery of aztreonam lysine (AZLI): an adult mechanical ventilation model

BACKGROUND

The delivery profile of Aztreonam lysine (AZLI) during mechanical ventilation (MV) is unknown. We evaluated the amount of AZLI drug delivered using an in vitro model of adult MV.

METHODS

An adult lung model designed to mimic current clinical practice was used. Both nebulizers were placed before a Y-piece and 4 settings were tested: A) Aeroneb solo® [AS] with a t-piece; B) AS with the spacer; C) M-Neb® [MN] with a t-piece and D) MN with the spacer. Performance was evaluated in terms of: 1) Mass median aerodynamic diameter (MMAD); 2) Geometric standard deviation (GSD), 3) Fine particle dose (FPD), 4) Fine particle fraction (FPF), 5) Inhalable mass (IM), and 6) Recovery rate (RR).

RESULTS

Both devices showed an adequate delivery of AZLI during MV, with MMAD between 2.4-2.5 µm and 87% of FPF. The FPD (38.8 and 31.7), IM (44.8 and 36.1) and RR (30 and 24) were similar for AS and MN respectively. Nebulizer aerosol delivery increased (50 and 70% respectively) for both nebulizers when using the spacer.

CONCLUSION

Both AS and MN showed a good aerosol delivery profile for AZLI during in vitro mechanical ventilation. Better aerosol delivery performance was obtained using the spacer.

Aerosol delivery during invasive mechanical ventilation: a systematic review

BACKGROUND

This systematic review aimed to assess inhaled drug delivery in mechanically ventilated patients or in animal models. Whole lung and regional deposition and the impact of the ventilator circuit, the artificial airways and the administration technique for aerosol delivery were analyzed.

METHODS

In vivo studies assessing lung deposition during invasive mechanical ventilation were selected based on a systematic search among four databases. Two investigators independently assessed the eligibility and the risk of bias.

RESULTS

Twenty-six clinical and ten experimental studies were included. Between 30% and 43% of nominal drug dose was lost to the circuit in ventilated patients. Whole lung deposition of up to 16% and 38% of nominal dose (proportion of drug charged in the device) were reported with nebulizers and metered-dose inhalers, respectively. A penetration index inferior to 1 observed in scintigraphic studies indicated major proximal deposition. However, substantial concentrations of antibiotics were measured in the epithelial lining fluid (887 (406-12,819) μg/mL of amikacin) of infected patients and in sub-pleural specimens (e.g., 197 μg/g of amikacin) dissected from infected piglets, suggesting a significant distal deposition. The administration technique varied among studies and may explain a degree of the variability of deposition that was observed.

CONCLUSIONS

Lung deposition was lower than 20% of nominal dose delivered with nebulizers and mostly occurred in proximal airways. Further studies are needed to link substantial concentrations of antibiotics in infected pulmonary fluids to pulmonary deposition. The administration technique with nebulizers should be improved in ventilated patients in order to ensure an efficient but safe, feasible and reproducible technique.

Current options in aerosolised drug therapy for children receiving respiratory support

Inhalation of aerosolised medications are the mainstay of treatment for a number of chronic lung diseases and have several advantages over systemically-administered medications. These include more rapid onset of action for drugs such as β-adrenergic agonists when compared with oral medication, high luminal doses for inhaled antibiotics when used to treat endobronchial infection, and an improved therapeutic index compared with systemic delivery for these and other classes of drugs such as corticosteroids. The use of aerosolised drugs to treat patients whose tracheas are intubated is less well established, in part because systemic delivery via the intravenous route can be a simpler alternative for many drugs. Consequently, research in this area is largely limited to a number of in vitro studies and very few clinical trials. Unfortunately, a lack of focus in this area has resulted in a number of practices which at best are ineffective, and at worst dangerous for the patient. Although there have been some attempts to re-invigorate research in order to improve delivery systems, current devices are, to a great extent, based on long-standing technology developed more than 50 years ago. In this review, we explore current knowledge and provide guidance as to when and how the inhaled route may be of value when treating patients whose tracheas are intubated, and we set out the challenges facing those attempting to advance the topic. We conclude by reviewing current areas of interest that may lead to more effective and widespread use of aerosols in the treatment of intubated patients.

Nebulized antibiotics in mechanically ventilated patients: a challenge for translational research from technology to clinical care

Nebulized antibiotic therapy directly targets airways and lung parenchyma resulting in high local concentrations and potentially lower systemic toxicities. Experimental and clinical studies have provided evidence for elevated lung concentrations and rapid bacterial killing following the administration of nebulized antibiotics during mechanical ventilation. Delivery of high concentrations of antibiotics to infected lung regions is the key to achieving efficient nebulized antibiotic therapy. However, current non-standardized clinical practice, the difficulties with implementing optimal nebulization techniques and the lack of robust clinical data have limited its widespread adoption. The present review summarizes the techniques and clinical constraints for optimal delivery of nebulized antibiotics to lung parenchyma during invasive mechanical ventilation. Pulmonary pharmacokinetics and pharmacodynamics of nebulized antibiotic therapy to treat ventilator-associated pneumonia are discussed and put into perspective. Experimental and clinical pharmacokinetics and pharmacodynamics support the use of nebulized antibiotics. However, its clinical benefits compared to intravenous therapy remain to be proved. Future investigations should focus on continuous improvement of nebulization practices and techniques. Before expanding its clinical use, careful design of large phase III randomized trials implementing adequate therapeutic strategies in targeted populations is required to demonstrate the clinical effectiveness of nebulized antibiotics in terms of patient outcomes and reduction in the emergence of antibiotic resistance.

Heat and moisture exchangers (HMEs) and heated humidifiers (HHs) in adult critically ill patients: a systematic review, meta-analysis and meta-regression of randomized controlled trials

BACKGROUND

The aims of this systematic review and meta-analysis of randomized controlled trials are to evaluate the effects of active heated humidifiers (HHs) and moisture exchangers (HMEs) in preventing artificial airway occlusion and pneumonia, and on mortality in adult critically ill patients. In addition, we planned to perform a meta-regression analysis to evaluate the relationship between the incidence of artificial airway occlusion, pneumonia and mortality and clinical features of adult critically ill patients.

METHODS

Computerized databases were searched for randomized controlled trials (RCTs) comparing HHs and HMEs and reporting artificial airway occlusion, pneumonia and mortality as predefined outcomes. Relative risk (RR), 95% confidence interval for each outcome and I ² were estimated for each outcome. Furthermore, weighted random-effect meta-regression analysis was performed to test the relationship between the effect size on each considered outcome and covariates.

RESULTS

Eighteen RCTs and 2442 adult critically ill patients were included in the analysis. The incidence of artificial airway occlusion (RR = 1.853; 95% CI 0.792-4.338), pneumonia (RR = 932; 95% CI 0.730-1.190) and mortality (RR = 1.023; 95% CI 0.878-1.192) were not different in patients treated with HMEs and HHs. However, in the subgroup analyses the incidence of airway occlusion was higher in HMEs compared with HHs with non-heated wire (RR = 3.776; 95% CI 1.560-9.143). According to the meta-regression, the effect size in the treatment group on artificial airway occlusion was influenced by the percentage of patients with pneumonia (β = -0.058; p = 0.027; favors HMEs in studies with high prevalence of pneumonia), and a trend was observed for an effect of the duration of mechanical ventilation (MV) (β = -0.108; p = 0.054; favors HMEs in studies with longer MV time).

CONCLUSIONS

In this meta-analysis we found no superiority of HMEs and HHs, in terms of artificial airway occlusion, pneumonia and mortality. A trend favoring HMEs was observed in studies including a high percentage of patients with pneumonia diagnosis at admission and those with prolonged MV. However, the choice of humidifiers should be made according to the clinical context, trying to avoid possible complications and reaching the appropriate performance at lower costs.

Aerosol Delivery with Two Nebulizers Through High-Flow Nasal Cannula: A Randomized Cross-Over Single-Photon Emission Computed Tomography-Computed Tomography Study

BACKGROUND

High-flow nasal cannula use is developing in ICUs. The aim of this study was to compare aerosol efficiency by using two nebulizers through a high-flow nasal cannula: the most commonly used jet nebulizer (JN) and a more efficient vibrating-mesh nebulizer (VN).

METHODS

Aerosol delivery of diethylenetriaminepentaacetic acid labeled with technetium-99m (4 mCi/4 mL) to the lungs by using a VN (Aerogen Solo^®; Aerogen Ltd., Galway, Ireland) and a constant-output JN (Opti-Mist Plus Nebulizer^®; ConvaTec, Bridgewater, NJ) through a high-flow nasal cannula (Optiflow^®; Fisher & Paykel, New Zealand) was compared in six healthy subjects. Flow rate was set at 30 L/min through the heated humidified circuit. Pulmonary and extrapulmonary deposition was measured by single-photon emission computed tomography combined with a low-dose computed tomographic scan and by planar scintigraphy.

RESULTS

Lung deposition was only 3.6 (2.1-4.4) and 1 (0.7-2)% of the nominal dose with the VN and the JN, respectively (p < 0.05). The JN showed higher retained doses than the VN. However, both nebulizers were associated with substantial deposition in the single limb circuit, the humidification chamber, and the nasal cannula [58.2 (51.6-61.6)% of the nominal dose with the VN versus 19.2 (15.8-22.9)% of the nominal dose with the JN, p < 0.05] and in the upper respiratory tract [17.6 (13.4-27.9)% of the nominal dose with the VN and 8.6 (6.0-11.0)% of the nominal dose with the JN, p < 0.05], especially in the nasal cavity.

CONCLUSIONS

In the specific conditions of the study, pulmonary drug delivery through the high-flow nasal cannula is about 1%-4% of the initial amount of drugs placed in the nebulizer, despite the higher efficiency of the VN as compared with the JN.

Clinical outcome associated with the use of different inhalation method with and without humidification in asthmatic mechanically ventilated patients

BACKGROUND

Inhaled-medication delivered during mechanical-ventilation is affected by type of aerosol-generator and humidity-condition. Despite many in-vitro studies related to aerosol-delivery to mechanically-ventilated patients, little has been reported on clinical effects of these variables. The aim of this study was to determine effect of humidification and type of aerosol-generator on clinical status of mechanically ventilated asthmatics.

METHOD

72 (36 females) asthmatic subjects receiving invasive mechanical ventilation were enrolled and assigned randomly to 6 treatment groups of 12 (6 females) subjects each received, as possible, all inhaled medication using their assigned aerosol generator and humidity condition during delivery. Aerosol-generators were placed immediately after humidifier within inspiratory limb of mechanical ventilation circuit. First group used vibrating-mesh-nebulizer (Aerogen Solo; VMN) with humidification; Second used VMN without humidification; Third used metered-dose-inhaler with AeroChamber Vent (MDI-AV) with humidification; Forth used MDI-AV without humidification; Fifth used Oxycare jet-nebulizer (JN) with humidification; Sixth used JN without humidification. Measured parameters included clinical-parameters reflected patient response (CP) and endpoint parameters e.g. length-of-stay in the intensive-care-unit (ICU-days) and mechanical-ventilation days (MV-days).

RESULTS

There was no significant difference between studied subjects in the 6 groups in baseline of CP. VMN resulted in trend to shorter ICU-days (∼1.42days) compared to MDI-AV (p = 0.39) and relatively but not significantly shorter ICU-days (∼0.75days) compared JN. Aerosol-delivery with or without humidification did not have any significant effect on any of parameters studied with very light insignificant tendency of delivery at humid condition to decrease MV-days and ICU-days. No significant effect was found of changing humidity during aerosol-delivery to ventilated-patient.

CONCLUSIONS

VMN to deliver aerosol in ventilated patient resulted in trend to decreased ICU-days compared to JN and MDI-AV. Aerosol-delivery with or without humidification did not have any significant effect on any of parameters studied. However, we recommend increasing the number of patients studied to corroborate this finding.

An abrupt reduction in end tidal carbon di oxide concentration in a mechanically ventilated patient in neurocritical care ward: a capnogram artifact

In patients with normal lung and reasonable cardiac function such as head injury patients, the PETCo₂ can be used as a surrogate for partial pressure of Carbon dioxide (PaCO₂) in mechanically ventilated patients. Thus early interpretation and accurate assessment of capnogram is crucial in neurocritical care patients. Here we present and discuss a scenario where in connection of a jet nebulizer to the ventilator lead to abrupt decrease in end tidal carbon dioxide leading to a diagnostic dilemma. Also this report highlights and discusses the importance of the proper placement of breathing circuit components to ensure accurate CO₂ readings in particular the use of a jet nebulizer.

Aerosol Drug Delivery During Noninvasive Positive Pressure Ventilation: Effects of Intersubject Variability and Excipient Enhanced Growth

BACKGROUND

Nebulized aerosol drug delivery during the administration of noninvasive positive pressure ventilation (NPPV) is commonly implemented. While studies have shown improved patient outcomes for this therapeutic approach, aerosol delivery efficiency is reported to be low with high variability in lung-deposited dose. Excipient enhanced growth (EEG) aerosol delivery is a newly proposed technique that may improve drug delivery efficiency and reduce intersubject aerosol delivery variability when coupled with NPPV.

MATERIALS AND METHODS

A combined approach using in vitro experiments and computational fluid dynamics (CFD) was used to characterize aerosol delivery efficiency during NPPV in two new nasal cavity models that include face mask interfaces. Mesh nebulizer and in-line dry powder inhaler (DPI) sources of conventional and EEG aerosols were both considered.

RESULTS

Based on validated steady-state CFD predictions, EEG aerosol delivery improved lung penetration fraction (PF) values by factors ranging from 1.3 to 6.4 compared with conventional-sized aerosols. Furthermore, intersubject variability in lung PF was very high for conventional aerosol sizes (relative differences between subjects in the range of 54.5%-134.3%) and was reduced by an order of magnitude with the EEG approach (relative differences between subjects in the range of 5.5%-17.4%). Realistic in vitro experiments of cyclic NPPV demonstrated similar trends in lung delivery to those observed with the steady-state simulations, but with lower lung delivery efficiencies. Reaching the lung delivery efficiencies reported with the steady-state simulations of 80%-90% will require synchronization of aerosol administration during inspiration and reducing the size of the EEG aerosol delivery unit.

CONCLUSIONS

The EEG approach enabled high-efficiency lung delivery of aerosols administered during NPPV and reduced intersubject aerosol delivery variability by an order of magnitude. Use of an in-line DPI device that connects to the NPPV mask appears to be a convenient method to rapidly administer an EEG aerosol and synchronize the delivery with inspiration.

Fundamentals of aerosol therapy in critical care

Drug dosing in critically ill patients is challenging due to the altered drug pharmacokinetics–pharmacodynamics associated with systemic therapies. For many drug therapies, there is potential to use the respiratory system as an alternative route for drug delivery. Aerosol drug delivery can provide many advantages over conventional therapy. Given that respiratory diseases are the commonest causes of critical illness, use of aerosol therapy to provide high local drug concentrations with minimal systemic side effects makes this route an attractive option. To date, limited evidence has restricted its wider application. The efficacy of aerosol drug therapy depends on drug-related factors (particle size, molecular weight), device factors, patient-related factors (airway anatomy, inhalation patterns) and mechanical ventilation-related factors (humidification, airway). This review identifies the relevant factors which require attention for optimization of aerosol drug delivery that can achieve better drug concentrations at the target sites and potentially improve clinical outcomes.