Nebulized Ceftazidime and Amikacin in Ventilator-associated Pneumonia Caused byPseudomonas aeruginosa

A consensus of European experts on the definition of ventilator-associated pneumonia recurrences obtained by the Delphi method: the RECUVAP study

BACKGROUND

There are recognized diagnostic criteria for a first ventilator-associated pneumonia (VAP) episode, but not for recurrences. Many randomized clinical trials (RCTs) have used the recurrence of VAP as a criterion for efficacy evaluation. Still, the different definitions used in RCTs make it difficult to compare studies. We aimed to develop a consensual definition of VAP recurrences and of the various types of VAP recurrences.

METHODS

Thirty-six European experts constituting a multidisciplinary group of physicians (critical care, infectious diseases, microbiology) with special interest in the management of VAP were polled using the Delphi methodology.

RESULTS

After the completion of four iterations of the DELPHI method, 94% of experts agreed that the diagnostic criteria for a first VAP episode could also be used for recurrences, except for the radiological criterion, which not all the experts considered to be mandatory. Consensus was also reached regarding the definition of four distinct entities: relapse, persistent VAP, superinfection, and new-pathogen VAP. For relapse and persistent VAP, bacteriological findings were identical for different VAP episodes, whereas they differed for superinfection and new-pathogen VAP. The distinction between relapse and persistent VAP, and between superinfection and new-pathogen VAP depended on the timing of antibiotic treatment (before or after 48-72 h after the end of antibiotic therapy) and the clinical course. Microbiological criteria were proposed to facilitate the diagnosis of persistent VAP.

CONCLUSION

This consensus by European experts proposes four different VAP recurrence entities which should facilitate the harmonization of recurrence criteria for clinical practice and future studies.

Impact of Hydrophobic, Hydrophilic, and Mucus-Binding Motifs on the Therapeutic Potential of Ceftazidime Analogs for Pulmonary Administration

Background/Objectives: The pulmonary administration of antibiotics can be advantageous in treating pulmonary infections by promoting high intrapulmonary drug concentrations with reduced systemic exposure. However, limited benefits have been observed for pulmonary administration versus other administration routes due to its rapid clearance from the lung. Here, the effects of structural modifications on the epithelial permeability and antibacterial potency of a third-generation cephalosporin were investigated to improve the understanding of drug properties that promote intrapulmonary retention and how they may impact efficacy. Methods: Ceftazidime was modified by attaching 18 hydrophobic, hydrophilic, and mucus-binding motifs to the carboxylic acid distant from the beta-lactam by amidation. Epithelial permeability was investigated by drug transport assays using human bronchial epithelial air-liquid interface cultures. Antibacterial potency was determined by microtiter MIC assays with B. pseudomallei, P. aeruginosa, E. coli, and S. aureus. Results: A 40-50% reduction in the transepithelial transport rate was exhibited by two PEGylated ceftazidime analogs (mPEG8- and PEG5-pyrimidin-2-amine-ceftazidime) and n-butyl-ceftazidime. An increase in the transport rate was exhibited by four analogs bearing small and hydrophobic or negatively charged motifs (n-heptane-, phenyl ethyl-, glutamic acid-, and 4-propylthiophenyl boronic acid-ceftazidime). The antibacterial potency was reduced by ≥10-fold for most ceftazidime analogs against B. pseudomallei, P. aeruginosa, and E. coli but was retained by seven ceftazidime analogs primarily bearing hydrophobic motifs against S. aureus. Conclusions: The covalent conjugation of PEGs with MW > 300 Da reduced the epithelial permeability of ceftazidime, but these modifications severely reduced antibacterial activity. To improve the pulmonary retention of antibiotics with low membrane permeability, this work suggests future molecular engineering studies to explore high-molecular-weight prodrug strategies.

Nebulized aminoglycosides for ventilator-associated pneumonia: Methodological considerations and lessons from experimental studies

Aminoglycosides are concentration-dependent antibiotics exerting a bactericidal effect when concentrations at the site of infection are equal to or greater than 5 times the minimum inhibitory concentrations (MIC). When administered intravenously, they exhibit poor lung penetration and high systemic renal and ototoxicity, imposing to restrict their administration to 5 days. Experimental studies conducted in anesthetized and mechanically ventilated sheep and pigs provide evidence that high doses of nebulized aminoglycosides induce a rapid and potent bacterial killing in the infected lung parenchyma. They also confirm that the alveolar-capillary membrane, either normal or injured by the infectious process, restricts the penetration of intravenous aminoglycosides in the infected lung parenchyma, precluding a bactericidal effect at the site of infection. However, injury of the alveolar-capillary membrane promotes the systemic diffusion of nebulized aminoglycosides. Based on experimental data obtained in animals with inoculation pneumonia, it challenges the classical belief that nebulization protects against systemic toxicity. Loss of lung aeration decreases the lung penetration of nebulized aminoglycosides. Nevertheless, lung tissue concentrations measured in non-aerated lung regions with severe and extended pneumonia are most often greater than 5 times the MICs, resulting in a bactericidal effect followed by a progressive pulmonary reaeration. It is likely that the penetration into the consolidated lung, results from the bronchial diffusion of nebulized aminoglycosides toward adjacent non-aerated infected alveolar spaces and their penetration into mechanical ventilation-induced intraparenchymal pseudocysts and distended bronchioles. In animals receiving nebulized aminoglycosides, epithelial lining fluid concentrations grossly overestimate lung interstitial fluid concentrations because of the bronchial contamination of the distal tip of the bronchoscope during the bronchoalveolar procedures. Lung microdialysis is the only technique able to accurately assess lung pharmacokinetics in animals with inoculation pneumonia treated by nebulized aminoglycosides. In 2024, the European Investigators Network for Nebulized Antibiotics in Ventilator-associated Pneumonia (ENAVAP) called for the creation of an international research network for Lung Microdialysis applied to Nebulized Antibiotics (LUMINA) to promote multicentered, experimental, randomized, and controlled studies addressing lung pharmacokinetics of intravenous vs. nebulized antibiotics, using different dosing and ventilator settings.

Inhaled antibiotics for treating pneumonia in invasively ventilated patients in intensive care unit: a meta-analysis of randomized clinical trials with trial sequential analysis

BACKGROUND

The use of inhaled antibiotics for treating pneumonia in invasively ventilated patients offers a direct approach, allowing for high local concentrations of the drug in the lower respiratory tract while simultaneously reducing systemic toxicity. However, the real efficacy and safety of nebulized antibiotics remain unclear. The aim of the present is to assess among critically adult patients with pneumonia and invasive ventilation, whether receiving adjuvant inhaled antibiotics improves the rate of microbiological eradication.

METHODS

A comprehensive literature search of randomized clinical trials (RCTs) was conducted (from inception until September 20, 2024, PROSPERO-CRD592906) across Medline, Embase, and Scopus. Randomized controlled trials, enrolling intensive care units (ICU) patients with pneumonia and comparing nebulized antimicrobial therapy (inhaled group) with intravenous antimicrobial treatment or intravenous antimicrobial therapy plus inhaled placebo (control group), were included. The primary outcome was the rate of microbiological eradication after treatment. Secondary outcomes were the rate of clinical recovery, the incidence of drug-related adverse events, ICU and hospital mortality. A qualitative analysis was conducted according to the GRADE framework. Data were pooled using an odds-ratio analysis. The heterogeneity and reliability of our results were evaluated using the I2-statistic and trial sequential analysis (TSA), respectively.

RESULTS

A total of 11 RCTs (1472 patients) met the inclusion criteria. Compared to controls, the use of adjuvant inhaled antibiotics determined a greater rate of microbiological eradication (OR 2.63, 95% CI 1.36-5.09; low certainty of evidence). The TSA confirmed the reliability of our primary outcome. Moreover, nebulized antibiotics increased the risk of bronchospasm (OR 3.15, 95% CI 1.33-7.47; high evidence), while nephrotoxicity, clinical recovery, ICU and hospital survival (either in the case of pneumonia caused by MDR bacteria or not) were not different between groups.

CONCLUSIONS

In conclusion, compared to the sole intravenous therapy, the use of adjuvant inhaled antibiotics for treatment of pneumonia in invasively ventilated critically ill patients was associated with a greater incidence of microbiological eradication (low GRADE and high risk of publication bias), but not with clinical recovery and survival.

The efficacy and safety of inhaled antibiotics for pneumonia: A systematic review and meta-analysis

OBJECTIVES

The aim of this study was to evaluate the efficacy and safety of inhaled antibiotics for adults with pneumonia by meta-analysis.

METHODS

Literature retrieval was completed through five databases (PubMed, Embase, Cochrane Library, Web of Science and Scopus) by the deadline of May 31, 2024. The process of study selection and data extraction were performed independently by two reviewers. The quality of observational studies and randomized controlled trial (RCT) studies were evaluated by Newcastle Ottawa scale and Jadad scale, respectively. The primary outcomes included mortality, clinical cure, and microbiological cure. Secondary outcomes were recurrence and renal impairment.

RESULTS

There were 30 studies were analyzed, including 12 RCT studies and 18 observational studies. Inhaled antibiotics did not significantly reduce mortality in RCT studies (odds ratio (OR) = 1.06, 95 % confidence interval (CI): 0.80-1.41). Inhaled antibiotics were associated with higher rates of clinical cure (OR = 1.47 95%CI: 0.82-2.66 in RCT studies and OR = 2.09, 95%CI: 1.36-3.21 in observational studies) and microbiological cure (OR = 7.00 in RCT studies and OR = 2.20 in observational studies). Subgroup analysis showed patients received inhaled antibiotics combined with intravenous administration and inhaled amikacin had better improvements of mortality, clinical cure and microbiological cure. Inhaled antibiotics were not associated with recurrence. The pooled OR of renal impairment were 0.65 (95%CI: 0.27-1.13; I-squared = 43.5 %, P = 0.124) and 0.63(95%CI: 0.26-1.11; I-squared = 69.0 %, P = 0.110) in RCT studies and observational studies, respectively.

CONCLUSIONS

Inhaled antibiotics decreased risk of renal impairment and achieved significant improvements of clinical and microbiological cure in patients with pneumoniae.

Efficacy and safety of different polymyxin-containing regimens for the treatment of pneumonia caused by multidrug-resistant gram-negative bacteria: a systematic review and network meta-analysis

BACKGROUND

The optimal administration of polymyxins for treating multidrug-resistant gram-negative bacterial (MDR-GNB) pneumonia remains unclear. This study aimed to systematically assess the efficacy and safety of three polymyxin-containing regimens by conducting a comprehensive network meta-analysis.

METHODS

We comprehensively searched nine databases. Overall mortality was the primary outcome, whereas the secondary outcomes encompassed microbial eradication rate, clinical success, acute kidney injury, and incidence of bronchospasm. Extracted study data were analyzed by pairwise and network meta-analyses. Version 2 of the Cochrane risk-of-bias tool and the Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) assessment tool were used to assess the risk of bias in randomized trials and cohort studies, respectively.

RESULTS

This study included 19 observational studies and 3 randomized controlled trials (RCTs), encompassing 3318 patients. Six studies with high risk of bias were excluded from the primary analysis. In the pairwise meta-analysis, compared to the intravenous (IV) polymyxin-containing regimen, the intravenous plus inhaled (IV + IH) polymyxin-containing regimen showed a significant decrease in overall mortality, while no statistically significant difference was found in the inhaled (IH) polymyxin-containing regimen. The network meta-analysis indicated that the IV + IH polymyxin-containing regimen had significantly lower overall mortality (OR 0.67; 95% confidence interval [CI] 0.50-0.88), higher clinical success rate (OR 1.90; 95% CI 1.20-3.00), better microbial eradication rate (OR 2.70; 95% CI 1.90-3.90) than the IV polymyxin-containing regimen, and significantly better microbial eradication rate when compared with the IH polymyxin-containing regimen (OR 2.30; 95% CI 1.30-4.20). Furthermore, compared with IV + IH and IV polymyxin-containing regimens, the IH polymyxin-containing regimen showed a significant reduction in acute kidney injury.

CONCLUSIONS

Our study indicates that among the three administration regimens, the IV + IH polymyxin-containing regimen may be the most effective for treating MDR-GNB pneumonia, with a significantly lower overall mortality compared to the IV regimen and a considerably higher microbial eradication rate compared to the IH regimen. The IH regimen may be considered superior to the IV regimen due to its substantially lower incidence of acute kidney injury, even though the reduction in overall mortality was not significant.

Cavitation is the determining mechanism for the atomization of high-viscosity liquid

Piezoelectric atomization is becoming mainstream in the field of inhalation therapy due to its significant advantages. With the rapid development of high-viscosity gene therapy drugs, the demand for piezoelectric atomization devices is increasing. However, conventional piezoelectric atomizers with a single-dimensional energy supply are unable to provide the energy required to atomize high-viscosity liquids. To address this problem, our team has designed a flow tube internal cavitation atomizer (FTICA). This study focuses on dissecting the atomization mechanism of FTICA. In contrast to the widely supported capillary wave hypothesis, our study provides evidence in favor of the cavitation hypothesis, proving that cavitation is the key to atomizing high-viscosity liquids with FTICA. In order to prove that the cavitation is the key to atomizing in the structure of FTICA, the performance of atomization is experimented after changing the cavitation conditions by heating and stirring of the liquids.

A prospective phase IIA multicenter double-blinded randomized placebo-controlled clinical trial evaluating the efficacy and safety of inhaled Tobramycin in patients with ventilator-associated pneumonia (iToVAP)

OBJECTIVE

Treatment of ventilated pneumonia is often unsuccessful, even when patients are treated according to current guidelines. Therefore, we aimed to investigate the efficacy of the adjunctive inhaled Tobramycin in patients with pneumonia caused by Gram-negative pathogens in addition to the standard systemic treatment.

DESIGN

Prospective, multicenter, double-blinded, randomized, placebo-controlled clinical trial.

SETTING

26 patients in medical and surgical ICUs.

PATIENTS

Patients with ventilator-associated pneumonia caused by Gram-negative pathogens.

MEASUREMENT AND MAIN RESULTS

Fourteen patients were assigned to the Tobramycin Inhal group and 12 patients to the control group. The microbiological eradication of the Gram-negative pathogens was significantly higher in the intervention group than in the control group (p < 0.001). The probability of eradication was 100% in the intervention group [95% Confidence Interval: 0.78-1.0] and 25% in the control group [95% CI: 0.09-0.53]. The increased eradication frequency was not associated with increased patient survival.

CONCLUSION

Inhaled aerosolized Tobramycin demonstrated clinically meaningful efficacy in patients with Gram-negative ventilator-associated pneumonia. The probability of eradication in the intervention group was 100%. However, the successful eradication was not associated with a reduction in systemic anti-infective therapy, a shorter ICU stay, or even a survival benefit. In the presence of multidrug-resistant Gram-negative pathogens that are sensitive only to colistin and/or aminoglycosides, supplemental inhaled therapy with nebulizers suitable for this purpose should be considered in addition to systemic antibiotic therapy.

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

INTRODUCTION

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

METHODS AND ANALYSIS

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

DISCUSSION

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

TRIAL REGISTRATION

ClinicalTrails.Gov Registry (NCT05635903).

Inhaled antibiotics in children with tracheostomy tubes: A descriptive study

INTRODUCTION

Respiratory tract infections (RTIs) are common in children with tracheostomy tubes. Anecdotally, inhaled antibiotics are commonly prescribed, although to date there are no studies describing their use in this patient population. The objective of this study was to assess the variability of this practice at a single tertiary care children's hospital.

METHODS

All children admitted to our hospital with a tracheostomy tube who were prescribed inhaled antibiotics between 2013 and 2020 were included. Patient characteristics and data regarding inhaled antibiotic use were obtained retrospectively from the electronic medical record.

RESULTS

A total of 424 courses of inhaled antibiotics were prescribed during the study period. 296 (69.8%) courses were prescribed to treat an acute RTI, whereas 128 (30.2%) were prescribed prophylactically to prevent RTIs. 58.9% of children with tracheostomy tubes hospitalized during the study period received at least one course of inhaled antibiotics. The most common antibiotics prescribed were tobramycin and gentamicin; several different doses were used. In 53.2% of treatment courses, inhaled antibiotics were co-prescribed with systemic antibiotics. Therapy duration for treatment varied from 3 to 28 days. Respiratory cultures were used variably and antimicrobial susceptibility was often not taken into account when prescribing inhaled antibiotics.

CONCLUSIONS

Inhaled antibiotics were frequently prescribed as treatment and prophylaxis in children with tracheostomy tubes at our center, with significant variation in the prescribed antibiotic type, dose, frequency, duration, and co-prescription with systemic antibiotics. Prospective studies are needed to define best practice regarding inhaled antibiotics in this patient population.

Advances in inhaled antibiotics for management of respiratory tract infections

PURPOSE OF REVIEW

The incidence of bacterial respiratory tract infections is growing. In a context of increasing antibiotic resistance and lack of new classes of antibiotics, inhaled antibiotics emerge as a promising therapeutic strategy. Although they are generally used for cystic fibrosis, their use in other conditions is becoming more frequent, including no-cystic fibrosis bronchiectasis, pneumonia and mycobacterial infections.

RECENT FINDINGS

Inhaled antibiotics exert beneficial microbiological effects in bronchiectasis and chronic bronchial infection. In nosocomial and ventilator-associated pneumonia, aerosolized antibiotics improve cure rates and bacterial eradication. In refractory Mycobacterium avium complex infections, amikacin liposome inhalation suspension is more effective in achieving long-lasting sputum conversion. In relation to biological inhaled antibiotics (antimicrobial peptides, interfering RNA and bacteriophages), currently in development, there is no still enough evidence that support their use in clinical practice.

SUMMARY

The effective antimicrobiological activity of inhaled antibiotics, added to their potential to overcoming resistances to systemic antibiotics, make inhaled antibiotics a plausible alternative.

Administration of Bacteriophages via Nebulization during Mechanical Ventilation: In Vitro Study and Lung Deposition in Macaques

Bacteriophages have been identified as a potential treatment option to treat lung infection in the context of antibiotic resistance. We performed a preclinical study to predict the efficacy of delivery of bacteriophages against Pseudomonas aeruginosa (PA) when administered via nebulization during mechanical ventilation (MV). We selected a mix of four anti-PA phages containing two Podoviridae and two Myoviridae, with a coverage of 87.8% (36/41) on an international PA reference panel. When administered via nebulization, a loss of 0.30–0.65 log of infective phage titers was measured. No difference between jet, ultrasonic and mesh nebulizers was observed in terms of loss of phage viability, but a higher output was measured with the mesh nebulizer. Interestingly, Myoviridae are significantly more sensitive to nebulization than Podoviridae since their long tail is much more prone to damage. Phage nebulization has been measured as compatible with humidified ventilation. Based on in vitro measurement, the lung deposition prediction of viable phage particles ranges from 6% to 26% of the phages loaded in the nebulizer. Further, 8% to 15% of lung deposition was measured by scintigraphy in three macaques. A phage dose of 1 × 109 PFU/mL nebulized by the mesh nebulizer during MV predicts an efficient dose in the lung against PA, comparable with the dose chosen to define the susceptibility of the strain.

Inhaled amikacin for pneumonia treatment and dissemination prevention: an experimental model of severe monolateral Pseudomonas aeruginosa pneumonia

BACKGROUND

Pseudomonas aeruginosa pneumonia is commonly treated with systemic antibiotics to ensure adequate treatment of multidrug resistant (MDR) bacteria. However, intravenous (IV) antibiotics often achieve suboptimal pulmonary concentrations. We therefore aimed to evaluate the effect of inhaled amikacin (AMK) plus IV meropenem (MEM) on bactericidal efficacy in a swine model of monolateral MDR P. aeruginosa pneumonia.

METHODS

We ventilated 18 pigs with monolateral MDR P. aeruginosa pneumonia for up to 102 h. At 24 h after the bacterial challenge, the animals were randomized to receive 72 h of treatment with either inhaled saline (control), IV MEM only, or IV-MEM plus inhaled AMK (MEM + AMK). We dosed IV MEM at 25 mg/kg every 8 h and inhaled AMK at 400 mg every 12 h. The primary outcomes were the P. aeruginosa burden and histopathological injury in lung tissue. Secondary outcomes included the P. aeruginosa burden in tracheal secretions and bronchoalveolar lavage fluid, the development of antibiotic resistance, the antibiotic distribution, and the levels of inflammatory markers.

RESULTS

The median (25-75th percentile) P. aeruginosa lung burden for animals in the control, MEM only, and MEM + AMK groups was 2.91 (1.75-5.69), 0.72 (0.12-3.35), and 0.90 (0-4.55) log10 CFU/g (p = 0.009). Inhaled therapy had no effect on preventing dissemination compared to systemic monotherapy, but it did have significantly higher bactericidal efficacy in tracheal secretions only. Remarkably, the minimum inhibitory concentration of MEM increased to > 32 mg/L after 72-h exposure to monotherapy in 83% of animals, while the addition of AMK prevented this increase (p = 0.037). Adjunctive therapy also slightly affected interleukin-1β downregulation. Despite finding high AMK concentrations in pulmonary samples, we found no paired differences in the epithelial lining fluid concentration between infected and non-infected lungs. Finally, a non-significant trend was observed for higher amikacin penetration in low-affected lung areas.

CONCLUSIONS

In a swine model of monolateral MDR P. aeruginosa pneumonia, resistant to the inhaled AMK and susceptible to the IV antibiotic, the use of AMK as an adjuvant treatment offered no benefits for either the colonization of pulmonary tissue or the prevention of pathogen dissemination. However, inhaled AMK improved bacterial eradication in the proximal airways and hindered antibiotic resistance.

How to Use Nebulized Antibiotics in Severe Respiratory Infections

Difficult-to-treat pulmonary infections caused by multidrug-resistant (MDR) pathogens are of great concern because their incidence continues to increase worldwide and they are associated with high morbidity and mortality. Nebulized antibiotics are increasingly being used in this context. The advantages of the administration of a nebulized antibiotic in respiratory tract infections due to MDR include the potential to deliver higher drug concentrations to the site of infection, thus minimizing the systemic adverse effects observed with the use of parenteral or oral antibiotic agents. However, there is an inconsistency between the large amount of experimental evidence supporting the administration of nebulized antibiotics and the paucity of clinical studies confirming the efficacy and safety of these drugs. In this narrative review, we describe the current evidence on the use of nebulized antibiotics for the treatment of severe respiratory infections.

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.

Using Restricted Cubic Splines to Study the Duration of Antibiotic Use in the Prognosis of Ventilator-Associated Pneumonia

Background: Ventilator-associated pneumonia (VAP) is the most widespread and life-threatening nosocomial infection in intensive care units (ICUs). The duration of antibiotic use is a good predictor of prognosis in patients with VAP, but the ideal duration of antibiotic therapy for VAP in critically ill patients has not been confirmed. Research is therefore needed into the optimal duration of antibiotic use and its impact on VAP. Methods: The Medical Information Mart for Intensive Care database included 1,609 patients with VAP. Chi-square or Student's t-tests were used to compare groups, and Cox regression analysis was used to investigate the factors influencing the prognoses of patients with VAP. Nonlinear tests were performed on antibiotic use lasting <7, 7-10, and >10 days. Significant factors were included in the model for sensitivity analysis. For the subgroup analyses, the body mass indexes (BMIs) of patients were separated into BMI <30 kg/m2 and BMI ≥30 kg/m2, with the criterion of statistical significance set at p < 0.05. Restricted cubic splines were used to analyze the relationship between antibiotic use duration and mortality risk in patients with VAP. Results: In patients with VAP, the effects of antibiotic use duration on the outcomes were nonlinear. Antibiotic use for 7-10 days in models 1-3 increased the risk of antibiotic use by 2.6020-, 2.1642-, and 2.3263-fold relative to for >10 days, respectively. The risks in models 1-3 for <7 days were 2.6510-, 1.9933-, and 2.5151-fold higher than those in models with >10 days of antibiotic use, respectively. These results were robust across the analyses. Conclusions: The duration of antibiotic treatment had a nonlinear effect on the prognosis of patients with VAP. Antibiotic use durations of <7 days and 7-10 days both presented risks, and the appropriate duration of antibiotic use can ensure the good prognosis of patients with VAP.

How to use new antibiotics in the therapy of ventilator-associated pneumonia

PURPOSE OF REVIEW

Ventilator-associated pneumonia (VAP) is a common nosocomial infection in critically ill patients requiring endotracheal intubation and mechanical ventilation. Recently, the emergence of multidrug-resistant Gram-negative bacteria, including carbapenem-resistant Enterobacterales, multidrug-resistant Pseudomonas aeruginosa and Acinetobacter species, has complicated the selection of appropriate antimicrobials and contributed to treatment failure. Although novel antimicrobials are crucial to treating VAP caused by these multidrug-resistant organisms, knowledge of how to optimize their efficacy while minimizing the development of resistance should be a requirement for their use.

RECENT FINDINGS

Several studies have assessed the efficacy of novel antimicrobials against multidrug-resistant organisms, but high-quality studies focusing on optimal dosing, infusion time and duration of therapy in patients with VAP are still lacking. Antimicrobial and diagnostic stewardship should be combined to optimize the use of these novel agents.

SUMMARY

Improvements in diagnostic tests, stewardship practices and a better understanding of dosing, infusion time, duration of treatment and the effects of combining various antimicrobials should help optimize the use of novel antimicrobials for VAP and maximize clinical outcomes while minimizing the development of resistance.

Tracheobronchitis in children with tracheostomy tubes: Overview of a challenging problem

Tracheobronchitis is common in children with tracheostomy tubes. These children are predisposed to respiratory infections due to the bypassing of normal upper airway defense mechanisms by the tracheostomy, bacterial colonization of the tracheostomy tube itself, and underlying medical conditions. Diagnosis of bacterial tracheobronchitis is challenging due to the difficulty in differentiating between bacterial colonization and infection, as well as between viral and bacterial etiologies. Difficulty in diagnosis complicates management decisions, and there are currently no consensus guidelines to assist clinicians in the treatment of these patients. Frequent administration of systemic antibiotics causes adverse effects and leads to the emergence of resistant organisms. Topical administration of antibiotics via nebulization or direct instillation may lead to a significantly higher concentration of drug in the upper and lower airways without causing systemic side effects, although therapeutic trials in children with tracheostomy tubes are lacking. Several preventative measures such as regular airway clearance and the use of a speaking valve may mitigate the risk of developing respiratory infections.

Improvement of pneumonia by curcumin-loaded bionanosystems based on platycodon grandiflorum polysaccharides via calming cytokine storm

Pneumonia can lead to high morbidity and mortality secondary to uncontrolled inflammation of the lung tissue. Blocking cytokine storm storms may be the key to saving the life of patients with severe pneumonia. According to the medicinal guide theory of Traditional Chinese Medicine (TCM) and the inherent affinity with macrophages for the site of inflammation, we constructed the drug delivery platform (MNPs) derived from macrophage-membrane encapsulated reaction oxygen species (ROS)-responsive Platycodon grandiflorum polysaccharides (PGP) nanoparticles (PNPs) to calm the cytokine storm and improve lung inflammation. By loading the anti-inflammatory agent Curcumin (Cur), we demonstrated that MNPs@Cur significantly attenuated inflammation and cytokine storm syndrome in acute lung injury (ALI) mice by suppressing pro-inflammatory factor production and inflammatory cell infiltration. Interestingly, we observed that the PNPs also have potent pulmonary targeting ability compared to other polysaccharide carriers, which is in line with the medicinal guide theory of TCM. Our study revealed the rational design of drug delivery platforms to improve the treatment of lung injury, which inherits and develops the important theories of TCM through the perfect combination of guide theory and biomimetic nanotechnology and provides the experimental scientific basis for the clinical application of channel ushering drugs.

The Unfulfilled Promise of Inhaled Therapy in Ventilator-Associated Infections: Where Do We Go from Here?

Respiratory infection is common in intubated/tracheotomized patients and systemic antibiotic therapy is often unrewarding. In 1967, the difficulty in treating Gram-negative respiratory infections led to the use of inhaled gentamicin, targeting therapy directly to the lungs. Fifty-three years later, the effects of topical therapy in the intubated patient remain undefined. Clinical failures with intravenous antibiotics persist and instrumented patients are now infected by many more multidrug-resistant Gram-negative species as well as methicillin-resistant Staphylococcus aureus. Multiple systematic reviews and meta-analyses suggest that there may be a role for inhaled delivery but “more research is needed.” Yet there is still no Food and Drug Administration (FDA) approved inhaled antibiotic for the treatment of ventilator-associated infection, the hallmark of which is the foreign body in the upper airway. Current pulmonary and infectious disease guidelines suggest using aerosols only in the setting of Gram-negative infections that are resistant to all systemic antibiotics or not to use them at all. Recently two seemingly well-designed large randomized placebo-controlled Phase 2 and Phase 3 clinical trials of adjunctive inhaled therapy for the treatment of ventilator-associated pneumonia failed to show more rapid resolution of pneumonia symptoms or effect on mortality. Despite evolving technology of delivery devices and more detailed understanding of the factors affecting delivery, treatment effects were no better than placebo. What is wrong with our approach to ventilator- associated infection? Is there a message from the large meta-analyses and these two large recent multisite trials? This review will suggest why current therapies are unpredictable and have not fulfilled the promise of better outcomes. Data suggest that future studies of inhaled therapy, in the milieu of worsening bacterial resistance, require new approaches with completely different indications and endpoints to determine whether inhaled therapy indeed has an important role in the treatment of ventilated patients.

Nebulized Antibiotics for Healthcare- and Ventilator-Associated Pneumonia

Global emergence of multidrug-resistant and extensive drug-resistant gram-negative bacteria has increased the risk of treatment failure, especially for healthcare- or ventilator-associated pneumonia (HAP/VAP). Nebulization of antibiotics, by providing high intrapulmonary antibiotic concentrations, represents a promising approach to optimize the treatment of HAP/VAP due to multidrug-resistant and extensive drug-resistant gram-negative bacteria, while limiting systemic antibiotic exposure. Aminoglycosides and colistin methanesulfonate are the most common nebulized antibiotics. Although optimal nebulized drug dosing regimen is not clearly established, high antibiotic doses should be administered using vibrating-mesh nebulizer with optimized ventilator settings to ensure safe and effective intrapulmonary concentrations. When used preventively, nebulized antibiotics reduced the incidence of VAP without any effect on mortality. This approach is not yet recommended and large randomized controlled trials should be conducted to confirm its benefit and explore the impact on antibiotic selection pressure. Compared with high-dose intravenous administration, high-dose nebulized colistin methanesulfonate seems to be more effective and safer in the treatment of ventilator-associated tracheobronchitis and VAP caused by multidrug resistant and extensive-drug resistant gram-negative bacteria. Adjunctive nebulized aminoglycosides could increase the clinical cure rate and bacteriological eradication in patients suffering from HAP/VAP due to multidrug-resistant and extensive drug-resistant gram-negative bacteria. As nebulized aminoglycosides broadly diffuse in the systemic circulation of patients with extensive bronchopneumonia, monitoring of plasma trough concentrations is recommended during the period of nebulization. Large randomized controlled trials comparing high dose of nebulized colistin methanesulfonate to high dose of intravenous colistin methanesulfonate or to intravenous new β-lactams in HAP/VAP due to multidrug-resistant and extensive drug-resistant gram-negative bacteria are urgently needed.

Aerosolized antibiotics in the treatment of hospital-acquired pneumonia/ventilator-associated pneumonia

Aerosolized antibiotics are being increasingly used to treat respiratory infections, especially those caused by drug-resistant pathogens. Their use in the treatment of hospital-acquired pneumonia and ventilator-associated pneumonia in critically ill patients is especially significant. They are also used as an efficient alternative to overcome the issues caused by systemic administration of antibiotics, including the occurrence of drug-resistant strains, drug toxicity, and insufficient drug concentration at the target site. However, the rationale for the use of aerosolized antibiotics is limited owing to their insufficient efficacy and the potential for underestimated risks of developing side effects. Despite the lack of availability of high-quality evidence, the use of aerosolized antibiotics is considered as an attractive alternative treatment approach, especially in patients with multidrug-resistant pathogens. In this review, we have discussed the effectiveness and side effects of aerosolized antibiotics as well as the latest advancements in this field and usage in the Republic of Korea.

Successful treatment of pneumonia caused by multidrug-resistant Pseudomonas aeruginosa after allogeneic hematopoietic stem cell transplantation with colistin and amikacin inhalation therapy

Pseudomonas aeruginosa is a Gram-negative bacillus that often causes severe infections during immunosuppression in patients with hematologic malignancies. P. aeruginosa can easily acquire drug resistance, and often develops into multidrug-resistant P. aeruginosa (MDRP). Although many antibiotics are used in combination to treat MDRP infections, colistin and amikacin are less likely to be transferred to the lungs, and inhalation therapy may be used. Herein, we report a Case of pneumonia caused by MDRP after allogeneic hematopoietic stem cell transplantation (HSCT) treated with inhaled colistin and amikacin. This 61-year-old female patient was diagnosed with myelodysplastic syndromes and underwent allogeneic HSCT from an 8/8 HLA-matched unrelated donor after reduced-intensity conditioning. On the day of the stem cell infusion, the patient's sputum culture was found to be positive for MDRP. The patient subsequently developed bacteremia, pneumonia, and lung abscess caused by MDRP, and we administered multidrug antibiotic therapy including colistin and amikacin inhalation therapy. The patient's blood cultures were subsequently turned negative, and the lung abscess disappeared. To our knowledge, this is the first case of MDRP pneumonia after HSCT in which colistin and amikacin inhalation therapy was effective.

Inhaled amikacin versus placebo to prevent ventilator-associated pneumonia: the AMIKINHAL double-blind multicentre randomised controlled trial protocol

INTRODUCTION

Pre-emptive inhaled antibiotics may be effective to reduce the occurrence of ventilator-associated pneumonia among critically ill patients. Meta-analysis of small sample size trials showed a favourable signal. Inhaled antibiotics are associated with a reduced emergence of antibiotic resistant bacteria. The aim of this trial is to evaluate the benefit of a 3-day course of inhaled antibiotics among patients undergoing invasive mechanical ventilation for more than 3 days on the occurrence of ventilator-associated pneumonia.

METHODS AND ANALYSIS

Academic, investigator-initiated, parallel two group arms, double-blind, multicentre superiority randomised controlled trial. Patients invasively ventilated more than 3 days will be randomised to receive 20 mg/kg inhaled amikacin daily for 3 days or inhaled placebo (0.9% Sodium Chloride). Occurrence of ventilator-associated pneumonia will be recorded based on a standardised diagnostic framework from randomisation to day 28 and adjudicated by a centralised blinded committee.

ETHICS AND DISSEMINATION

The protocol and amendments have been approved by the regional ethics review board and French competent authorities (Comité de protection des personnes Ouest I, No.2016-R29). All patients will be included after informed consent according to French law. Results will be disseminated in international scientific journals.

TRIAL REGISTRATION NUMBERS

EudraCT 2016-001054-17 and NCT03149640.

Nebulized antibiotics for ventilator-associated pneumonia: methodological framework for future multicenter randomized controlled trials

PURPOSE OF REVIEW

Although experimental evidence supports the use of nebulized antibiotics in ventilator-associated pneumonia (VAP), two recent multicenter randomized controlled trials (RCTs) have failed to demonstrate any benefit in VAP caused by Gram-negative bacteria (GNB). This review examines the methodological requirements concerning future RCTs.

RECENT FINDINGS

High doses of nebulized antibiotics are required to reach the infected lung parenchyma. Breath-synchronized nebulizers do not allow delivery of high doses. Mesh nebulizers perform better than jet nebulizers. Epithelial lining fluid concentrations do not reflect interstitial lung concentrations in patients receiving nebulized antibiotics. Specific ventilator settings for optimizing lung deposition require sedation to avoid patient's asynchrony with the ventilator.

SUMMARY

Future RCTs should compare a 3-5 day nebulization of amikacin or colistimethate sodium (CMS) to a 7-day intravenous administration of a new cephalosporine/ß-lactamase inhibitor. Inclusion criteria should be a VAP or ventilator-associated tracheobronchitis caused by documented extensive-drug or pandrug resistant GNB. If the GNB remains susceptible to aminoglycosides, nebulized amikacin should be administered at a dose of 40 mg/kg/day. If resistant to aminoglycosides, nebulized CMS should be administered at a dose of 15 millions international units (IU)/day. In VAP caused by pandrug-resistant GNB, 15 millions IU/day nebulized CMS (substitution therapy) should be compared with a 9 millions IU/day intravenous CMS.

Optimizing Antimicrobial Drug Dosing in Critically Ill Patients

A fundamental step in the successful management of sepsis and septic shock is early empiric antimicrobial therapy. However, for this to be effective, several decisions must be addressed simultaneously: (1) antimicrobial choices should be adequate, covering the most probable pathogens; (2) they should be administered in the appropriate dose, (3) by the correct route, and (4) using the correct mode of administration to achieve successful concentration at the infection site. In critically ill patients, antimicrobial dosing is a common challenge and a frequent source of errors, since these patients present deranged pharmacokinetics, namely increased volume of distribution and altered drug clearance, which either increased or decreased. Moreover, the clinical condition of these patients changes markedly over time, either improving or deteriorating. The consequent impact on drug pharmacokinetics further complicates the selection of correct drug schedules and dosing during the course of therapy. In recent years, the knowledge of pharmacokinetics and pharmacodynamics, drug dosing, therapeutic drug monitoring, and antimicrobial resistance in the critically ill patients has greatly improved, fostering strategies to optimize therapeutic efficacy and to reduce toxicity and adverse events. Nonetheless, delivering adequate and appropriate antimicrobial therapy is still a challenge, since pathogen resistance continues to rise, and new therapeutic agents remain scarce. We aim to review the available literature to assess the challenges, impact, and tools to optimize individualization of antimicrobial dosing to maximize exposure and effectiveness in critically ill patients.

Effectiveness and safety of adjunctive inhaled antibiotics for ventilator-associated pneumonia: A systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

The efficacy and safety of adjunctive inhaled antibiotic therapy for ventilator-associated pneumonia (VAP) was systematically reviewed based on updated studies.

METHODS

We searched four databases and four clinical trial registration platforms to identify relevant studies published prior to May 19, 2020. Randomized controlled trials (RCTs) assessing adjunctive antibiotic inhalation treatment for VAP patients were eligible for this review. Two reviewers independently screened the articles and extracted the data. Information on inhaled therapy and clinical outcomes was collected. Study quality was assessed with the Cochrane risk of bias tool. The meta-analysis was conducted with Review Manager and R software. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines were used to evaluate the quality of evidence for each pooled outcome.

RESULTS

Eleven RCTs and 1210 patients were included in this analysis after the application of the inclusion and exclusion criteria. Compared with the use of intravenous injection alone, the use of adjunctive inhaled antibiotic therapy improved the rates of clinical cure (relative risk (RR) 1.13, 95% CI [1.02,1.26]) and microbiological eradication (RR 1.45, 95% CI [1.19,1.76]) in VAP patients. However, despite these improvements, mortality was not reduced (RR 1.00, 95% CI [0.82,1.21]). Adjunctive antibiotics delivered through the respiratory tract were not associated with a higher risk of renal impairment but were associated with an increased risk of bronchospasm (RR 2.74, 95% CI [1.31,5.73] during treatment.

CONCLUSIONS

Adjunctive inhaled antibiotics improved the clinical outcomes in VAP patients, but the increased rates clinical cure and microbiological eradication were not associated with reduced mortality. The use of nebulized antibiotics is not supported by the currently available evidence as a routine therapeutic strategy for VAP.

PROSPERO REGISTRATION NUMBER

CRD42020186970.

Pulmonary biofilm-based chronic infections and inhaled treatment strategies

Certain pulmonary diseases, such as cystic fibrosis (CF), non-CF bronchiectasis, chronic obstructive pulmonary disease, and ventilator-associated pneumonia, are usually accompanied by respiratory tract infections due to the physiological alteration of the lung immunological defenses. Recurrent infections may lead to chronic infection through the formation of biofilms. Chronic biofilm-based infections are challenging to treat using antimicrobial agents. Therefore, effective ways to eradicate biofilms and thus relieve respiratory tract infection require the development of efficacious agents for biofilm destruction, the design of delivery carriers with biofilm-targeting and/or penetrating abilities for these agents, and the direct delivery of them into the lung. This review provides an in-depth description of biofilm-based infections caused by pulmonary diseases and focuses on current existing agents that are administered by inhalation into the lung to treat biofilm, which include i) inhalable antimicrobial agents and their combinations, ii) non-antimicrobial adjuvants such as matrix-targeting enzymes, mannitol, glutathione, cyclosporin A, and iii) liposomal formulations of anti-biofilm agents. Finally, novel agents that have shown promise against pulmonary biofilms as well as traditional and new devices for pulmonary delivery of anti-biofilm agents into the lung are also discussed.

Comparison of Inhaled Colistin with Inhaled Amikacin-Fosfomycin in the Treatment of Ventilator-Associated Pneumonia Caused by Extensively Drug-Resistant (XDR) Acinetobacter: A Clinical Trial

Background: This study aimed to compare the effects of inhaled colistin and inhaled amikacin-fosfomycin combination in the treatment of ventilator-associated pneumonia (VAP) caused by extensively drug-resistant (XDR) Acinetobacter. This clinical trial is the first study to evaluate the effect of inhaled fosfomycin on VAP in Iran. Methods: In this clinical trial, 60 patients with Acinetobacter VAP were divided into two groups of 30 patients. The empirical regimen changed to meropenem plus intravenous colistin in both groups. Inhaled colistin in the first group and inhaled amikacin-fosfomycin in the second group were added to the intravenous therapy. Next, the mortality rate, if any, duration of treatment success, and patient withdrawal from VAP were evaluated in the two groups. Results: Although the mean clinical pulmonary infection score (CPIS) before treatment was not significantly different between the two groups, the mean score of the amikacin-fosfomycin group was significantly lower at 72 hours and seven days after the onset of treatment and at the end of treatment. Based on the intra-group assessments, the CPIS in both groups was significantly reduced (P < 0.001). Also, in the inter-group assessments, the mean CPIS changes were significantly different between the two groups, and in the amikacin-fosfomycin group, a greater reduction in the CPIS was observed (P = 0.007). Conclusions: The findings of the present study showed that the use of amikacin-fosfomycin nebulization could lead to increased recovery and reduced treatment duration in patients with VAP, caused by drug-resistant Acinetobacter baumannii.

Still Relevant Today: The Asinger Multicomponent Reaction

The Asinger multicomponent reaction is a versatile synthetic tool which gives access to multiple drug-like scaffolds such as 3-thiazolines. The diversity and easy access of its starting materials, its operational simplicity combined with mild conditions and relatively good yields, renders the Asinger reaction, today more than ever, a cornerstone not only in heterocyclic chemistry and modern synthesis but also in medicinal chemistry. In this review, we perform a thorough analysis of the scope and limitations on the different reaction variants with their starting materials, the three-dimensional solid-state conformations of the Asinger derivatives, and we underline and classify all the major post-modifications that have been described. In addition, we report all the major applications in drug discovery projects.

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.

Amikacin nebulization for the adjunctive therapy of gram-negative pneumonia in mechanically ventilated patients: a systematic review and meta-analysis of randomized controlled trials

Treatment of ventilated patients with gram-negative pneumonia (GNP) is often unsuccessful. We aimed to assess the efficacy and safety of nebulized amikacin (NA) as adjunctive therapy to systemic antibiotics in this patient population. PubMed, Embase, China national knowledge infrastructure, Wanfang, and the Cochrane database were searched for randomized controlled trials (RCTs) investigating the effect of NA as adjunctive therapy in ventilated adult patients with GNP. Heterogeneity was explored using subgroup analysis and sensitivity analysis. The Grading of recommendations assessment, development, and evaluation approach was used to assess the certainty of the evidence. Thirteen RCTs with 1733 adults were included. The pooled results showed NA had better microbiologic eradication (RR = 1.51, 95% CI 1.35 to 1.69, P < 0.0001) and improved clinical response (RR = 1.23; 95% CI 1.13 to 1.34; P < 0.0001) when compared with control. Meanwhile, overall mortality, pneumonia associated mortality, duration of mechanical ventilation, length of stay in ICU and change of clinical pneumonia infection scores were similar between NA and control groups. Additionally, NA did not add significant nephrotoxicity while could cause more bronchospasm. The use of NA adjunctive to systemic antibiotics therapy showed better benefits in ventilated patients with GNP. More well-designed RCTs are still needed to confirm our results.

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.

Correlation and clinical relevance of animal models for inhaled pharmaceuticals and biopharmaceuticals

Nonclinical studies are fundamental for the development of inhaled drugs, as for any drug product, and for successful translation to clinical practice. They include in silico, in vitro, ex vivo and in vivo studies and are intended to provide a comprehensive understanding of the inhaled drug beneficial and detrimental effects. To date, animal models cannot be circumvented during drug development programs, acting as surrogates of humans to predict inhaled drug response, fate and toxicity. Herein, we review the animal models used during the different development stages of inhaled pharmaceuticals and biopharmaceuticals, highlighting their strengths and limitations.

A comparative study between effect of combined intravenous and nebulized amikacin versus intravenous amikacin alone in mechanically ventilated patients with ventilator-associated pneumonia (VAP)

Background

Aerosolized antibiotic administration offers the theoretical advantages of achieving high drug concentrations at the infection site together with lower systemic absorption. This study aims to compare the effect of combining nebulized amikacin with intravenous amikacin to the effect of the usual intravenous route alone in the treatment of patients with ventilator-associated pneumonia and its impact on the duration of mechanical ventilation, laboratory, and clinical picture of the patients.

Results

This study was carried out on 64 mechanically ventilated patients with Gram-negative VAP. The patients were divided into 2 groups. Group A included 32 patients treated with nebulized amikacin plus IV amikacin, and group B included 32 patients treated with IV amikacin alone. The duration of treatment for both groups was 8 days with a daily assessment of Clinical Pulmonary Infection Score (CPIS) and monitoring of clinical and laboratory parameters. Sputum cultures were obtained thereafter. In our study, the CPIS score and overall ICU mortality were less in the nebulized than in the IV group but the difference failed to be statistically significant. Increase of oxygenation level (Pao2/Fio2 ratio), organism clearance, decrease in serum creatinine level, duration of mechanical ventilation, and length of ICU stay were significantly different in favor of group A than group B.

Conclusion

Nebulized and IV amikacin offered better oxygenation, organism clearance, less nephrotoxicity, and less duration of mechanical ventilation and ICU stay than the IV group. Combined and IV routes were comparable regarding the decrease in CPIS score and ICU mortality with no significant difference between them. However, we prefer to use the combined regimen for the mentioned reasons. Further large-scale studies are required to confirm these findings and to establish a definite conclusion.

Pulmonary infections complicating ARDS

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

Heterogeneous approach to nebulization of antimicrobial agents in mechanically ventilated adults in a German tertiary care hospital: a cross-sectional survey

There is lack of standardization of practices and limited evidence on efficacy and safety of nebulization of antimicrobials. We sought to determine inhalation practices in one tertiary care hospital by performing a cross-sectional survey. Eleven adult ICUs were included in the analysis. Three units followed established protocols. Ventilation circuit filters were exchanged at least daily in all but one units. Dosages of aminoglycosides and CMS depended on indication and unit. Nebulization of antimicrobials was generally regarded as safe and efficacious. Our data indicate that approach to nebulization of antimicrobials may be heterogeneous even in a single center.

Nebulization of Vancomycin Provides Higher Lung Tissue Concentrations than Intravenous Administration in Ventilated Female Piglets with Healthy Lungs

BACKGROUND

Intravenous vancomycin is used to treat ventilator-associated pneumonia caused by methicillin-resistant Staphylococcus aureus, but achieves high rates of failure. Vancomycin nebulization may be efficient to provide high vancomycin lung tissue concentrations. The aim of this study was to compare lung tissue and serum concentrations of vancomycin administered intravenously and by aerosol in mechanically ventilated and anesthetized healthy piglets.

METHODS

Twelve female piglets received a single intravenous dose of vancomycin (15 mg/kg) and were killed 1 (n = 6) or 12 h (n = 6) after the end of administration. Twelve piglets received a single nebulized dose of vancomycin (37.5 mg/kg) and were killed 1 (n = 6) or 12 h (n = 6) after the end of the aerosol administration. In each group, vancomycin lung tissue concentrations were assessed on postmortem lung specimens using high-performance liquid chromatography. Blood samples were collected for serum vancomycin concentration measurement 30 min and 1, 2, 4, 6, 8, and 12 h after the end of vancomycin administration. Pharmacokinetics was analyzed by nonlinear mixed effect modeling.

RESULTS

One hour after vancomycin administration, lung tissue concentrations in the aerosol group were 13 times the concentrations in the intravenous group (median and interquartile range: 161 [71, 301] μg/g versus 12 [4, 42] μg/g; P < 0.0001). Twelve hours after vancomycin administration, lung tissue concentrations in the aerosol group were 63 (23, 119) μg/g and 0 (0, 19) μg/g in the intravenous group (P < 0.0001). A two-compartment weight-scaled allometric model with first-order absorption and elimination best fit serum pharmacokinetics after both routes of administration. Area under the time-concentration curve from 0 to 12 h was lower in the aerosol group in comparison to the intravenous group (56 [8, 70] mg · h · l vs. 121 [103, 149] mg · h · l, P = 0.002). Using a population model, vancomycin bioavailability was 13% (95% CI, 6 to 69; coefficient of variation = 85%) and absorption rate was slow (absorption half life = 0.3 h).

CONCLUSIONS

Administration of vancomycin by nebulization resulted in higher lung tissue concentrations than the intravenous route.

Assessment of polymyxin B-doxycycline in combination against Pseudomonas aeruginosa in vitro and in a mouse model of acute pneumonia

The increasing prevalence of antibiotic resistance in Pseudomonas aeruginosa has created an urgent need for suitable therapy. This study explored the pairing of doxycycline with other antipseudomonal antibiotics, and found that polymyxin B in combination with doxycycline had a synergistic effect against clinical strains of P. aeruginosa. This synergistic combination was studied by checkerboard assays and time-kill curve analysis. Further, in-vitro biofilm disruption, pyoverdine inhibition assays were performed. The efficacy of polymyxin B-doxycycline in combination, administered by inhalation, was evaluated using a mouse model of acute pneumonia. The combination was found to have a synergistic effect in both in-vitro and in-vivo studies. The combination decreased biofilms of P. aeruginosa and reduced the level of pyoverdine, an important siderophore of P. aeruginosa. In addition, the combination decreased the P. aeruginosa population by 3 log₁₀ (P<0.01) in the mouse model of acute pneumonia, and showed an improvement in lung function by inhalation. To the best of the authors' knowledge, this is the first in-vivo study to evaluate the efficacy of polymyxin B in combination with doxycycline against P. aeruginosa, showing a possible promising option for acute pneumonia due to multi-drug-resistant P. aeruginosa.

Nebulized Heparin in Burn Patients with Inhalation Trauma-Safety and Feasibility

BACKGROUND

Pulmonary hypercoagulopathy is intrinsic to inhalation trauma. Nebulized heparin could theoretically be beneficial in patients with inhalation injury, but current data are conflicting. We aimed to investigate the safety, feasibility, and effectiveness of nebulized heparin.

METHODS

International multicenter, double-blind, placebo-controlled randomized clinical trial in specialized burn care centers. Adult patients with inhalation trauma received nebulizations of unfractionated heparin (25,000 international unit (IU), 5 mL) or placebo (0.9% NaCl, 5 mL) every four hours for 14 days or until extubation. The primary outcome was the number of ventilator-free days at day 28 post-admission. Here, we report on the secondary outcomes related to safety and feasibility.

RESULTS

The study was prematurely stopped after inclusion of 13 patients (heparin N = 7, placebo N = 6) due to low recruitment and high costs associated with the trial medication. Therefore, no analyses on effectiveness were performed. In the heparin group, serious respiratory problems occurred due to saturation of the expiratory filter following nebulizations. In total, 129 out of 427 scheduled nebulizations were withheld in the heparin group (in 3 patients) and 45 out of 299 scheduled nebulizations were withheld in the placebo group (in 2 patients). Blood-stained sputum or expected increased bleeding risks were the most frequent reasons to withhold nebulizations.

CONCLUSION

In this prematurely stopped trial, we encountered important safety and feasibility issues related to frequent heparin nebulizations in burn patients with inhalation trauma. This should be taken into account when heparin nebulizations are considered in these patients.

Ventilator-associated pneumonia in adults: a narrative review

Ventilator-associated pneumonia (VAP) is one of the most frequent ICU-acquired infections. Reported incidences vary widely from 5 to 40% depending on the setting and diagnostic criteria. VAP is associated with prolonged duration of mechanical ventilation and ICU stay. The estimated attributable mortality of VAP is around 10%, with higher mortality rates in surgical ICU patients and in patients with mid-range severity scores at admission. Microbiological confirmation of infection is strongly encouraged. Which sampling method to use is still a matter of controversy. Emerging microbiological tools will likely modify our routine approach to diagnosing and treating VAP in the next future. Prevention of VAP is based on minimizing the exposure to mechanical ventilation and encouraging early liberation. Bundles that combine multiple prevention strategies may improve outcomes, but large randomized trials are needed to confirm this. Treatment should be limited to 7 days in the vast majority of the cases. Patients should be reassessed daily to confirm ongoing suspicion of disease, antibiotics should be narrowed as soon as antibiotic susceptibility results are available, and clinicians should consider stopping antibiotics if cultures are negative.

Nebulized Amikacin and Fosfomycin for Severe Pseudomonas aeruginosa Pneumonia: An Experimental Study

OBJECTIVES

Latest trials failed to confirm merits of nebulized amikacin for critically ill patients with nosocomial pneumonia. We studied various nebulized and IV antibiotic regimens in a porcine model of severe Pseudomonas aeruginosa pneumonia, resistant to amikacin, fosfomycin, and susceptible to meropenem.

DESIGN

Prospective randomized animal study.

SETTING

Animal Research, University of Barcelona, Spain.

SUBJECTS

Thirty female pigs.

INTERVENTIONS

The animals were randomized to receive nebulized saline solution (CONTROL); nebulized amikacin every 6 hours; nebulized fosfomycin every 6 hours; IV meropenem alone every 8 hours; nebulized amikacin and fosfomycin every 6 hours; amikacin and fosfomycin every 6 hours, with IV meropenem every 8 hours. Nebulization was performed through a vibrating mesh nebulizer. The primary outcome was lung tissue bacterial concentration. Secondary outcomes were tracheal secretions P. aeruginosa concentration, clinical variables, lung histology, and development of meropenem resistance.

MEASUREMENTS AND MAIN RESULTS

We included five animals into each group. Lung P. aeruginosa burden varied among groups (p < 0.001). In particular, IV meropenem and amikacin and fosfomycin + IV meropenem groups presented lower P. aeruginosa concentrations versus amikacin and fosfomycin, amikacin, CONTROL, and fosfomycin groups (p < 0.05), without significant difference between these two groups undergoing IV meropenem treatment. The sole use of nebulized antibiotics resulted in dense P. aeruginosa accumulation at the edges of the interlobular septa. Amikacin, amikacin and fosfomycin, and amikacin and fosfomycin + IV meropenem effectively reduced P. aeruginosa in tracheal secretions (p < 0.001). Pathognomonic clinical variables of respiratory infection did not differ among groups. Resistance to meropenem increased in IV meropenem group versus amikacin and fosfomycin + meropenem (p = 0.004).

CONCLUSIONS

Our findings corroborate that amikacin and fosfomycin alone efficiently reduced P. aeruginosa in tracheal secretions, with negligible effects in pulmonary tissue. Combination of amikacin and fosfomycin with IV meropenem does not increase antipseudomonal pulmonary tissue activity, but it does reduce development of meropenem-resistant P. aeruginosa, in comparison with the sole use of IV meropenem. Our findings imply potential merits for preemptive use of nebulized antibiotics in order to reduce resistance to IV meropenem.

Aerosol delivery during invasive mechanical ventilation: development of a preclinical ex vivo respiratory model for aerosol regional deposition

In intensive care units, nebulization is a usual route for drug administration to patients under mechanical ventilation (MV). The effectiveness of inhalation devices as well as depositions sites of aerosols for ventilated patients remain poorly documented. In vivo human inhalation studies are scarce due to ethical restrictions because imaging techniques require radioaerosols to assess regional aerosol deposition. Thus, we developed an ex vivo respiratory model under invasive MV for preclinical aerosol deposition studies. The model was composed of ex vivo porcine respiratory tracts. MV was achieved thanks to a tracheal intubation and a medical ventilator under controlled conditions. Respiratory features were studied using analogical sensors. Then regional homogeneity of gas-ventilation was assessed with ^81mKrypton scintigraphies. Finally, a proof of concept study for aerosol deposition was performed. Obtained respiratory features as well as gamma-imaging techniques, which demonstrated a homogenous regional ventilation and about 18% ± 4% of the nebulized dose deposited the respiratory tract, were in good agreement with human data available in the literature. This original ex vivo respiratory model provides a feasible, reproducible and cost-effective preclinical tool to achieve aerosol deposition studies under MV.

Influence of diluent volume of colistimethate sodium on aerosol characteristics and pharmacokinetics in ventilator-associated pneumonia caused by MDR bacteria

Objectives

Nebulized colistimethate sodium (CMS) can be used to treat ventilator-associated pneumonia caused by MDR bacteria. The influence of the diluent volume of CMS on aerosol delivery has never been studied. The main objectives of the study were to compare aerosol particle characteristics and plasma and urine pharmacokinetics between two diluent volumes in patients treated with nebulized CMS.

Methods

A crossover study was conducted in eight patients receiving nebulized CMS every 8 h. After inclusion, nebulization started with 4 million international units (MIU) of CMS diluted either in 6 mL (experimental dilution) or in 12 mL (recommended dilution) of normal saline in a random order. For each diluent volume, CMS aerosol particle sizes were measured and plasma and urine samples were collected every 2 h. Nebulization time and stability of colistin in normal saline were assessed.

Results

The mass median aerodynamic diameters were 1.4 ± 0.2 versus 0.9 ± 0.2 μm (P < 0.001) for 6 and 12 mL diluent volumes, respectively. The plasma area under the concentration-time curve from 0 to 8 h (AUC0-8) of colistinA+B was 6.6 (4.3-17.0) versus 6.7 (3.6-14.0) μg·h/mL (P = 0.461) for each dilution. The total amount of colistin and CMS eliminated in the urine represented, respectively, 17% and 13% of the CMS initially placed in the nebulizer chamber for 6 and 12 mL diluent volumes (P = 0.4). Nebulization time was shorter [66 (58-75) versus 93 (69-136) min, P = 0.042] and colistin stability was better with the 6 mL diluent volume.

Conclusions

Nebulization with a higher concentration of CMS in saline (4 MIU in 6 mL) decreases nebulization time and improves colistin stability without changing plasma and urine pharmacokinetics or aerosol particle characteristics for lung deposition.