How best to deliver aerosol medications to mechanically ventilated patients

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.

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.

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 delivery of inhalation devices with different add-on connections to invasively ventilated COPD subjects: An in-vivo study

Aerosol delivery to mechanically ventilated patients requires add-on connections to place the inhalation device within the ventilation circuit. The study aimed to evaluate the performance of Combihaler in dual limb invasive mechanical ventilation (IMV). A ventilator with a humidified dual limb circuit was adjusted to volume-controlled mode to imitate the adult breathing parameters. 24 (12 females) intubated chronic obstructive pulmonary disease (COPD) subjects had undergone the study. All patients were prescribed inhaled salbutamol dose delivered by either a metered-dose inhaler (pMDI) or vibrating mesh nebulizer (VMN). Each subject received salbutamol in four different inhalation device/connection conditions; pMDI+VMN+Combihaler, VMN+Combihaler, VMN+T-piece, and pMDI+T-piece. They were individually placed in the inspiratory limb at Y-piece. 5mg salbutamol was delivered by VMN with and without 2 pMDI puffs of salbutamol (100 µg), and 500µg was delivered by pMDI+T-piece. After aerosol delivery, two urine samples were collected from the patient; 30 min post-inhalation (USAL0.5) and cumulatively 24 h post-inhalation (USAL24) as indexes of lung deposition and systemic absorption, respectively. For the ex-vivo study, a collecting filter was placed before an endotracheal tube (ETT) to collect the delivered inhalable dose. In-vitro aerodynamic characteristics were also investigated. pMDI+VMN+Combihaler delivered more salbutamol to the lung and the ex-vivo filter than VMN+T-piece (p˂0.05, p≤0.01, respectively). VMN delivered a higher salbutamol amount to the lung, systemically, and the ex-vivo filter than pMDI+T-piece (p˂0.001). pMDI+VMN+Combihaler and VMN+Combihaler delivered aerosols with a less mass median aerodynamic diameter (MMAD) and higher fine particle fraction (FPF) compared to VMN+T-piece (p≤0.01 for MMAD, p˂0.01 for FPF) and pMDI+T-piece (p˂0.01 for both MMAD and FPF). Results of the study showed that pMDI+VMN+ Combihaler delivered more salbutamol than VMN+T-piece in IMV and demonstrate that 5 puffs (500-µg) of salbutamol with pMDI+T-piece has a lower aerosol delivering power at the level of USAL0.5, USAL24, and the ex-vivo inhalable dose than 5 mg nebulized salbutamol by VMNs in IMV.

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.

Aerosol delivery via noninvasive ventilation: role of models and bioanalysis

Non-invasive ventilation (NIV) is external support for respiration to assist breathing in case of respiratory failure (either hypercapnic or hypoxemic) without patient intubation. Nowadays, medicated aerosols are normally delivered to mechanically ventilated patients by nebulizers and pressurized metered-dose inhaler (pMDI) attached to adapter or spacer that fit into the ventilated circuit. Studies with obstructive lung disease patients have shown that aerosol delivery during mechanical ventilation is possible and of benefit. There are several models for investigating the aerosol delivery and deposition during mechanical ventilation such as in vitro, in vivo, and ex vivo models, these models depend on the technique used for quantitative or qualitative measurement of the deposited aerosol. In vitro models could be used for calculating the total emitted doses from different aerosol-generating devices or for aerodynamic characterization of the deposited inhaled medications. In vivo models dependents of extracting drugs from biological samples for measuring its concentration and bioavailability (pharmacokinetic model) or be dependent on the imaging technique of the radioactive aerosol. Applying different methods to predict aerosol efficiency before starting NIV and to quantify aerosol delivery during NIV are promising approaches that guide clinicians to avoid treatment failure before and during patient therapy.

Systemic pharmacokinetics and safety of high doses of nebulized colistimethate sodium in critically ill patients with hospital-acquired and ventilator-associated pneumonia

OBJECTIVES

To assess the pharmacokinetics of formed colistin in plasma and the safety of two different high doses of colistimethate sodium administered via nebulization in critically ill surgical patients with hospital-acquired pneumonia (HAP) or ventilator-associated pneumonia (VAP).

PATIENTS AND METHODS

Formed colistin plasma concentrations were measured in critically ill surgical patients with pneumonia treated with two different doses of nebulized colistimethate sodium (3 MIU/8 h versus 5 MIU/8 h). Adverse events possibly related to nebulized colistimethate sodium were recorded.

RESULTS

Twenty-seven patients (15 in the 3 MIU/8 h group and 12 in the 5 MIU/8 h group) were included. Colistin plasma concentrations were unquantifiable (<0.1 mg/L) in eight (53.3%) patients in the 3 MIU/8 h group and in seven patients (58.3%) in the 5 MIU/8 h group. Median (IQR) quantifiable colistin plasma concentrations before nebulization and at 1, 4 and 8 h were 0.17 (0.12-0.33), 0.20 (0.11-0.24), 0.17 (0.12-0.23) and 0.17 (0.11-0.32) mg/L, respectively, in the 3 MIU/8 h group and 0.20 (0.11-0.35), 0.24 (0.12-0.44), 0.24 (0.10-0.49) and 0.23 (0.11-0.44) mg/L, respectively, in the 5 MIU/8 h group, with no differences between the two groups at any time. Renal impairment during nebulized treatment was observed in three patients in each group, but was unlikely to be related to colistimethate sodium treatment. Nebulized colistimethate sodium therapy was well tolerated and no bronchospasms or neurotoxicity events were observed.

CONCLUSIONS

In this limited observational case series of critically ill patients with HAP or VAP treated with high doses of nebulized colistimethate sodium, systemic exposure was minimal and the treatment was well tolerated.

Aerosol Therapy for Pneumonia in the Intensive Care Unit

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

Evaluation of inhaled salbutamol effectiveness under supportive use of electrical impedance tomography in ventilated ICU patients: study protocol for a randomised controlled clinical trial

INTRODUCTION

The inhalative administration of drugs is a non-invasive application form that is regularly used in the treatment of ventilated patients in critical care setting. However, assessment of effectiveness or distribution of nebulised drugs is one of the lacking cornerstones of modern intensive care monitoring. Electrical impedance tomography (EIT) may provide a promising new monitoring and guiding tool for an adequate optimisation of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and evaluate associated pathologies at bedside. This study aims to elucidate the extent to which the effectiveness of inhaled salbutamol can be increased by the additional use of EIT for optimisation of respirator settings.

METHODS AND ANALYSIS

This study is a randomised, open-label, superiority trial conducted on an intensive care unit of a German university hospital, comparing two groups of mechanically ventilated patients with an acute or chronic bronchial airway obstruction according to the effectiveness of inhaled salbutamol with (intervention) or without (control) additional use of EIT for optimising ventilator settings. The primary outcome is change in airway resistance 30 min after salbutamol inhalation.

ETHICS AND DISSEMINATION

The study has received approval from the Ethics Committee of the Medical Faculty of Ruhr-University Bochum (17-6306). The results will be made available to critical care survivors, their caregivers, the funders, the critical care societies and other researchers by publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

DRKS00014706; Pre-results.

Inhaled amikacin for severe Gram-negative pulmonary infections in the intensive care unit: current status and future prospects

Recently, the use of nebulized antibiotics in the intensive care unit, in particular amikacin, has been the subject of much discussion, owing to unconvincing results from the latest randomized clinical trials. Here, we examine and reappraise the evidence in favor and against this therapeutic strategy; we then discuss the potential factors that might have played a role in the negative findings of recent clinical trials. Also, we call attention to several factors that are seldom considered by study developers and regulatory agencies, to promote translational research in this field and improve the design of future randomized clinical trials.

Safety of Nebulized Epinephrine in Smoke Inhalation Injury

This pilot study was conducted to profile safety of nebulized racemic epinephrine when used as a therapy for smoke inhalation injury in severely burned children. We enrolled 16 patients who were 7 to 19 years of age ([mean ± SD], 12 ± 4 years) with burns covering more than 30% of the TBSA (55 ± 17%) and smoke inhalation injury, as diagnosed by bronchoscopy at burn center admission. Patients were randomized to receive either standard of care (n = 8), which consisted of nebulized acetylcysteine, nebulized heparin, and nebulized albuterol, or to receive standard of care plus nebulized epinephrine (n = 8). Primary endpoints were death, chest pain, and adverse changes in cardiopulmonary hemodynamics (arrhythmia, arterial blood pressure, electrocardiographic [ST segment] changes, and peak inspiratory pressure). Additional endpoints included total days on ventilator, pulmonary function, and physiological cardiopulmonary measurements at intensive care unit discharge. No adverse events were observed during or after the nebulization of epinephrine, and no deaths were reported that were attributable to the administration of nebulized epinephrine. The groups did not significantly differ with regard to age, sex, burn size, days on ventilator, pulmonary function, or cardiopulmonary fitness. Results of this pilot trial indicate epinephrine to be safe when administered to pediatric burn patients with smoke inhalation injury. Current data warrant future efficacy studies with a greater number of patients.

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.

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.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Nebulization of Antiinfective Agents in Invasively Mechanically Ventilated Adults: A Systematic Review and Meta-analysis

BACKGROUND

Nebulization of antiinfective agents is a common but unstandardized practice in critically ill patients.

METHODS

A systematic review of 1,435 studies was performed in adults receiving invasive mechanical ventilation. Two different administration strategies (adjunctive and substitute) were considered clinically relevant. Inclusion was restricted to studies using jet, ultrasonic, and vibrating-mesh nebulizers. Studies involving children, colonized-but-not-infected adults, and cystic fibrosis patients were excluded.

RESULTS

Five of the 11 studies included had a small sample size (fewer than 50 patients), and only 6 were randomized. Diversity of case-mix, dosage, and devices are sources of bias. Only a few patients had severe hypoxemia. Aminoglycosides and colistin were the most common antibiotics, being safe regarding nephrotoxicity and neurotoxicity, but increased respiratory complications in 9% (95% CI, 0.01 to 0.18; I = 52%), particularly when administered to hypoxemic patients. For tracheobronchitis, a significant decrease in emergence of resistance was evidenced (risk ratio, 0.18; 95% CI, 0.05 to 0.64; I = 0%). Similar findings were observed in pneumonia by susceptible pathogens, without improvement in mortality or ventilation duration. In pneumonia caused by resistant pathogens, higher clinical resolution (odds ratio, 1.96; 95% CI, 1.30 to 2.96; I = 0%) was evidenced. These findings were not consistently evidenced in the assessment of efficacy against pneumonia caused by susceptible pathogens.

CONCLUSIONS

Performance of randomized trials evaluating the impact of nebulized antibiotics with more homogeneous populations, standardized drug delivery, predetermined clinical efficacy, and safety outcomes is urgently required. Infections by resistant pathogens might potentially have higher benefit from nebulized antiinfective agents. Nebulization, without concomitant systemic administration of the drug, may reduce nephrotoxicity but may also be associated with higher risk of respiratory complications.

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.

Inhalation therapy in patients with tracheostomy: a guide to clinicians

INTRODUCTION

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

Aerosol delivery with two ventilation modes during mechanical ventilation: a randomized study

BACKGROUND

Volume-controlled ventilation has been suggested to optimize lung deposition during nebulization although promoting spontaneous ventilation is targeted to avoid ventilator-induced diaphragmatic dysfunction. Comparing topographic aerosol lung deposition during volume-controlled ventilation and spontaneous ventilation in pressure support has never been performed. The aim of this study was to compare lung deposition of a radiolabeled aerosol generated with a vibrating-mesh nebulizer during invasive mechanical ventilation, with two modes: pressure support ventilation and volume-controlled ventilation.

METHODS

Seventeen postoperative neurosurgery patients without pulmonary disease were randomly ventilated in pressure support or volume-controlled ventilation. Diethylenetriaminepentaacetic acid labeled with technetium-99m (2 mCi/3 mL) was administrated using a vibrating-mesh nebulizer (Aerogen Solo(®), provided by Aerogen Ltd, Galway, Ireland) connected to the endotracheal tube. Pulmonary and extrapulmonary particles deposition was analyzed using planar scintigraphy.

RESULTS

Lung deposition was 10.5 ± 3.0 and 15.1 ± 5.0 % of the nominal dose during pressure support and volume-controlled ventilation, respectively (p < 0.05). Higher endotracheal tube and tracheal deposition was observed during pressure support ventilation (27.4 ± 6.6 vs. 20.7 ± 6.0 %, p < 0.05). A similar penetration index was observed for the right (p = 0.210) and the left lung (p = 0.211) with both ventilation modes. A high intersubject variability of lung deposition was observed with both modes regarding lung doses, aerosol penetration and distribution between the right and the left lung.

CONCLUSIONS

In the specific conditions of the study, volume-controlled ventilation was associated with higher lung deposition of nebulized particles as compared to pressure support ventilation. The clinical benefit of this effect warrants further studies. Clinical trial registration NCT01879488.

Inhaled Antibiotics for Gram-Negative Respiratory Infections

Gram-negative organisms comprise a large portion of the pathogens responsible for lower respiratory tract infections, especially those that are nosocomially acquired, and the rate of antibiotic resistance among these organisms continues to rise. Systemically administered antibiotics used to treat these infections often have poor penetration into the lung parenchyma and narrow therapeutic windows between efficacy and toxicity. The use of inhaled antibiotics allows for maximization of target site concentrations and optimization of pharmacokinetic/pharmacodynamic indices while minimizing systemic exposure and toxicity. This review is a comprehensive discussion of formulation and drug delivery aspects, in vitro and microbiological considerations, pharmacokinetics, and clinical outcomes with inhaled antibiotics as they apply to disease states other than cystic fibrosis. In reviewing the literature surrounding the use of inhaled antibiotics, we also highlight the complexities related to this route of administration and the shortcomings in the available evidence. The lack of novel anti-Gram-negative antibiotics in the developmental pipeline will encourage the innovative use of our existing agents, and the inhaled route is one that deserves to be further studied and adopted in the clinical arena.

In vitro comparison of five nebulizers during noninvasive ventilation: analysis of inhaled and lost doses

BACKGROUND

Few studies on performance comparison of nebulizer systems coupled with a single-limb circuit bilevel ventilator are available. Most of these data compared the aerosol drug delivery for only two different systems. Using an adult lung bench model of noninvasive ventilation, we compared inhaled and lost doses of three nebulizer systems coupled with a single-limb circuit bilevel ventilator, as well as the influence of the nebulizer position.

METHOD

Three vibrating mesh nebulizers (Aeroneb(®) Pro, Aeroneb(®) Solo, and NIVO(®)), one jet nebulizer (Sidestream(®)), and one ultrasonic nebulizer (Servo Ultra Nebulizer 145(®)) coupled with a bilevel ventilator were tested. They were charged with amikacin solution (500 mg/4 mL) and operated at two different positions: before and after the exhalation port (starting from the lung). The inhaled dose, the expiratory wasted dose, and the estimated lost dose were assessed by the residual gravimetric method.

RESULTS

The doses varied widely among the nebulizer types and position. When the nebulizer was positioned before the exhalation port, the vibrating mesh nebulizer delivered the highest inhaled dose (p<0.001), the jet nebulizer the highest expiratory wasted dose (p<0.001), and the ultrasonic device the highest total lost dose (p<0.001). When the nebulizer was positioned after the exhalation port, the vibrating mesh nebulizers delivered the highest inhaled (p<0.001) and expiratory wasted doses (p<0.001), and the ultrasonic device the highest total lost dose (p<0.001). The most efficient nebulizers were NIVO and Aeroneb Solo when placed before the exhalation port.

CONCLUSIONS

In a single-limb circuit bilevel ventilator, vibrating mesh nebulizers positioned between the exhalation port and lung model are more efficient for drug delivery compared with jet or ultrasonic nebulizers. In this position, the improved efficiency of vibrating mesh nebulizers was due to an increase in the inhaled dose and a reduction in the exhaled wasted dose compared with placement between the ventilator and the expiratory port. Because of the high total lost dose, the ultrasonic device should not be recommended. Nebulizer placement before the exhalation port increased the inhaled dose and decreased the expiratory wasted dose, except for the jet nebulizer.

Inhalation therapy in mechanical ventilation

Patients with obstructive lung disease often require ventilatory support via invasive or noninvasive mechanical ventilation, depending on the severity of the exacerbation. The use of inhaled bronchodilators can significantly reduce airway resistance, contributing to the improvement of respiratory mechanics and patient-ventilator synchrony. Although various studies have been published on this topic, little is known about the effectiveness of the bronchodilators routinely prescribed for patients on mechanical ventilation or about the deposition of those drugs throughout the lungs. The inhaled bronchodilators most commonly used in ICUs are beta adrenergic agonists and anticholinergics. Various factors might influence the effect of bronchodilators, including ventilation mode, position of the spacer in the circuit, tube size, formulation, drug dose, severity of the disease, and patient-ventilator synchrony. Knowledge of the pharmacological properties of bronchodilators and the appropriate techniques for their administration is fundamental to optimizing the treatment of these patients.

Colistin for lung infection: an update

Increasing incidence of resistance of gram-negative bacteria against even newer antibiotic including carbapenem has generated interest in the old antibiotic colistin, which are being used as salvage therapy in the treatment of multidrug resistant infection. Colistin has excellent bactericidal activity against most gram-negative bacilli. It has shown persist level in the liver, kidney, heart, and muscle; while it is poorly distributed to the bones, cerebrospinal fluid, lung parenchyma, and pleural cavity. Being an old drug, colistin was never gone through the drug development process needed for compliance with competent regulatory authorities that resulted in very much limited understanding of pharmacokinetic (PK) and pharmacodynamic (PD) parameters, such as C_max/MIC ratio, AUC/MIC and T > MIC that could predict the efficacy of colistin. In available PK/PD studies of colistin, mean maximum serum concentration (C_max) of colistin were found just above the MIC breakpoint at steady states that would most probably lead to suboptimal for killing the bacteria, even at dosages of 3.0 million international units (MIU) i.e., 240 mg of colistimethate sodium (CMS) intravenously every 8 h. These finding stresses to use high loading as well as high maintenance dose of intravenous colistin. It is not only suboptimal plasma concentration of colistin but also poor lung tissue concentration, which has been demonstrated in recent studies, poses major concern in using intravenous colistin. Combination therapy mainly with carbapenems shows synergistic effect. In recent studies, inhaled colistin has been found promising in treatment of lung infection due to MDR gram-negative bacteria. New evidence shows less toxicity than previously reported.

Influence of inspiratory flow pattern and nebulizer position on aerosol delivery with a vibrating-mesh nebulizer during invasive mechanical ventilation: an in vitro analysis

BACKGROUND

Aerosol delivery during invasive mechanical ventilation (IMV) depends on nebulizer type, placement of the nebulizer and ventilator settings. The purpose of this study was to determine the influence of two inspiratory flow patterns on amikacin delivery with a vibrating-mesh nebulizer placed at different positions on an adult lung model of IMV equipped with a proximal flow sensor (PFS).

METHODS

IMV was simulated using a ventilator connected to a lung model through an 8-mm inner-diameter endotracheal tube. The impact of a decelerating and a constant flow pattern on aerosol delivery was evaluated in volume-controlled mode (tidal volume 500 mL, 20 breaths/min, inspiratory time of 1 sec, bias flow of 10 L/min). An amikacin solution (250 mg/3 mL) was nebulized with Aeroneb Solo(®) placed at five positions on the ventilator circuit equipped with a PFS: connected to the endotracheal tube (A), to the Y-piece (B), placed at 15 cm (C) and 45 cm upstream of the Y-piece (D), and placed at 15 cm of the inspiratory outlet of the ventilator (E). The four last positions were also tested without PFS. Deposited doses of amikacin were measured using the gravimetric residual method.

RESULTS

Amikacin delivery was significantly reduced with a decelerating inspiratory flow pattern compared to a constant flow (p<0.05). With a constant inspiratory flow pattern, connecting the nebulizer to the endotracheal tube enabled similar deposited doses than these obtained when connecting the nebulizer close to the ventilator. The PFS reduced deposited doses only when the nebulizer was connected to the Y-piece with both flow patterns or placed at 15 cm of the Y-piece with a constant inspiratory flow (p<0.01).

CONCLUSIONS

Using similar tidal volume and inspiratory time, a constant flow pattern (30 L/min) delivers a higher amount of amikacin through an endotracheal tube compared to a decelerating inspiratory flow pattern (peak inspiratory flow around 60 L/min). The optimal nebulizer position depends on the inspiratory flow pattern and the presence of a PFS.

Aerosolized amphotericin B lipid complex as adjunctive treatment for fungal lung infection in patients with cancer-related immunosuppression and recipients of hematopoietic stem cell transplantation

STUDY OBJECTIVE

Aerosolized amphotericin B lipid complex (aeABLC) has been successfully used to prevent fungal disease. Experience with aeABLC as treatment of fungal lung disease is limited.

DESIGN

We evaluated the safety and efficacy of aeABLC adjunct therapy for fungal lung disease in a retrospective study of 32 immunosuppressed adults. All values are given as ± standard deviation.

SETTING

National Cancer Institute-designated Comprehensive Cancer Center.

PATIENTS

Acute leukemia (69%) and severe neutropenia (63%) were common. Fifty-six percent of patients had undergone allogeneic hematopoietic stem cell transplantation 185 ± 424 days prior to aeABLC was commenced.

MEASUREMENT AND MAIN RESULTS

High-dose corticosteroids were administered during aeABLC in 28% of patients. Fungal lung disease was proven or probable in 41% of patients. Most patients (78%) received concurrent systemic antifungal therapy for a median of 14 ± 18 days before aeABLC. The median cumulative aeABLC dose was 1050 ± 2368 mg, and the median duration of aeABLC therapy was 28 ± 130 days. Most patients (78%) received 50 mg aeABLC twice daily. Partial or complete resolution of fungal lung disease was noted in 50% of patients. In three patients (9%) modest cough, mild bronchospasm, and transient chest pain with accompanying nausea and vomiting resolved completely after discontinuation of aeABLC. No patient required hospitalization for drug toxicity or had a serious (grade III or IV) drug-related adverse event.

CONCLUSION

Treatment with aeABLC was tolerated without serious toxicity and may be considered in the setting of severe immunosuppression, cancer, and/or hematopoietic stem cell transplantation in patients with difficult-to-treat fungal lung disease.

Delivery and performance of surfactant replacement therapies to treat pulmonary disorders

Lung surfactant is crucial for optimal pulmonary function throughout life. An absence or deficiency of surfactant can affect the surfactant pool leading to respiratory distress. Even if the coupling between surfactant dysfunction and the underlying disease is not always well understood, using exogenous surfactants as replacement is usually a standard therapeutic option in respiratory distress. Exogenous surfactants have been extensively studied in animal models and clinical trials. The present article provides an update on the evolution of surfactant therapy, types of surfactant treatment, and development of newer-generation surfactants. The differences in the performance between various surfactants are highlighted and advanced research that has been conducted so far in developing the optimal delivery of surfactant is discussed.

Metered dose inhalers versus nebulizers for aerosol bronchodilator delivery for adult patients receiving mechanical ventilation in critical care units

BACKGROUND

Nebulizers and metered dose inhalers (MDI) have both been adapted for delivering aerosol bronchodilation to mechanically ventilated patients, but there is incomplete knowledge as to the most effective method of delivery.

OBJECTIVES

To compare the effectiveness of nebulizers and MDIs for bronchodilator delivery in invasively ventilated, critically ill adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 5); Ovid MEDLINE (1950 to Week 19 2012); Ovid EMBASE (1980 to Week 19 2012); CINAHL via EBSCOhost (1982 to Week 19 2012) and reference lists of articles. We searched conference proceedings and reference lists of articles. We also contacted manufacturers and researchers in this field. There were no constraints based on language or publication status.

SELECTION CRITERIA

Randomized controlled trials (RCTs), including randomized cross-over trials where the order of the intervention was randomized, comparing the nebulizer and MDI for aerosol bronchodilation in mechanically ventilated adult patients in critical care units.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information where required. We collected information about adverse effects from the trials.

MAIN RESULTS

This review included three trials, two addressing the primary outcome measure of a reduction of airway resistance (measured as a reduction in interrupter and additional airway resistance) with a total of 28 patients (n =10, n =18) and two addressing adverse changes to haemodynamic observations with a total of 36 patients (n =18, n =18). Limitations in data availability and reporting in the included trials precluded meta-analysis and therefore the present review consisted of a descriptive analysis. Risk of bias in the included trials was judged as low or of unknown risk across the majority of items in the 'Risk of bias' tool.Cautious interpretation of the included study results suggests that nebulizers could be a more effective method of bronchodilator administration than MDI in terms of a change in resistance. No apparent changes to haemodynamic observations (measured as an increase in heart rate) were associated with either mode of delivery. Due to missing data issues, meta analyses were not possible. Additionally, small sample sizes and variability between the studies with regards to patient diagnoses, bronchodilator agent and administration technique mean that it would be speculative to infer definitive recommendations based on these results at this time. This is insufficient evidence to determine which is the most effective delivery system between nebuliser and MDI for aerosol bronchodilation in adult patients receiving mechanical ventilation.

AUTHORS' CONCLUSIONS

Existing randomized controlled trials, including randomized cross-over trials where the order of the intervention was randomized, comparing nebulizer and MDI for aerosol bronchodilation in mechanically ventilated adult patients do not provide sufficient evidence to support either delivery method at this time.

Inhalation therapy in patients receiving mechanical ventilation: an update

Incremental gains in understanding the influence of various factors on aerosol delivery in concert with technological advancements over the past 2 decades have fueled an ever burgeoning literature on aerosol therapy during mechanical ventilation. In-line use of pressurized metered-dose inhalers (pMDIs) and nebulizers is influenced by a host of factors, some of which are unique to ventilator-supported patients. This article reviews the impact of various factors on aerosol delivery with pMDIs and nebulizers, and elucidates the correlation between in-vitro estimates and in-vivo measurement of aerosol deposition in the lung. Aerosolized bronchodilator therapy with pMDIs and nebulizers is commonly employed in intensive care units (ICUs), and bronchodilators are among the most frequently used therapies in mechanically ventilated patients. The use of inhaled bronchodilators is not restricted to mechanically ventilated patients with chronic obstructive pulmonary disease (COPD) and asthma, as they are routinely employed in other ventilator-dependent patients without confirmed airflow obstruction. The efficacy and safety of bronchodilator therapy has generated a great deal of interest in employing other inhaled therapies, such as surfactant, antibiotics, prostacyclins, diuretics, anticoagulants and mucoactive agents, among others, in attempts to improve outcomes in critically ill ICU patients receiving mechanical ventilation.

Aerosolized antibiotics in the intensive care unit

This review summarizes recent clinical data examining the use of aerosolized antimicrobial therapy for the treatment of respiratory tract infections in mechanically ventilated patients in the intensive care unit. Aerosolized antibiotics provide high concentrations of drug in the lung without the systemic toxicity associated with the intravenous antibiotics. First introduced in the 1960s as a treatment of tracheobronchitis and bronchopneumonia caused by Pseudomonas aeruginosa, now, more than 40 years later, there is a resurgence of interest in using this mode of delivery as a primary therapy for ventilator-associated tracheobronchitis and an adjunctive therapy for ventilator-associated pneumonia.

Inhaled antibiotic therapy for ventilator-associated tracheobronchitis and ventilator-associated pneumonia: an update

Ventilator-associated pneumonia (VAP) remains a leading cause of morbidity and mortality in mechanically-ventilated patients in the Intensive Care Unit (ICU). Ventilator-associated tracheobronchitis (VAT) was previously believed to be an intermediate stage between colonization of the lower respiratory tract and VAP. More recent data, however, suggest that VAT may be a separate entity that increases morbidity and mortality, independently of the occurrence of VAP. Some, but not all, patients with VAT progress to develop VAP. Although inhaled antibiotics alone could be effective for the treatment of VAP, the current consensus of opinion favors their role as adjuncts to systemic antimicrobial therapy for VAP. Inhaled antibiotics are increasingly employed for salvage therapy in patients with VAP due to multi-drug resistant Gram-negative bacteria. In contrast to VAP, VAT could be effectively treated with inhaled antibiotic therapy alone or in combination with systemic antimicrobials.

Aerosol drug delivery: developments in device design and clinical use

Aerosolised drugs are prescribed for use in a range of inhaler devices and systems. Delivering drugs by inhalation requires a formulation that can be successfully aerosolised and a delivery system that produces a useful aerosol of the drug; the particles or droplets need to be of sufficient size and mass to be carried to the distal lung or deposited on proximal airways to give rise to a therapeutic effect. Patients and caregivers must use and maintain these aerosol drug delivery devices correctly. In recent years, several technical innovations have led to aerosol drug delivery devices with efficient drug delivery and with novel features that take into account factors such as dose tracking, portability, materials of manufacture, breath actuation, the interface with the patient, combination therapies, and systemic delivery. These changes have improved performance in all four categories of devices: metered dose inhalers, spacers and holding chambers, dry powder inhalers, and nebulisers. Additionally, several therapies usually given by injection are now prescribed as aerosols for use in a range of drug delivery devices. In this Review, we discuss recent developments in the design and clinical use of aerosol devices over the past 10-15 years with an emphasis on the treatment of respiratory disorders.

Mechanical Ventilation

Mechanical ventilation is a common therapeutic modality required for the management of patients unable to maintain adequate intrinsic ventilation and oxygenation. Mechanical ventilators can be found within various hospital and nonhospital environments (ie, nursing homes, skilled nursing facilities, and patient’s home residence), but these devices generally require the skill of a multidisciplinary health care team to optimize therapeutic outcomes. Unfortunately, pharmacists have been excluded in the discussion of mechanical ventilation since this therapeutic modality may be perceived as irrelevant to drug utilization and the usual scope of practice of a hospital pharmacist. However, the pharmacist provides a crucial role as a member of the multidisciplinary team in the management of the mechanically ventilated patient by verifying accuracy of prescribed medications, providing recommendations of alternative drug selections, monitoring for drug and disease interactions, assisting in the development of institutional weaning protocols, and providing quality assessment of drug utilization. Pharmacists may be intimidated by the introduction of advanced ventilator microprocessor technology, but understanding and integrating ventilator management with the pharmacotherapeutic needs of the patient will ultimately help the pharmacist be a better qualified and respected practitioner. The goal of this article is to assist the pharmacy practitioner with a better understanding of mechanical ventilation and to apply this information to improve delivery of pharmaceutical care.

Inhaled colistin for the treatment of tracheobronchitis and pneumonia in critically ill children without cystic fibrosis

Data regarding the role of inhaled colistin in critically ill pediatric patients without cystic fibrosis are scarce. Three children (one female), admitted to the intensive care unit (ICU) of a tertiary-care pediatric hospital in Athens, Greece, during 2004-2009 received inhaled colistin as monotherapy for tracheobronchitis (two children), and as adjunctive therapy for necrotizing pneumonia (one child). Colistin susceptible Acinetobacter baumannii and Pseudomonas aeruginosa were isolated from the cases' bronchial secretions specimens. All three children received inhaled colistin at a dosage of 75 mg diluted in 3 ml of normal saline twice daily (1,875,000 IU of colistin daily), for a duration of 25, 32, and 15 days, respectively. All three children recovered from the infections. Also, a gradual reduction, and finally total elimination of the microbial load in bronchial secretions was observed during inhaled colistin treatment in the reported cases. All three cases were discharged from the ICU. No bronchoconstriction or any other type of toxicity of colistin was observed. In conclusion, inhaled colistin was effective and safe for the treatment of two children with tracheobronchitis, and one child with necrotizing pneumonia. Further studies are needed to clarify further the role of inhaled colistin in pediatric critically ill patients without cystic fibrosis.

Aerosolized antibiotics in critically ill ventilated patients

PURPOSE OF REVIEW

This review will summarize recent clinical data examining the efficacy of aerosolized antimicrobial therapy in treating respiratory tract infections in mechanically ventilated patients in the ICU.

RECENT FINDINGS

Aerosolized antibiotics provide high levels of drug in the lung and reduce the systemic toxicity associated with intravenous antibiotics. First introduced in the 1970s as a form of prophylaxis for ventilator-associated pneumonia (VAP), now, more than 30 years later, there is a resurgence of interest in using this mode of delivery as primary or adjunctive treatment for ventilator-associated tracheobronchitis (VAT) or VAP. Increasingly resistant organisms are colonizing and infecting critically ill patients, and direct delivery of antibiotic to the lung is being re-evaluated as a means to treat these highly resistant organisms that may not respond to systemic therapy. There are new data emerging that suggest these agents may effectively treat these pathogens when used in targeted, time limited protocols.

SUMMARY

Aerosolized antibiotic therapy may provide an efficacious means of treating respiratory tract infection when targeted at mechanically ventilated patients with proximal airway infection, VAT (with or without VAP) and with highly resistant organisms.

Inhaled therapeutics for prevention and treatment of pneumonia

The lungs are the most common site of serious infection owing to their large surface area exposed to the external environment and minimum barrier defense. However, this architecture makes the lungs readily available for topical therapy. Therapeutic aerosols include those directed towards improving mucociliary clearance of pathogens, stimulation of innate resistance to microbial infection, cytokine stimulation of immune function and delivery of antibiotics. In our opinion inhaled antimicrobials are underused, especially in patients with difficult-to-treat lung infections. The use of inhaled antimicrobial therapy has become an important part of the treatment of airway infection with Pseudomonas aeruginosa in cystic fibrosis and the prevention of invasive fungal infection in patients undergoing heart and lung transplantation. Cytokine inhaled therapy has also been explored in the treatment of neoplastic and infectious disease. The choice of pulmonary drug delivery systems remains critical as air-jet and ultrasonic nebulizer may deliver sub-optimum drug concentration if not used properly. In future development of this field, we recommend an emphasis on the study of the use of aerosolized hypertonic saline solution to reduce pathogen burden in the airways of subjects infected with microbes of low virulence, stimulation of innate resistance to prevent pneumonia in immunocompromised subjects using cytokines or synthetic pathogen-associated molecular pattern analogues and more opportunities for the use of inhaled antimicrobials. These therapeutics are still in their infancy but show great promise.

Aerosolized antibiotics to treat ventilator-associated pneumonia

PURPOSE OF REVIEW

This review summarizes the recent data on antibiotic aerosolization to treat ventilator-associated pneumonia.

RECENT FINDINGS

Most studies on antibiotic aerosolization have been case reports or descriptive studies. The results of a recent randomized, placebo-controlled trial indicated that adjunctive use of nebulized antibiotic with intravenous antibiotics to treat purulent tracheobronchitis was associated with a better outcome than placebo aerosolization. A randomized study, so far published only as an abstract, showed that amikacin aerosolized with a vibrating-mesh nebulizer--a new-generation device--was well distributed in the lung parenchyma and might lead to less intravenous antibiotic use. Several thorough reviews on nebulization devices, techniques and drawbacks have been published recently.

SUMMARY

Despite recent promising findings, the widespread use of aerosolized antibiotics to treat ventilator-associated pneumonia cannot be recommended. It should be restricted to the treatment of multidrug-resistant Gram-negative ventilator-associated pneumonia.