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There is a paucity of literature describing the research productivity among trainees in intensive care medicine. We sought to examine the occurrence and determinants of successful publication outcomes associated with intensive care training. The study cohort consisted of all individuals admitted to fellowship of the College of Intensive Care Medicine of Australia and New Zealand (CICM) from 2012 to 2019. The primary outcome measure of this study was manuscripts indexed on PubMed within one year after and four years prior to admittance to CICM fellowship. Four hundred and eighty-five fellows were identified of whom 216 (45%) had at least one publication; 129 (27%) had one, 34 (7%) had two, 21 (4%) had three and 32 (7%) had four or more publications. Overall 138 (28%) fellows had at least one publication that was likely associated with their mandatory CICM training project for which they were first (n = 110; 80%) and/or corresponding (n = 72; 52%) author in the majority of cases. Overall 107 different senior/mentor authors were identified, with 13 individuals supporting more than one publication. Although gender and location at the time of fellowship award were not associated, location of receipt of medical degree, shorter time period between medical school graduation and fellowship award, more recent year of award, and completion of medical degree/fellowship in the same geographical region were associated with project publication. A minority of CICM fellows have PubMed-indexed publications related to their training. Further efforts are warranted to better define the determinants of successful project publication to optimise future opportunities. [ABSTRACT FROM AUTHOR]

While pulmonary and systemic pharmacokinetic data can guide optimal aerosol drug dosing in the critically ill, there are limited pharmacokinetic-pharmacodynamic data with aerosolized therapy in ICU affecting effective drug dosing. Airway size, nebulizer position, heated humidification (HH), bias flow, and patient-ventilator dyssynchrony are some factors affecting aerosol drug delivery [[1]]. Amongst the machines that help save lives in the intensive care unit (ICU) environment, aerosol drug delivery devices play a special role. Aerosol drug formulations and dosing In ICU, aerosolized drugs consist of specific aerosol formulations, such as bronchodilators and off-label use of intravenous formulations, e.g., tobramycin. [Extracted from the article]

Extracorporeal membrane oxygenation (ECMO) therapy could affect drug concentrations via adsorption onto the oxygenator and/or associated circuit. We describe a case of a 33‐year‐old man with severe respiratory failure due to Pneumocystis jirovecii infection on a background of recently diagnosed human immunodeficiency virus infection. He required venovenous ECMO therapy for refractory respiratory failure. Intravenous sulfamethoxazole‐trimethoprim (100 and 20 mg/kg/day) was administered in a dosing regimen every 6 hours. Pre‐oxygenator, post‐oxygenator, and arterial blood samples were collected after antibiotic administration and were analyzed for total sulfamethoxazole and trimethoprim concentrations. The peak sulfamethoxazole and trimethoprim concentrations were 122 mg/L and 5.3 mg/L, respectively. The volume of distribution for sulfamethoxazole was 0.37 and 2.30 L/kg for trimethoprim. The clearance for sulfamethoxazole was 0.35 ml/minute/kg and for trimethoprim was 1.64 ml/minute/kg. The pharmacokinetics of sulfamethoxazole and trimethoprim appear not to be affected by ECMO therapy, and dosing adjustment may not be required. [ABSTRACT FROM AUTHOR]

Background: The aim of our work was to develop and validate a hydrophilic interaction liquid chromatography-electrospray ionization-tandem mass spectrometry (HILIC-ESI-MS/MS) methods for the quantification of tobramycin (TMC) and lincomycin (LMC)in plasma, microdialysis fluid and urine. Methods: Protein precipitation was used to extract TMC and LMC from plasma, while microdialysis fluid and urine sample were diluted prior to instrumental analysis. Mobile phase A consisted of 2 mM ammonium acetate in 10% acetonitrile with 0.2% formic acid (v/v) and mobile phase B consisted of 2 mM ammonium acetate in 90% acetonitrile with 0.2% formic acid (v/v). Gradient separation (80%–10% of mobile phase B) for TMC was done using a SeQuant zic-HILIC analytical guard column. While separation of LMC was performed using gradient elution (100%–40% of mobile phase B) on a SeQuant zic-HILIC analytical column equipped with a SeQuant zic-HILIC guard column. Vancomycin (VCM) was used as an internal standard. A quadratic calibration was obtained over the concentration range for plasma of 0.1–20 mg/L for TMC and 0.05–20 mg/L for LMC, for microdialysis fluid of 0.1–20 mg/L for both TMC and LMC, and 1–100 mg/L for urine for both TMC and LMC. Results: For TMS and LMC, validation testing for matrix effects, precision and accuracy, specificity and stability were all within acceptance criteria of ±15%. Conclusions: The methods described here meet validation acceptance criteria and were suitable for application in a pilot pharmacokinetic research study performed in a sheep model. [ABSTRACT FROM AUTHOR]

Background: Nebulized antibiotics may be used to treat ventilator-associated pneumonia. In previous pharmacokinetic studies, lung interstitial space fluid concentrations have never been reported. The aim of the study was to compare intravenous and nebulized tobramycin concentrations in the lung interstitial space fluid, epithelial lining fluid, and plasma in mechanically ventilated sheep with healthy lungs.Methods: Ten anesthetized and mechanically ventilated healthy ewes underwent surgical insertion of microdialysis catheters in upper and lower lobes of both lungs and the jugular vein. Five ewes were given intravenous tobramycin 400 mg, and five were given nebulized tobramycin 400 mg. Microdialysis samples were collected every 20 min for 8 h. Bronchoalveolar lavage was performed at 1 and 6 h.Results: The peak lung interstitial space fluid concentrations were lower with intravenous tobramycin 20.2 mg/l (interquartile range, 12 mg/l, 26.2 mg/l) versus the nebulized route 48.3 mg/l (interquartile range, 8.7 mg/l, 513 mg/l), P = 0.002. For nebulized tobramycin, the median epithelial lining fluid concentrations were higher than the interstitial space fluid concentrations at 1 h (1,637; interquartile range, 650, 1,781, vs. 16 mg/l, interquartile range, 7, 86, P < 0.001) and 6 h (48, interquartile range, 17, 93, vs. 4 mg/l, interquartile range, 2, 9, P < 0.001). For intravenous tobramycin, the median epithelial lining fluid concentrations were lower than the interstitial space fluid concentrations at 1 h (0.19, interquartile range, 0.11, 0.31, vs. 18.5 mg/l, interquartile range, 9.8, 23.4, P < 0.001) and 6 h (0.34, interquartile range, 0.2, 0.48, vs. 3.2 mg/l, interquartile range, 0.9, 4.4, P < 0.001).Conclusions: Compared with intravenous tobramycin, nebulized tobramycin achieved higher lung interstitial fluid and epithelial lining fluid concentrations without increasing systemic concentrations. [ABSTRACT FROM AUTHOR]

Extra-corporeal membrane oxygenation (ECMO) therapy could affect effective drug concentrations via adsorption onto the oxygenator or associated circuit. We describe a case of a 25-year-old female who required a veno-arterial ECMO therapy for refractory cardiac arrest due to massive pulmonary embolism. She had mild renal dysfunction as a result of the cardiac arrest. A total of 2 g of intravenous cefazolin 8-hourly was administered. Pre- and post-oxygenator blood samples were collected at 0, 1, 4, and 8 h post antibiotic administration. Samples were analyzed for total and unbound cefazolin concentrations. Protein binding was ∼60%. Clearance was reduced due to impaired renal function. The pharmacokinetics of cefazolin appear to not be affected by ECMO therapy and dosing adjustment may not be required. [ABSTRACT FROM AUTHOR]

Hemoptysis and pulmonary embolism (PE) are life-threatening pulmonary emergencies that, when present together, create a therapeutic conundrum. We present an illustrative case of a 65-year-old man with unprovoked submassive PE and moderate hemoptysis due to pulmonary infarction. Hemoptysis precluded systemic anticoagulation. Failing a conservative management strategy, we administered nebulized tranexamic acid. After four doses of nebulized tranexamic acid 500 mg, 6 hours apart, hemoptysis had ceased. Systemic anticoagulation with intravenous heparin was then successfully commenced 12 hours after the last episode of hemoptysis. The patient was weaned off high-flow nasal oxygen therapy over the course of the next 5 days with no hemoptysis recurrence. Noting the absence of trial evidence, but good pharmacological rationale and our positive experience, we suggest tranexamic acid is a useful noninvasive treatment option for the management of such conditions. Consent for this publication was obtained from the patient. [ABSTRACT FROM AUTHOR]

Background Preservative-free tobramycin is commonly used as aerosolized therapy for ventilator associated pneumonia. The comparative delivery profile of the formulations of two different concentrations (100 mg/ml and 40 mg/ml) is unknown. This study aims to evaluate the aerosol characteristics of these tobramycin formulations in a simulated adult mechanical ventilation model. Methods Simulated adult mechanical ventilation set up and optimal settings were used in the study. Inhaled mass study was performed using bacterial/viral filters at the tip of the tracheal tube and in the expiratory limb of circuit. Laser diffractometer was used for characterising particle size distribution. The physicochemical characteristics of the formulations were described and nebulization characteristics compared using two airways, an endotracheal tube (ET) and a tracheostomy tube (TT). For each type of tube, three internal tube diameters were studied, 7 mm, 8 mm and 9 mm. Results The lung dose was significantly higher for 100 mg/ml solution (mean 121.3 mg vs 41.3 mg). Viscosity was different (2.11cp vs 1.58cp) for 100 mg/ml vs 40 mg/ml respectively but surface tension was similar. For tobramycin 100 mg/ml vs 40 mg/ml, the volume median diameter (2.02 vs 1.9 μm) was comparable. The fine particle fraction (98.5 vs 85.4%) was higher and geometric standard deviation (1.36 vs 1.62 μm) was significantly lower for 100 mg/ml concentration. Nebulization duration was longer for 100 mg/ml solution (16.9 vs 10.1 min). The inhaled dose percent was similar (30%) but the exhaled dose was higher for 100 mg/ml solution (18.9 vs 10.4%). The differences in results were non-significant for type of tube or size except for a small but statistically significant reduction in inhaled mass with TT compared to ET (0.06%). Conclusion Aerosolized tobramycin 100 mg/ml solution delivered higher lung dose compared to tobramycin 40 mg/ml solution. Tracheal tube type or size did not influence the aerosol characteristics and delivery parameters. [ABSTRACT FROM AUTHOR]

Abstract: Pneumonia is a form of lung infection that may be caused by various micro-organisms. The predominant site of infection in pneumonia is debatable. Advances in the fields of diagnostic and therapeutic medicine have had a less than optimal effect on the outcome of pneumonia and one of the many causes is likely to be inadequate antimicrobial concentrations at the site of infection in lung tissue. Traditional antimicrobial therapy guidelines are based on indirect modelling from blood antimicrobial levels. However, studies both in humans and animals have shown the fallacy of this concept in various tissues. Many different methods have been employed to study lung tissue antimicrobial levels with limited success, and each has limitations that diminish their utility. An emerging technique being used to study the pharmacokinetics of antimicrobial agents in lung tissue is microdialysis. Development of microdialysis catheters, along with improvement in analytical techniques, has improved the accuracy of the data. Unfortunately, very few studies have reported the use of microdialysis in lung tissue, and even fewer antimicrobial classes have been studied. These studies generally suggest that this technique is a safe and effective way of assessing the pharmacokinetics of antimicrobial agents in lung tissue. Further descriptive studies need to be conducted to study the pharmacokinetics and pharmacodynamics of different antimicrobial classes in lung tissue. Data emanating from these studies could inform decisions for appropriate dosing schedules of antimicrobial agents in pneumonia. [ABSTRACT FROM AUTHOR]

• Pharmacokinetics of intravenous fluconazole and ganciclovir were measured in a patient receiving extracorporeal membrane oxygenation therapy (ECMO). • The patient had been newly diagnosed with human immunodeficiency virus/acquired immunodeficiency syndrome, and required fluconazole prophylaxis and ganciclovir therapy for cytomegalovirus infection. • Pre-oxygenator, post-oxygenator and peripheral arterial samples were taken. • Intravenous fluconazole 6 mg/kg (24-h) is adequate for prophylaxis and intravenous ganciclovir 5 mg/kg (12-h) is adequate for therapy in patients on ECMO. Extracorporeal membrane oxygenation (ECMO) can affect antimicrobial pharmacokinetics. This case report describes a 33-year-old male with newly diagnosed acquired immunodeficiency syndrome presenting in acute severe type 1 respiratory failure. On investigation, the patient had positive cultures for Candida albicans from respiratory specimens and high blood cytomegalovirus titres, and required venovenous ECMO therapy for refractory respiratory failure. Intravenous fluconazole (6 mg/kg, 24-h) and ganciclovir (5 mg/kg, 12-h) was commenced. Pre-oxygenator, post-oxygenator and arterial blood samples were collected after antibiotic administration, and were analysed for total fluconazole and ganciclovir concentrations. Although there was a 40% increase in the volume of distribution for fluconazole relative to healthy volunteers, the pharmacodynamic targets for prophylaxis were still met. The area under the curve exposure of ganciclovir (50.78 mg•h/L) achieved target thresholds. The ECMO circuit had no appreciable effect on achievement of therapeutic exposures of fluconazole and ganciclovir. [ABSTRACT FROM AUTHOR]

Pigs are commonly maintained on total intravenous anaesthesia when used in comparative medical research to study controlled manual ventilation of the lung. In this case study, four pigs were anaesthetised with a total intravenous anaesthetic infusion of alfaxalone and dexmedetomidine for up to 24 h whilst being mechanically ventilated. Cardiovascular parameters, blood gas values and body temperature were minimally affected throughout the anaesthetic period. Additional analgesia is recommended when utilising this drug combination for procedures that involve noxious stimuli. [ABSTRACT FROM AUTHOR]

• Pulmonary drug distribution was compared for intravenous and nebulized radiolabeled tobramycin • A mechanically-ventilated healthy ovine model was used • Qualitative and quantitative pulmonary drug deposition was compared • Whole and regional lung deposition was lower with nebulized compared with intravenous tobramycin Ventilator-associated pneumonia is common and is treated using nebulized antibiotics. Although adequate pulmonary biodistribution is important for antibiotic effect, there is a lack of data for both intravenous (IV) and nebulized antibiotic administration during mechanical ventilation. To describe the comparative pulmonary regional distribution of IV and nebulized technetium-99m-labeled tobramycin (99mTc-tobramycin) 400 mg in a mechanically-ventilated ovine model. The study was performed in a mechanically-ventilated ovine model. 99mTc-tobramycin 400 mg was obtained using a radiolabeling process. Computed tomography (CT) was performed. Ten sheep were given 99mTc-tobramycin 400 mg via either an IV (five sheep) or nebulized (five sheep) route. Planar images (dorsal, ventral, left lateral and right lateral) were obtained using a gamma camera. Blood samples were obtained every 15 min for 1 h (4 time points) and lung, liver, both kidney, and urine samples were obtained post-mortem. Ten sheep were anesthetized and mechanically ventilated. Whole-lung deposition of nebulized 99mTc-tobramycin 400 mg was significantly lower than with IV (8.8% vs. 57.1%, P <0.001). For both administration routes, there was significantly lower deposition in upper lung zones compared with the rest of the lungs. Dorsal deposition was significantly higher with nebulized 99mTc-tobramycin 400 mg compared with IV (68.9% vs. 58.9%, P =0.003). Lung concentrations of 99mTc-tobramycin were higher with IV compared with nebulized administration. There were significantly higher concentrations of 99mTc-tobramycin in blood, liver and urine with IV administration compared with nebulized. Nebulization resulted in lower whole and regional lung deposition of 99mTc-tobramycin compared with IV administration and appeared to be associated with low blood and extra-pulmonary organ concentrations. [ABSTRACT FROM AUTHOR]

Objective: The advent of new technologies has made it possible to explore alternative ventilator manufacturing to meet the worldwide shortfall for mechanical ventilators especially in pandemics. We describe a method using rapid prototyping technologies to create an electro-mechanical ventilator in a cost effective, timely manner and provide results of testing using an in vitro–in vivo testing model. Results: Rapid prototyping technologies (3D printing and 2D cutting) were used to create a modular ventilator. The artificial manual breathing unit (AMBU) bag connected to wall oxygen source using a flow meter was used as air reservoir. Controlled variables include respiratory rate, tidal volume and inspiratory: expiratory (I:E) ratio. In vitro testing and In vivo testing in the pig model demonstrated comparable mechanical efficiency of the test ventilator to that of standard ventilator but showed the material limits of 3D printed gears. Improved gear design resulted in better ventilator durability whilst reducing manufacturing time (< 2-h). The entire cost of manufacture of ventilator was estimated at 300 Australian dollars. A cost-effective novel rapid prototyped ventilator for use in patients with respiratory failure was developed in < 2-h and was effective in anesthetized, healthy pig model. [ABSTRACT FROM AUTHOR]

Background: Nebulised antibiotics are frequently used for the prevention or treatment of ventilator-associated pneumonia. Many factors may influence pulmonary drug concentrations with inaccurate dosing schedules potentially leading to therapeutic failure and/or the emergence of antibiotic resistance. We describe a research pathway for studying the pharmacokinetics of a nebulised antibiotic during mechanical ventilation using in vitro methods and ovine models, using tobramycin as the study antibiotic.Methods: In vitro studies using a laser diffractometer and a bacterial-viral filter were used to measure the effect of the type and size of tracheal tubes and antibiotic concentration on the particle size distribution of the tobramycin 400 mg (4 ml; 100 mg/ml) and 160 mg (4 ml, 40 mg/ml) aerosol and nebulised mass delivered. To compare the regional drug distribution in the lung of two routes (intravenous and nebulised) of drug administration of tobramycin 400 mg, technetium-99m-labelled tobramycin 400 mg with planar nuclear medicine imaging was used in a mechanically ventilated ovine model. To measure tobramycin concentrations by intravenous and nebulised tobramycin 400 mg (4 ml, 100 mg/ml) administration in the lung interstitial space (ISF) fluid and blood of mechanically ventilated sheep, the microdialysis technique was used over an 8-h duration.Results: Tobramycin 100 mg/ml achieved a higher lung dose (121.3 mg) compared to 40 mg/ml (41.3 mg) solution. The imaging study with labelled tobramycin indicated that nebulised tobramycin distributed more extensively into each lung zone of the mechanically ventilated sheep than intravenous administration. A higher lung ISF peak concentration of tobramycin was observed with nebulised tobramycin (40.8 mg/l) compared to intravenous route (19.0 mg/l).Conclusions: The research methods appear promising to describe lung pharmacokinetics for formulations intended for nebulisation during mechanical ventilation. These methods need further validation in an experimental pneumonia model to be able to contribute toward optimising dosing regimens to inform clinical trials and/or clinical use. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The Royal Brisbane and Women's Hospital has introduced an extracorporeal membrane oxygenation (ECMO) cardiopulmonary resuscitation (E-CPR) service with collaboration between ED and ICU teams for refractory cardiac arrest patients. E-CPR is potentially beneficial to patients who do not gain return of spontaneous circulation after conventional advanced cardiac life support treatments, provided specific demographic and biochemical inclusion criteria are met. A joint ICU and ED decision is reached to commence ECMO flow. We discuss our rationale to use the ED and the emergency physician role in leading the multidisciplinary team, with ICU leading the cannulation team. The development of ED processes and the increased availability of this intervention can significantly impact the survivability of refractory cardiac arrest with good neurological outcomes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Neutropenic fever is a frequently encountered complication when caring for cancer patients and can lead to intensive care admission, with high mortality rates in those patients who require invasive mechanical ventilation (IMV). Although hospital survival in this population has improved, long‐term outcomes of critically ill neutropenic cancer patients have not been well defined. Aims: To evaluate short‐ and long‐term outcomes of neutropenic cancer patients admitted to intensive care, according to requirement for invasive ventilation. Additionally, we aimed to determine predictors of poor clinical outcomes in this group. Methods: A retrospective cohort study of neutropenic cancer patients admitted to our intensive care unit (ICU) from 2008 to 2016. Results: We included 192 cancer patients of whom 100 (52.1%) required IMV. Overall ICU mortality was 29.7% and 12‐month post‐ICU mortality was 61.5%. Patients requiring IMV had significantly higher short‐ and long‐term mortality (P < 0.001). Multivariate analysis determined three variables to be predictors of mortality at ICU discharge in the whole cohort: IMV (OR 13.52), renal replacement therapy (RRT, OR 2.37) and higher APACHE II scores (OR 1.1 for each unit increase). These variables were identical in the subgroup requiring invasive ventilation, with RRT (OR 2.76) and APACHE II scores (OR 1.1 for each unit increase) predicting short‐term mortality. Conclusion: Neutropenic cancer patients admitted to ICU have lower short‐term mortality than previously reported in cohort studies, however their mortality rises significantly following discharge from ICU. Those patients who require IMV are at significantly increased risk of both short‐ and long‐term mortality. [ABSTRACT FROM AUTHOR]

Why and when to administer nebulized aminoglycosides and colistin in VAP The main reason for nebulizing aminoglycosides and colistin in VAP is to bypass the alveolar-capillary barrier which offers a severe obstacle to lung penetration following intravenous administration. In comparison to intravenous route, nebulized aminoglycosides and colistin can achieve significantly higher lung tissue concentrations necessary for the effective treatment of VAP due to MDR GNB [[1]]. In 2018, the French Society of Anaesthesia and Intensive Care Medicine (FSAICM) and the French Intensive Care Society (FICS) published guidelines regarding hospital-acquired pneumonia (HAP) in the intensive care unit [[11]], and recommended nebulized colistin and/or aminoglycosides alone in HAP due to MDR GNB susceptible to colistin and/or aminoglycosides, when no other antibiotics can be used. [Extracted from the article]

Highlights • Epithelial lining fluid (ELF) penetration is variable following systemic antibiotic administration • ELF concentrations of nebulised antibiotics exceed that possible with systemic administration of antibiotics • The pharmacokinetic/pharmacodynamic targets in the ELF have not been described Abstract Background Knowledge of antibiotic concentrations achievable in the epithelial lining fluid (ELF) will help guide antibiotic dosing for treating patients with Gram-negative bacillary ventilator-associated pneumonia (VAP). Objective To compare: (1) the ELF:serum penetration ratio of antibiotics in patients with pneumonia, including VAP, with that in healthy study participants; and (2) the ELF and/or tracheal aspirate antibiotic concentrations following intravenous and nebuliser delivery. Methods Web of Science, EMBASE and PubMed databases were searched and a systematic review undertaken. Results Fifty-two studies were identified. ELF penetration ratios for aminoglycosides and most β-lactam antibiotics administered intravenously were between 0.12 and 0.57, whereas intravenous colistin may be undetectable in the ELF. In contrast, estimated mean fluoroquinolone ELF penetration ratios of up to 1.31 were achieved. Importantly, ELF penetration ratios appear reduced in critically ill patients with pneumonia compared with in healthy volunteers receiving intravenous ceftazidime, levofloxacin and fosfomycin; thus, dose adjustment is likely to be required in critically ill patients. In contrast to the systemic administration route, nebulisation of antibiotics achieves high ELF concentrations. Nebulised 400 mg twice-daily amikacin resulted in a median peak ELF steady-state concentration of 976.01 mg/L (interquartile range 410.3–2563.1 mg/L). Similarly, nebulised 1 million international units of colistin resulted in a peak ELF concentration of 6.73 mg/L (interquartile range 4.80–10.10 mg/L). Conclusion Further pharmacokinetic studies investigating the mechanisms for ELF penetration in infected patients and healthy controls are needed to guide antibiotic dosing in VAP and to determine the potential benefits of nebulised therapy. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Mechanically ventilated patients commonly suffer from ventilator-associated pneumonia, hypoxemia, and other lower respiratory tract infection as a result of pathogen colonization and poor sputum clearance. Consequently, there is a high rate of morbidity and mortality in these patients. Dry powder mannitol increases sputum clearance, and therefore, we developed a system to administer it to mechanically ventilated patients without disconnection from the ventilator. Methods: The inspiratory line from a ventilator was split by using a three-way valve into two parallel lines where one contains a humidifier for normal breathing cycle and the other line contains a dry powder inhaler (Osmohaler™). The inspiratory air went through the dry powder line and aerosolized the mannitol powder only when its administration to a patient is required. We determined the delivered dose and particle size distributions of emitted aerosols in vitro from 9.5 mm endotracheal and 7.5 mm tracheostomy tubes, with inspiratory airflow of 60, 70, and 80 L/min. Results: This novel setup was able to deliver 24.6% ± 3.33% of the 160 mg loaded dose mannitol powder (4 × 40 mg capsules) and 26.7% ± 2.19% of the 320 mg dose (4 × 80 mg capsules) when the endotracheal tube was used. With the shorter tracheostomy tube, the delivery dose increased to 35.6% ± 3.01% and 39.5% ± 2.04% of the 160 and 320 mg doses, respectively. The volume median diameters of the aerosols were in the respirable range with the largest value being 5.17 ± 0.87 μm. Conclusions: This delivery system has been shown to consistently deliver a high respirable dose of mannitol powder. Since this setup does not require disconnection of patients from the ventilator, it is safer for hypoxemic patients and easier to be adapted in a real clinical use. [ABSTRACT FROM AUTHOR]

The original version of this article unfortunately contained a mistake. There was a typographical error in Figure 1: "Nebulization time ≤ 30 min" (first light blue square) should be replaced by "Nebulization time ≤ 90 min". The authors apologize for the mistake. [ABSTRACT FROM AUTHOR]