Investigation of pulmonary inflammatory responses following intratracheal instillation of and inhalation exposure to polypropylene microplastics.

BACKGROUND: Microplastics have been detected in the atmosphere as well as in the ocean, and there is concern about their biological effects in the lungs. We conducted a short-term inhalation exposure and intratracheal instillation using rats to evaluate lung disorders related to microplastics. We conducted an inhalation exposure of polypropylene fine powder at a low concentration of 2 mg/m3 and a high concentration of 10 mg/m3 on 8-week-old male Fischer 344 rats for 6 h a day, 5 days a week for 4 weeks. We also conducted an intratracheal instillation of polypropylene at a low dose of 0.2 mg/rat and a high dose of 1.0 mg/rat on 12-week-old male Fischer 344 rats. Rats were dissected from 3 days to 6 months after both exposures, and bronchoalveolar lavage fluid (BALF) and lung tissue were collected to analyze lung inflammation and lung injury. RESULTS: Both exposures to polypropylene induced a persistent influx of inflammatory cells and expression of CINC-1, CINC-2, and MPO in BALF from 1 month after exposure. Genetic analysis showed a significant increase in inflammation-related factors for up to 6 months. The low concentration in the inhalation exposure of polypropylene also induced mild lung inflammation. CONCLUSION: These findings suggest that inhaled polypropylene, which is a microplastic, induces persistent lung inflammation and has the potential for lung disorder. Exposure to 2 mg/m3 induced inflammatory changes and was thought to be the Lowest Observed Adverse Effect Level (LOAEL) for acute effects of polypropylene. However, considering the concentration of microplastics in a real general environment, the risk of environmental hazards to humans may be low.

Do Thresholds for Invasive Ventilation in Hypoxemic Respiratory Failure Exist? A Cohort Study.

Rationale: Invasive ventilation is a significant event for patients with respiratory failure. Physiologic thresholds standardize the use of invasive ventilation in clinical trials, but it is unknown whether thresholds prompt invasive ventilation in clinical practice. Objectives: To measure, in patients with hypoxemic respiratory failure, the probability of invasive ventilation within 3 hours after meeting physiologic thresholds. Methods: We studied patients admitted to intensive care receiving FiO2 of 0.4 or more via nonrebreather mask, noninvasive positive pressure ventilation, or high-flow nasal cannula, using data from the Medical Information Mart for Intensive Care (MIMIC)-IV database (2008-2019) and the Amsterdam University Medical Centers Database (AmsterdamUMCdb) (2003-2016). We evaluated 17 thresholds, including the ratio of arterial to inspired oxygen, the ratio of saturation to inspired oxygen ratio, composite scores, and criteria from randomized trials. We report the probability of invasive ventilation within 3 hours of meeting each threshold and its association with covariates using odds ratios (ORs) and 95% credible intervals (CrIs). Measurements and Main Results: We studied 4,726 patients (3,365 from MIMIC, 1,361 from AmsterdamUMCdb). Invasive ventilation occurred in 28% (1,320). In MIMIC, the highest probability of invasive ventilation within 3 hours of meeting a threshold was 20%, after meeting prespecified neurologic or respiratory criteria while on vasopressors, and 19%, after a ratio of arterial to inspired oxygen of <80 mm Hg. In AmsterdamUMCdb, the highest probability was 34%, after vasopressor initiation, and 25%, after a ratio of saturation to inspired oxygen of <90. The probability after meeting the threshold from randomized trials was 9% (MIMIC) and 13% (AmsterdamUMCdb). In MIMIC, a race/ethnicity of Black (OR, 0.75; 95% CrI, 0.57-0.96) or Asian (OR, 0.6; 95% CrI, 0.35-0.95) compared with White was associated with decreased probability of invasive ventilation after meeting a threshold. Conclusions: The probability of invasive ventilation within 3 hours of meeting physiologic thresholds was low and associated with patient race/ethnicity.

Universal paediatric videolaryngoscopy and glottic view grading: a prospective observational study.

BACKGROUND: Although videolaryngoscopy has been proposed as a default technique for tracheal intubation in children, published evidence on universal videolaryngoscopy implementation programmes is scarce. We aimed to determine if universal, first-choice videolaryngoscopy reduces the incidence of restricted glottic views and to determine the diagnostic performance of the Cormack and Lehane classification to discriminate between easy and difficult videolaryngoscopic tracheal intubations in children. METHODS: We conducted a prospective observational study within a structured universal videolaryngoscopy implementation programme. We used C-MAC™ (Karl Storz, Tuttlingen, Germany) videolaryngoscopes in all anaesthetised children undergoing elective tracheal intubation for surgical procedures. The direct and videolaryngoscopic glottic views were classified using a six-stage grading system. RESULTS: There were 904 tracheal intubations in 809 children over a 16-month period. First attempt and overall success occurred in 607 (67%) and 903 (> 99%) tracheal intubations, respectively. Difficult videolaryngoscopic tracheal intubation occurred in 47 (5%) and airway-related adverse events in 42 (5%) tracheal intubations. Direct glottic view during laryngoscopy was restricted in 117 (13%) and the videolaryngoscopic view in 32 (4%) tracheal intubations (p < 0.001). Videolaryngoscopy improved the glottic view in 57/69 (83%) tracheal intubations where the vocal cords were only just visible, and in 44/48 (92%) where the vocal cords were not visible by direct view. The Cormack and Lehane classification discriminated poorly between easy and difficult videolaryngoscopic tracheal intubations with a mean area under the receiver operating characteristic curve of 0.68 (95%CI 0.59-0.78) for the videolaryngoscopic view compared with 0.80 (95%CI 0.73-0.87) for the direct glottic view during laryngoscopy (p = 0.005). CONCLUSIONS: Universal, first-choice videolaryngoscopy reduced substantially the incidence of restricted glottic views. The Cormack and Lehane classification was not a useful tool for grading videolaryngoscopic tracheal intubation in children.

Prospective development and validation of a universal classification for paediatric videolaryngoscopic tracheal intubation: the PeDiAC score.

BACKGROUND: The VIDIAC score, a prospectively developed universal classification for videolaryngoscopy, has shown excellent diagnostic performance in adults. However, there is no reliable classification system for videolaryngoscopic tracheal intubation in children. We aimed to develop and validate a multivariable logistic regression model and easy-to-use score to classify difficult videolaryngoscopic tracheal intubation in children and to compare it with the Cormack and Lehane classification. A secondary aim was to externally validate the VIDIAC score in children. METHODS: We conducted a prospective observational study within a structured universal videolaryngoscopy implementation programme. We used C-MAC™ videolaryngoscopes in all children undergoing tracheal intubation for elective surgical procedures. We validated the VIDIAC score externally and assessed its performance. We then identified eligible co-variables for inclusion in the PeDiAC score, developed a multivariable logistic regression model and compared its performance against the Cormack and Lehane classification. RESULTS: We studied 809 children undergoing 904 episodes of tracheal intubation. The VIDIAC score outperformed the Cormack and Lehane classification when classifying the difficulty of videolaryngoscopic tracheal intubation, with an area under the receiver operating characteristic curve of 0.80 (95%CI 0.73-0.87) vs. 0.69 (95%CI 0.62-0.76), respectively, p = 0.018. Eight eligible tracheal intubation-related factors, that were selected by 100-times repeated 10-fold cross-validated least absolute shrinkage selector operator regression, were used to develop the PeDiAC model. The PeDiAC model and score showed excellent diagnostic performance and model calibration. The PeDiAC score achieved significantly better diagnostic performance than the Cormack and Lehane classification, with an area under the receiver operating characteristic curve of 0.97 (95%CI 0.96-0.99) vs. 0.69 (95%CI 0.62-0.76), respectively, p < 0.001. CONCLUSION: We developed and validated a specifically tailored classification for paediatric videolaryngoscopic tracheal intubation with excellent diagnostic performance and calibration that outperformed the Cormack and Lehane classification.

Hyperangulated vs. Macintosh videolaryngoscopy in adults with anticipated difficult airway management: a randomised controlled trial.

BACKGROUND: It is not certain whether the blade geometry of videolaryngoscopes, either a hyperangulated or Macintosh shape, affects glottic view, success rate and/or tracheal intubation time in patients with expected difficult airways. We hypothesised that using a hyperangulated videolaryngoscope blade would visualise a higher percentage of glottic opening compared with a Macintosh videolaryngoscope blade in patients with expected difficult airways. METHODS: We conducted an open-label, patient-blinded, randomised controlled trial in adult patients scheduled to undergo elective ear, nose and throat or oral and maxillofacial surgery, who were anticipated to have a difficult airway. All airway operators were consultant anaesthetists. Patients were allocated randomly to tracheal intubation with either hyperangulated (C-MAC D-BLADE™) or Macintosh videolaryngoscope blades (C-MAC™). The primary outcome was the percentage of glottic opening. First attempt success was designated a key secondary outcome. RESULTS: We assessed 2540 adults scheduled for elective head and neck surgery for eligibility and included 182 patients with expected difficult airways undergoing orotracheal intubation. The percentage of glottic opening visualised, expressed as median (IQR [range]), was 89 (69-99 [0-100])% with hyperangulated videolaryngoscope blades and 54 (9-90 [0-100])% with Macintosh videolaryngoscope blades (p < 0.001). First-line hyperangulated videolaryngoscopy failed in one patient and Macintosh videolaryngoscopy in 12 patients (13%, p = 0.002). First attempt success rate was 97% with hyperangulated videolaryngoscope blades and 67% with Macintosh videolaryngoscope blades (p < 0.001). CONCLUSIONS: Glottic view and first attempt success rate were superior with hyperangulated videolaryngoscope blades compared with Macintosh videolaryngoscope blades when used by experienced anaesthetists in patients with difficult airways.

Safety of propofol-assisted deep extubation in the dental treatment of children-a retrospective, observational study.

PURPOSE: Awake extubation and deep extubation are commonly used anesthesia techniques. In this study, the safety of propofol-assisted deep extubation in the dental treatment of children was assessed. MATERIALS AND METHODS: Children with severe caries who received dental treatment under general anesthesia and deep extubation between January 2017 and June 2023 were included in this study. Data were collected on the following variables: details and time of anesthesia, perioperative vital signs, and incidence of postoperative complications. The incidence of laryngeal spasm (LS) was considered to be the primary observation indicator. RESULTS: The perioperative data obtained from 195 children undergoing dental treatment was reviewed. The median age was 4.2 years (range: 2.3 to 9.6 years), and the average duration of anesthesia was 2.56 h (range 1 to 4.5 h). During intubation with a videoscope, purulent mucus was found in the pharyngeal cavity of seven children (3.6%); LS occurred in five of them (2.6%), and one child developed a fever (T = 37.8 °C) after discharge. Five children (2.6%) experienced emergence agitation (EA) in the recovery room. Also, 13 children (6.7%) experienced epistaxis; 10 had a mild experience and three had a moderate experience. No cases of airway obstruction (AO) and hypoxemia were recorded. The time to open eyes (TOE) was 16.3 ± 7.2 min. The incidence rate of complications was 23/195 (11.8%). Emergency tracheal reintubation was not required. Patients with mild upper respiratory tract infections showed a significantly higher incidence of complications (P < 0.001). CONCLUSIONS: Propofol-assisted deep extubation is a suitable technique that can be used for pediatric patients who exhibited non-cooperation in the outpatient setting. Epistaxis represents the most frequently encountered complication. Preoperative upper respiratory tract infection significantly increases the risk of complications. The occurrence of EA was notably lower than reported in other studies.

Efficacy and safety of video double-lumen tube intubation in lateral position in patients undergoing thoracic surgery: a randomized controlled trial.

BACKGROUND: Video double-lumen tube (VDLT) intubation in lateral position is a potential alternative to intubation in supine position in patients undergoing thoracic surgery. This non-inferiority trial assessed the efficacy and safety of VDLT intubation in lateral position. METHODS: Patients (18-70 yr) undergoing right thoracoscopic lung surgery were randomized to either the left lateral position group (group L) or the supine position group (group S). The VDLT was placed under video larygoscopy. The primary endpoint was the intubation time. Secondary endpoints included VDLT displacement rate, intubation failure rate, the satisfaction of surgeon and nurse, and intubation-related adverse events. RESULTS: The analysis covered 80 patients. The total intubation time was 52.0 [20.4]s in group L and 34.3 [13.2]s in group S, with a mean difference of 17.6 s [95% confidence interval (CI): 9.9 s to 25.3 s; P = 0.050], failing to demonstrate non-inferiority with a non-inferiority margin of 10 s. Group L, compared with group S, had significantly lower VDLT displacement rate (P = 0.017) and higher nurse satisfaction (P = 0.026). No intubation failure occurred in any group. Intubation complications (P = 0.802) and surgeon satisfaction (P = 0.415) were comparable between two groups. CONCLUSIONS: The lateral VDLT intubation took longer time than in the supine position, and non-inferiority was not achieved. The incidence of displacement as the secondary endpoint was lower in the L group, possibly due to changing body positions beforehand. The indication of lateral VDLT intubation should be based on a balance between the safety of airway management and the lower incidence of displacement. TRIAL REGISTRATION: The study was registered at Chictr.org.cn with the number ChiCTR2200064831 on 19/10/2022.

Biological effects of molybdenum(IV) sulfide nanoparticles and microparticles in the rat after repeated intratracheal administration.

In this study, molybdenum(IV) sulfide (MoS2 ) nanoparticles (97 ± 32 nm) and microparticles (1.92 ± 0.64 µm) stabilized with poly (vinylpolypyrrolidone) (PVP) were administered intratracheally to male and female rats (dose of 1.5 or 5 mg/kg bw), every 14 days for 90 days (seven administrations in total). Blood parameters were assessed during and at the end of the study (hematology, biochemistry including glucose, albumins, uric acid, urea, high density lipoprotein HDL, total cholesterol, triglycerides, aspartate transaminase, and alanine transaminase ALT). Bronchoalveolar lavage fluid (BALF) analyses included cell viability, biochemistry (total protein concentration, lactate dehydrogenase, and glutathione peroxidase activity), and cytokine levels (tumor necrosis factor α, TNF-α, macrophage inflammatory protein 2-alpha, MIP-2, and cytokine-induced neutrophil chemoattractant-2, CINC-2). Tissues were subjected to routine histopathological and electron microscopy (STEM) examinations. No overt signs of chronic toxicity were observed. Differential cell counts in BALF revealed no significant differences between the animal groups. An increase in MIP-2 and a decrease in TNF-α were observed in BALF in the exposed males. The histopathological changes in the lung evaluated according to a developed classification system (based on severity of inflammation, range 0-4, with 4 indicating the most severe changes) showed average histopathological score of 1.33 for animals exposed to nanoparticles and microparticles at the lower dose, 1.72 after exposure to nanoparticles at the higher dose, and 2.83 for animals exposed to microparticles at the higher dose. In summary, it was shown that nanosized and microsized MoS2 can trigger dose-dependent inflammatory reactions in the lungs of rats after multiple intratracheal instillation irrespective of the animal sex. Some evidence indicates a higher lung pro-inflammatory potential of the microform.

A prospective randomized comparative trial of pediatric C-MAC D-blade video laryngoscope with McCoy direct laryngoscope for intubation in children posted for elective surgical procedures under general anesthesia.

BACKGROUND: Pediatric airway management requires careful clinical evaluation and experienced execution due to anatomical, physiological, and developmental considerations. Video laryngoscopy in pediatric airways is a developing area of research, with recent data suggesting that video laryngoscopes are better than standard Macintosh blades. Specifically, there is a paucity of literature on the advantages of the C-MAC D-blade compared to the McCoy direct laryngoscope. METHODS: After Ethics Committee approval, 70 American Society of Anesthesiologists physical status 1 and 2 children aged 4-12 years scheduled for elective surgery under general anesthesia were recruited. Patients were randomly allocated to intubation using a C-MAC video laryngoscope size 2 D-blade (Group 1) and a McCoy laryngoscope size 2 blade (Group 2). The Intubation Difficulty Scale (IDS) for ease of intubation was the primary outcome, while Cormack-Lehane grades, duration of laryngoscopy and intubation, hemodynamic responses, and incidence of any airway complications were secondary outcomes. RESULTS: Both groups were comparable in terms of patient characteristics. The median (IQR) Intubation Difficulty Scale (IDS) score was better but was statistically nonsignificant with C-MAC (0 [0-0] vs. 0 [0-2], p = .055). The glottic views were superior (CL grade I in 32/35 vs. 23/35, p = .002), and the time to best glottic view (6 s [5-7] vs. 8.0 s [6-10], p = .006) was lesser in the C-MAC D-blade group while the total duration of intubation was comparable (20 s [16-22] vs. 18 s [15-22], p = .374). All the patients could be successfully intubated on the first attempt. None of the patients had any complications. CONCLUSION: The C-MAC video laryngoscope size 2 D-blade provided faster and better glottic visualization but similar intubation difficulty compared to McCoy size 2 laryngoscope in children. The shorter time to achieve glottic view demonstrated with the C-MAC failed to translate into a shorter total duration of intubation when compared to the McCoy laryngoscope attributable to a pronounced curvature of the D-blade.

Repeated intratracheal instillation of whole-cigarette smoke condensate to assess lung damage in a rat model.

Cigarette smoke induces an inflammatory response in the lungs by recruiting inflammatory cells, leading to lung diseases such as lung cancer, chronic obstructive pulmonary disease, and pulmonary fibrosis. Existing inhalation exposure methods for assessing the adverse effects of cigarette smoke require expensive equipment and are labor-intensive. Therefore, we attempted to develop a novel method to assess these adverse effects using intratracheal instillation (ITI) of whole cigarette smoke condensate (WCSC). The WCSC (0, 5, 10, or 20 mg/mL) was administered by ITI once daily for 6 or 12 days using an automatic video instillator. Repeated WCSC ITI increased the lung weight, and monocyte chemoattractant protein-1 (MCP-1), neutrophil, and lymphocyte levels within bronchoalveolar lavage fluid compared to the control. In the histopathological analysis of the lung tissue, a mild inflammatory response was observed in the 6 and 12 days 20 mg/mL WCSC exposure groups. The genome-wide RNA-seq expression patterns revealed that inflammatory and immune response-related genes, such as the chemokine signaling pathway, Th1/Th2 cell differentiation, and cytokine-cytokine receptor interaction, were employed following WCSC exposure. In addition, MCP-1 was time-dependent and increased in the 10 mg/mL exposure group compared to the control group. These results suggested that the WCSC might induce the potential pulmonary inflammatory response. Furthermore, we proposed that ITI may be a rapid and effective method of evaluating the adverse effects of WCSC within a short exposure period (less than 2 weeks), and it can be used to evaluate cigarette inhalation toxicity studies as an alternative method.

A Novel Intubation Technique: Bougie Introduction Via Ducanto Suction Catheter.

BACKGROUND: Airway management is a defining skill that demands mastery by emergency physicians. Airway emergencies pose considerable morbidity and mortality risks. Familiarity with, and mastery of, a variety of airway management approaches and equipment can prove invaluable for management of anatomically and physiologically difficult airways. CASE REPORT: A 67-year-old woman presented to a level II trauma after a motor vehicle collision. Emergency medical services reported left-sided injuries, including diminished breath sounds. She arrived in extremis with dyspnea and hypoxia refractory to supplemental oxygen. A portable chest x-ray study showed a considerable traumatic diaphragmatic hernia. Initial attempts at intubation via video laryngoscopy were unsuccessful. Difficulties were attributed to anatomic variation, possibly due to the traumatic diaphragmatic hernia, and hematemesis. The airway was repositioned after removal of a cervical collar and suction-assisted laryngoscopy airway decontamination was performed under video guidance. During airway decontamination, the tip of a DuCanto suction catheter (SSCOR) became located at the level of the vocal cords, prompting the decision to control the airway via utilization of the DuCanto suction catheter and a bougie. The suction tubing was disconnected, a bougie was inserted through the catheter, and the DuCanto was subsequently removed and replaced with a cuffed endotracheal tube. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Airway emergencies are imminent life threats. Familiarity with a variety of tools and techniques allows for definitive airway management via primary, back-up, and contingency plans to secure anatomically or physiologically difficult airway.

Development of an evidence-based nursing practice program for preventing unplanned endotracheal extubations in the intensive care unit: A Delphi method study.

AIMS: This study aims to develop an evidence-based nursing practice program to prevent unplanned endotracheal extubation (UEE) among adult patients in the intensive care unit (ICU). DESIGN: This study uses the Delphi method to develop an evidence-based nursing practice program. METHODS: A comprehensive review of 18 databases and evidence-based websites was conducted to gather, assess and synthesize evidence on preventing UEEs in adult patients. Using this synthesized evidence, a questionnaire was formulated for further investigation. Subsequently, input was solicited from experts through Delphi surveys to establish an evidence-based nursing practice protocol for preventing UEEs in adult ICU patients. Consistency in consultation results guided subsequent rounds of consultation. RESULTS: The developed program comprised 43 evidence items categorized into nine dimensions, including risk assessment for unplanned extubation, sedation, analgesia, delirium, balloon management, psychosocial care, early extubation, catheter immobilization and protective restraints. Two rounds of expert inquiry yielded recovery rates of 94.7% and 100% for the first and second questionnaires, respectively. Kendall W values ranged from .224 to .353 (p < .001). CONCLUSION: This study developed an evidence-based nursing practice program to prevent UEE in adult ICU patients, employing evidence-based practices and Delphi expert consultation methods. However, further validation of the program's effectiveness is warranted. REPORTING METHOD: Findings were reported according to the Standards for Reporting Qualitative Research checklist. PATIENT OR PUBLIC CONTRIBUTION: Nurses contributed to the study by participating in investigations. IMPLICATIONS FOR THE PROFESSION AND PATIENT CARE: The program developed in this study offers an evidence-based framework for preventing unplanned extubation in hospitals, thereby reducing its incidence and enhancing the quality of nursing care.

Conquering the obstacles during the intervention of a proximal chronic total occlusion of right coronary artery with a concurrent significant ostial stenosis: a case report.

Percutaneous coronary intervention (PCI) on a proximal chronic total occlusion (CTO) of the right coronary artery (RCA) with concurrent ostial stenosis can be challenging because of the significant difficulty in properly engaging the catheter and providing stable support during the procedure. We report the case of a 57-year-old man with chronic coronary syndrome who underwent an elective PCI at the Dr. Soetomo General Hospital in Surabaya, on April 13th, 2022. At the beginning of the procedure, there was difficulty in intubating the RCA, which required the guide catheter replacement. The angiography revealed a significant lesion at the ostium, a CTO at proximal to mid- RCA with bridging collaterals, and a significant distal lesion. Several strategies to improve guiding catheter support during PCI are using large and supportive shape guide catheters, deep guide catheter intubation, extra support wire, microcatheter and guide catheter extension. The risk of pressure dampening and ischaemia upon engagement should always be kept under consideration.

Factors associated with intubation in patients with acute hypoxaemic respiratory failure treated with high-flow nasal cannula oxygen therapy: A prospective, observational study.

BACKGROUND: High-flow nasal cannula (HFNC) oxygen is an alternative to conventional oxygen in acute hypoxaemic respiratory failure. Some patients require intubation, with a risk of delay; thus, early predictors may identify those requiring earlier intubation. The "ROX" index (ratio of pulse oximetry/fraction of inspired oxygen to respiratory rate) predicts intubation in patients with pneumonia treated with HFNC therapy, but this index has not been validated in non-pneumonia causes of acute hypoxaemic respiratory failure. AIM/OBJECTIVE: The aim of this study was to identify factors associated with intubation in a heterogeneous group of patients with acute hypoxaemic respiratory failure treated with HFNC oxygen. METHODS: This prospective observational study was undertaken in an Australian tertiary intensive care unit and included patients over 18 y of age with acute hypoxaemic respiratory failure who were treated with oxygen via HFNC. Vital signs and arterial blood gases were recorded prospectively at baseline and regular prespecified intervals for 48 h after HFNC initiation. Multivariate logistic regression was used to identify the factors associated with intubation. RESULTS: Forty-three patients were included (N = 43). The multivariate factors associated with intubation were admission Sequential Organ Failure Assessment score (odds ratio [OR]: 1.94 [95% confidence interval {CI}: 1.06-3.57]; p = 0.032) and Pneumonia Severity Index (OR: 0.95 [95% CI: 0.90-0.99]; p = 0.034). The ROX index was not independently associated with intubation when adjusted for Sequential Organ Failure Assessment score (OR: 0.71 [95% CI: 0.47-1.06]; p = 0.09). There was no difference in mortality between patients intubated early (<24 h) compared to those intubated late. CONCLUSIONS: Intubation was associated with admission Sequential Organ Failure Assessment score and Pneumonia Severity Index. The ROX index was not associated with intubation when adjusted for admission Sequential Organ Failure Assessment score. Outcomes were similar irrespective of whether patients were intubated late rather than early.

Optimizing anesthesia and delivery approaches for dosing into lungs of mice.

Microbes, toxins, therapeutics, and cells are often instilled into lungs of mice to model diseases and test experimental interventions. Consistent pulmonary delivery is critical for experimental power and reproducibility, but we observed variation in outcomes between handlers using different anesthetic approaches for intranasal dosing in mice. We therefore used a radiotracer to quantify lung delivery after intranasal dosing under inhalational (isoflurane) versus injectable (ketamine/xylazine) anesthesia in C57BL/6 mice. We found that ketamine/xylazine anesthesia resulted in delivery of a greater proportion (52 ± 9%) of an intranasal dose to lungs relative to isoflurane anesthesia (30 ± 15%). This difference in pulmonary dose delivery altered key outcomes in models of viral and bacterial pneumonia, with mice anesthetized with ketamine/xylazine for intranasal infection with influenza A virus or Pseudomonas aeruginosa developing more robust lung inflammation responses relative to control animals randomized to isoflurane anesthesia. Pulmonary dosing efficiency through oropharyngeal aspiration was not affected by anesthetic method and resulted in delivery of 63 ± 8% of dose to lungs, and a nonsurgical intratracheal dosing approach further increased lung delivery to 92 ± 6% of dose. The use of either of these more precise dosing methods yielded greater experimental power in the bacterial pneumonia model relative to intranasal infection. Both anesthetic approach and dosing route can impact pulmonary dosing efficiency. These factors affect experimental power and so should be considered when planning and reporting studies involving delivery of fluids to lungs of mice.NEW & NOTEWORTHY Many lung research studies involve dosing fluids into lungs of mice. In this study, the authors measure lung deposition using intranasal (i.n.), oropharyngeal aspiration (o.a.), and intratracheal (i.t.) dosing methods in mice. Anesthetic approach and administration route were found to affect pulmonary dosing efficiency. The authors demonstrate that refinements to dosing techniques can enable reductions in the number of animals needed for bacterial and viral pneumonia studies.

An optimized protocol for the generation and monitoring of conditional orthotopic lung cancer in the KP mouse model using an adeno-associated virus vector compatible with biosafety level 1.

BACKGROUND: The inducible Kras/p53 lung adenocarcinoma mouse model, which faithfully recapitulates human disease, is routinely initiated by the intratracheal instillation of a virus-based Cre recombinase delivery system. Handling virus-based delivery systems requires elevated biosafety levels, e.g., biosafety level 2 (BSL-2). However, in experimental animal research facilities, following exposure to viral vectors in a BSL-2 environment, rodents may not be reclassified to BSL-1 according to standard practice, preventing access to small animal micro-computed tomography (micro-CT) scanners that are typically housed in general access areas such as BSL-1 rooms. Therefore, our goal was to adapt the protocol so that the Cre-induced KP mouse model could be handled under BSL-1 conditions during the entire procedure. RESULTS: The Kras-Lox-STOP-Lox-G12D/p53 flox/flox (KP)-based lung adenocarcinoma mouse model was activated by intratracheal instillation of either an adenoviral-based or a gutless, adeno-associated viral-based Cre delivery system. Tumor growth was monitored over time by micro-CT. We have successfully substituted the virus-based Cre delivery system with a commercially available, gutless, adeno-associated, Cre-expressing vector that allows the KP mouse model to be handled and imaged in a BSL-1 facility. By optimizing the anesthesia protocol and switching to a microscope-guided vector instillation procedure, productivity was increased and procedure-related complications were significantly reduced. In addition, repeated micro-CT analysis of individual animals allowed us to monitor tumor growth longitudinally, dramatically reducing the number of animals required per experiment. Finally, we documented the evolution of tumor volume for different doses, which revealed that individual tumor nodules induced by low-titer AAV-Cre transductions can be monitored over time by micro-CT. CONCLUSION: Modifications to the anesthesia and instillation protocols increased the productivity of the original KP protocol. In addition, the switch to a gutless, adeno-associated, Cre-expressing vector allowed longitudinal monitoring of tumor growth under BSL-1 conditions, significantly reducing the number of animals required for an experiment, in line with the 3R principles.

Effect of intravenous pulses of methylprednisolone 250 mg versus dexamethasone 6 mg in hospitalised adults with severe COVID-19 pneumonia: An open-label randomised trial.

BACKGROUND: The efficacy and safety of high versus medium doses of glucocorticoids for the treatment of patients with COVID-19 has shown mixed outcomes in controlled trials and observational studies. We aimed to evaluate the effectiveness of methylprednisolone 250 mg bolus versus dexamethasone 6 mg in patients with severe COVID-19. METHODS: A randomised, open-label, controlled trial was conducted between February and August 2021 at four hospitals in Spain. The trial was suspended after the first interim analysis since the investigators considered that continuing the trial would be futile. Patients were randomly assigned in a 1:1 ratio to receive dexamethasone 6 mg once daily for up to 10 days or methylprednisolone 250 mg once daily for 3 days. RESULTS: Of the 128 randomised patients, 125 were analysed (mean age 60 ± 17 years; 82 males [66%]). Mortality at 28 days was 4.8% in the 250 mg methylprednisolone group versus 4.8% in the 6 mg dexamethasone group (absolute risk difference, 0.1% [95% CI, -8.8 to 9.1%]; p = 0.98). None of the secondary outcomes (admission to the intensive care unit, non-invasive respiratory or high-flow oxygen support, additional immunosuppressive drugs, or length of stay), or prespecified sensitivity analyses were statistically significant. Hyperglycaemia was more frequent in the methylprednisolone group at 27.0 versus 8.1% (absolute risk difference, -18.9% [95% CI, -31.8 to - 5.6%]; p = 0.007). CONCLUSIONS: Among severe but not critical patients with COVID-19, 250 mg/d for 3 days of methylprednisolone compared with 6 mg/d for 10 days of dexamethasone did not result in a decrease in mortality or intubation.

Mechanisms of pulmonary disease in F344 rats after workplace-relevant inhalation exposure to cross-linked water-soluble acrylic acid polymers.

BACKGROUND: Recently in Japan, six workers at a chemical plant that manufactures resins developed interstitial lung diseases after being involved in loading and packing cross-linked water-soluble acrylic acid polymers (CWAAPs). The present study focused on assessing lung damage in rats caused by workplace-relevant inhalation exposure to CWAAP and investigated the molecular and cellular mechanisms involved in lung lesion development. METHODS: Using a whole-body inhalation exposure system, male F344 rats were exposed once to 40 or 100 mg/m3 of CWAAP-A for 4 h or to 15 or 40 mg/m3 of CWAAP-A for 4 h per day once per week for 2 months (9 exposures). In a separate set of experiments, male F344 rats were administered 1 mg/kg CWAAP-A or CWAAP-B by intratracheal instillation once every 2 weeks for 2 months (5 doses). Lung tissues, mediastinal lymph nodes, and bronchoalveolar lavage fluid were collected and subjected to biological and histopathological analyses. RESULTS: A single 4-h exposure to CWAAP-A caused alveolar injury, and repeated exposures resulted in regenerative changes in the alveolar epithelium with activation of TGFß signaling. During the recovery period after the last exposure, some alveolar lesions were partially healed, but other lesions developed into alveolitis with fibrous thickening of the alveolar septum. Rats administered CWAAP-A by intratracheal instillation developed qualitatively similar pulmonary pathology as rats exposed to CWAAP-A by inhalation. At 2 weeks after intratracheal instillation, rats administered CWAAP-B appeared to have a slightly higher degree of lung lesions compared to rats administered CWAAP-A, however, there was no difference in pulmonary lesions in the CWAAP-A and CWAAP-B exposed rats examined 18 weeks after administration of these materials. CONCLUSIONS: The present study reports our findings on the cellular and molecular mechanisms of pulmonary disease in rats after workplace-relevant inhalation exposure to CWAAP-A. This study also demonstrates that the lung pathogenesis of rats exposed to CWAAP-A by systemic inhalation was qualitatively similar to that of rats administered CWAAP-A by intratracheal instillation.

A review of pulmonary neutrophilia and insights into the key role of neutrophils in particle-induced pathogenesis in the lung from animal studies of lunar dusts and other poorly soluble dust particles.

The mechanisms of particle-induced pathogenesis in the lung remain poorly understood. Neutrophilic inflammation and oxidative stress in the lung are hallmarks of toxicity. Some investigators have postulated that oxidative stress from particle surface reactive oxygen species (psROS) on the dust produces the toxicopathology in the lungs of dust-exposed animals. This postulate was tested concurrently with the studies to elucidate the toxicity of lunar dust (LD), which is believed to contain psROS due to high-speed micrometeoroid bombardment that fractured and pulverized lunar surface regolith. Results from studies of rats intratracheally instilled (ITI) with three LDs (prepared from an Apollo-14 lunar regolith), which differed 14-fold in levels of psROS, and two toxicity reference dusts (TiO2 and quartz) indicated that psROS had no significant contribution to the dusts' toxicity in the lung. Reported here are results of further investigations by the LD toxicity study team on the toxicological role of oxidants in alveolar neutrophils that were harvested from rats in the 5-dust ITI study and from rats that were exposed to airborne LD for 4 weeks. The oxidants per neutrophils and all neutrophils increased with dose, exposure time and dust's cytotoxicity. The results suggest that alveolar neutrophils play a critical role in particle-induced injury and toxicity in the lung of dust-exposed animals. Based on these results, we propose an adverse outcome pathway (AOP) for particle-associated lung disease that centers on the crucial role of alveolar neutrophil-derived oxidant species. A critical review of the toxicology literature on particle exposure and lung disease further supports a neutrophil-centric mechanism in the pathogenesis of lung disease and may explain previously reported animal species differences in responses to poorly soluble particles. Key findings from the toxicology literature indicate that (1) after exposures to the same dust at the same amount, rats have more alveolar neutrophils than hamsters; hamsters clear more particles from their lungs, consequently contributing to fewer neutrophils and less severe lung lesions; (2) rats exposed to nano-sized TiO2 have more neutrophils and more severe lesions in their lungs than rats exposed to the same mass-concentration of micron-sized TiO2; nano-sized dust has a greater number of particles and a larger total particle-cell contact surface area than the same mass of micron-sized dust, which triggers more alveolar epithelial cells (AECs) to synthesize and release more cytokines that recruit a greater number of neutrophils leading to more severe lesions. Thus, we postulate that, during chronic dust exposure, particle-inflicted AECs persistently release cytokines, which recruit neutrophils and activate them to produce oxidants resulting in a prolonged continuous source of endogenous oxidative stress that leads to lung toxicity. This neutrophil-driven lung pathogenesis explains why dust exposure induces more severe lesions in rats than hamsters; why, on a mass-dose basis, nano-sized dusts are more toxic than the micron-sized dusts; why lung lesions progress with time; and why dose-response curves of particle toxicity exhibit a hockey stick like shape with a threshold. The neutrophil centric AOP for particle-induced lung disease has implications for risk assessment of human exposures to dust particles and environmental particulate matter.

Design Considerations for Intratracheal Delivery Devices to Achieve Proof-of-Concept Dry Powder Biopharmaceutical Delivery in Mice.

PURPOSE: Intratracheal delivery and consistent dosing of dry powder vaccines is especially challenging in mice. To address this issue, device design of positive pressure dosators and actuation parameters were assessed for their impacts on powder flowability and in vivo dry powder delivery. METHODS: A chamber-loading dosator assembled with stainless-steel, polypropylene or polytetrafluoroethylene needle-tips was used to determine optimal actuation parameters. Powder loading methods including tamp-loading, chamber-loading and pipette tip-loading were compared to assess performance of the dosator delivery device in mice. RESULTS: Available dose was highest (45%) with a stainless-steel tip loaded with an optimal mass and syringe air volume, primarily due to the ability of this configuration to dissipate static charge. However, this tip encouraged more agglomeration along its flow path in the presence of humidity and was too rigid for intubation of mice compared to a more flexible polypropylene tip. Using optimized actuation parameters, the polypropylene pipette tip-loading dosator achieved an acceptable in vivo emitted dose of 50% in mice. After administering two doses of a spray dried adenovirus encapsulated in mannitol-dextran, high bioactivity was observed in excised mouse lung tissue three days post-infection. CONCLUSIONS: This proof-of-concept study demonstrates for the first time that intratracheal delivery of a thermally stable, viral-vectored dry powder can achieve equivalent bioactivity to the same powder, reconstituted and delivered intratracheally. This work may guide the design and device selection process for murine intratracheal delivery of dry powder vaccines to help progress this promising area of inhalable therapeutics.