Porcine Trachea Research Articles

Scalable Extraction of Airway Mucins from Porcine Trachea.

Mucins are a major component of the innate defense system in the airways and their biological functions are important to consider in pulmonary disease research. However, the available mucus models for basic research relevant to the lung can be difficult to acquire in sufficient quantity to conduct such studies. Here, we present a new strategy to isolate airway mucins from pig trachea at the milligram to gram scale for use in pulmonary disease research. Using this protocol, we were able to isolate mucins with minimal DNA contamination consisting of ∼70% by weight protein. Compared to porcine gastric mucins extracted with the same procedure, the porcine tracheal extract possessed significantly greater O-linked glycoprotein (mucin) content. Particle tracking microrheology was used to evaluate the biophysical properties of porcine trachea mucins. We found porcine tracheal mucins formed a much tighter mesh network and possessed a significantly greater microviscosity compared to lab extracted porcine gastric mucins. In comparison to mucus harvested from human airway tissue cultures, we found porcine tracheal mucins also possessed a greater microviscosity suggesting these mucins can form into a gel-like material at physiological total solids concentrations. These studies establish an accessible means to isolate airway mucins from porcine trachea at large scale for use in pulmonary disease research.

Functional outcome of cell seeded tracheal scaffold after mechanical stress in vitro

Tracheal tissue engineering is still facing major challenges: realization of efficient vascularization and mechanical properties comparable to native trachea need to be achieved. In this study, we present a strategy for the manufacturing of a construct for tracheal tissue engineering by conditioning through cell seeding followed by mechanical stimulation in vitro. Scaffolds derived from porcine trachea decellularized with supercritical carbon dioxide were seeded with stem cells of different tissue sources and cultured in a bioreactor for 21 days under mechanical stimulation. Enhanced chondrogenic development was demonstrated, with improved sulphated glycosaminoglycan secretion and cellular alignment which resulted in mechanical properties resembling native trachea. This method may provide a useful addition to tracheal tissue engineering strategies aimed at optimizing cartilage formation.

The lysogenic filamentous Pseudomonas bacteriophage phage Pf slows mucociliary transport.

Pseudomonas aeruginosa is a major pulmonary pathogen causing chronic pulmonary infections in people with cystic fibrosis (CF). The P. aeruginosa filamentous and lysogenic bacteriophage, Pf phage, is abundant in the airways of many people with CF and has been associated with poor outcomes in a cross-sectional cohort study. Previous studies have identified roles for Pf phage in biofilm formation, specifically forming higher-order birefringent, liquid crystals when in contact with other biopolymers in biofilms. Liquid crystalline biofilms are more adherent and viscous than those without liquid crystals. A key feature of biofilms is to enhance bacterial adherence and resist physical clearance. The effect of Pf phage on mucociliary transport is unknown. We found that primary CF and non-CF nasal epithelial cells cultured at air-liquid interface treated with Pf phage exhibit liquid crystalline structures in the overlying mucus. On these cell cultures, Pf phage entangles cilia but does not affect ciliary beat frequency. In both these in vitro cell cultures and in an ex vivo porcine trachea model, introduction of Pf phage decreases mucociliary transport velocity. Pf phage also blocks the rescue of mucociliary transport by CF transmembrane conductance regulator modulators in CF cultures. Thus, Pf phage may contribute to the pathogenesis of P. aeruginosa-associated CF lung disease via induction of liquid crystalline characteristics to airway secretions, leading to impaired mucociliary transport. Targeting Pf phage may be useful in treatment CF as well as other settings of chronic P. aeruginosa infections.

Long-Term Survival and Regeneration Following Transplantation of 3D-Printed Biodegradable PCL Tracheal Grafts in Large-Scale Porcine Models.

Polycaprolactone (PCL) implants in large animals show great promise for tracheal transplantation. However, the longest survival time achieved to date is only about three weeks. To meet clinical application standards, it is essential to extend the survival time and ensure the complete integration and functionality of the implant. Our study investigates the use of three-dimensional (3D)-printed, biodegradable, PCL-based tracheal grafts for large-scale porcine tracheal transplantation, assessing the feasibility and early structural integrity crucial for long-term survival experiments. A biodegradable PCL tracheal graft was fabricated using a BIOX bioprinter and transplanted into large-scale porcine models. The grafts, measuring 20 × 20 × 1.5 mm, were implanted following a 2 cm circumferential resection of the porcine trachea. The experiment design was traditionally implanted in eight porcines to replace four-ring tracheal segments, only two of which survived more than three months. Data were collected on the graft construction and clinical outcomes. The 3D-printed biosynthetic grafts replicated the native organ with high fidelity. The implantations were successful, without immediate complications. At two weeks, bronchoscopy revealed significant granulation tissue around the anastomosis, which was managed with laser ablation. The presence of neocartilage, neoglands, and partial epithelialization near the anastomosis was verified in the final pathology findings. Our study demonstrates in situ regenerative tissue growth with intact cartilage following transplantation, marked by neotissue formation on the graft's exterior. The 90-day survival milestone was achieved due to innovative surgical strategies, reinforced with strap muscle attached to the distal trachea. Further improvements in graft design and granulation tissue management are essential to optimize outcomes.

Comparing Simulation Training of Bronchoscopy-Guided Percutaneous Dilatational Tracheostomy Using Conventional Versus 3D Printed Simulators (TRAC-Sim Study).

Background: Individual implementation rate of bronchoscopy-guided percutaneous dilatational tracheostomy (PDT) varies among intensivists. Simulation training (ST) can increase the safety of medical procedures by reducing stress levels of the performing team. The aim of this study was to evaluate the benefit of ST in PDT regarding procedural time, quality of performance, and percepted feelings of safety of the proceduralist and to compare conventional simulators (CSIM) with simulators generated from 3D printers (3DSIM). Methods: We conducted a prospective, single-center, randomized, blinded cross-over study comparing the benefit of CSIM versus 3DSIM for ST of PDT. Participants underwent a standardized theoretical training and were randomized to ST with CSIM (group A) or 3DSIM (group B). After ST, participants' performance was assessed by two blinded examiners on a porcine trachea regarding time required for successful completion of PDT and correct performance (assessed by a performance score). Percepted feelings of safety were assessed before and after ST. This was followed by a second training and second assessment of the same aspects with crossed groups. Results: 44 participants were included: 24 initially trained with CSIM (group A) and 20 with 3DSIM (group B). Correctness of the PDT performance increased significantly in group B (p < .01) and not significantly in group A (p = .14). Mean procedural time required for performing a PDT after their second ST compared to the first assessment (p < .01) was lower with no difference between group A and group B and irrespective of the participants' previous experience regarding PDT, age, and sex. Moreover, percepted feelings of safety increased after the first ST in both groups (p < .001). Conclusions: ST can improve procedural skills, procedural time, and percepted feelings of safety of the proceduralist in simulated PDT.

Dexamethasone eluting polydopaminated polycaprolactone-poly (lactic-co-glycolic) acid for treatment of tracheal stenosis.

Tracheal stenosis is commonly caused by injury, resulting in inflammation and fibrosis. Inhibiting inflammation and promoting epithelization can reduce recurrence after initial successful treatment of tracheal stenosis. Steroids play an important role in tracheal stenosis management. This study in vitro evaluated effectiveness of a polydopaminated polycaprolactone stent coated with dexamethasone-eluting poly(lactic-co-glycolic) acid microparticles (μPLGA) for tracheal stenosis management. Polydopamination was characterized by Raman spectroscopy and promoted epithelialization while dexamethasone delivery reduced macrophage activity, assessed by individual cell area measurements and immunofluorescent staining for inducible nitric oxide synthase (iNOS). Dexamethasone release was quantified by high-performance liquid chromatography over 30 days. Activation-related increase in cell area and iNOS production by RAW 264.7 were both reduced significantly (p < .05) through dexamethasone release. Epithelial cell spreading was higher on polydopaminated polycaprolactone (PCL) than PCL-alone (p < .05). Force required for stent migration was measured by pullout tests of PCL-μPLGA stents from cadaveric rabbit and porcine tracheas (0.425 ± 0.068 N and 1.082 ± 0.064 N, respectively) were above forces estimated to occur during forced respiration. Biomechanical support provided by stents to prevent airway collapse was assessed by comparing compressive circumferential stiffness, and stiffness of the stent was about 1/10th of the rabbit trachea (0.156 ± 0.023 N/mm vs. 1.420 ± 0.194 N/mm, respectively). A dexamethasone-loaded PCL-μPLGA stent platform can deliver dexamethasone and exhibits sufficient mechanical properties to anchor within the trachea and polydopamination of PCL is conducive to epithelial layer formation. Therefore, a polydopaminated PCL-μPLGA stent is a promising candidate for in vivo evaluation for treatment of tracheal restenosis.

MATLAB-Based Algorithm and Software for Analysis of Wavy Collagen Fibers.

Knowledge of soft tissue fiber structure is necessary for accurate characterization and modeling of their mechanical response. Fiber configuration and structure informs both our understanding of healthy tissue physiology and of pathological processes resulting from diseased states. This study develops an automatic algorithm to simultaneously estimate fiber global orientation, abundance, and waviness in an investigated image. To our best knowledge, this is the first validated algorithm which can reliably separate fiber waviness from its global orientation for considerably wavy fibers. This is much needed feature for biological tissue characterization. The algorithm is based on incremental movement of local regions of interest (ROI) and analyzes two-dimensional images. Pixels belonging to the fiber are identified in the ROI, and ROI movement is determined according to local orientation of fiber within the ROI. The algorithm is validated with artificial images and ten images of porcine trachea containing wavy fibers. In each image, 80-120 fibers were tracked manually to serve as verification. The coefficient of determination R2 between curve lengths and histograms documenting the fiber waviness and global orientation were used as metrics for analysis. Verification-confirmed results were independent of image rotation and degree of fiber waviness, with curve length accuracy demonstrated to be below 1% of fiber curved length. Validation-confirmed median and interquartile range of R2, respectively, were 0.90 and 0.05 for curved length, 0.92 and 0.07 for waviness, and 0.96 and 0.04 for global orientation histograms. Software constructed from the proposed algorithm was able to track one fiber in about 1.1 s using a typical office computer. The proposed algorithm can reliably and accurately estimate fiber waviness, curve length, and global orientation simultaneously, moving beyond the limitations of prior methods.

Establishment and application of cricothyrotomy in vivo

BackgroundCricothyrotomy is a procedure performed to establish an airway in critical airway events. It is performed only rarely and anesthesiologists are often unprepared when called upon to perform it. This study aimed to simulate cricothyrotomy using pig larynx and trachea models to help anesthesiologists master cricothyrotomy and improve the ability to establish cricothyrotomy quickly.MethodsThe porcine larynx and trachea were dissected and covered with pigskin to simulate the structure of the anterior neck of a human patient. An animal model of cricothyrotomy was established. Forty anesthesiologists were randomly divided into four groups. Each physician performed three rounds of cricothyrotomy, and recorded the time to accomplish each successful operation. After training the cricothyrotomy procedure, a questionnaire survey was conducted for the participating residents using a Likert scale. The participants were asked to score the utility of the training course on a scale of 1 ((minimum) to 5 ((maximum).ResultsThrough repeated practice, compared with the time spent in the first round of the operation (67 ± 29 s), the time spent in the second round of the operation (47 ± 21 s) and the time spent in the third round of the operation (36 ± 11 s) were significantly shortened (P < 0.05). Results of the survey after training were quite satisfied, reflecting increased the ability of proficiency in locating the cricothyroid membrane and performing a surgical cricothyrotomy.ConclusionThe porcine larynx and trachea model is an excellent animal model for simulating and practicing cricothyrotomy, helping anesthesiologists to master cricothyrotomy and to perform it proficiently when required.

Evaluation of Structural Viability of Porcine Tracheal Scaffolds after 3 and 6 Months of Storage under Three Different Protocols.

Tracheal replacement with a bioengineered tracheal substitute has been developed for long-segment tracheal diseases. The decellularized tracheal scaffold is an alternative for cell seeding. It is not defined if the storage scaffold produces changes in the scaffold's biomechanical properties. We tested three protocols for porcine tracheal scaffold preservation immersed in PBS and alcohol 70%, in the fridge and under cryopreservation. Ninety-six porcine tracheas (12 in natura, 84 decellularized) were divided into three groups (PBS, alcohol, and cryopreservation). Twelve tracheas were analyzed after three and six months. The assessment included residual DNA, cytotoxicity, collagen contents, and mechanical properties. Decellularization increased the maximum load and stress in the longitudinal axis and decreased the maximum load in the transverse axis. The decellularization of the porcine trachea produced structurally viable scaffolds, with a preserved collagen matrix suitable for further bioengineering. Despite the cyclic washings, the scaffolds remained cytotoxic. The comparison of the storage protocols (PBS at 4 °C, alcohol at 4 °C, and slow cooling cryopreservation with cryoprotectants) showed no significant differences in the amount of collagen and in the biomechanical properties of the scaffolds. Storage in PBS solution at 4 °C for six months did not change the scaffold mechanics.

Point-of-care ultrasound-guided submucosal paclitaxel injection in tracheal stenosis model.

Transcutaneous point-of-care ultrasound (POCUS) is a good tool to monitor the trachea in many clinical practices. The aim of our study is to verify the feasibility of POCUS-guided submucosal injection as a potential drug delivery method for the treatment of tracheal stenosis. The inner wall of the trachea was monitored via a bronchoscope during the POCUS-guided submucosal injection of methylene blue in fresh ex vivo porcine trachea to evaluate the distribution of methylene blue. The feasibility and eficacy of POCUS-guided submucosal injection were evaluated in a tracheal stenosis rabbit model. Animals were divided into sham group, tracheal stenosis group, and treatment group. Ten days after the scraping of the tracheal mucosa or sham operation, POCUS-guided submucosal injection of paclitaxel or saline was performed. Seven days after the submucosal injection, the trachea was assessed by cervical computed tomography (CT) scan and ultrasound. The distribution of methylene blue in trachea proved the technical feasibility of POCUS-guided submucosal injection. CT evaluation revealed that the tracheal stenosis index and the degree of tracheal stenosis increased significantly in the stenosis group, while POCUS-guided submucosal injection of paclitaxel partially reversed the tracheal stenosis. POCUS-guided submucosal injection of paclitaxel also decreased the lamina propria thickness and collagen deposition in the stenosed trachea. POCUS-guided submucosal paclitaxel injection alleviated tracheal stenosis induced by scraping of the tracheal mucosa. POCUS-guided submucosal injection might be a potential method for the treatment of tracheal stenosis.

Perpendicular implantation of porcine trachea extracellular matrix for enhanced xenogeneic scaffold surface epithelialization in a canine model.

The availability of clinically applied medical materials in thoracic surgery remains insufficient, especially materials for treating tracheal defects. Herein, the potential of porcine extracellular matrix (P-ECM) as a new airway reconstruction material was explored by xenotransplanting it into a canine trachea. P-ECM was first transplanted into the buttocks of Narc Beagle dogs (n = 3) and its overall immuno-induced effects were evaluated. Subsequently, nine dogs underwent surgery to create a tracheal defect that was 1 × 2 cm. In group A, the P-ECM was implanted parallel to the tracheal axis (n = 3), whereas in group B the P-ECM was implanted perpendicular to the tracheal axis (n = 6). The grafts were periodically observed by bronchoscopy and evaluated postoperatively at 1 and 3 months through macroscopic and microscopic examinations. Immunosuppressants were not administered. Statistical evaluation was performed for Bronchoscopic stenosis rate, graft epithelialization rate, shrinkage rate and ECM live-implantation rate. No sign of P-ECM rejection was observed after its implantation in the buttocks. Bronchoscopic findings showed no improvement concerning stenosis in group A until 3 months after surgery; epithelialization of the graft site was not evident, and the ECM site appeared scarred and faded. In contrast, stenosis gradually improved in group B, with continuous epithelium within the host tissues and P-ECM. Histologically, the graft site contracted longitudinally and no epithelialization was observed in group A, whereas full epithelialization was observed on the P-ECM in group B. No sign of cartilage regeneration was confirmed in both groups. No statistically significant differences were found in bronchoscopic stenosis rate, shrinkage rate and ECM live-implantation rate, but graft epithelialization rate showed a statistically significant difference (G-A; sporadic (25%) 3, vs. G-B; full covered (100%) 3; p = 0.047). P-ECM can support full re-epithelialization without chondrocyte regeneration, with perpendicular implantation facilitating epithelialization of the ECM. Our results showed that our decellularized tracheal matrix holds clinical potential as a biological xenogeneic material for airway defect repair.

Establishing the Ideal Conditions to Create an Airway Fire Using a Porcine Airway Model.

Airway fires are a rare but devastating complication of airway surgery. Although protocols for managing airway fires have been discussed, the ideal conditions for igniting airway fires remain unclear. This study examined the oxygen level required to ignite a fire during a tracheostomy. Porcine Model. Laboratory. Porcine tracheas were intubated with a 7.5 air-filled polyvinyl endotracheal tube. A tracheostomy was performed. Monopolar and bipolar cautery were used in independent experiments to assess the ignition capacity. Seven trials were performed for each fraction of inspired oxygen (FiO2): 1.0, 0.9, 0.7, 0.6, 0.5, 0.4, and 0.3. The primary outcome was ignition of a fire. The time was started once the cautery function was turned on. The time was stopped when a flame was produced. Thirty seconds was used as the cut-off for "no fire." The average time to ignition for monopolar cautery at FiO2 of 1.0, 0.9, 0.8, 0.7, and 0.6 was found to be 9.9, 6.6, 6.9, 9.6, and 8.4 s, respectively. FiO2 ≤ 0.5 did not produce a flame. No flame was created using the bipolar device. Dry tissue eschar shortened the time to ignition, whereas moisture in the tissue prolonged the time to ignition. However, these differences were not quantified. Dry tissue eschar, monopolar cautery, and FiO2 ≥ 0.6 are more likely to result in airway fires.

Modular assembly of bioprinted perfusable blood vessel and tracheal epithelium for studying inflammatory respiratory diseases

In vitro organ models allow for the creation of precise preclinical models that mimic organ physiology. During a pandemic of a life-threatening acute respiratory disease, an improved trachea model (TM) is required. We fabricated a modular assembly of the blood vessel and TMs using 3D bioprinting technology. First, decellularized extracellular matrix (dECM) were prepared using the porcine trachea and blood vessels. A trachea module was fabricated based on the tracheal mucosa-derived dECM and microporous membrane. Further, a blood vessel module was manufactured using the prepared vascular-tissue-derived dECM. By assembling each manufactured module, a perfusable vascularized TM simulating the interface between the tracheal epithelium and blood vessels was fabricated. This assembled model was manufactured with efficient performance, and it offered respiratory symptoms, such as inflammatory response and allergen-induced asthma exacerbation. These characteristics indicate the possibility of manufacturing a highly functional organ model that mimics a complex organ environment in the future.

Investigating Stress-relaxation and Failure Responses in the Trachea.

The biomechanical properties of the trachea directly affect the airflow and contribute to the biological function of the respiratory system. Understanding these properties is critical to understanding the injury mechanism in this tissue. This protocol describes an experimental approach to study the stress-relaxation behavior of porcine trachea that were pre-stretched to 0% or 10% strain for 300 s, followed by mechanical tensile loading until failure. This study provides details of the experimental design, data acquisition, analyses, and preliminary results from the porcine tracheae biomechanical testing. Using the detailed steps provided in this protocol and the data analysis MATLAB code, future studies can investigate the time-dependent viscoelastic behavior of trachea tissue, which is critical to understanding its biomechanical responses during physiological, pathological, and traumatic conditions. Furthermore, in-depth studies of the biomechanical behavior of the trachea will critically aid in improving the design of related medical devices such as endotracheal implants that are widely used during surgeries.

An Ex Vivo Model of Posterior Tracheomalacia With Evaluation of Potential Treatment Modalities.

Posterior tracheomalacia (TM) is characterized by excessive intraluminal displacement of the tracheal membranous wall. Recently, novel surgical strategies for repair of posterior TM have been introduced. To our knowledge, these strategies have not been evaluated in a model of posterior TM. Thus, we sought to design an ex vivo mechanical model of posterior TM to evaluate potential repair interventions. A model for posterior TM was created with partial thickness longitudinal incisions to the posterior aspect of ex vivo porcine trachea. Three groups of tracheas were tested: (1) control (unmanipulated), (2) posterior TM (injury), and (3) intervention (repair). Interventions included external splinting with 0.3 and 0.5 mm bioresorbable plates, posterior tracheopexy, and injection tracheoplasty with calcium hydroxylapatite. An airtight tracheal system was created to measure tracheal wall collapse with changes in negative pressure. A bronchoscope and pressure transducer were connected to either end. Cross-sectional area of the tracheal lumen was analyzed using ImageJ software (National Institutes of Health, Bethesda, MD). Average percent reduction in cross-sectional area of the tracheal lumen was compared using a two-tailed paired t-test. Significant differences were found between control and TM groups (p< 0.019). There was no significant difference between control and external splinting and posterior tracheopexy groups (p> 0.14). We describe an ex vivo model for posterior TM that replicates airway collapse. External splinting and tracheopexy interventions showed recovery of the injured tracheal segment. Injection tracheoplasty did not improve the TM. N/A Laryngoscope, 133:2000-2006, 2023.

Performance Based Evaluation of Cricothyroidotomy Simulators for Training

The U.S. military has become increasingly reliant on simulators to train combat medical personnel. Human patient simulators that exist for training medical procedures represent task elements with varying degrees of fidelity. The goal of this research was to evaluate the functional fidelity of two commonly used simulators to train surgical cricothyroidotomy to experienced participants. Following a task analysis informed by experts, we collected performance training and test data from 14 experienced trainees. Each participant performed surgical cricothyroidotomies on porcine tracheas before and after five training sessions using one of two simulators. Comparisons of procedure completion times and errors showed development of task mastery by members of both training groups. Analyses of transfer of training from the final training session to the porcine posttest suggested that experienced participants were sensitive to differences between the training simulators and conditions of the posttest. Implications are presented as they relate to the use of simulation technologies for training cricothyroidotomy and the application of a standard method for fidelity assessment.

Changes in the Hemagglutinin and Internal Gene Segments Were Needed for Human Seasonal H3 Influenza A Virus to Efficiently Infect and Replicate in Swine.

The current diversity of influenza A viruses (IAV) circulating in swine is largely a consequence of human-to-swine transmission events and consequent evolution in pigs. However, little is known about the requirements for human IAVs to transmit to and subsequently adapt in pigs. Novel human-like H3 viruses were detected in swine herds in the U.S. in 2012 and have continued to circulate and evolve in swine. We evaluated the contributions of gene segments on the ability of these viruses to infect pigs by using a series of in vitro models. For this purpose, reassortant viruses were generated by reverse genetics (rg) swapping the surface genes (hemagglutinin-HA and neuraminidase-NA) and internal gene segment backbones between a human-like H3N1 isolated from swine and a seasonal human H3N2 virus with common HA ancestry. Virus growth kinetics in porcine intestinal epithelial cells (SD-PJEC) and in ex-vivo porcine trachea explants were significantly reduced by replacing the swine-adapted HA with the human seasonal HA. Unlike the human HA, the swine-adapted HA demonstrated more abundant attachment to epithelial cells throughout the swine respiratory tract by virus histochemistry and increased entry into SD-PJEC swine cells. The human seasonal internal gene segments improved replication of the swine-adapted HA at 33 °C, but decreased replication at 40 °C. Although the HA was crucial for the infectivity in pigs and swine tissues, these results suggest that the adaptation of human seasonal H3 viruses to swine is multigenic and that the swine-adapted HA alone was not sufficient to confer the full phenotype of the wild-type swine-adapted virus.

Evaluation of Biomechanical Properties and Morphometric Structures of the Trachea in Pigs and Rabbits.

Animals differ in the biochemical composition, attachments, and mechanical properties of tracheal cartilage. This study examined the biomechanical properties and morphological structure of the trachea of pigs, and rabbits as preclinical models. The trachea in pigs and rabbits can be divided into four regions, cranial cervical, middle cervical, thoracic inlet, and intra-thoracic parts. The total number of tracheal rings in pigs and rabbits was 32-35 and 34-38 rings, respectively. The pig bronchus first branches from the trachea, reaching the cranial lobe of the lungs before branching to the main bronchus, while the rabbit bronchus branched after the main bronchus. A comparison of the posterior region of the crosssectional trachea shows that the rabbit has a C-shape with cartilage connected to the tracheal muscle, and the pig has the tracheal muscle covered with cartilage. The trachea of pigs and rabbits decreased in tracheal thickness and size from the thoracic inlet toward the lungs. The stress-strain in the longitudinal and transverse tensile test was higher in rabbits than in pigs. The tensile stress of the four regions was significantly different in the transverse tensile test (p<0.001). In the bending test, more force was required to bend pig than rabbit tracheas. Microscopic and scanning electron microscopy showed no structural differences in tracheal cartilage between the two species. These results suggest that there is great variation in morphology and physical properties of the trachea in pigs and rabbits. We found porcine tracheas have similar biomechanical properties to those of humans.

Share the Airway: An Interdisciplinary Course for Management of the Unexpected Difficult Airway

IntroductionWithin the scope of practice of oral and maxillofacial surgery, the unexpected difficult airway may occur in the trauma bay, operating theater, postoperative, or office-based setting. Oral and maxillofacial surgeons must be trained to diagnose and intervene in anatomically or anesthetically compromised airways. An interdisciplinary training course hosted by an anesthesiology airway expert and oral and maxillofacial surgeon is a novel resident training opportunity. Materials and methodsIn August 2019 and October 2020, the department of anesthesiology and the division of oral and maxillofacial surgery at Weill Cornell Medical College/NewYork-Presbyterian Hospital, New York, NY, co-hosted interdisciplinary educational sessions focused on management of the unexpected difficult airway, taught to residents and faculty. A SurveyMonkey (San Mateo, CA) questionnaire was taken 2 weeks before and after the course, with 10 questions assessing fund of knowledge in airway anatomy and physiology, etiology of difficult airway scenarios, difficult airway algorithm, and performance of emergency surgical airways. An interactive lecture on likely scenarios, airway algorithms, relevant surgical anatomy, routine and emergency airway management, airway devices, and emergency surgical airway techniques was conducted. A hands-on cricothyroidotomy tutorial using Crico-Trainer “Pig” (VBM, Sulz, DE) anatomic models with fresh porcine tracheas to simulate human airway anatomy were used. A post-course test consisted of a timed, filmed performance followed by a debriefing session. ResultsIncreased fund of knowledge and comfort with airway anatomy, difficult airway diagnosis and management, and emergency surgical airway techniques was evident between pre-and post-course surveys and was clearly demonstrated across multiple years. The sample size (n = 10, 2019; n = 7, 2020) was insufficient for statistical analysis. ConclusionInterdisciplinary didactic and clinical training in emergency airway management are of paramount importance to the oral and maxillofacial surgeon. Between years, a drop-off in knowledge base and technical skills occurred, even among senior staff, and all attendees agreed that periodic repetition is worthwhile. This course is now offered as part of the core curriculum on an annual basis and may be expanded to additional specialties for whom airway management is important.

Quantitative proteomics reveals tissue-specific toxic mechanisms for acute hydrogen sulfide-induced injury of diverse organs in pig

Hydrogen sulfide (H2S) is a highly toxic gas in many environmental and occupational places. It can induce multiple organ injuries particularly in lung, trachea and liver, but the relevant mechanisms remain poorly understood. In this study, we used a TMT-based discovery proteomics to identify key proteins and correlated molecular pathways involved in the pathogenesis of acute H2S-induced toxicity in porcine lung, trachea and liver tissues. Pigs were subjected to acute inhalation exposure of up to 250 ppm of H2S for 5 h for the first time. Changes in hematology and biochemical indexes, serum inflammatory cytokines and histopathology demonstrated that acute H2S exposure induced organs inflammatory injury and dysfunction in the porcine lung, trachea and liver. The proteomic data showed 51, 99 and 84 proteins that were significantly altered in lung, trachea and liver, respectively. Gene ontology (GO) annotation, KEGG pathway and protein-protein interaction (PPI) network analysis revealed that acute H2S exposure affected the three organs via different mechanisms that were relatively similar between lung and trachea. Further analysis showed that acute H2S exposure caused inflammatory damages in the porcine lung and trachea through activating complement and coagulation cascades, and regulating the hyaluronan metabolic process. Whereas antigen presentation was found in the lung but oxidative stress and cell apoptosis was observed exclusively in the trachea. In the liver, an induced dysfunction was associated with protein processing in the endoplasmic reticulum and lipid metabolism. Further validation of some H2S responsive proteins using western blotting indicated that our proteomics data were highly reliable. Collectively, these findings provide insight into toxic molecular mechanisms that could potentially be targeted for therapeutic intervention for acute H2S intoxication.