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Accurate segmentation of the pulmonary airway tree is crucial for diagnosing lung diseases. To tackle the issues of low segmentation accuracy and frequent leaks in existing methods, this paper proposes a precise segmentation method using quasi-spherical region-constrained wavefront propagation with tracheal wall gap sealing. Based on the characteristic that the surface formed by seed points approximates the airway cross-section, the width of the unsegmented airway is calculated, determining the initial quasi-spherical constraint region. Using the wavefront propagation method, seed points are continuously propagated and segmented along the tracheal wall within the quasi-spherical constraint region, thus overcoming the need to determine complex segmentation directions. To seal tracheal wall gaps, a morphological closing operation is utilized to extract the characteristics of small holes and locate low-brightness tracheal wall gaps. By filling the CT values at these gaps, the method seals the tracheal wall gaps. Extensive experiments on the EXACT09 dataset demonstrate that our algorithm ranks third in segmentation completeness. Moreover, its performance in preventing airway leaks is significantly better than the top-two algorithms, effectively preventing large-scale leak-induced spread.

This study aimed to investigate the effects of intravenous injection of iodine contrast agent on the tracheal diameter and lung volume. In this retrospective study, a total of 221 patients (71.1 ± 12.4 years, 174 males) who underwent vascular dynamic CT examination including chest were included. Unenhanced, arterial phase, and delayed-phase images were scanned. The tracheal luminal diameters at the level of the thoracic inlet and both lung volumes were evaluated by a radiologist using a commercial software, which allows automatic airway and lung segmentation. The tracheal diameter and both lung volumes were compared between the unenhanced vs. arterial and delayed phase using a paired t-test. The Bonferroni correction was performed for multiple group comparisons. The tracheal diameter in the arterial phase (18.6 ± 2.4 mm) was statistically significantly smaller than those in the unenhanced CT (19.1 ± 2.5 mm) (p < 0.001). No statistically significant difference was found in the tracheal diameter between the delayed phase (19.0 ± 2.4 mm) and unenhanced CT (p = 0.077). Both lung volumes in the arterial phase were 4131 ± 1051 mL which was significantly smaller than those in the unenhanced CT (4332 ± 1076 mL) (p < 0.001). No statistically significant difference was found in both lung volumes between the delayed phase (4284 ± 1054 mL) and unenhanced CT (p = 0.068). In conclusion, intravenous infusion of iodine contrast agent transiently decreased the tracheal diameter and both lung volumes., (© 2024. The Author(s).)

This study aimed to investigate the relationship between cervical measurements and difficult airways using ultrasonographic measurements. American Society of Anesthesiologists grade I to III, male or female, 120 adult patients, undergoing elective surgery were enrolled in the study. The study involved measuring the distance of the trachea, cricoid cartilage, thyroid cartilage, vocal cord anterior commissure, and hyoid bone to the skin using a 10 to 13 MHz linear ultrasound probe in the transverse plane. Additionally, the length of the cricothyroid and thyrohyoid membranes, along with their distance from the skin, were measured using the probe in the sagittal plane. Subsequently, another experienced anesthesiologist conducted mask ventilation and intubation after the patient's induction of general anesthesia. Throughout this process, the patient was assessed for difficulties in mask ventilation, laryngoscopy, and intubation. 28 (23.3%) patients had a difficult airway. Analyzing the measurements associated with difficult airways, the most reliable predictor was the epiglottis midline-skin distance [AUC (area under the curve): 0.847, P < .001, cutoff: >19.9, sensitivity: 78.6%, specificity: 79.4%]. Additionally, other factors such as hyoid bone to skin distance, thyroid cartilage to skin distance, thyrohyoid membrane to skin distance, and vocal cord anterior commissure-skin distance were also identified as predictors for a difficult airway. The increase in the distance of the epiglottis midline, vocal cord anterior commissure, hyoid bone, thyrohyoid membrane, and thyroid cartilage to the skin at the level of the isthmus measured by ultrasonography is predictive of difficult airways. Based on our study outcomes, we assert that ultrasonographic evaluation can be used in the prediction of difficult airways., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

The larynx is in the lower respiratory tract and has the function of protecting the airways, controlling, and modulating breathing, assisting the circulatory system, and vocalizing. This study aims to describe the anatomy and histology of the skeleton of the larynx and trachea of the species Chelonia mydas, Caiman yacare and Caiman latirostris. The study was conducted at the Federal University of Espírito Santo (UFES), using nine specimens of Ch. mydas, 20 of Ca. yacare and four of Ca. latirostris. Samples of the larynx and trachea were collected, fixed, and sent for dissection of the structures and subsequent macroscopic analysis. For histology, samples were processed by the routine paraffin embedding method and stained with hematoxylin-eosin and Verhoeff. For the three species, two arytenoid cartilages, a cricoid cartilage, a hyoid apparatus composed of a base and two horns were found. In Ch. mydas, two structures called thyroid wings were observed, not found in crocodilians. The trachea of crocodilians presented incomplete tracheal rings and musculature, while the trachea of Ch. mydas presented complete tracheal rings. Histologically, the entire cartilaginous skeleton of the larynx of the three species, as well as the tracheal rings, are constituted by hyaline cartilage.

Background: No studies have been conducted to define the lengths of the upper airway's different segments in normal healthy adults., Aims/objectives: This study aimed to determine the length of the subglottis and extrathoracic trachea and the factors affecting it., Material and Methods: This was an observational retrospective review study. Included 102 adult patients who underwent CT scan during the quiet inspiration phase of the upper airway., Results: The results revealed significant positive linear relationships between height and both anterior and posterior subglottic measurements (p < 0.001). Additionally, a statistically significant, moderately strong negative correlation between age and extrathoracic tracheal measurements (p > 0.001) was observed. Men exhibited longer anterior (p < 0.001) and posterior (p > 0.001) subglottic measurements. In both sexes, the average length of the anterior subglottis was 14.16 (standard deviation [SD]: 2.72) mm, posterior subglottis was 14.51 (SD: 2.85) mm and extrathoracic trachea was 66.37 (SD: 13.71) mm., Conclusion and Significance: We concluded that a normal healthy adult's anterior subglottis length is 6.3-19.3 mm (mean: 14.16 [SD: 2.72] mm), posterior subglottis length is 6.1-20.0 mm (mean: 14.51 [SD: 2.85] mm) and extrathoracic trachea length is 25.2-98.5 mm (mean: 66.37 [SD: 13.71] mm). Age, height and sex affected the upper airway length., (© 2024. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Purpose: There have been numerous studies focused on the stiffness of tracheal cartilage. However, no research has been conducted specifically on the annular ligament, nor have any regional differences in the annular ligament been identified. The purpose of this study was to investigate the stiffness of the ligaments present between the thyroid, cricoid and tracheal cartilages., Methods: The ligaments were identified in the cervical region of living subjects with ultrasonography. The stiffness of the ligaments was measured from the body surface using a digital palpation device (MyotonPRO). Since it is impossible to measure the entire trachea in a living subject, an additional measurement was performed on human cadavers., Results: Both in vivo and cadaveric investigations found that the stiffness of annular ligaments decreased gradually from the superior to inferior parts. There was no difference in the stiffness between males and females in the superior part of the trachea. However, the stiffness of the middle and inferior parts was predominantly higher in females than in males. Furthermore, males showed significant differences in stiffness between the superior and middle parts, while females showed no significant differences., Conclusion: These results reveal that there are regional and sex-related differences in the stiffness of human tracheal ligaments., (© 2024. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Organs have a distinctive yet often overlooked spatial arrangement in the body 1-5 . We propose that there is a logic to the shape of an organ and its proximity to its neighbours. Here, by using volumetric scans of many Drosophila melanogaster flies, we develop methods to quantify three-dimensional features of organ shape, position and interindividual variability. We find that both the shapes of organs and their relative arrangement are consistent yet differ between the sexes, and identify unexpected interorgan adjacencies and left-right organ asymmetries. Focusing on the intestine, which traverses the entire body, we investigate how sex differences in three-dimensional organ geometry arise. The configuration of the adult intestine is only partially determined by physical constraints imposed by adjacent organs; its sex-specific shape is actively maintained by mechanochemical crosstalk between gut muscles and vascular-like trachea. Indeed, sex-biased expression of a muscle-derived fibroblast growth factor-like ligand renders trachea sexually dimorphic. In turn, tracheal branches hold gut loops together into a male or female shape, with physiological consequences. Interorgan geometry represents a previously unrecognized level of biological complexity which might enable or confine communication across organs and could help explain sex or species differences in organ function., (© 2024. The Author(s).)

Vocal production in birds has been the target of considerable research that mostly has focused on phylogenetically well-nested songbirds. Anatomical descriptions and recordings of many non-songbirds have often only focused on a single ontogenetic stage or sex. While basic morphology of the vocal organ (syrinx) of ostrich (Palaeognathae, Struthio camelus) has been known since the 1800s, descriptions of its vocal repertoire and syrinx anatomy since then have been incomplete or inconsistent. New toolkits now enable detailed qualitative description of internal anatomy and meristic data and allow it to be compared to vocal production. Here we describe the anatomy of the syrinx in Struthio camelus for three post-hatching ontogenetic stages and both an adult male and female utilizing dissection and contrast enhanced X-ray computed tomography (diceCT). We find changes in ring geometry and spacing through ontogeny as well as lateral labia thickness. We document a small unpaired, midline, cartilaginous structure, a "pessuliform process" at the tracheobronchial juncture present throughout ontogeny and in both males and females. Investigation of the vocal repertoire of ostriches across ontogeny using a new dataset of 77 recordings led to identification of four vocalizations not previously reported in the literature, including the simultaneous production of a hiss and tonal. We find syrinx morphology largely consistent across ontogeny and in male and female adults. Both are capable of producing long duration tonal calls, but these may be more frequent in male birds. Closed-mouth boom calls remain unique to males. A detailed understanding of diversity in parts of early diverging clades is pivotal in attempting to estimate features of the ancestral syrinx in birds and how avian vocalization evolved., (© 2023 Anatomical Society.)

The numerical simulation of inhaled aerosols in medical research starts to play a crucial role in understanding local deposition within the respiratory tract, a feat often unattainable experimentally. Research on children is particularly challenging due to the limited availability of in vivo data and the inherent morphological intricacies. CFD solvers based on Finite Volume Methods (FVM) have been widely employed to solve the flow field in such studies. Recently, Lattice Boltzmann Methods (LBM), a mesoscopic approach, have gained prominence, especially for their scalability on High-Performance Computers. This study endeavours to compare the effectiveness of LBM and FVM in simulating particulate flows within a child's respiratory tract, supporting research related to particle deposition and medication delivery using LBM. Considering a 5-year-old child's airway model at a steady inspiratory flow, the results are compared with in vitro experiments. Notably, both LBM and FVM exhibit favourable agreement with experimental data for the mean velocity field and the turbulence intensity. For particle deposition, both numerical methods yield comparable results, aligning well with in vitro experiments across a particle size range of 0.1-20 µm. Discrepancies are identified in the upper airways and trachea, indicating a lower deposition fraction than in the experiment. Nonetheless, both LBM and FVM offer invaluable insights into particle behaviour for different sizes, which are not easily achievable experimentally. In terms of practical implications, the findings of this study hold significance for respiratory medicine and drug delivery systems - potential health impacts, targeted drug delivery strategies or optimisation of respiratory therapies., Competing Interests: Declaration of competing interest All authors declare that they have no conflicts of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The origin of novel traits, those that are not direct modifications of a pre-existing ancestral structure, remains a fundamental problem in evolutionary biology. For example, little is known about the evolutionary and developmental origins of the novel avian vocal organ, the syrinx. Located at the tracheobronchial junction, the syrinx is responsible for avian vocalization, but it is unclear whether avian vocal folds are homologous to the laryngeal vocal folds in other tetrapods or convergently evolved. Here, we identify a core developmental program involved in avian vocal fold formation and infer the morphology of the syrinx of the ancestor of modern birds. We find that this ancestral syrinx had paired sound sources induced by a conserved developmental pathway and show that shifts in these signals correlate with syringeal diversification. We show that, despite being derived from different developmental tissues, vocal folds in the syrinx and larynx have similar tissue composition and are established through a strikingly similar developmental program, indicating that co-option of an ancestral developmental program facilitated the origin of vocal folds in the avian syrinx., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023. Published by Elsevier Inc.)

The symmetry of the right and left bronchi, proposed in a previous comparative anatomical study as the basic model of the mammalian bronchial tree, was examined to determine if it applied to the embryonic human bronchial tree. Imaging data of 41 human embryo specimens at Carnegie stages (CS) 16-23 (equivalent to 6-8 weeks after fertilization) belonging to the Kyoto collection were obtained using phase-contrast X-ray computed tomography. Three-dimensional bronchial trees were then reconstructed from these images. Bronchi branching from both main bronchi were labeled as dorsal, ventral, medial, or lateral systems based on the branching position with numbering starting cranially. The length from the tracheal bifurcation to the branching point of the labeled bronchus was measured, and the right-to-left ratio of the same labeled bronchus in both lungs was calculated. In both lungs, the human embryonic bronchial tree showed symmetry with an alternating pattern of dorsal and lateral systems up to segmental bronchus B9 as the basic shape, with a more peripheral variation. This pattern is similar to that described in adult human lungs. Bronchial length increased with the CS in all labeled bronchi, whereas the right-to-left ratio was constant at approximately 1.0. The data demonstrated that the prototype of the human adult bronchial branching structure is formed and maintained in the embryonic stage. The morphology and branching position of all lobar bronchi and B6, B8, B9, and the subsegmental bronchus of B10 may be genetically determined. On the other hand, no common structures between individual embryos were found in the peripheral branches after the subsegmental bronchus of B10, suggesting that branch formation in this region is influenced more by environmental factors than by genetic factors., (© 2023 Anatomical Society.)

The aim of this study was to describe the morphology of the trachea and syrinx at macroscopic and light microscopy levels of three species of birds from different orders that inhabit the Brazilian cerrado. For that, five adult specimens (three males and two females of each species) of white-eyed parakeet (Psittacara leucophthalmus), red-winged tinamou (Rhynchotus rufescens) and red-legged seriema (Cariama cristata) were used. The trachea and syrinx of the birds were collected and destined for anatomical and histological studies. The trachea of the studied birds presented an elongated path and originated in the larynx and extended caudally to the syrinx. No sexual dimorphism was observed in the syrinx of the studied species, probably because it is associated with their song, which is very similar between males and females of these species. The findings of this study allowed us to classify the syrinx as tracheal in the white-eyed parakeet and tracheobronchial in the red-winged tinamou and red-legged seriema. In general, the morphological features of the trachea and syrinx were similar to those described for other species of birds, such as the presence of intrinsic and extrinsic syringeal muscles, and the lateral and medial tympaniform membranes, which would represent important anatomical structures in sound production through vibration during expiration and eventual inspiration. The morphological structure of the syrinx in the three avian species of the Brazilian cerrado is consistent with the ability of these avian species to perform a potential vocalization, especially the red-legged seriema that emits characteristic sounds very loud and can carry several kilometres., (© 2023 Wiley-VCH GmbH. Published by John Wiley & Sons Ltd.)

Objective: In a postlaryngectomy patient, tracheoesophageal (TE) speech is considered to be the most effective and preferred method of communication. Previous research has demonstrated that despite an appropriately sized TE prosthesis placement at the time of puncture, there are a portion of patients that require resizing postoperatively. The purpose of this study was to report on the variability of the tracheoesophageal prosthesis length., Study Design: Retrospective chart review., Setting: Tertiary care academic medical center., Methods: This was a retrospective chart review of 62 patients who underwent secondary tracheoesophageal puncture (TEP) at a tertiary care academic medical center from January 2008 to November 2019. Patient demographic information, average changes in prosthesis length, number of prosthesis adjustments, and timing of prosthesis exchanges were collected., Results: 62 patients met criteria for study inclusion. Mean age was 61.96 years old with 49 being male (79%) and 13 (21%) females. Overall change in prosthesis length was - 3.85 mm ± 3.58 with time to first prosthesis change at 2.29 months ± 2.73. There was an average of 4.37 changes ± 3.43 before reaching a stable length. Twenty-six patients (41.9%) had increases in their prosthesis length resulting in closure of the tracheoesophageal fistula requiring seven patients (11.3%) to return to the operating room for repuncturing. History of smoking (P = 0.02), Blom-Singer prosthesis type (P = 0.03), and larger diameter (P = 0.01) appeared to be predisposing factors for a fluctuating prosthesis length., Conclusion: Tracheoesophageal prosthesis length decreases over time for secondary punctures, requiring adjustments with a speech language pathologist. There are a clinically significant portion that have fluctuations in prosthesis length resulting in an increased risk for requiring re-puncturing., (Published by Elsevier Inc.)

Background: The visceral or middle mediastinum contains nonvascular (trachea, carina, esophagus, and lymph nodes) and vascular structures (heart, ascending aorta, aortic arch, descending aorta, superior vena cava, intrapericardial pulmonary arteries, thoracic duct)., Objectives: The various pathologies of the visceral mediastinum and imaging features are presented., Materials and Methods: Plain film radiography shows the gross anatomy and allows visualization of larger pathologies. However, for detailed anatomic and structural classification more sophisticated imaging techniques are required. Especially computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) are well suited for structural and functional assessment of mediastinal lesions., Conclusion: This article summarizes the major pathologies of the visceral mediastinum., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

The larynx serves as the gateway between the upper and lower respiratory tracts and is involved in the tasks of phonation, deglutition, and airway protection. Familiarity with the complex anatomy of the larynx is critical for detecting and characterizing disease in the region, especially in cancer staging. In this article, we review the anatomy of the larynx and cervical trachea, including an overview of their cartilages, supporting tissues, muscles, mucosal spaces, neurovascular supply, and lymphatics, followed by correlation to the clinically relevant anatomic sites of the larynx. Imaging techniques for evaluating the larynx and trachea will also be discussed briefly., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The object of the research is the painting, Portrait of a Musician''. Upon closer examination of the painting, we discovered three details. Two have the shape of trachea and bronchi and the third a larynx. By moving the details through the program Paint X we got an image of the larynx, trachea and bronchi. The larynx is presented by thyroid and cricoid cartilage. The characteristic cartilaginous rings are distinguished on the trachea. The right and left main bronchi are also seen. In our opinion, Leonardo da Vinci reflected the elements of the respiratory system in the, Portrait of a Musician'', thus emphasizing the fact that the bronchi, trachea and larynx are involved in the production of sound., (Copyright © 2020 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

Different introducers are available to assist with tracheal intubation. Subtle differences in the design of introducers can have a marked effect on safety and performance. The Difficult Airway Society's Airway Device Evaluation Project Team proposal states that devices should only be purchased for which there is at least a case-control study on patients assessing airway devices. However, resources are not currently available to carry out a case-control study on all introducers available on the market. This study comprised a laboratory and manikin-based investigation to identify introducers that could be suitable for clinical investigation. We included six different introducers in laboratory-based assessments (design characteristics) and manikin-based assessments involving the participation of 30 anaesthetists. Each anaesthetist attempted placement in the manikin's trachea with each of the six introducers in a random order. Outcomes included first-time insertion success rate; insertion success rate; number of attempts; time to placement; and distance placed. Each anaesthetist also completed a questionnaire. First-time insertion success rate depended significantly on the introducer used (p = 0.0016) and varied from 47% (Armstrong and P3) to 77% (Intersurgical and Frova). Median time to placement (including oesophageal placement) varied from 10 s (Eschmann and Frova) to 20 s (P3) (p = 0.0025). Median time to successful placement in the trachea varied from 9 s (Frova) to 22 s (Armstrong) (p = 0.037). We found that the Armstrong and P3 devices were not as acceptable as other introducers and, without significant improvements to their design and characteristics, the use of these devices in studies on patients is questionable. The study protocol is suitable for differentiating between different introducers and could be used as a basis for assessing other types of devices., (© 2021 Association of Anaesthetists.)

We investigated the potential inhibitory effects of docosahexaenoic acid (DHA) on the contractions of guinea pig tracheal smooth muscles in response to U46619 (a thromboxane A 2 (TXA 2 ) mimetic) and prostaglandin F 2α (PGF 2α ) to examine whether this n-3 polyunsaturated fatty acid suppresses prostanoid-induced tracheal contractions. DHA (3 × 10 -5  M) significantly suppressed tracheal contractions elicited by lower concentrations of U46619 (10 -8  M) and PGF 2α (5 × 10 -7  M) (vs. control), although it did not suppress the contractions induced by higher concentrations (U46619: 10 -7  M; PGF 2α : 10 -5  M). Supporting these findings, DHA (4 × 10 -5  M/6 × 10 -5  M) shifted the concentration-response curves for U46619 (10 -9 -10 -6  M) and PGF 2α (10 -8 -10 -5  M) to the right. However, the slope of the regression line in the Schild plot of DHA vs. U46619/PGF 2α was larger than unity. The tracheal contractions induced by U46619 (10 -8  M) and PGF 2α (5 × 10 -7  M) were significantly suppressed by the prostanoid TP receptor antagonist SQ 29,548 (10 -6  M) (vs. ethanol-treated). In contrast, DHA (4 × 10 -5  M) did not show significant inhibitory effects on the contractions induced by acetylcholine (10 -8 -10 -4  M), histamine (10 -8 -10 -4  M), and leukotriene D 4 (10 -11 -10 -7  M) (vs. ethanol-treated). These findings indicate that DHA selectively suppresses tracheal contractions induced by U46619 and PGF 2α . Therefore, DHA may be a useful therapeutic agent against asthma associated with tracheal/bronchial hyper-constriction caused by prostanoids including TXA 2 and PGF 2α .

Objective: Define the length of the subglottis and trachea in children to predict a safe intubation depth., Methods: Patients <18 years undergoing rigid bronchoscopy from 2013 to 2020 were included. The carina and inferior borders of the cricoid and true vocal folds were marked on a bronchoscope and distances were measured. Patient age, weight, height, and chest height were recorded. Four styles of cuffed pediatric endotracheal tubes (ETT) were measured and potential positions of each cuff and tip were calculated within each trachea using five depth of intubation scenarios. Multivariate linear regression was performed to identify predictors of subglottic and tracheal length., Results: Measurements were obtained from 210 children (141 male, 69 female), mean (SD) age 3.21 (3.66) years. Patient height was the best predictor of subglottic length (R 2 : 0.418): Length sg (mm) = 0.058 * height (cm) + 2.8, and tracheal length (R 2 : 0.733): Length t (mm) = 0.485 * height (cm) + 21.3. None of the depth of intubation scenarios maintained a cuff-free subglottis for all ETT styles investigated. A formula for depth of intubation: Length di (mm) = 0.06 * height (cm) + 8.8 found that no ETT cuffs would be in the subglottis and all tips would be above the carina., Conclusion: Current strategies for determining appropriate depth of intubation pose a high risk of subglottic ETT cuff placement. Placing the inferior border of the vocal cords 0.06 * height (cm) + 8.8 from the superior border of the inflated ETT cuff may prevent subglottic cuff placement and endobronchial intubation., Level of Evidence: 4 Laryngoscope, 132:S1-S10, 2022., (© 2021 The American Laryngological, Rhinological and Otological Society, Inc.)

The influences of the profiles and cross-sectional areas of glottal aperture on the upper respiratory airway are investigated using an idealized cast-based mouth-throat model and three dimensional computational fluid dynamics (CFD). The open source CFD code OpenFOAM is employed. The transient flows are modeled using the very-large eddy simulation with the Smagorinsky sub-grid scale (SGS) model. Five different shapes of glottis are considered, including circular glottis with 100 %, 75 % and 50 % cross-sectional area and elliptic glottis with 75 % and 50 % cross-sectional area. Both instantaneous and averaged flow fields are analyzed. It is found that the variations of glottis have great impacts on the properties of downstream flow fields such as the secondary flow, laryngeal jet, recirculation zone, turbulent kinetic energy, and vortex. Evident impacts are observed in the region within 6 tracheal diameters downstream of the glottis. The profile of the glottis has more impacts on the laryngeal shape, while the cross-sectional area has more impacts on velocity of the laryngeal jet and turbulent intensity. It is concluded that both the glottal areas and profiles are critical for an idealized geometrical mouth-throat model., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Robot-assisted cervical esophagectomy (RACE) enables radical surgery for tumors of the middle and upper esophagus, avoiding a transthoracic approach. However, the cervical access, narrow working space, and complex topographic anatomy make this procedure particularly demanding. Our study offers a stepwise description of appropriate dissection planes and anatomical landmarks to facilitate RACE. Macroscopic dissections were performed on formaldehyde-fixed body donors (three females, three males), according to the surgical steps during RACE. The topographic anatomy and surgically relevant structures related to the cervical access route to the esophagus were described and illustrated, along with the complete mobilization of the cervical and upper thoracic segment. The carotid sheath, intercarotid fascia, and visceral fascia were identified as helpful landmarks, used as optimal dissection planes to approach the cervical esophagus and preserve the structures at risk (trachea, recurrent laryngeal nerves, thoracic duct, sympathetic trunk). While ventral dissection involved detachment of the esophagus from the tracheal cartilage and membranous part, the dorsal dissection plane comprised the prevertebral compartment harboring the thoracic duct and right intercosto-bronchial artery. On the left side, the esophagus was attached to the aortic arch by the aorto-esophageal ligament; on the right side, the esophagus was bordered by the azygos vein, right vagus nerve, and cardiac nerves. The stepwise, illustrated topographic anatomy addressed specific surgical demands and perspectives related to the left cervical approach and dissection of the esophagus, providing an anatomical basis to facilitate and safely implement the RACE procedure., (© The Author(s) 2021. Published by Oxford University Press on behalf of International Society for Diseases of the Esophagus. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Dynein-decorated doublet microtubules (DMTs) are critical components of the oscillatory molecular machine of cilia, the axoneme, and have luminal surfaces patterned periodically by microtubule inner proteins (MIPs). Here we present an atomic model of the 48-nm repeat of a mammalian DMT, derived from a cryoelectron microscopy (cryo-EM) map of the complex isolated from bovine respiratory cilia. The structure uncovers principles of doublet microtubule organization and features specific to vertebrate cilia, including previously unknown MIPs, a luminal bundle of tektin filaments, and a pentameric dynein-docking complex. We identify a mechanism for bridging 48- to 24-nm periodicity across the microtubule wall and show that loss of the proteins involved causes defective ciliary motility and laterality abnormalities in zebrafish and mice. Our structure identifies candidate genes for diagnosis of ciliopathies and provides a framework to understand their functions in driving ciliary motility., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objectives/hypothesis: Novel laryngotracheal wound coverage devices are limited by complex anatomy, smooth surfaces, and dynamic pressure changes and airflow during breathing. We hypothesize that a bioinspired mucoadhesive patch mimicking how geckos climb smooth surfaces will permit sutureless wound coverage and also allow drug delivery., Study Design: ex-vivo., Methods: Polycaprolactone (PCL) fibers were electrospun onto a substrate and polyethylene glycol (PEG) - acrylate flocks in varying densities were deposited to create a composite patch. Sample topography was assessed with laser profilometry, material stiffness with biaxial mechanical testing, and mucoadhesive testing determined cohesive material failure on porcine tracheal tissue. Degradation rate was measured over 21 days in vitro along with dexamethasone drug release profiles. Material handleability was evaluated via suture retention and in cadaveric larynges., Results: Increased flocking density was inversely related to cohesive failure in mucoadhesive testing, with a flocking density of PCL-PEG-2XFLK increasing failure strength to 6880 ± 1810 Pa compared to 3028 ± 791 in PCL-PEG-4XFLK density and 1182 ± 262 in PCL-PEG-6XFLK density. The PCL-PEG-2XFLK specimens had a higher failure strength than PCL alone (1404 ± 545 Pa) or PCL-PEG (2732 ± 840). Flocking progressively reduced composite stiffness from 1347 ± 15 to 763 ± 21 N/m. Degradation increased from 12% at 7 days to 16% after 10 days and 20% after 21 days. Cumulative dexamethasone release at 0.4 mg/cm 2 concentration was maintained over 21 days. Optimized PCL-PEG-2XFLK density flocked patches were easy to maneuver endoscopically in laryngeal evaluation., Conclusions: This novel, sutureless, patch is a mucoadhesive platform suitable to laryngeal and tracheal anatomy with drug delivery capability., Level of Evidence: NA Laryngoscope, 131:1958-1966, 2021., (© 2020 American Laryngological, Rhinological and Otological Society Inc, "The Triological Society" and American Laryngological Association (ALA).)

Objectives/hypothesis: Intubation with inappropriately sized endotracheal tubes (ETT) can cause long-term tracheal and laryngeal injuries often requiring surgical intervention. Although tracheal size has been demonstrated to vary based on height and sex, it is unclear whether these guidelines are regularly implemented in patients undergoing endotracheal intubation. The objective of this study is to determine the rate of appropriate ETT size selection in patients undergoing intubation and assess provider decision making in ETT size selection., Study Design: Retrospective cohort study., Methods: The study population was all patients who underwent endotracheal intubation over a two-week period at a tertiary academic medical center. Data were collected on patient age, gender, height, BMI, comorbidities, ETT size, duration of intubation, bronchoscopies, and type of practitioner who performed the intubation. A height-based nomogram for ETT size selection was used to determine the recommended ETT size for each patient., Results: One hundred five patients met the inclusion criteria. 22% of patients were intubated with an inappropriately large tube, defined as 1.0 mm larger than the recommended size. Women were more likely to be intubated with an inappropriately large ETT (OR = 13.58, P = .001), as were patients with height less than 160 cm (OR = 141, P = .001). Other factors related to disease severity, anticipation for bronchoscopy, and BMI were not risk factors for the use of inappropriately large ETT., Conclusions: Although there is compelling evidence that height is a strong predictor of tracheal morphology and appropriate ETT size, height-based guidelines have yet to be universally adopted for ETT size selection. Laryngoscope, 131:1967-1971, 2021., (© 2020 American Laryngological, Rhinological and Otological Society Inc, “The Triological Society” and American Laryngological Association (ALA).)

Objectives: We aimed to comprehensively investigate different upper airway segments in adults, determine the predictors of the size of each segment, and identify an appropriate endotracheal tube (ETT) size chart., Study Design: Retrospective chart review., Setting: Tertiary care center., Materials and Methods: The data for patients aged >18 years who underwent neck computed tomography were screened. Patients with existing tumors, trauma, or any pathology that can alter the normal airway anatomy and those with intubation, tracheostomy, or nasogastric tubes were excluded. Computed tomography software was used to measure the anteroposterior diameter (APD), transverse diameter (TD), and cross-sectional area (CSA) at the glottic, proximal subglottic, distal subglottic, and tracheal levels. Multiple regression analysis was used to identify the predictors of the airway size., Results: One hundred patients were reviewed. The TD was consistently smaller than or equal to the APD at each level in all but 3 patients. The mean CSA and TD (170 mm 2 and 11.3 mm, respectively) of the glottis indicated that the glottis was most often the narrowest level, followed by the proximal subglottis where the mean CSA and TD were 192.1 mm 2 and 12.7 mm, respectively. Moreover, the mean APD was the smallest at the level of the trachea (20.1 mm). Multiple regression analysis confirmed that height and sex were the predominant predictors of measurements for the 4 airway segments. In addition, age was associated with the TD and CSA of the distal subglottic and tracheal segments, respectively., Conclusion: One-third of our participants exhibited a proximal subglottic diameter that was equal to or smaller than the glottic diameter. Our findings also suggested that the height and sex of the patients are important variables for the selection of an appropriate ETT size.

BACKGROUND Respiratory function usually worsens in the elderly with aging. This study aimed to retrospectively investigate tracheal changes caused by "normal aging" through use of low-dose CT (LDCT) in non-smoking asymptomatic urban residents and the related factors influencing tracheal changes. MATERIAL AND METHODS A total of 733 Chinese subjects who underwent LDCT were recruited. The trachea shape, width, and calcification degree of the tracheal wall were measured and compared between males and females and among different age groups. The effects of age, sex, trachea morphology, BMI, BP, GLU, TC, TG, HDL, and LDL on the width and calcification of tracheal wall were analyzed by multiple linear regression. RESULTS Significant sex differences in trachea shape were found, as type II and type I were found mainly in the males and females, respectively. The values of anterior-posterior inner diameter (AP), left-right inner diameter (LR), width, and calcification score of tracheae in the males were higher than that in the females. In both males and females, trachea AP, wall width, and calcification scores increased with age, but this trend was not observed in tracheal LR. Age, sex, and trachea shape had significant effects on the width and calcification scores of tracheal walls, and trachea calcification was one of the factors influencing tracheal wall width. CONCLUSIONS Tracheal aging can be evaluated by measuring trachea shape, thickness, and the degree of calcification of the tracheal wall by LDCT, while sex and age should be taken into consideration comprehensively for judging normal trachea aging. In addition, obesity may aggravate trachea aging.

Among amniote vertebrates, nonavian reptiles (chelonians, crocodilians, and lepidosaurs) are regarded as using vocal signals rarely (compared to birds and mammals). In all three reptilian clades, however, certain taxa emit distress calls and advertisement calls using modifications of regions of the upper respiratory tract. There is no central tendency in either acoustic mechanisms or the structure of the vocal apparatus, and many taxa that vocalize emit only relatively simple sounds. Available evidence indicates multiple origins of true vocal abilities within these lineages. Reptiles thus provide opportunities for studying the early evolutionary stages of vocalization. The early literature on the diversity of form of the laryngotracheal apparatus of reptiles boded well for the study of form-function relationships, but this potential was not extensively explored. Emphasis shifted away from anatomy, however, and centered instead on acoustic analysis of the sounds that are produced. New investigative techniques have provided novel ways of studying the form-function aspects of the structures involved in phonation and have brought anatomical investigation to the forefront again. In this review we summarize what is known about hearing in reptiles in order to contextualize the vocal signals they generate and the sound-producing mechanisms responsible for them. The diversity of form of the sound producing apparatus and the increasing evidence that reptiles are more dependent upon vocalization as a communication medium than previously thought indicates that they have a significant role to play in the understanding of the evolution of vocalization in amniotes., (© 2020 American Association for Anatomy.)

Background: Emergency front-of-neck airway rescue is recommended in a can't intubate, can't oxygenate clinical scenario. Cannula cricothyroidotomy has been reported as having a high failure rate. Our primary aim was to estimate the angle of the trachea in relation to the horizontal axis in a simulated emergency front-of-neck airway rescue position. Our secondary aims were to estimate the optimal cannula angle of approach and evaluate the anatomical relationship of the cricothyroid membrane (CTM) to adjacent structures. We also assessed whether the CTM lies above or below the neck midpoint, a point equidistant from the suprasternal notch (SSN), and the chin surface landmarks. All measurements were compared between the male and female subjects., Methods: Subjects having elective computed tomography of their thorax were consented to have extension of the computed tomography to include their neck. A preliminary radiation dose and risk assessment deemed the additional radiation to be of very low risk (level IIa). Subjects were positioned supinely on the computed tomography table. Standard neck extension was achieved by placing a pillow under the scapulae and a rolled towel under the neck to simulate emergency front-of-neck airway rescue positioning., Results: Fifty-two subjects were included in this study: 31 men and 21 women. The mean angle of the trachea in relation to the horizontal axis was 25.5° (95% confidence interval [CI], 21.8-29.1) in men and 14.0° (95% CI, 11.5-16.5) in women. The mean minimum angles required for hypothetical cannula cricothyroidotomy for men and women were 55.2° (95% CI, 51.8-58.7) and 50.5° (95% CI, 45.4-55.6), respectively. The CTM was located lower in the neck in men compared to women. The CTM was located below the neck midpoint in 30 of 30 (100%) male subjects and 11 of 20 (55%) female subjects (P < .001)., Conclusions: The trachea angulates posteriorly in a simulated emergency front-of-neck airway rescue position in supine subjects and to a greater degree in men compared to women (P < .001). The minimum angle required for hypothetical cannula cricothyroidotomy was >45° in the majority (75%) of subjects studied. A steeper cannula angle of approach may be more reliable and warrants further clinical study. If airway anatomy is indistinct and performing a vertical scalpel cricothyroidotomy, consideration should be given to performing this incision lower in the neck in men compared to women., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 International Anesthesia Research Society.)

Objective: To systematically review the methods for estimating endotracheal tube (ETT) insertion depth in neonates., Study Design: Medline, Embase, Cochrane Central, and Cumulative Index to Nursing and Allied Health Literature databases searched for randomized clinical trials (RCTs). RCTs comparing two or more different methods to estimate ETT insertion depth were included. Two co-authors independently extracted the data and assessed the risk of bias. The primary outcome includes the proportion of optimally placed ETT tips identified on chest X-ray., Results: Eight RCTs evaluating seven different estimation methods were included. Trials varied defining the optimal position of the ETT tip. Overall, the percentage of optimal position ranged from 8.8 to 93%. The weight, gestation nomogram, and vocal cord estimation methods resulted in malpositioning of ETT tips in more than half of infants ≤30 weeks' gestational age. The rates of optimal ETT tip placement with the digital palpation method differ between moderately (83-93%; two RCTs) and extremely (47%; one RCT) preterm infants. Meta-analysis showed no difference between weight-based and digital palpation methods (relative risk = 0.88; 95% confidence interval = 0.75-1.04; three RCTs; participants = 205; I 2  = 0%; quality of evidence, low)., Conclusion: Commonly used estimation methods for ETT tip placement are inaccurate and unreliable. Further research is required to improve the accuracy of estimation methods and also to identify the usefulness of the digital palpation method in large clinical trials., Competing Interests: None declared., (Thieme. All rights reserved.)

Objective(s): To create and validate a synthetic simulator for teaching tracheostomy and laryngotracheal reconstruction (LTR) using anterior costal cartilage and thyroid ala cartilage grafts., Methods: A late adolescent/adult neck and airway simulator was constructed based on CT scans from a cadaver and a live patient. Images were segmented to create three-dimensional printed molds from which anatomical parts were casted. To evaluate the simulator, expert otolaryngologists - head and neck surgeons performed tracheostomy and LTR using anterior costal cartilage and thyroid ala cartilage grafts on a live anesthetized porcine model (gold standard) followed by the synthetic simulator. They evaluated each model for face validity (realism and anatomical accuracy) and content validity (perceived effectiveness as a training tool) using a five-point Likert scale. For each expert, differences for each item on each simulator were compared using Wilcoxon Signed-Rank tests with Sidak correction., Results: Nine expert faculty surgeons completed the study. Experts rated face and content validity of the synthetic simulator an overall median of 4 and 5, respectively. There was no difference in scores between the synthetic model and the live porcine model for any of the steps of any of the surgical procedures., Conclusion: The synthetic simulator created for this study has high face and content validity for tracheostomy and LTR with anterior costal cartilage and thyroid ala cartilage grafts and was not found to be different than the live porcine model for these procedures., Level of Evidence: 5 Laryngoscope, 131:E2378-E2386, 2021., (© 2021 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective: Endotracheal intubation is a frequent procedure performed in neonates with respiratory distress. Clinicians use different methods to estimate the intubation insertion depth, but, unfortunately, the improper insertion results are very high. In this study, we aimed to compare the two different methods (Tochen's formula = weight in kilograms + 6 cm; and nasal septum-tragus length [NTL] + 1 cm) used to determine the endotracheal tube (ETT) insertion depth., Study Design: Infants who had intubation indications were enrolled in this study. The intubation tube was fixed using the Tochen formula (Tochen group) or the NTL + 1 cm formula (NTL group). After intubation, the chest radiograph was evaluated (above T1, proper place, and below T2)., Results: A total of 167 infants (22-42 weeks of gestational age) were included in the study. The proper tube placement rate in both groups was similar (32.4 vs. 30.4% for infants < 34 weeks of gestational age and 56.8 vs. 45.0% in infants > 34 weeks of gestational age). The ETT was frequently placed below T2 at a higher rate in infants with a gestational age of <34 weeks, especially in the NTL group (46% in the Tochen group and 60.7% in the NTL group)., Conclusion: The NTL + 1 cm formula led to a higher rate of ETT placement below T2, especially in infants with a birth weight of <1,500 g. Therefore, more studies are needed to determine the optimal ETT insertion depth., Competing Interests: None declared., (Thieme. All rights reserved.)

Background: Accurate tracheoesophageal prosthesis (TEP) size is essential for optimal functioning. Current sizing techniques do not afford direct visualization. The clinical utility of direct visualization with unsedated transnasal esophagoscopy (TNE) to improve TEP sizing accuracy has not been established., Aims/objectives: The purpose of this investigation was to determine if endoscopic visualization with TNE during TEP fitting improves sizing accuracy., Material and Methods: Participants undergoing secondary TEP placement had their TEP sized without visualization and with visualization during TNE. The effect of endoscopic visualization on TEP sizing was assessed., Results: The mean age (SD) of the cohort ( N  = 15) was 61.20 (±10.19) years. The percent disagreement between non-visualized and endoscopic-visualized puncture tract measurement was 60%. The mean difference in puncture tract length with visualization compared to without visualization was 1.75 mm (±1.91). Discordance between non-visualized and endoscopic-visualized puncture tract length was worse for persons with a history of radiation (66.7%) than without radiation (33.3%) ( p  < .05). The overall test agreement between endoscopic and non-endoscopic sizing techniques was moderate (Cohen's kappa coefficient = 0.254; ( p  < .05)., Conclusion and Significance: The percent disagreement between non-visualized and endoscopic-visualized TEP sizing is high (60%). The data suggest that endoscopic visualization with TNE improves sizing accuracy during TEP placement.

How respiratory structures vary with, or are constrained by, an animal's environment is of central importance to diverse evolutionary and comparative physiology hypotheses. To date, quantifying insect respiratory structures and their variation has remained challenging due to their microscopic size, hence only a handful of species have been examined. Several methods for imaging insect respiratory systems are available, in many cases however, the analytical process is lethal, destructive, time consuming and labour intensive. Here, we explore and test a different approach to measuring tracheal volume using X-ray micro-tomography (µCT) scanning (at 15 µm resolution) on living, sedated larvae of the cerambycid beetle Cacosceles newmannii across a range of body sizes at two points in development. We provide novel data on resistance of the larvae to the radiation dose absorbed during µCT scanning, repeatability of imaging analyses both within and between time-points and, structural tracheal trait differences provided by different image segmentation methods. By comparing how tracheal dimension (reflecting metabolic supply) and basal metabolic rate (reflecting metabolic demand) increase with mass, we show that tracheal oxygen supply capacity increases during development at a comparable, or even higher rate than metabolic demand. Given that abundant gas delivery capacity in the insect respiratory system may be costly (due to e.g. oxygen toxicity or space restrictions), there are probably balancing factors requiring such a capacity that are not linked to direct tissue oxygen demand and that have not been thoroughly elucidated to date, including CO 2 efflux. Our study provides methodological insights and novel biological data on key issues in rapidly quantifying insect respiratory anatomy on live insects., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

When selecting the nasotracheal tube diameter for nasotracheal intubation, atraumatic introduction of the tube through the nasal passage and a safe location of the tube's cuff and tip should be ensured simultaneously. To maintain safety margin for the tube's cuff and tip from the vocal cords and carina (2 cm and 3 cm, respectively), the maximum allowable proximal-cuff-to-tip distance was calculated as 5 cm less than the measured vocal cords-to-carina distance. The primary aim of this study was to find a single predictive preoperative factor of the nostril size and maximum allowable proximal-cuff-to-tip distance of nasotracheal tubes. The secondary aim was to compare the difference in the safety margin between the maximum allowable proximal-cuff-to-tip distance based on the patient's airway and the actual proximal-cuff-to-tip distance of the selected tube. We used fiberoptic bronchoscope to measure the distance from the vocal cords to the carina for the calculation of the maximum allowable proximal-cuff-to-tip distance. We analyzed the association of preoperative characteristics such as age, sex, height, and weight with the nostril size and maximum allowable proximal-cuff-to-tip distance. The proportion of patients with appropriate locations of both the cuff and tip was evaluated. Sex and height were significant predictive factors of the nostril size and maximum allowable proximal-cuff-to-tip distance, respectively (p = 0.0001 and p = 0.0048). The difference in the safety margin was significantly decreased when the tube diameter was selected based on the nostril size rather than by sex (p<0.0001). The proportion of patients who had the appropriate cuff/tip location was significantly larger (75.2%) when the tube diameter was selected by sex compared to when it was selected by the nostril size (65%) (p<0.0001). It is more suitable to select the nasotracheal tube diameter based on sex rather than by nostril size to ensure the safe location of the tube's cuff and tip simultaneously., Competing Interests: The authors have declared that no competing interests exist.

Airway simulators, or training manikins, are frequently used in research studies for device development and training purposes. This study was designed to determine the anatomic accuracy of the most frequently used low-fidelity airway training manikins. Computerised tomography scans and ruler measurements were taken of the SynDaver ® , Laerdal ® and AirSim ® manikins. These measurements were compared with human computerised tomography (CT) scans (n = 33) from patients at the University of Michigan Medical Center or previously published values. Manikin measurements were scored as a percentile among the distribution of the same measurements in the human population and 10 out of 27 manikin measurements (nine measurements each in three manikins) were outside of two standard deviations from the mean in the participants. All three manikins were visually identifiable as outliers when plotting the first two dimensions from multidimensional scaling. In particular, the airway space between the epiglottis and posterior pharyngeal wall, through which airway devices must pass, was too large in all three manikins. SynDaver, Laerdal and AirSim manikins do not have anatomically correct static dimensions in relation to humans and these inaccuracies may lead to imprecise airway device development, negatively affect training and cause over-confidence in users., (© 2020 The Authors. Anaesthesia published by John Wiley & Sons Ltd on behalf of Association of Anaesthetists.)

The knowledge of airway length is the theoretical basis in the diagnosis and management of airway disease. The objective of this study is to measure the length of trachea and left and right main bronchus in Chinese Shanghai population. A total of 153 consecutive adult patients with minor pulmonary disease in Xinhua hospital were enrolled for bronchoscopy examination. Measurements were conducted on head and neck neutral position and height, weight and age for each patient were recorded either. Student t test and multiple linear regression was used to compare means between males and females and to analyze correlation among height, weight, sexual dimorphism and the lengths of the trachea and bronchus. The lengths of the trachea and left main bronchus are significantly different between male and female patients (P < 0.01), but not for the lengths of right main bronchus between man and woman. Multiple linear regression analysis showed that height but not sexual dimorphism and weight correlated with the lengths of the trachea and right main bronchus. The lengths of the trachea and left main bronchus are significantly longer in males than in females. Moreover, height but not sexual dimorphism and weight influenced the length of airway.

The tracheal system of scutigeromorph centipedes (Chilopoda) is special, as it consists of dorsally arranged unpaired spiracles. In this study, we investigate the tracheal systems of five different scutigeromorph species. They are strikingly similar to each other but depict unique characters compared to the tracheal systems of pleurostigmophoran centipedes, which has engendered an ongoing debate over a single versus independent origin of tracheal systems in Chilopoda. Up to now, only the respiratory system of Scutigera coleoptrata was investigated intensively using LM-, TEM-, and SEM-techniques. We supplement this with data for species from all three families of Scutigeromorpha. These reveal interspecific differences in atrial width and the shape and branching pattern of the tracheal tubules. Further, we investigated the tracheal system of Scutigera coleoptrata with three additional techniques: light sheet microscopy, microCT and synchrotron radiation based microCT analysis. This set of techniques allows a comparison between fresh versus fixed and dried material. The question of a unique vs. multiple origin of tracheal systems in centipedes and in Myriapoda as a whole is discussed with regard to their structural similarities and differences and the presence of hemocyanin as an oxygen carrier. We used morphological and molecular data and the fossil record to evaluate the alternative hypotheses., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Relapsing polychondritis (RP) is a rare systemic disease of unknown origin, with cartilaginous involvement in multiple organs. Airway involvement is the most important prognostic factor in RP., Objectives: Spirometric measurements and minimum tracheal cross-sectional area (mtCSA) have been reported as useful to assess the degree of airway stenosis. Because the length and severity of tracheal involvement in RP can vary, mtCSA might not provide enough information to assess tracheal abnormalities. We introduced tracheal volume (TrV) as a new method to evaluate correlations between chest computed tomography (CT) measurements and pulmonary function tests, including impulse oscillometry (IOS)., Method: We analyzed chest CT images, spirometry, and IOS collected at our institution from April 2004 to March 2019. We calculated correlations between chest CT measurements using software (TrV, TrV/tracheal length [TrV/TL], and mtCSA) and pulmonary function parameters., Results: Twenty-five of 73 clinically diagnosed patients with RP were included. Spirometric findings showed moderate airway obstruction. Peak flow (PEF) was strongly correlated with mtCSA, TrV, and TrV/TL (ρ = 0.74, p < 0.001). FEV1 was significantly correlated with mtCSA (ρ = 0.56, p = 0.004), TrV (ρ = 0.52, p = 0.007), and TrV/TL (ρ = 0.53, p = 0.006). Whereas respiratory resistance at 5 Hz (R5) and 20 Hz (R20) and resonant frequencies (RFs) were significantly correlated with TrV (ρ = -0.46, p = 0.021; ρ = -0.46, p = 0.046; and ρ = -0.42, p = 0.037, respectively), IOS parameters and mtCSA were not., Conclusions: In patients with RP, TrV and mtCSA were strongly correlated with spirometric measurements. Respiratory resistances assessed by IOS correlated only with TrV. This suggests TrV assessment reflects pulmonary function in patients with RP more appropriately than mtCSA., (© 2021 S. Karger AG, Basel.)

Objectives: Determine whether the insertion site of the recurrent laryngeal nerve (RLN) occurs at a predictable distance from the midline trachea, to help guide safe dissection during thyroid surgery., Design: Prospective clinical trial. At the inferior edge of the cricoid cartilage, we measured the distance from mildline trachea to the RLN insertion site., Setting: Single institution., Participants: 50 consecutive patients undergoing thyroid surgery., Main Outcome Measures: Distance from midline trachea to laryngeal insertion of RLN., Results: The study population included 36 women and 14 men, with 72 total nerves measured. The average distance-to-midline + standard deviation (range) of the RLN was 20.7 + 2.3 (17-26) mm in women compared to 26.3 + 2.1 (22-32) mm in men., Conclusion: The insertion point of the RLN into the larynx at the level of inferior border of the cricoid cartilage can be reliably predicted, to facilitate early identification of the RLN during thyroid surgery., (© 2020 John Wiley & Sons Ltd.)

This paper presents an automatic lobe-based labeling of airway tree method, which can detect the bifurcation points for reconstructing and labeling the airway tree from a computed tomography image. A deep learning-based network structure is designed to identify the four key bifurcation points. Then, based on the detected bifurcation points, the entire airway tree is reconstructed by a new region-growing method. Finally, with the basic airway tree anatomy and topology knowledge, individual branches of the airway tree are classified into different categories in terms of pulmonary lobes. There are several advantages in our method such as the detection of the bifurcation points does not depend on the segmentation of airway tree and only four bifurcation points need to be manually labeled for each sample to prepare the training dataset. The segmentation of airway tree is guided by the detected points, which overcomes the difficulty of manual seed selection of conventional region-growing algorithm. In addition, the bifurcation points can help analyze the tree structure, which provides a basis for effective airway tree labeling. Experimental results show that our method is fast, stable, and the accuracy of our method is 97.85%, which is higher than that of the traditional skeleton-based method. Graphical Abstract The pipeline of our proposed lobe-based airway tree labeling method. Given a raw CT volume, a neural network structure is designed to predict major bifurcation points of airway tree. Based on the detected points, airway tree is reconstructed and labeled in terms of lobes.

The synchronization of flight mechanics with respiration and echolocation call emission by bats, while economizing these behaviors, presumably puts compressive loads on the cartilaginous rings that hold open the respiratory tract. Previous work has shown that during postnatal development of Artibeus jamaicensis (Phyllostomidae), the onset of adult echolocation call emission rate coincides with calcification of the larynx, and the development of flight coincides with tracheal ring calcification. In the present study, I assessed the level of reinforcement of the respiratory system in 13 bat species representing six families that use stereotypical modes of echolocation (i.e. duty cycle % and intensity). Using computed tomography, the degree of mineralization or ossification of the tracheal rings, cricoid, thyroid and arytenoid cartilages were determined for non-echolocators, tongue clicking, low-duty cycle low-intensity, low-duty cycle high-intensity, and high-duty cycle high-intensity echolocating bats. While all bats had evidence of cervical tracheal ring mineralization, about half the species had evidence of thoracic tracheal ring calcification. Larger bats (Phyllostomus hastatus and Pterpodidae sp.) exhibited more extensive tracheal ring mineralization, suggesting an underlying cause independent of laryngeal echolocation. Within most of the laryngeally echolocating species, the degree of mineralization or ossification of the larynx was dependent on the mode of echolocation system used. Low-duty cycle low-intensity bats had extensively mineralized cricoids, and zero to very minor mineralization of the thyroids and arytenoids. Low-duty cycle high-intensity bats had extensively mineralized cricoids, and patches of thyroid and arytenoid mineralization. The high-duty cycle high-intensity rhinolophids and hipposiderid had extensively ossified cricoids, large patches of ossification on the thyroids, and heavily ossified arytenoids. The high-duty cycle high-intensity echolocator, Pteronotus parnellii, had mineralization patterns and laryngeal morphology very similar to the other low-duty cycle high-intensity mormoopid species, perhaps suggesting relatively recent evolution of high-duty cycle echolocation in P. parnellii compared with the Old World high-duty cycle echolocators (Rhinolophidae and Hipposideridae). All laryngeal echolocators exhibited mineralized or ossified lateral expansions of the cricoid for articulation with the inferior horn of the thyroid, these were most prominent in the high-duty cycle high-intensity rhinolophids and hipposiderid, and least prominent in the low-duty cycle low-intensity echolocators. The non-laryngeal echolocators had extensively ossified cricoid and thyroid cartilages, and no evidence of mineralization/ossification of the arytenoids or lateral expansions of the cricoid. While the non-echolocators had extensive ossification of the larynx, it was inconsistent with that seen in the laryngeal echolocators., (© 2020 Anatomical Society.)

Tight barriers are crucial for animals. Insect respiratory cells establish barriers through their extracellular matrices. These chitinous-matrices must be soft and flexible to provide ventilation, but also tight enough to allow oxygen flow and protection against dehydration, infections, and environmental stresses. However, genes that control soft, flexible chitin-matrices are poorly known. We investigated the genes of the chitinolytic glycosylhydrolase-family 18 in the tracheal system of Drosophila melanogaster. Our findings show that five chitinases and three chitinase-like genes organize the tracheal chitin-cuticles. Most of the chitinases degrade chitin from airway lumina to enable oxygen delivery. They further improve chitin-cuticles to enhance tube stability and integrity against stresses. Unexpectedly, some chitinases also support chitin assembly to expand the tube lumen properly. Moreover, Chitinase2 plays a decisive role in the chitin-cuticle formation that establishes taenidial folds to support tube stability. Chitinase2 is apically enriched on the surface of tracheal cells, where it controls the chitin-matrix architecture independently of other known cuticular proteins or chitinases. We suppose that the principle mechanisms of chitin-cuticle assembly and degradation require a set of critical glycosylhydrolases for flexible and not-flexible cuticles. The same glycosylhydrolases support thick laminar cuticle formation and are evolutionarily conserved among arthropods.

Numerous chameleon species possess an out-pocketing of the trachea known as the gular pouch. After surveying more than 250 specimens, representing nine genera and 44 species, we describe two different morphs of the gular pouch. Species of the genera Bradypodion and Chamaeleo, as well as Trioceros goetzei, all possess a single gular pouch (morph one) formed from ventral expansion of soft tissue where the larynx and trachea meet. Furcifer oustaleti and Furcifer verrucosus possess from one to four gular pouches (morph two) formed by the expansion of soft tissue between sequential hyaline cartilage rings of the trachea. In Trioceros melleri, examples of both morphs of the gular pouch were observed. Morphometric data are presented for 100 animals representing eight species previously known to possess a gular pouch and two additional species, Bradypodion thamnobates and Bradypodion transvaalense. In the species with the absolutely and relatively largest gular pouch, Chamaeleo calyptratus, a significant difference was found between sexes in its width and volume, but not its length. In C. calyptratus, we show that an inflated gular pouch is in contact with numerous hyoid muscles and the tongue. Coupled with the knowledge that C. calyptratus generates vibrations from the throat region, we posit that the tongue (M. accelerator linguae and M. hyoglossus) and supporting hyoid muscles (i.e., Mm. sternohyoideus profundus et superficialis and Mm. mandibulohyoideus) are involved in the production of vibrations to produce biotremors that are amplified by the inflated gular pouch and used in substrate-borne communication., (© 2019 American Association for Anatomy.)

Feline herpesvirus-1 (FHV-1) is the primary cause of viral respiratory and ocular disease in cats. While commercial vaccines can provide clinical protection, they do not protect from infection or prevent latency. Moreover, they are not safe for intranasal administration. Our overall objective is to develop a new mucosal vaccine against FHV-1 disease to address these shortcomings. Feline herpesvirus-1 deletion mutants of glycoprotein C (gC-), gE (gE-), US3-encoded serine/threonine protein kinase (PK-), and both gE and thymidine kinase (gE-TK-) were generated by bacterial artificial chromosome (BAC) mutagenesis. Tracheal tissue explants from eight cats were used to compare the pattern of viral infection and associated tissue damage, as well as virus spread through the basement membrane following inoculation with wild-type virus (WT), and gE-, gE-TK-, PK-, and gC- mutants. Tissues were collected at 24, 48, or 72  hours post-inoculation (hpi) followed by immunohistochemistry (IHC) for FHV-1. Histological changes were graded based on the distribution of virus infected cells and the severity of tissue damage. Inoculations with the WT virus resulted in maximal scores at 72 hpi both at a multiplicity of infection (MOI) of 1 and 0.1. Inoculation with the gE- mutant produced scores similar to scores of explants inoculated with the WT virus at 24 and 48 hpi, but scores were significantly decreased at 72 hpi. Explants inoculated with the gE-TK- mutant showed significantly decreased scores at all time points. Further, the majority of explants inoculated with the PK- mutant resulted in scores of zero at all time points, regardless of MOI. Finally, inoculation with WT resulted in significant stromal invasion below the infected epithelium, while stromal invasion was observed in less than 50 % of the samples following inoculation with gE-, gE-TK-, PK-, or gC- mutants and confined closely to the area surrounding the infected epithelium. In conclusion, the gE-TK- and PK- mutants exhibited significantly reduced virulence, tissue damage and spread to the underlying stroma, suggesting that they may be good vaccine candidates for in vivo testing., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Difficult tracheal intubation is the third most common respiratory-related adverse co-morbid episode and can lead to death or brain damage. Since difficult tracheal intubation is less frequent, trainees have fewer opportunities to perform difficult tracheal intubation; this leads to the need to practice with a hyper-realistic intubation simulator. However, conventional simulators are expensive, relatively stiffer than the human airway, and have a lack of diversity in terms of disease variations and anatomic reproducibility. Therefore, we proposed the development of a patient-specific and hyper-realistic difficult tracheal intubation simulator using three-dimensional printing technology and silicone moulding and to test the feasibility of patient-specific and hyper-realistic difficult intubation simulation using 3D phantom for the trainee. This difficult tracheal intubation phantom can provide a realistic simulation experience of managing various difficult tracheal intubation cases to trainees, which could minimise unexpected tissue damage before anaesthesia. To achieve a more realistic simulation, a patient-specific phantom was fabricated to mimic human tissue with realistic mouth opening and accurate difficult airway shape. This has great potential for the medical education and training field.

Objective: To investigate the measurement of small airways by high-resolution CT and image post-processing software. Screen and analyze the reconstructed airway parameters in order to find the best imaging biomarker parameters of small airway changes and calculate the reference value range; meanwhile, explore its influencing factors. Methods: From a water plant and a medical school, 169 cases of the general population aged 20 to 60 were selected as research objects, and questionnaire surveys and CT tests were performed, and CT data were reconstructed with image post-processing software. The reference value range of the general population was evaluated, and a linear mixed effect model was used to adjust the age, gender, height, BMI, and smoking status, and analyze the influencing factors of airway parameters. Results: The ratio of sixth-grade tracheal wall area to total tracheal area in the Left B1+2 to carina was (53.01±13.35) %, Left B9 to carina was (50.44±12.98) %, Right B1 to carina was (52.73±12.22) %, and Right B9 to carina was (52.93±11.85) %. The ratio of nineth-grade tracheal wall area to total tracheal area in the Left B1+2 to carina was (44.08±14.66) %, Left B9 to carina was (42.44±15.89) %, Right B1 to carina was (46.51±14.03) %, and Right B9 to carina is (43.54±15.87) %. BMI affect the area of the tracheal wall, all p value<0.05. Conclusion: High-resolution CT small airway morphology can make a preliminary assessment of the susceptible population of small airway-related diseases based on a range of reference values, and prevent and control it in combination with influencing factors.

Many insects show discontinuous respiration with three phases, open, closed, and fluttering, in which the spiracles open and close rapidly. The relative durations of the three phases and the rate of fluttering during the flutter phase vary for individual insects depending on developmental stage and activity, vary between insects of the same species, and vary even more between different species. We studied how the rate of oxygen uptake during the flutter phase depends on the rate of fluttering. Using a mathematical model of oxygen diffusion in the insect tracheal system, we derive a formula for oxygen uptake during the flutter phase and how it depends on the length of the tracheal system, percentage of time open during the flutter phase, and the flutter rate. Surprisingly, our results show that an insect can have its spiracles closed a high percentage of time during the flutter phase and yet receive almost as much oxygen as if the spiracles were always open, provided the spiracles open and close rapidly. We investigate the respiratory gain due to fluttering for four specific insects. Our formula shows that respiratory gain increases with body size and with increased rate of fluttering. Therefore, insects can regulate their rate of oxygen uptake by varying the rate of fluttering while keeping the spiracles closed during a large fraction of the time during the flutter phase. We also use a mathematical model to show that water loss is approximately proportional to the percentage of time the spiracles are open. Thus, insects can achieve both high oxygen intake and low water loss by keeping the spiracles closed most of the time and fluttering while open, thereby decoupling the challenge of preventing water loss from the challenge of obtaining adequate oxygen uptake., Competing Interests: The authors have declared that no competing interests exist.