De novo identification of mammalian ciliary motility proteins using cryo-EM.

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.

The sex of organ geometry.

Organs have a distinctive yet often overlooked spatial arrangement in the body1-5. 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.

Ostrich (Struthio camelus) syrinx morphology and vocal repertoire across postnatal ontogeny and sex: Implications for understanding vocal evolution in birds.

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.

Bronchial tree of the human embryo: Examination based on a mammalian model.

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.

Morphological comparison of the larynx and trachea of Chelonia mydas (Linnaeus, 1758), Caiman yacare (Daudin, 1802) and Caiman latirostris (Daudin, 1802).

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.

Regional variations and sex-related differences of stiffness in human tracheal ligaments.

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.

Measurement of the lengths of different sections of the upper airway and their predictive factors.

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.

Docosahexaenoic Acid Selectively Suppresses U46619- and PGF2α-Induced Contractions in Guinea Pig Tracheal Smooth Muscles.

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 A2 (TXA2) mimetic) and prostaglandin F2α (PGF2α) 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 PGF2α (5 × 10-7 M) (vs. control), although it did not suppress the contractions induced by higher concentrations (U46619: 10-7 M; PGF2α: 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 PGF2α (10-8-10-5 M) to the right. However, the slope of the regression line in the Schild plot of DHA vs. U46619/PGF2α was larger than unity. The tracheal contractions induced by U46619 (10-8 M) and PGF2α (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 D4 (10-11-10-7 M) (vs. ethanol-treated). These findings indicate that DHA selectively suppresses tracheal contractions induced by U46619 and PGF2α. Therefore, DHA may be a useful therapeutic agent against asthma associated with tracheal/bronchial hyper-constriction caused by prostanoids including TXA2 and PGF2α.

An assessment of introducers used for airway management.

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.

Emergency Front-of-Neck Airway Rescue Via the Cricothyroid Membrane: A High-Resolution Computed Tomography Study of Airway Anatomy in Adults.

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.

Factors Associated with Age-Related Changes in Non-Smoking Urban Men and Women in China Determined by Low-Dose Computed Tomography Imaging.

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.

Correlation between Computed Tomographic Analysis and Pulmonary Function Measurements in Patients with Relapsing Polychondritis.

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.

Anatomic accuracy of airway training manikins compared with humans.

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.

Surgical anatomy of the upper esophagus related to robot-assisted cervical esophagectomy.

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.

Identity and novelty in the avian syrinx.

In its most basic conception, a novelty is simply something new. However, when many previously proposed evolutionary novelties have been illuminated by genetic, developmental, and fossil data, they have refined and narrowed our concept of biological "newness." For example, they show that these novelties can occur at one or multiple levels of biological organization. Here, we review the identity of structures in the avian vocal organ, the syrinx, and bring together developmental data on airway patterning, structural data from across tetrapods, and mathematical modeling to assess what is novel. In contrast with laryngeal cartilages that support vocal folds in other vertebrates, we find no evidence that individual cartilage rings anchoring vocal folds in the syrinx have homology with any specific elements in outgroups. Further, unlike all other vertebrate vocal organs, the syrinx is not derived from a known valve precursor, and its origin involves a transition from an evolutionary "spandrel" in the respiratory tract, the site where the trachea meets the bronchi, to a target for novel selective regimes. We find that the syrinx falls into an unusual category of novel structures: those having significant functional overlap with the structures they replace. The syrinx, along with other evolutionary novelties in sensory and signaling modalities, may more commonly involve structural changes that contribute to or modify an existing function rather than those that enable new functions.

Human airway branch variation and chronic obstructive pulmonary disease.

Susceptibility to chronic obstructive pulmonary disease (COPD) beyond cigarette smoking is incompletely understood, although several genetic variants associated with COPD are known to regulate airway branch development. We demonstrate that in vivo central airway branch variants are present in 26.5% of the general population, are unchanged over 10 y, and exhibit strong familial aggregation. The most common airway branch variant is associated with COPD in two cohorts (n = 5,054), with greater central airway bifurcation density, and with emphysema throughout the lung. The second most common airway branch variant is associated with COPD among smokers, with narrower airway lumens in all lobes, and with genetic polymorphisms within the FGF10 gene. We conclude that central airway branch variation, readily detected by computed tomography, is a biomarker of widely altered lung structure with a genetic basis and represents a COPD susceptibility factor.

Is Nasal Septum-Tragus Length Measurement Appropriate for Endotracheal Tube Intubation Depth in Neonates? A Randomized Controlled Study.

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.

Methods for Estimating Endotracheal Tube Insertion Depth in Neonates: A Systematic Review and Meta-Analysis.

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.

Lung Parenchymal and Tracheal CT Morphology: Evaluation before and after Bariatric Surgery.

Background There is significant pulmonary functional deficit related to obesity, but no prospective CT studies have evaluated the effects of obesity on the lungs and trachea. Purpose To evaluate lung parenchymal and tracheal CT morphology before and 6 months after bariatric surgery, with functional and symptomatic correlation. Materials and Methods A prospective longitudinal study of 51 consecutive individuals referred for bariatric surgery was performed (from November 2011 to November 2013). All individuals had undergone limited (three-location) inspiratory and end-expiratory thoracic CT before and after surgery, with concurrent pulmonary function testing, body mass index calculation, and modified Medical Research Council (mMRC) dyspnea scale and Epworth scoring. Two thoracic radiologists scored the CT extent of mosaic attenuation, end-expiratory air trapping, and tracheal shape. The inspiratory and end-expiratory cross-sectional areas of the trachea were measured. The paired t test or Wilcoxon signed-rank test was used for pre- and postsurgical comparisons. Spearman correlation and logistic regression were used to evaluate correlations between CT findings and functional and symptom indexes. Results A total of 51 participants (mean age, 52 years ± 8 [standard deviation]; 20 men) were evaluated. Before surgery, air trapping extent correlated most strongly with decreased total lung capacity (Spearman rank correlation coefficient [rs] = -0.40, P = .004). After surgery, there were decreases in percentage mosaic attenuation (0% [interquartile range {IQR}: 0%-2.5%] vs 0% [IQR: 0%-0%], P < .001), air trapping (9.6% [IQR: 5.8%-15.8%] vs 2.5% [IQR: 0%-6.7%], P < .001), and tracheal collapse (201 mm2 [IQR: 181-239 mm2] vs 229 mm2 [186-284 mm2], P < .001). After surgery, mMRC dyspnea score change correlated positively with air trapping extent change (rs = 0.46, P = .001) and end-expiratory tracheal shape change (rs = 0.40, P = .01). At multivariable analysis, air trapping was the main determinant for decreased dyspnea after surgery (odds ratio, 1.2; 95% confidence interval: 1.1, 1.2; P = .03). Conclusion Dyspnea improved in obese participants after weight reduction, which correlated with less tracheal collapse and air trapping at end-expiration chest CT. © RSNA, 2020 Online supplemental material is available for this article.

Reinforcement of the larynx and trachea in echolocating and non-echolocating bats.

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.