Analysis of airway structural parameters in Han Chinese adults: a prospective cross-sectional study.

INTRODUCTION: Establishing reference ranges for central airway parameters and exploring their influencing factors in Han Chinese non-smoking adults. METHODS: This prospective cross-sectional study was conducted on Han Chinese non-smoking adults who underwent chest CT scans at the Tongzhou Campus of Dongzhimen Hospital Affiliated with the Beijing University of Chinese Medicine between September 2022 and November 2022. The SYNAPSE 3D image analysis software was utilized, enabling the extraction of critical parameters such as central airway length, airway wall thickness (AWT), airway lumen area (ALA), and subcarinal angle (SCA). Pearson's correlation coefficient analysis and multiple linear regression analysis methods were employed to evaluate the relationship between central airway parameters and age, sex, weight, and height. RESULTS: The study encompassed 888 Han Chinese non-smoking adults, comprising 456 females and 432 males. Significant sex differences were noted in central airway length, AWT, and ALA, with measurements in males exceeding those in females (p < 0.01) with no significant difference in SCA. Correlation analyses unveiled relationships between central airway parameters and age, sex, weight, and height. During multiple linear regression analyses, no conclusive evidence emerged to demonstrate the independent or combined explanatory or predictive capacity of the aforementioned variables for central airway length and SCA. Although sex has a significant impact on AWT and ALA, its capability in explanation or prediction remains limited. The conclusions drawn from the primary analysis receive reinforcement from the outcomes of sensitivity analyses. CONCLUSION: Establishing the distribution range of central airway parameters in non-smoking Han Chinese adults. It observed significant sex differences in these parameters, except for the SCA. However, the study found that the predictive or explanatory power of age, sex, weight, and height for central airway parameters was either limited or non-significant.

New insights into the variability of upper airway morphology in modern humans.

The biological adaptation of the human lineage to its environment is a recurring question in paleoanthropology. Particularly, how eco-geographic factors (e.g., environmental temperature and humidity) have shaped upper airway morphology in hominins have been subject to continuing debate. Nasal shape is the result of many intertwined factors that include, but are not limited to, genetic drift, sexual selection, or adaptation to climate. A quantification of nasal airway (NA) morphological variation in modern human populations is crucial to better understand these multiple factors. In the present research, we study 195 in vivo CT scans of adult individuals collected in five different geographic areas (Chile, France, Cambodia, Russia, and South Africa). After segmentation of the nasal airway, we reconstruct 3D meshes that are analyzed with a landmark-free geometric morphometrics method based on surface deformation. Our results highlight subtle but statistically significant morphological differences between our five samples. The two morphologically closest groups are France and Russia, whose NAs are longer and narrower, with an important protrusion of the supero-anterior part. The Cambodian sample is the most morphologically distinct and clustered sample, with a mean NA that is wider and shorter. On the contrary, the Chilean sample form the most scattered cluster with the greatest intra-population variation. The South African sample is morphologically close to the Cambodian sample, but also partially overlaps the French and Russian variation. Interestingly, we record no correlation between NA volume and geographic groups, which raises the question of climate-related metabolic demands for oxygen consumption. The other factors of variation (sex and age) have no influence on the NA shape in our samples. However, NA volume varies significantly according both to sex and age: it is higher in males than in females and tends to increase with age. In contrast, we observe no effect of temperature or humidity on NA volume. Finally, we highlight the important influence of asymmetries related to nasal septum deviations in NA shape variation.

Morbimortalidade por doenças do aparelho respiratório no brasil: um estudo ecológico / Morbimortality from respiratory system diseases in Brazil: an ecological study / Morbimortalidad por enfermedades del sistema respiratorio en Brasil: un estudio ecológico

Introdução:As doenças do aparelho respiratório se configuram como o segundo principal motivo de internações hospitalares no Brasil entre 2013 e 2017. Objetivo:Analisar a morbimortalidade de doenças do aparelho respiratório da população brasileira, segundo faixa etária,no período compreendido entre os anos de 2015 a 2019. Metodologia:Trata-se de um estudo do tipo ecológico, retrospectivo, realizado sobre o território brasileiro. Os dados foram coletados a partir do Departamento de Informática do Sistema Único de Saúde, nas seções de Morbidade Hospitalar, de Mortalidade e População Residente. Foram analisados os dados entre 2015 a 2019 e de todas as faixas etárias. Resultados:Ao investigar a mortalidade por doenças do sistema respiratório entre os anos de 2015 e 2019, as cinco causas mais frequentes foram: influenza e pneumonia; doenças crônicas das vias aéreas inferiores; outras doenças do aparelho respiratório; outras doenças respiratórias que afetam principalmente interstício; doenças pulmonares devidas a agentes externos, nessa ordem. Enquanto as cinco causas de morbidades mais frequentes foram: pneumonia; outras doenças do aparelho respiratório; bronquite, enfisema e outras doenças pulmonares obstrutivas crônicas; asma; bronquite aguda e bronquiolite aguda. Conclusões:Verificou-se que a pneumonia, influenza, doenças respiratórias do trato inferior e outras doenças crônicas respiratórias foram as mais prevalentes entre a população respectivamente. Dentre o público mais acometido, foi possível constatar que o público infantil e a população idosa foram os mais atingidos tanto na mortalidade quanto na morbidade (AU).

Introduction:Introduction: Respiratory diseases are the second main reason for hospital admissions in Brazil between 2013 and 2017. Objective:To analyze the morbidity and mortality of respiratory diseases of the Brazilian population, according to age group, in the period from 2015 to 2019. Methodology:This is an ecological, retrospective study conducted on the Brazilian territory. Data were collected from the Informatics Department of the Unified Health System, in the Sections of Hospital Morbidity, Mortality and Resident Population. Data were analyzed between 2015 and 2019 and all age groups. Results:When investigating mortality from respiratory system diseases between 2015 and 2019, the five most frequent causes were: influenza and pneumonia; chronic diseases of the lower airways; other diseases of the respiratory system; other respiratory diseases that mainly affect interstitium; diseases due to external agents, in that order. Conclusions:It was found that pneumonia, influenza, respiratory diseases of the lower tract and other chronic respiratory diseases were the most prevalent among the population, respectively. Among the most affected public, it was possible to observe that the child's public and the elderly population were the most affected in both mortality and morbidity (AU).

Introducción: Las enfermedades respiratorias son la segunda razón principal de los ingresos hospitalarios en Brasil entre 2013 y 2017. Objetivo: Analizar la morbilidad y mortalidad de las enfermedades respiratorias de la población brasileña, según el grupo de edad, en el período comprendido entre 2015 y 2019.Metodología: Se trata de un estudio ecológico y retrospectivo realizado en territorio brasileño. Los datos fueron recogidos del Departamento de Informática del Sistema Unificado de Salud, en las Secciones de Morbilidad Hospitalaria, Mortalidad y Población Residente. Los datos se analizaron entre 2015 y 2019 y todos los grupos de edad. Resultados: Al investigar la mortalidad por enfermedades del sistema respiratorio entre 2015 y 2019, las cinco causas más frecuentes fueron: gripe y neumonía; enfermedades crónicas de las vías respiratorias inferiores; otras enfermedades del sistema respiratorio; otras enfermedades respiratorias que afectan principalmente al intersticio; enfermedades debidas a agentes externos, en ese orden.Mientras que las cinco causas más frecuentes de morbilidad fueron: neumonía; otras enfermedades del sistema respiratorio; bronquitis, enfisema y otras enfermedades pulmonares obstructivas crónicas; asma; bronquiolitis aguda y bronquiolitis aguda. While the five most frequent causes of morbidities were: pneumonia; other diseases of the respiratory system; bronchitis, emphysema and other chronic obstructive pulmonary diseases; asthma; acute bronchitis and acute bronchiolitis. Conclusiones: Se encontróque la neumonía, la influenza, las enfermedades respiratorias de las vías inferiores y otras enfermedades respiratorias crónicas eran las más prevalentes entre la población, respectivamente. Entre el público más afectado, se pudo observar que el público del niño y la población de edad avanzada eran los más afectados tanto en la mortalidad como en la morbilidad (AU).

Nomograms for predicting difficult airway based on ultrasound assessment.

BACKGROUND: Accurate prediction of the difficult airway (DA) could help to prevent catastrophic consequences in emergency resuscitation, intensive care, and general anesthesia. Until now, there is no nomogram prediction model for DA based on ultrasound assessment. In this study, we aimed to develop a predictive model for difficult tracheal intubation (DTI) and difficult laryngoscopy (DL) using nomogram based on ultrasound measurement. We hypothesized that nomogram could utilize multivariate data to predict DTI and DL. METHODS: A prospective observational DA study was designed. This study included 2254 patients underwent tracheal intubation. Common and airway ultrasound indicators were used for the prediction, including thyromental distance (TMD), modified Mallampati test (MMT) score, upper lip bite test (ULBT) score temporomandibular joint (TMJ) mobility and tongue thickness (TT). Univariate and the Akaike information criterion (AIC) stepwise logistic regression were used to identify independent predictors of DTI and DL. Nomograms were constructed to predict DL and DTL based on the AIC stepwise analysis results. Receiver operating characteristic (ROC) curves were used to evaluate the accuracy of the nomograms. RESULTS: Among the 2254 patients enrolled in this study, 142 (6.30%) patients had DL and 51 (2.26%) patients had DTI. After AIC stepwise analysis, ULBT, MMT, sex, TMJ, age, BMI, TMD, IID, and TT were integrated for DL nomogram; ULBT, TMJ, age, IID, TT were integrated for DTI nomogram. The areas under the ROC curves were 0.933 [95% confidence interval (CI), 0.912-0.954] and 0.974 (95% CI, 0.954-0.995) for DL and DTI, respectively. CONCLUSION: Nomograms based on airway ultrasonography could be a reliable tool in predicting DA. TRIAL REGISTRATION: Chinese Clinical Trial Registry (No. ChiCTR-RCS-14004539 ), registered on 13th April 2014.

Impact of lung structure on airway opening index during mechanical versus manual chest compressions in a porcine model of cardiac arrest.

OBJECTIVES: The exhaled CO2 signal provides guidance during cardiopulmonary resuscitation. The Airway opening index (AOI) has been recently used to quantify chest-compression (CC) induced expired CO2 oscillations. We aimed to determine whether levels of intrathoracic pressures developed during CC or parameters related to lung structure may affect AOI. METHODS: Secondary analysis of a randomized animal study (n = 12) in a porcine model of cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) during ambulance transport. Animals were randomized to 18-min of manual or mechanical CCs. Changes in AOI and right atrial pressure (ΔRAP) were recorded during CCs in animals undergoing manual (n = 6) or mechanical (n = 6) CCs. Lung CT scan and measurement of the respiratory system compliance (Cpl,rs) were performed immediately after return of spontaneous circulation. RESULTS: Animals undergoing mechanical CCs had a lower AOI compared to animals treated with manual CCs (p < 0.001). AOI negatively correlated with the swings of intrathoracic pressure, as measured by the change in ΔRAP (ρ=-0.727, p = 0.007). AOI correlated with the lung density (ρ=-0.818, p = 0.001) and with the Cpl,rs (ρ = 0.676, p = 0.016). Animals with cardiopulmonary resuscitation associated lung edema (CRALE) (i.e. mean CT≥-500 HU) showed lower levels of AOI compared to animals without it (29 ± 12 % versus 50 ± 16 %, p = 0.025). CONCLUSIONS: Animals undergoing mechanical CCs had lower levels of AOI compared to animals undergoing manual CCs. A higher swing of intrathoracic pressure during CC, a denser and a stiffer lung were associated with an impaired CO2 exhalation during CC as observed by a lower AOI.

Comparison of VividTrac, King Vision and Macintosh laryngoscopes in normal and difficult airways during simulated cardiopulmonary resuscitation among novices.

INTRODUCTION: Early endotracheal intubation improves neurological outcomes in cardiopulmonary resuscitation, although cardiopulmonary resuscitation is initially carried out by personnel with limited experience in a significant proportion of cases. Videolaryngoscopes might decrease the number of attempts and time needed, especially among novices. We sought to compare videolaryngoscopes with direct laryngoscopes in simulated cardiopulmonary resuscitation scenarios. MATERIALS AND METHODS: Forty-four medical students were recruited to serve as novice users. Following brief, standardized training, students executed endotracheal intubation with the King Vision®, Macintosh and VividTrac® laryngoscopes, on a cardiopulmonary resuscitation trainer in normal and difficult airway scenarios. We evaluated the time to and proportion of successful intubation, the best view of the glottis, esophageal intubation, dental trauma and user satisfaction. RESULTS: In the normal airway scenario, significantly shorter intubation times were achieved using the King Vision® than the Macintosh laryngoscope. In the difficult airway scenario, we found that the VividTrac® was superior to the King Vision® and Macintosh laryngoscopes in the laryngoscopy time. In both scenarios, we noted no difference in the first-attempt success rate, but the best view of the glottis and dental trauma, esophageal intubation and bougie use were more frequent with the Macintosh laryngoscope than with the videolaryngoscopes. The shortest tube insertion times were achieved using the King Vision® in both scenarios. CONCLUSION: All providers achieved successful intubation within three attempts, but we found no device superior in any of our scenarios regarding the first-attempt success rate. The King Vision® was superior to the Macintosh laryngoscope in the intubation time in the normal airway scenario and noninferior in the difficult airway scenario for novice users. We noted significantly less esophageal intubation using the videolaryngoscopes than using the Macintosh laryngoscope in both scenarios. Based on our results, the KingVision® might be recommended over the VividTrac® and Macintosh laryngoscopes for further evaluation.

Evaluation of sex-based differences in airway size and the physiological implications.

Recent evidence suggests healthy females have significantly smaller central conducting airways than males when matched for either height or lung volume during analysis. This anatomical sex-based difference could impact the integrative response to exercise. Our review critically evaluates the literature on direct and indirect techniques to measure central conducting airway size and their limitations. We present multiple sources highlighting the difference between male and female central conducting airway size in both pediatric and adult populations. Following the discussion of measurement techniques and results, we discuss the functional implications of these differences in central conducting airway size, including work of breathing, oxygen cost of breathing, and how these impacts will continue into elderly populations. We then discuss a range of topics for the future direction of airway differences and the benefits they could provide to both healthy and diseased populations. Specially, these sex-differences in central conducting airway size could result in different aerosol deposition or how lung disease manifests. Finally, we detail emerging techniques that uniquely allow for high-resolution imaging to be paired with detailed physiological measures.

Diagnostic Imaging of the Respiratory Tract of the Reptile Patient.

Detailed information is given about technique and image interpretation of radiography and computed tomography of the respiratory tract in reptiles. MRI and sonography are mentioned when supporting differential diagnoses. Various diseases and imaging pitfalls are described with multiple figures and graphics. One focus is on lung compression in chelonians, which may be misinterpreted as pneumonia in dyspneic patients without the help of imaging tools.

Respiratory Disorders in Chelonians.

"Respiratory tract disease in chelonians can be difficult to treat and as such proper diagnostics are paramount. Infectious agents that can affect the respiratory tract of chelonians include viral, bacterial, fungal, and parasitic organisms. Noninfectious diseases can also develop. Because chelonians lack a proper diaphragm, changes in size of celomic organs can cause compression of the respiratory system. These conditions result in clinical signs that could be attributed to the respiratory system, such as open-mouth breathing. In this article, anatomy, physiology, and current standards for diagnostics and treatments of major diseases of the respiratory tract in chelonians are discussed."

First Pass Success Without Adverse Events Is Reduced Equally with Anatomically Difficult Airways and Physiologically Difficult Airways.

INTRODUCTION: The goal of emergency airway management is first pass success without adverse events (FPS-AE). Anatomically difficult airways are well appreciated to be an obstacle to this goal. However, little is known about the effect of the physiologically difficult airway with regard to FPS-AE. This study evaluates the effects of both anatomically and physiologically difficult airways on FPS-AE in patients undergoing rapid sequence intubation (RSI) in the emergency department (ED). METHODS: We analyzed prospectively recorded intubations in a continuous quality improvement database between July 1, 2014-June 30, 2018. Emergency medicine (EM) or emergency medicine/pediatric (EM-PEDS) residents recorded patient, operator, and procedural characteristics on all consecutive adult RSIs performed using a direct or video laryngoscope. The presence of specific anatomically and physiologically difficult airway characteristics were also documented by the operator. Patients were analyzed in four cohorts: 1) no anatomically or physiologically difficult airway characteristics; 2) one or more anatomically difficult airway characteristics; 3) one or more physiologically difficult airway characteristics; and 4) both anatomically and physiologically difficult airway characteristics. The primary outcome was FPS-AE. We performed a multivariable logistic regression analysis to determine the association between anatomically difficult airways or physiologically difficult airways and FPS-AE. RESULTS: A total of 1513 intubations met inclusion criteria and were analyzed. FPS-AE for patients without any difficult airway characteristics was 92.4%, but reduced to 82.1% (difference = -10.3%, 95% confidence interval (CI), -14.8% to -5.6%) with the presence of one or more anatomically difficult airway characteristics, and 81.7% (difference = -10.7%, 95% CI, -17.3% to -4.0%) with the presence of one or more physiologically difficult airway characteristics. FPS-AE was further reduced to 70.9% (difference = -21.4%, 95% CI, -27.0% to -16.0%) with the presence of both anatomically and physiologically difficult airway characteristics. The adjusted odds ratio (aOR) of FPS-AE was 0.37 [95% CI, 0.21 - 0.66] in patients with anatomically difficult airway characteristics and 0.36 [95% CI, 0.19 - 0.67] for patients with physiologically difficult airway characteristics, compared to patients with no difficult airway characteristics. Patients who had both anatomically and physiologically difficult airway characteristics had a further decreased aOR of FPS-AE of 0.19 [95% CI, 0.11 - 0.33]. CONCLUSION: FPS-AE is reduced to a similar degree in patients with anatomically and physiologically difficult airways. Operators should assess and plan for potential physiologic difficulty as is routinely done for anatomically difficulty airways. Optimization strategies to improve FPS-AE for patients with physiologically difficult airways should be studied in randomized controlled trials.

Light Sheet Microscopy-Assisted 3D Analysis of SARS-CoV-2 Infection in the Respiratory Tract of the Ferret Model.

The visualization of viral pathogens in infected tissues is an invaluable tool to understand spatial virus distribution, localization, and cell tropism in vivo. Commonly, virus-infected tissues are analyzed using conventional immunohistochemistry in paraffin-embedded thin sections. Here, we demonstrate the utility of volumetric three-dimensional (3D) immunofluorescence imaging using tissue optical clearing and light sheet microscopy to investigate host-pathogen interactions of pandemic SARS-CoV-2 in ferrets at a mesoscopic scale. The superior spatial context of large, intact samples (>150 mm3) allowed detailed quantification of interrelated parameters like focus-to-focus distance or SARS-CoV-2-infected area, facilitating an in-depth description of SARS-CoV-2 infection foci. Accordingly, we could confirm a preferential infection of the ferret upper respiratory tract by SARS-CoV-2 and suggest clustering of infection foci in close proximity. Conclusively, we present a proof-of-concept study for investigating critically important respiratory pathogens in their spatial tissue morphology and demonstrate the first specific 3D visualization of SARS-CoV-2 infection.

Postcranial Skeletal Pneumaticity in Cuculidae.

Postcranial skeletal pneumaticity (i.e., epithelial-lined, air-filled bones) is a condition unique to birds among extant tetrapods. Previous research reveals extensive variation in the expression of this trait in different bird species, from taxa that pneumatize nearly the entire skeleton to others that do not pneumatize a single bone. These studies, however, have primarily focused on aquatic/semi-aquatic birds, specifically Anseriformes (screamers, ducks, geese, swans) and Aequorlitornithes (loons, gulls, penguins, storks, etc.). This is the first clade-centric study of pneumaticity in an exclusively terrestrial clade (i.e., a group without any proclivities for water), Cuculidae. Given the variation in body size and ecology exhibited by cuckoos, they represent an ideal group for evaluating previously established trends in pneumaticity patterns. Similar to previous studies, our results indicate that cuckoos do exhibit extensive postcranial skeletal pneumaticity but with much more limited variation in expression. Of the surveyed species, 30 of 41 display an identical expression pattern, pneumatizing all postaxial vertebrae, the humerus, sternum, and pelvic girdle. The remaining species (11/41) deviate from this pattern by no more than two elements (i.e., the femur or the scapula/coracoid). All variable species expand upon the basic cuckoo pattern, with five species pneumatizing the femur and the remaining six taxa pneumatizing both the scapula and coracoid. Furthermore, most variation occurs in early diverging clades, with distinct subclades associated with specific anatomical expansions in pneumaticity (e.g., pneumatic femora in Neomorphinae and pneumatic scapulae/coracoids in select members of Couinae and Centropodinae). Limited variation noted in Cuculidae may be the result of the relatively high base level of pneumaticity when compared with previously sampled groups of water-oriented birds. Additional analyses indicate a positive relationship between body mass and pneumaticity, with possible (i.e., non-quantifiable) relationships noted between the limited expansions from the basic cuckoo pattern and specific locomotor behaviors (e.g., pneumatic femora present in species with enhanced cursorial behavior). These basic trends have also been observed in other densely sampled neognath clades. Taken together, the data presented herein supports the hypothesis that changes in pneumaticity expression may be correlated with shifts in biomechanical loading regimes rather than solely as a weight saving (i.e., density-altering) mechanism.

Experimental tracking and numerical mapping of novel coronavirus micro-droplet deposition through nasal inhalation in the human respiratory system.

It is essential to study the viral droplet's uptake in the human respiratory system to better control, prevent, and treat diseases. Micro-droplets can easily pass through ordinary respiratory masks. Therefore, the SARS-COV-2 transmit easily in conversation with a regular mask with 'silent spreaders' in the most physiological way of breathing through the nose, indoor and at rest condition. The results showed that the amount of deposited micro-droplets in the olfactory epithelium area is low. Also, due to receptors and long droplet residence time in this region, the possibility of absorption increases in the cribriform plate. This phenomenon eventually could lead to brain lesion damage and, in some cases, leads to stroke. In all inlet flow rates lower than 30 L/min inlet boundary conditions, the average percentage of viral contamination for upper respiratory tract is always less than 50% and more than 50% for the lungs. At 6L/min and 15L/min flow rates, the average percentage of lung contamination increases to more than 87%, which due to the presence of the Coronavirus receptor in the lungs, the involvement of the lungs increases significantly. This study's other achievements include the inverse relationship between droplets deposition efficiency in some parts of the upper airway, which have the most deformation in the tract. Also, the increased deformities per minute applied to the trachea and nasal cavity, which is 1.5 times more than usual, could lead to chest and head bothers.

African lungfish genome sheds light on the vertebrate water-to-land transition.

Lungfishes are the closest extant relatives of tetrapods and preserve ancestral traits linked with the water-to-land transition. However, their huge genome sizes have hindered understanding of this key transition in evolution. Here, we report a 40-Gb chromosome-level assembly of the African lungfish (Protopterus annectens) genome, which is the largest genome assembly ever reported and has a contig and chromosome N50 of 1.60 Mb and 2.81 Gb, respectively. The large size of the lungfish genome is due mainly to retrotransposons. Genes with ultra-long length show similar expression levels to other genes, indicating that lungfishes have evolved high transcription efficacy to keep gene expression balanced. Together with transcriptome and experimental data, we identified potential genes and regulatory elements related to such terrestrial adaptation traits as pulmonary surfactant, anxiolytic ability, pentadactyl limbs, and pharyngeal remodeling. Our results provide insights and key resources for understanding the evolutionary pathway leading from fishes to humans.

Using µCT in live larvae of a large wood-boring beetle to study tracheal oxygen supply during development.

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 CO2 efflux. Our study provides methodological insights and novel biological data on key issues in rapidly quantifying insect respiratory anatomy on live insects.

Anatomic and histologic analysis of paca larynx (Cuniculus paca, Linnaeus 1766) / [Análise anatômica e histológica da laringe da paca (Cuniculus paca, Linnaeus 1766)]

Paca (Cuniculus paca) has encouraged research as an experimental model both in the human medicine and veterinary, as well as the economic exploitation of its meat cuts, which favored its zootechnical use. There are no anatomical, microscopic descriptions and measurements of the larynx in this rodent. Eight pacas were dissected from the wild animal's sector of the Faculty of Agricultural and Veterinary Sciences of the University of the State of São Paulo. The larynx was observed located in the ventral region of the neck, ventral to the esophagus, connecting the pharynx to the trachea, with cylindrical and irregular shape. Laryngeal cartilages (epiglottic, thyroid, cricoid and arytenoid) are interconnected and have different shapes. Thyroid showed greater length and width, compared to the others. Laryngeal cartilages were submitted to histological processing and stained with hematoxylin-eosin and Masson's trichrome. The epiglottic cartilage was stained with toluidine blue. Laryngeal cartilages thyroid, cricoid and the lower portion of the arytenoids are of hyaline origin and, in contrast, the epiglottis and the upper portion of the arytenoids are elastic. This latter cartilage demonstrated taste buds. The results will be able to auxiliate in veterinary care and as well as the conservation programs for this rodent.(AU)

A paca (Cuniculus paca) tem encorajado inúmeras pesquisas, tornando-a modelo experimental tanto em humanos como na veterinária, além da exploração econômica de seus cortes cárneos, que favoreceu diretamente sua importância zootécnica. Não há descrições anatômicas, microscópicas e mensurações da laringe desse roedor. Foram dissecadas oito laringes de pacas, provenientes do setor de Animais Silvestres da Faculdade de Ciências Agrárias e Veterinárias - Universidade Estadual Paulista. Observou-se que a laringe localiza-se na região ventral do pescoço, ventral ao esôfago, conectando a faringe à traqueia, possuindo formato cilíndrico e irregular. As cartilagens laríngeas (epiglote, tireóide, cricóide e aritenóidea) são interligadas e possuem formatos variados. A cartilagem tireóide demonstrou-se maior em comprimento e largura, comparativamente às demais. As cartilagens laríngeas foram submetidas a processamento histológico e coradas em hematoxilina-eosina e tricrômio de Masson. A cartilagem epiglote foi corada em azul de toluidina. As cartilagens laríngeas tireóide, cricóide e a porção inferior das aritenóides são de origem hialina; em contrapartida, a epiglote e a porção superior das aritenóides, de origem elástica. Esta última cartilagem demonstrou corpúsculos gustativos. Os resultados poderão auxiliar tanto nos atendimentos veterinários quanto nos programas de conservação desse roedor.(AU)

The evaluation of maximum condyle-tragus distance can predict difficult airway management without exposing upper respiratory tract; a prospective observational study.

BACKGROUND: Routine preoperative methods to assess airway such as the interincisor distance (IID), Mallampati classification, and upper lip bite test (ULBT) have a certain risk of upper respiratory tract exposure and virus spread. Condyle-tragus maximal distance(C-TMD) can be used to assess the airway, and does not require the patient to expose the upper respiratory tract, but its value in predicting difficult laryngoscopy compared to other indicators (Mallampati classification, IID, and ULBT) remains unknown. The purpose of this study was to observe the value of C-TMD to predict difficult laryngoscopy and the influence on intubation time and intubation attempts, and provide a new idea for preoperative airway assessment during epidemic. METHODS: Adult patients undergoing general anesthesia and tracheal intubation were enrolled. IID, Mallampati classification, ULBT, and C-TMD of each patient were evaluated before the initiation of anesthesia. The primary outcome was intubation time. The secondary outcomes were difficult laryngoscopy defined as the Cormack-Lehane Level > grade 2 and the number of intubation attempts. RESULTS: Three hundred four patients were successfully enrolled and completed the study, 39 patients were identified as difficult laryngoscopy. The intubation time was shorter with the C-TMD>1 finger group 46.8 ± 7.3 s, compared with the C-TMD<1 finger group 50.8 ± 8.6 s (p<0.01). First attempt success rate was higher in the C-TMD>1 finger group 98.9% than in the C-TMD<1 finger group 87.1% (P<0.01). The correlation between the C-TMD and Cormack-Lehane Level was 0.317 (Spearman correlation coefficient, P<0.001), and the area under the ROC curve was 0.699 (P<0.01). The C-TMD < 1 finger width was the most consistent with difficult laryngoscopy (κ = 0.485;95%CI:0.286-0.612) and its OR value was 10.09 (95%CI: 4.19-24.28), sensitivity was 0.469 (95%CI: 0.325-0.617), specificity was 0.929 (95%CI: 0.877-0.964), positive predictive value was 0.676 (95%CI: 0.484-0.745), negative predictive value was 0.847 (95%CI: 0.825-0.865). CONCLUSION: Compared with the IID, Mallampati classification and ULBT, C-TMD has higher value in predicting difficult laryngoscopy and does not require the exposure of upper respiratory tract. TRIAL REGISTRATION: The study was registered on October 21, 2019 in the Chinese Clinical Trial Registry ( ChiCTR1900026775 ).

Next-Generation Sequencing Analysis of the Within-Host Genetic Diversity of Influenza A(H1N1)pdm09 Viruses in the Upper and Lower Respiratory Tracts of Patients with Severe Influenza.

The influenza A(H1N1)pdm09 virus emerged in April 2009 with an unusual incidence of severe disease and mortality, and currently circulates as a seasonal influenza virus. Previous studies using consensus viral genome sequencing data have overlooked the viral genomic and phenotypic diversity. Next-generation sequencing (NGS) may instead be used to characterize viral populations in an unbiased manner and to measure within-host genetic diversity. In this study, we used NGS analysis to investigate the within-host genetic diversity of influenza A(H1N1)pdm09 virus in the upper and lower respiratory samples from nine patients who were admitted to the intensive care unit (ICU). A total of 47 amino acid substitution positions were found to differ between the upper and lower respiratory tract samples from all patients. However, the D222G/N substitution in hemagglutinin (HA) protein was the only amino acid substitution common to multiple patients. Furthermore, the substitution was detected only in the six samples from the lower respiratory tract. Therefore, it is important to investigate influenza A(H1N1)pdm09 virus populations using multiple paired samples from the upper and lower respiratory tract to avoid overlooking potentially important substitutions, especially in patients with severe disease.IMPORTANCE The D222G/N substitution in the hemagglutinin (HA) protein of influenza A(H1N1)pdm09 virus has been reported to be associated with disease severity and mortality in numerous previous studies. In the present study, 75% of lower respiratory samples contained heterogeneous influenza populations that carried different amino acids at position 222 of the HA protein, whereas all upper respiratory samples only contained the wild-type 222D. These results suggest the influenza A(H1N1)pdm09 virus has diversified inside the host owing to differences in tissue specificity. In this study, the within-host genetic diversity of influenza A(H1N1)pdm09 virus was investigated for the first time using next-generation sequencing analysis of the viral whole-genome in samples extracted from the upper and lower respiratory tracts of patients with severe disease.

Linking structure and function in the vertebrate respiratory system: A tribute to August Krogh.

High rates of pulmonary gas exchange require three things: 1) that gases at the contact surface of the lung's capillaries are replenished rapidly from the environment; 2) that this surface is large and thin; 3) that the capillaries are effectively perfused with blood. In spite of this uniform requirement, lungs have evolved complex and highly diverse architectures, but we have a poor understanding of the drivers of this diversity. Here, I briefly discuss some of the diversity in gross anatomical features directing airflow in avian and non-avian reptiles. I also review new insights into the cellular anatomy of the blood-gas barrier, which in mammals is composed of specialized endothelial as well as epithelial cells.

Comparisons of Respiratory Pupal Gill Development in Black Flies (Diptera: Simuliidae) Shed Light on the Origin of Dipteran Prothoracic Dorsal Appendages.

During the transformation of immature aquatic dipteran insects to terrestrial adults, the prothoracic pupal respiratory organ enables pupae to cope with flood-drought alternating environments. Despite its obvious importance, the biology of the organ, including its development, is poorly understood. In this study, the developing gills of several Simulium Latreille (Diptera: Simuliidae) spp. were observed using serial histological sections and compared with data on those of other dipteran families published previously. The formation of some enigmatic features that made the Simulium gill unique is detailed. Through comparisons between taxa, we describe a common developmental pattern in which the prothoracic dorsal disc cells not only morph into the protruding respiratory organ, which is partially or entirely covered with a cuticle layer of plastron, but also invaginate to form a multipart internal chamber that in part gives rise to the anterior spiracle of adult flies. The gill disc resembles wing and leg discs and undergoes cell proliferation, axial outgrowth, and cuticle sheath formation. The overall appendage-like characteristics of the dipteran pupal respiratory organ suggest an ancestral form that gave rise to its current forms, which added more dimensions to the ways that arthropods evolved through appendage adaptation. Our observations provide important background from which further studies into the evolution of the respiratory organ across Diptera can be carried out.