Assessing nasal airway resistance and symmetry: An approach to global perspective through computational fluid dynamics.

This study aimed to explore the variability in nasal airflow patterns among different sexes and populations using computational fluid dynamics (CFD). We focused on evaluating the universality and applicability of dimensionless parameters R (bilateral nasal resistance) and ϕ (nasal flow asymmetry), initially established in a Caucasian Spanish cohort, across a broader spectrum of human populations to assess normal breathing function in healthy airways. In this retrospective study, CT scans from Cambodia (20 males, 20 females), Russia (20 males, 18 females), and Spain (19 males, 19 females) were analyzed. A standardized CFD workflow was implemented to calculate R-ϕ parameters from these scans. Statistical analyses were conducted to assess and compare these parameters across different sexes and populations, emphasizing their distribution and variances. Our results indicated no significant sex-based differences in the R parameter across the populations. However, moderate sexual dimorphism in the ϕ parameter was observed in the Cambodian group. Notably, no geographical differences were found in either R or ϕ parameters, suggesting consistent nasal airflow characteristics across the diverse human groups studied. The study also emphasized the importance of using dimensionless variables to effectively analyze the relationships between form and function in nasal airflow. The observed consistency of R-ϕ parameters across various populations highlights their potential as reliable indicators in both medical practice and further CFD research, particularly in diverse human populations. Our findings suggest the potential applicability of dimensionless CFD parameters in analyzing nasal airflow, highlighting their utility across diverse demographic and geographic contexts. This research advances our understanding of nasal airflow dynamics and underscores the need for additional studies to validate these parameters in broader population cohorts. The approach of employing dimensionless parameters paves the way for future research that eliminates confounding size effects, enabling more accurate comparisons across different populations and sexes. The implications of this study are significant for the advancement of personalized medicine and the development of diagnostic tools that accommodate individual variations in nasal airflow.

Beyond skeletal studies: A computational analysis of nasal airway function in climate adaptation.

OBJECTIVES: Ecogeographic variation in human nasal anatomy has historically been analyzed on skeletal morphology and interpreted in the context of climatic adaptations to respiratory air-conditioning. Only a few studies have analyzed nasal soft tissue morphology, actively involved in air-conditioning physiology. MATERIALS AND METHODS: We used in vivo computer tomographic scans of (N = 146) adult individuals from Cambodia, Chile, Russia, and Spain. We conducted (N = 438) airflow simulations during inspiration using computational fluid dynamics to analyze the air-conditioning capacities of the nasal soft tissue in the inflow, functional, and outflow tract, under three different environmental conditions: cold-dry; hot-dry; and hot-humid. We performed statistical comparisons between populations and sexes. RESULTS: Subjects from hot-humid regions showed significantly lower air-conditioning capacities than subjects from colder regions in all the three conditions, specifically within the isthmus region in the inflow tract, and the anterior part of the internal functional tract. Posterior to the functional tract, no differences were detected. No differences between sexes were found in any of the tracts and under any of the conditions. DISCUSSION: Our statistical analyses support models of climatic adaptations of anterior nasal soft tissue morphology that fit with, and complement, previous research on dry skulls. However, our results challenge a morpho-functional model that attributes air-conditioning capacities exclusively to the functional tract located within the nasal cavity. Instead, our findings support studies that have suggested that both, the external nose and the intra-facial soft tissue airways contribute to efficiently warming and humidifying air during inspiration. This supports functional interpretations in modern midfacial variation and evolution.

Infección por bartonella henselae en pacientes pediátricos. Lesión pseudotumoral de calota. Reporte de caso

Los tumores de calota en pacientes pediátricos poseen múltiples etiologías. Dentro de las causas pseudotumorales, las infecciones juegan un rol importante, siendo la osteomielitis por Bartonella henselae (Enfermedad por Arañazo de Gato) una posibilidad diagnóstica rara, pero que debe ser estudiada y descartada. Se presenta el caso de una lactante de 1 año, con lesión expansiva de calota, a nivel frontal derecho, hipervascularizada e infiltrativa. Se realizó estudio con ultrasonido, tomografía cerebral y cintigrama óseo. Se realizó resección quirúrgica completa de la lesión, con preservación de la duramadre y zona fontanelar, además de un cuidadoso trato con el seno sagital superior. Evolucionó sin complicaciones perioperatorias. El resultado de la biopsia fue compatible con proceso inflamatorio crónico, osteomielitis supurada. Tinción de Warthin Starry positiva sugerente de Bartonella henselae. Se descartó etiología tuberculosa y fúngica. Serología positiva para Bartonella henselae. La paciente completó antibioticoterapia, azitromicina y cotrimoxazol, con evolución clínica favorable.

Calvarial tumors in pediatric patients have multiple etiologies. Among the pseudotumoral causes, infections play an important role, being Bartonella henselae osteomyelitis (Cat Scratch Disease) a rare diagnostic possibility, but it should be studied and ruled out. We present the case of a 1 year old infant, with an expansive lesion of the calvaria, at right frontal level, hypervascularized and infiltrative. Ultrasound, brain tomography and bone scintigram were performed. Complete surgical resection of the lesion was performed, with preservation of the dura mater and fontanel area, in addition to a careful treatment with the superior sagittal sinus. The patient evolved without perioperative complications. The biopsy result was compatible with a chronic inflammatory process, suppurative osteomyelitis. Positive Warthin Starry stain suggestive of Bartonella henselae. Tuberculous and fungal etiology was ruled out. Positive serology for Bartonella henselae. The patient completed antibiotic therapy, azithromycin and cotrimoxazole, with favorable clinical evolution.

Advancements in veterinary medicine: the use of Flowgy for nasal airflow simulation and surgical predictions in big felids (a case study in lions).

Flowgy is a semi-automated tool designed to simulate airflow across the nasal passage and detect airflow alterations in humans. In this study, we tested the use and accuracy of Flowgy in non-human vertebrates, using large felids as the study group. Understanding the dynamics of nasal airflow in large felids such as lions (Panthera leo) is crucial for their health and conservation. Therefore, we simulated airflow during inspiration through the nasal passage in three lions (Panthera leo), two of which were siblings (specimens ZPB_PL_002 and ZPB_PL_003), without breathing obstructions. However, one of the specimens (ZPB_PL_001) exhibited a slight obstruction in the nasal vestibule, which precluded the specimen from breathing efficiently. Computed tomography (CT) scans of each specimen were obtained to create detailed three-dimensional models of the nasal passage. These models were then imported into Flowgy to simulate the airflow dynamics. Virtual surgery was performed on ZPB_PL_001 to remove the obstruction and re-simulate the airflow. In parallel, we simulated the respiration of the two sibling specimens and performed an obstructive operation followed by an operation to remove the obstruction at the same level and under the same conditions as the original specimen (ZPB_PL_001). Thus, we obtained a pattern of precision for the operation by having two comparable replicas with the obstructed and operated specimens. The simulations revealed consistent airflow patterns in the healthy specimens, demonstrating the accuracy of Flowgy. The originally obstructed specimen and two artificially obstructed specimens showed a significant reduction in airflow through the right nostril, which was restored after virtual surgery. Postoperative simulation indicated an improvement of >100% in respiratory function. Additionally, the temperature and humidity profiles within the nostrils showed marked improvements after surgery. These findings underscore the potential of Flowgy in simulating nasal airflow and predicting the outcomes of surgical interventions in large felids. This could aid in the early detection of respiratory diseases and inform clinical decision-making, contributing to improved veterinary care and conservation efforts. However, further research is needed to validate these findings in other species and explore the potential of integrating Flowgy with other diagnostic and treatment tools in veterinary medicine.

The evolution, form and function of the human respiratory system.

This paper presents an updated view on the morphological and functional significance of the human respiratory system in the context of human evolutionary anatomy. While usually the respiratory system is treated either from a craniofacial perspective, mostly in the context of nasal evolution and air-conditioning, or from a postcranial perspective featuring on overall thoracic shape changes, here we pursue a holistic perspective on the form, function, integration, and evolutionary change of the entire organismal system in hominins. We first present a brief review of the most important morphological structures, their function, and its potential integration and interaction with the nasal cavity and thoracic skeleton. This is followed by an overview of the most important improvements in methods for the comparative study in recent humans and fossil hominins. We then overview and list a compendium of hominin fossil material currently available for the study. We propose four functional categories of hominin respiratory system configurations that differ potentially with respect to size, shape, biomechanics and/or bioenergetics. Finally, we discuss these and speculate on possible ways for future research into an anatomical system that, despite its under-investigated status, is central to the understanding of the form and functions of the hominin organism and its paleobiology.

Linking Chronic Otitis Media and Nasal Obstruction: A CFD Approach.

OBJECTIVES: To investigate a possible relationship between altered nasal flow and chronic otitis media (COM) using computational fluid dynamics (CFD). STUDY DESIGN: Retrospective case series. METHODS: Retrospective cohort sample of CT scans from patients with COM and controls without COM to compare the results of various nasal airflow parameters determined by CFD between a group of patients with COM (N = 60) and a control group of subjects without any evidence of ear disease (N = 81). The CT were subjected to various procedures to carry out CFD studies, determining the resistance to nasal flow, the proportion of flow through the right and left nasal cavity, and two nondimensional estimators. The results of CFD studies between patients with COM and controls were compared. RESULTS: Whereas only 12.3% of the controls had CFD alteration (10 out of 81), 43.3% of the patients suffering COM displayed alterations of our nondimensional parameters R-ϕ (26 out of 60). CONCLUSIONS: According to our results, the incidence of alterations in nasal airflow by studying with CFD is significantly higher in patients with COM than in controls. To our knowledge, this is the first article linking nasal cavity and COM using a CFD approach. Our results support the hypothesis that nasal flow alterations could be implicated in the etiopathogenesis of the COM. LEVEL OF EVIDENCE: 4 Laryngoscope, 132:1224-1230, 2022.

Three-dimensional form and function of the nasal cavity and nasopharynx in humans and chimpanzees.

The facial differences between recent Pan troglodytes and Homo sapiens can be used as a proxy for the reduction of facial prognathism that happened during evolutionary transition between Australopithecines and early Homo. The projecting nasal morphology of Homo has been considered both a passive consequence of anatomical reorganization related to brain and integrated craniofacial evolution as well as an adaptation related to air-conditioning during physiological and behavioral shifts in human evolution. Yet, previous research suggested impaired air-conditioning in Homo challenging respiratory adaptations based on computational fluid dynamics (CFD) and airflow simulations. Here we improved CFD model at the inflow region and also carried out three-dimensional (3D) geometric morphometrics to address the hypothesis of impaired air-conditioning in humans and species differences in airway shape. With the new CFD model we simulated pressure, velocity, and temperature changes in airflow of six adult humans and six chimpanzees and analyzed 164 semi-landmarks of 10 humans and 10 chimpanzees for 3D size and shape comparisons. Our finding shows significantly different internal 3D nasal airways. Also, species means of pressure, velocity, and temperature differed statistically significantly. However, form-related differences in temperature exchanges seem subtle and may question adaptive disadvantages. We rather support a hypothesis of craniofacial changes in the Australopithecus-Homo transition that are related to brain evolution and craniofacial integration with facial and nasal modifications that contribute to maintain respiratory adaptations related to air conditioning.

Three-dimensional analysis of sexual dimorphism in the soft tissue morphology of the upper airways in a human population.

OBJECTIVES: Several studies have analyzed the sexual dimorphism of the skeletal cranial airways. This study aimed to quantify the three-dimensional (3D) morphology of the soft tissues of the upper airways in a human population. We addressed hypotheses about morphological features related to respiratory and energetic aspects of nasal sexual dimorphism. METHODS: We reconstructed 3D models of 41 male and female soft tissue nasal airways from computed tomography data. We measured 280 landmarks and semilandmarks for 3D-geometric morphometric analyses to test for differences in size and 3D morphology of different functional compartments of the soft tissue airways. RESULTS: We found statistical evidence for sexual dimorphism: Males were larger than females. 3D features indicated taller and wider inflow tracts, taller outflow tracts and slightly taller internal airways in males. These characteristics are compatible with greater airflow in males. DISCUSSION: The differences in 3D nasal airway morphology are compatible with the respiratory-energetics hypothesis according to which males differ from females because of greater energetic demands. Accordingly, structures related to inflow and outflow of air show stronger signals than structures relevant for air-conditioning.

Nasal surgery handled by CFD tools.

Annually, hundreds of thousands of surgical interventions to correct nasal airway obstruction are performed throughout the world. Recent studies have noted that a significant number of patients have persistent symptoms of nasal obstruction postoperatively. In the present work, we introduce a new methodology that raises the success rate of nasal cavity surgery. In this procedure, the surgeon performs virtual surgery on a 3D nasal model of a patient prior to the real surgery. The main goal of the methodology is to guide the surgeon throughout the virtual operation using mathematical estimators based on CFD results. The virtual surgery intervention ends as soon as the estimators fall into a region of a Cartesian coordinate system with a high success probability. This region is defined according to a statistical analysis of estimators corresponding to sets of healthy and diseased cavities. As examples of this application, this study includes 2 surgical operations performed with this innovative methodology on patients with severe nasal obstruction. The patients underwent nasal surgery according to the final nasal geometry revealed by CFD-guided virtual surgery. Currently, both subjects show high degrees of satisfaction.

Cirugía virtual para pacientes con obstrucción nasal: empleo de un software basado en dinámica de fluidos (MeComLand(R), Digbody(R) & Noseland(R)) para documentar parámetros objetivos de flujo y optimizar resultados quirúrgicos / Virtual surgery for patients with nasal obstruction: Use of computational fluid dynamics (MeComLand(R), Digbody(R) & Noseland(R)) to document objective flow parameters and optimise surgical results

INTRODUCCIÓN: La dinámica de fluidos computacional (CFD) es una herramienta matemática que permite analizar el flujo aéreo. Presentamos un software innovador basado en CFD para mejorar los resultados de la cirugía nasal. MÉTODOS: Mediante colaboración de ingenieros especialistas en mecánica de fluidos y otorrinolaringólogos se ha desarrollado un software de fácil uso denominado MeComLand(R), que utilizando los cortes de tomografía computarizada de un paciente permite obtener gran cantidad de información como flujo, presiones, temperatura, velocidad o fricción sobre la pared de las fosas nasales. El programa DigBody(R) permite modificar en 3 D la anatomía del modelo y realizar cirugías virtuales para simular resultados antes de la cirugía real. Por último, NoseLand(R) permite viajar virtualmente por el interior de la fosa nasal, mostrando todo tipo de magnitudes termo-fluido mecánicas. OBJETIVO: Presentar un programa innovador para mejorar los resultados de la cirugía nasal. Emplear este software sobre cortes tomográficos de un paciente con desviación septal para planificar distintas opciones quirúrgicas (septoplastia, turbinectomía, spreader-grafts, colgajo en J y combinaciones) a fin de conseguir la mejor alternativa con la menor morbilidad. RESULTADOS: La combinación de todos los procedimientos considerados no produce los mejores resultados en cuanto a flujo nasal. Estos se consiguen asociando septoplastia y turbinectomía. La turbinectomía aislada obtuvo resultados muy similares a la septoplastia. CONCLUSIONES: La técnica computacional CFD proporciona una información complementaria valiosa en el diagnóstico del paciente con obstrucción nasal y sobre los resultados de distintas alternativas quirúrgicas respecto al flujo nasal, contribuyendo a un mejor manejo del enfermo. El software MeComLand(R) con sus respectivos módulos DigBody(R) y NoseLand(R) suponen una alternativa barata y no invasiva al estudio funcional del paciente con obstrucción nasal

INTRODUCTION: Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. We present a novel CFD software package to improve results following nasal surgery for obstruction. METHODS: A group of engineers in collaboration with otolaryngologists have developed a very intuitive CFD software package called MeComLand(R), which uses the patient's cross-sectional (tomographic) images, thus showing in detail results originated by CFD such as airflow distributions, velocity profiles, pressure, or wall shear stress. NOSELAND(R) helps medical evaluation with dynamic reports by using a 3D endoscopic view. Using this CFD-based software a patient underwent virtual surgery (septoplasty, turbinoplasty, spreader grafts, lateral crural J-flap and combinations) to choose the best improvement in nasal flow. OBJECTIVE: To present a novel software package to improve nasal surgery results. To apply the software on CT slices from a patient affected by septal deviation. To evaluate several surgical procedures (septoplasty, turbinectomy, spreader-grafts, J-flap and combination among them) to find the best alternative with less morbidity. RESULTS: The combination of all the procedures does not provide the best nasal flow improvement. Septoplasty plus turbinoplasty obtained the best results. Turbinoplasty alone rendered almost similar results to septoplasty in our simulation. CONCLUSIONS: CFD provides useful complementary information to cover diagnosis, prognosis, and follow-up of nasal pathologies based on quantitative magnitudes linked to fluid flow. MeComLand(R), DigBody(R) and NoseLand(R) represent a non-invasive, low-cost alternative for the functional study of patients with nasal obstruction

Virtual surgery for patients with nasal obstruction: Use of computational fluid dynamics (MeComLand®, Digbody® & Noseland®) to document objective flow parameters and optimise surgical results. / Cirugía virtual para pacientes con obstrucción nasal: empleo de un software basado en dinámica de fluidos (MeComLand®, Digbody® & Noseland®) para documentar parámetros objetivos de flujo y optimizar resultados quirúrgicos.

INTRODUCTION: Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. We present a novel CFD software package to improve results following nasal surgery for obstruction. METHODS: A group of engineers in collaboration with otolaryngologists have developed a very intuitive CFD software package called MeComLand®, which uses the patient's cross-sectional (tomographic) images, thus showing in detail results originated by CFD such as airflow distributions, velocity profiles, pressure, or wall shear stress. NOSELAND® helps medical evaluation with dynamic reports by using a 3D endoscopic view. Using this CFD-based software a patient underwent virtual surgery (septoplasty, turbinoplasty, spreader grafts, lateral crural J-flap and combinations) to choose the best improvement in nasal flow. OBJECTIVE: To present a novel software package to improve nasal surgery results. To apply the software on CT slices from a patient affected by septal deviation. To evaluate several surgical procedures (septoplasty, turbinectomy, spreader-grafts, J-flap and combination among them) to find the best alternative with less morbidity. RESULTS: The combination of all the procedures does not provide the best nasal flow improvement. Septoplasty plus turbinoplasty obtained the best results. Turbinoplasty alone rendered almost similar results to septoplasty in our simulation. CONCLUSIONS: CFD provides useful complementary information to cover diagnosis, prognosis, and follow-up of nasal pathologies based on quantitative magnitudes linked to fluid flow. MeComLand®, DigBody® and NoseLand® represent a non-invasive, low-cost alternative for the functional study of patients with nasal obstruction.