Reducing variability in nasal surgery outcomes through computational fluid dynamics and advanced 3D virtual surgery techniques.

Objectives: This study aims to delineate the specific impact of using computational fluid dynamics (CFD) and 3D virtual surgery techniques in otolaryngology surgery, focusing on their roles in enhancing the precision of nasal surgery and optimizing future patient outcomes. The central objective was to assess whether these advanced technologies could reduce variability in surgical approaches and decision-making among specialists, thereby improving the consistency and efficacy of patient care in cases of nasal obstruction. Methods and results: Our methodology involved a detailed analysis of pre- and post-operative scenarios using CFD feedback. Six otolaryngologists participated, employing virtual surgery techniques on two patients with diagnosed nasal obstruction. The CFD analysis focused on quantifying key airflow parameters: right nasal flow rate (QR), left nasal flow rate (QL), flow symmetry (Ф), and bilateral nasal resistance (R). These parameters were meticulously compared before and after the application of CFD feedback to evaluate changes in surgical planning and outcomes. Quantitative analysis revealed a notable decrease in the standard deviation of the measured parameters among the specialists post-CFD feedback, indicating reduced variability in surgical approaches. Specifically, for Patient #1 the standard deviation for QR values dropped from 0.694 L/min to 0.602 L/min, and for QL values from 0.676 L/min to 0.584 L/min, and for Patient #2, the standard deviation for QR values decreased from 2.204 L/min to 0.958 L/min, and for QL values from 2.295 L/min to 1.014 L/min. Moreover, the variability range, represented by the differences between the maximum and minimum values for Ф and R, diminished significantly. Post-operative average values for all parameters showed a convergence towards ideal basal levels, suggesting a more uniform and effective surgical strategy across different surgeons. Conclusions: Both integration of CFD and 3D virtual surgery techniques in otolaryngology can substantially reduce variability in surgical planning and decision-making, ultimately leading to improved patient outcomes. These advanced tools have the potential to standardize the diagnosis and treatment of nasal pathologies, contributing to more effective and consistent care. Future research in this area should focus on larger patient cohorts and further exploration of the potential benefits and applications of CFD and virtual surgery in otolaryngology.

A CFD approach to understand nasoseptal perforations.

INTRODUCTION: Nasoseptal perforations (NSP) are becoming common in the modern world, and can cause a wide variety of symptoms, including a sensation of nasal obstruction, epistaxis, crusting, dryness, headache, nasal pain and a whistling sound. There is an extensive range of surgical treatment techniques, but reported results were rarely statistically significant. The lack of consistent surgical results may be related to the lack of knowledge about the pathophysiology of NSP and how they affect the nasal flow. Computational fluid dynamics (CFD) has proved to be a very useful tool to study nasal function. METHODS: We have used CFD software (the program MECOMLAND® and the Digbody® tool for virtual surgery) to investigate the behaviour of the parameters R-[Formula: see text] based on CFD results, when four subjects underwent virtual surgery to induce a septal perforation: two subjects with healthy noses and two patients suffering from nasal airway obstruction. For each case a CFD study was performed, before and after creating an anterior (close to nostrils) or a posterior (close to choanae) NSP. RESULTS: In all cases analyzed, a posterior septal perforation did not result in a significant volumetric flow rate [Formula: see text] through the perforation between nasal passages. However, for anterior defects only in those nasal cavities considered diseased or unhealthy, high values of [Formula: see text] were found. CONCLUSION: The induced NSP only rendered significant flow alterations in noses with preexisting nasal airway obstruction alterations, whereas in nasal cavities considered as normal the creation of a NSP did not produce significant differences between both sides. We strongly suggest that this finding can explain the variety of symptoms and the number of asymptomatic patients bearing NSP.

DigBody®: A new 3D modeling tool for nasal virtual surgery.

BACKGROUND AND PURPOSE: Recent studies have demonstrated that a significant number of surgical procedures for nasal airway obstruction (NAO) have a high rate of surgical failure. In part, this problem is due to the lack of reliable objective clinical parameters to aid surgeons during preoperative planning. Modeling tools that allow virtual surgery to be performed do exist, but all require direct manipulation of computed tomography (CT) or magnetic resonance imaging (MRI) data. Specialists in Rhinology have criticized these tools for their complex user interface, and have requested more intuitive, user-friendly and powerful software to make virtual surgery more accessible and realistic. In this paper we present a new virtual surgery software tool, DigBody®. METHODS: This new surgery module is integrated into the computational fluid dynamics (CFD) program MeComLand®, which was developed exclusively to analyze nasal airflow. DigBody® works directly with a 3D nasal model that mimics real surgery. Furthermore, this surgery module permits direct assessment of the operated cavity following virtual surgery by CFD simulation. RESULTS: The effectiveness of DigBody® has been demonstrated by real surgery on two patients based on prior virtual operation results. Both subjects experienced excellent surgical outcomes with no residual nasal obstruction. CONCLUSIONS: This tool has great potential to aid surgeons in modeling potential surgical maneuvers, minimizing complications, and being confident that patients will receive optimal postoperative outcomes, validated by personalized CFD testing.

Robust nondimensional estimators to assess the nasal airflow in health and disease.

There are significant variations of both human nose shapes and airflow patterns inside nasal cavities, so it is difficult to provide a comprehensive medical identification using a universal template for what otolaryngologists consider normal breathing at rest. In addition, airflow patterns present even more random characteristics in diseased nasal cavities. To give a medical assessment to differentiate the nasal cavities in health and disease, we propose 2 nondimensional estimators obtained from both medical images and computational fluid dynamics. The first mathematical estimator ϕ is a function of geometric features and potential asymmetries between nasal passages, while the second estimator R represents in fluid mechanics terms the total nasal resistance that corresponds to the atmosphere-choana pressure drop. These estimators only require global information such as nasal geometry and magnitudes of flow determined by simulations under laminar conditions. We find that these estimators take low and high values for healthy and diseased nasal cavities, respectively. Our study, based on 24 healthy and 25 diseased Caucasian subjects, reveals that there is an interval of values associated with healthy cavities that clusters in a small region of the plane ϕ-R. Therefore, these estimators can be seen as a first approximation to provide nasal airflow data to the clinician in a noninvasive method, as the computed tomography scan that provides the required images is routinely obtained as a result of the preexisting naso-sinusal condition.

New CFD tools to evaluate nasal airflow.

Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. As currently CFD is not a usual tool for rhinologists, a group of engineers in collaboration with experts in Rhinology have developed a very intuitive CFD software. The program MECOMLAND® only required snapshots from the patient's cross-sectional (tomographic) images, being the output those results originated by CFD, such as airflow distributions, velocity profiles, pressure, temperature, or wall shear stress. This is useful complementary information to cover diagnosis, prognosis, or follow-up of nasal pathologies based on quantitative magnitudes linked to airflow. In addition, the user-friendly environment NOSELAND® helps the medical assessment significantly in the post-processing phase with dynamic reports using a 3D endoscopic view. Specialists in Rhinology have been asked for a more intuitive, simple, powerful CFD software to offer more quality and precision in their work to evaluate the nasal airflow. We present MECOMLAND® and NOSELAND® which have all the expected characteristics to fulfil this demand and offer a proper assessment with the maximum of quality plus safety for the patient. These programs represent a non-invasive, low-cost (as the CT scan is already performed in every patient) alternative for the functional study of the difficult rhinologic case. To validate the software, we studied two groups of patients from the Ear Nose Throat clinic, a first group with normal noses and a second group presenting septal deviations. Wall shear stresses are lower in the cases of normal noses in comparison with those for septal deviation. Besides, velocity field distributions, pressure drop between nasopharynx and the ambient, and flow rates in each nostril were different among the nasal cavities in the two groups. These software modules open up a promising future to simulate the nasal airflow behaviour in virtual surgery intervention scenarios under different pressure or temperature conditions to understand the effects on nasal airflow.

Aerosol properties of mineral dust and its mixtures in a regional background of north-central Iberian Peninsula.

To broaden the knowledge about desert dust (DD) aerosols in western Mediterranean Basin, their fingerprints on optical and microphysical properties are analyzed during DD episodes in the north-central plateau of the Iberian Peninsula between 2003 and 2014. Aerosol columnar properties obtained from the AErosol RObotic NETwork (AERONET), such as aerosol optical depth (AOD), Ångström exponent (AE), volume particle size distribution, volume concentration (VC), sphericity, single scattering albedo, among others, are analyzed in order to provide a general characterization, being some of them compared to particle mass surface concentrations PM10, PM2.5, and their ratio, data obtained from EMEP network. The mean intensity of DD episodes exhibits: AOD440nm=0.27±0.12, PM10=24±18µg/m3, AE=0.94±0.40 and PM2.5/PM10=0.54±0.16. The AOD and PM10 annual cycles show maximum intensity in March and summer and minima in winter. A customized threshold of AE=1 distinguishes two types of dusty days, those with a prevailing desert character and those of mixed type, which is corroborated by sphericity values. Three well established intervals are obtained with the fine mode volume fraction (VCF/VCT). Coarse-mode-dominated cases (VCF/VCT≤0.2) present a mineral dust character: e.g., particle maximum concentration about 2µm, non-sphericity, stronger absorption power at shorter wavelengths, among others. The relevance of the fine mode is noticeable in mixtures with a predominance of particles about 0.2-0.3µm radii. Conditions characterized by 0.2

Columnar and surface aerosol load over the Iberian Peninsula establishing annual cycles, trends, and relationships in five geographical sectors.

The study of atmospheric aerosol load over the Iberian Peninsula (IP) under a climatological perspective is accomplished by means of PM10 and AOD440 nm measurements from EMEP and AERONET networks, respectively, in the period 2000-2013. The PM10 annual cycles in five Iberian sectors show a main maximum in summer and a secondary maximum in spring, which is only observed in the southern area for the AOD climatology. The characteristics of PM10-AOD annual cycles of each geographical sector are explained by the different climatology of the air mass origins and their apportioning. The two magnitudes are correlated with a factor ranging between 20 and 90 depending on the sector. The temporal evolution of the aerosol load has shown a notable decrease in the IP since the 1980s. Statistically significant trends are obtained in the Northeastern sector with a reduction of 26% (period 1985-2000) for the total suspended particles, which continues for the PM10 data with a value of 35% per decade (2001-2013), and also in the whole column, 61% per decade in the AOD440 nm (2004-2013).

Influence of gestational diabetes mellitus on neonatal weight outcome in twin pregnancies.

AIMS: To evaluate the influence of gestational diabetes mellitus on neonatal birthweight, macrosomia and weight discrepancy in twin neonates. METHODS: An observational retrospective study was performed. One hundred and six women with gestational diabetes and twin pregnancy and 166 twin controls who delivered viable fetuses > 24 weeks were included. Impact of maternal pre-pregnancy BMI, smoking habit, method of conception, chorionicity, gestational age at delivery, mode of delivery and hypertensive complications were also analysed. The effect of maternal hyperglycaemia and metabolic control in gestational diabetes pregnancies was assessed. RESULTS: Gestational hypertension and pre-eclampsia were significantly higher in the group with gestational diabetes (21.5% vs. 6.3%, P = 0.007 and 6.2% vs. 0%, P = 0.025). There were no differences in the incidence of macrosomia (5.7% vs. 7.2%, P = 0.803), large for gestational age (10.3% vs. 13.2%, P = 0.570), small for gestational age (10.3% vs. 12.0%, P = 0.701), severely small for gestational age (6.6% vs. 7.8%, P = 0.814) or weight discrepancy (20.6% vs. 15.2%, P = 0.320) in the group with gestational diabetes compared with twin pregnancies without diabetes. There were no differences when comparing insulin-requiring gestational diabetes pregnancies and twins without diabetes for any of the neonatal weight outcomes. There was no relationship between third trimester HbA1c and neonatal birthweight or infant birthweight ratio. CONCLUSION: Gestational diabetes did not increase the risk of macrosomia or weight discrepancy of twin newborns. Furthermore, glycaemic control did not influence the rate of any of the weight outcomes in our study population. In twin pregnancies, gestational diabetes was associated with a higher risk of gestational hypertension and pre-eclampsia.

Body weight, weight gain and hyperglycaemia are associated with hypertensive disorders of pregnancy in women with gestational diabetes.

AIM: The aim of this study was to measure the capacity of glucose- and weight-related parameters to predict pregnancy-induced hypertensive disorders in women with gestational diabetes. METHODS: An observational study was conducted involving 2037 women with gestational diabetes. The associations of glycaemic and weight-related parameters with pregnancy-induced hypertensive disorders were obtained by univariate and adjusted multivariate analyses. Also, model predictability and attributable predictor risk percentages were calculated, and collinearity and factor interactions examined. RESULTS: Multivariate analyses revealed that hypertensive disorders were mainly predicted by average third-trimester glycated haemoglobin (HbA(1c)) levels ≥ 5.9%, by being overweight or obese before pregnancy and by excess gestational weight gain after adjusting for age, tobacco use, chronic hypertension, parity, urinary tract infections and gestational age at delivery. Prepregnancy body weight (overweight and obesity) had the strongest impact on pregnancy-related hypertensive disorders (attributable risk percentages were 51.5% and 88.8%, respectively). The effect of being overweight or obese on hypertensive disorders was enhanced by HbA(1c) levels and gestational weight gain, with elevated HbA(1c) levels multiplying the effect of being overweight before pregnancy. CONCLUSION: The average third-trimester HbA1c level is a novel risk factor for pregnancy-induced hypertensive disorders in women with gestational diabetes. HbA(1c) levels ≥ 5.9%, prepregnancy overweight or obesity and excess gestational weight gain are all independent risk factors of pregnancy-related hypertensive disorders in such women. In treated gestational diabetes patients, the strongest influence on hypertensive disorders is prepregnancy obesity.

Effects of the ambient temperature on the airflow across a Caucasian nasal cavity.

We analyse the effects of the air ambient temperature on the airflow across a Caucasian nasal cavity under different ambient temperatures using CFD simulations. A three-dimensional nasal model was constructed from high-resolution computed tomography images for a nasal cavity from a Caucasian male adult. An exhaustive parametric study was performed to analyse the laminar-compressible flow driven by two different pressure drops between the nostrils and the nasopharynx, which induced calm breathing flow rates ࣈ 5.7 L/min and ࣈ 11.3 L/min. The inlet air temperature covered the range - 10(o) C ⩽ To ⩽50(o) C. We observed that, keeping constant the wall temperature of the nasal cavity at 37(o) C, the ambient temperature affects mainly the airflow velocity into the valve region. Surprisingly, we found an excellent linear relationship between the ambient temperature and the air average temperature reached at different cross sections, independently of the pressure drop applied. Finally, we have also observed that the spatial evolution of the mean temperature data along the nasal cavity can be collapsed for all ambient temperatures analysed with the introduction of suitable dimensionless variables, and this evolution can be modelled with the help of hyperbolic functions, which are based on the heat exchanger theory.

Persistence of the effects of early experience on consumption of low-quality roughage by sheep.

The aim of this study was to determine the effects of experience early in life with cured weeping lovegrass (Eragrostis curvula) (low-quality roughage) or fresh oats (Avena sativa) (high-quality roughage) on voluntary intake and nitrogen retention when sheep ate a low-quality roughage 9 mo after initial exposure. From 1 to 5 mo of age, experienced wethers (EW) grazed cured weeping lovegrass, whereas inexperienced wethers (IW) grazed fresh oats (initial exposure). Then both EW and IW were fed sorghum (Sorghum bicolor) hay for 45 d, fresh weeping lovegrass for 105 d, and finally alfalfa hay for 120 d. Nine months after completion of the initial exposure EW and IW were offered sorghum hay (low-quality roughage), and, in addition, both groups were offered sorghum with ad libitum access simultaneously to alfalfa hay at six levels of availability. Experienced wethers ingested 15% more (P < .02) sorghum than IW. When given sorghum simultaneously with alfalfa at different levels of availability, EW ingested more (P < .10) sorghum than IW when only sorghum was freely available. Nitrogen retention was negative in both groups, but it was less negative in EW than in IW per unit of metabolic weight (P < .09) and per wether (P < .04). The results show that early dietary experience can have profound and persistent effects on consumption of foods low in nutritional quality, apparently through changes in critical physiological mechanisms.

Relationship of physical factors and salinity with indicator bacteria in Bahía Blanca estuary waters, Argentina.

The relationship between the number of Escherichia coli, terrestrial and marine heterotrophic bacteria, with certain physical and chemical parameters in Bahia Blanca estuary waters, were investigated by means of a statistical analysis of multiple linear regression. The samples were taken during a period of 16 months. Although distance from the sewage outlet seems to be the factor having the greatest effect on the number of alien bacteria, the models obtained for E. coli are inappropriate to predict bacterial behaviour in this particular natural habitat, while for heterotrophic bacteria descriptive models were selected. The results of this study suggest that many factors affect bacterial population densities in this estuarine ecosystem. This should be taken into account trying to solve the problem in order to avoid progressive degradation.

Relationship of physical factors and salinity with indicator bacteria in Bahía Blanca estuary waters, Argentina

The relationship between the number of Escherichia coli, terrestrial and marine heterotrophic bacteria, with certain physical and chemical parameters in Bahia Blanca estuary waters, were investigated by means of a statistical analysis of multiple linear regression. The samples were taken during a period of 16 months. Although distance from the sewage outlet seems to be the factor having the greatest effect on the number of alien bacteria, the models obtained for E. coli are inappropriate to predict bacterial behaviour in this particular natural habitat, while for heterotrophic bacteria descriptive models were selected. The results of this study suggest that many factors affect bacterial population densities in this estuarine ecosystem. This should be taken into account trying to solve the problem in order to avoid progressive degradation.

Relationship of physical factors and salinity with indicator bacteria in Bahía Blanca estuary waters, Argentina.

The relationship between the number of Escherichia coli, terrestrial and marine heterotrophic bacteria, with certain physical and chemical parameters in Bahia Blanca estuary waters, were investigated by means of a statistical analysis of multiple linear regression. The samples were taken during a period of 16 months. Although distance from the sewage outlet seems to be the factor having the greatest effect on the number of alien bacteria, the models obtained for E. coli are inappropriate to predict bacterial behaviour in this particular natural habitat, while for heterotrophic bacteria descriptive models were selected. The results of this study suggest that many factors affect bacterial population densities in this estuarine ecosystem. This should be taken into account trying to solve the problem in order to avoid progressive degradation.

[Spatial and temporal distribution of aerobic bacteria in the Bahía Blanca estuary, Argentina]. / Distribución espacial y temporal de bacterias aerobias en el estuario de Bahía Blanca, Argentina.

In order to study the baseline of the present bacteriological state in Bahia Blanca estuary (4) (Fig. 1 ), 13 sampling-stations were established Water samples were drawn from subsuperficial and 3 m depth from June 1984 to October 1985, during ten cruises. The heterotrophic aerobic, marine (BM) and terrestrial (BT) bacteria counts were subjected to analysis of variance (ANOVA), which were highly significant for both sampling stations and months of the year (Table 1). Scheffe's and Student-Newman-Keul's contrast tests were used to indicate which sampling stations and months of the year resulted in significant differences in number of bacteria (Tables 2, 3). Subsuperficial and 3 m counts were analysed by the signification F test. No significant differences were detected. Very good correlations were observed between BM and BT at each level (Table 4). Bacteria behaviour characteristics would be used to detect changes produced in the estuary due to human activities.

Distribución espacial y temporal de bacterias aerobias en el estuario de Bahía Blanca, Argentina. / [Spatial and temporal distribution of aerobic bacteria in the Bahía Blanca estuary, Argentina]

In order to study the baseline of the present bacteriological state in Bahia Blanca estuary (4) (Fig. 1 ), 13 sampling-stations were established Water samples were drawn from subsuperficial and 3 m depth from June 1984 to October 1985, during ten cruises. The heterotrophic aerobic, marine (BM) and terrestrial (BT) bacteria counts were subjected to analysis of variance (ANOVA), which were highly significant for both sampling stations and months of the year (Table 1). Scheffes and Student-Newman-Keuls contrast tests were used to indicate which sampling stations and months of the year resulted in significant differences in number of bacteria (Tables 2, 3). Subsuperficial and 3 m counts were analysed by the signification F test. No significant differences were detected. Very good correlations were observed between BM and BT at each level (Table 4).Bacteria behaviour characteristics would be used to detect changes produced in the estuary due to human activities.

Distribución espacial y temporal de bacterias aerobias en el estuario da Bahia Blanca, Argentina / Spatial and temporal distribution of aerobic bacteria in Bahia Blanca estuary, Argentina

Se establecieron 13 estaciones de muestreo en el estuario de Bahía Blanca con el objeto de realizar un estudo de base para conocer el estado bacteriológico actual de sus aguas. Durante el período comprendido entre junio 1984-octubre 1985 se realizaron 10 campañas para extraer muestras de agua subsuperficiales y a 3 m de profundidad. El análisis de varianza (ANOVA) realizado con el recuento de las bacterias heterótrofas aerobias, marinas (BM) y terrestres (BT), dio altamente significativo para las estaciones y para los meses del año. Mediante los contrastes de Scheffé y SNK, se determinaron las estaciones y los meses que dieron marcadas diferencias, en los recuentos bacterianos. La prueba F de significación no marcó diferencias entre los recuentos subsuperficiales y 3 m de cada grupo. Valores de correlación muy significativos se obtuvieron entre BM y BT en cada nivel. El patrón de comportamiento de las bacterias puede servir para detectar cambios, producidos en el estuario, por actividades humanas (AU)

Distribución espacial y temporal de bacterias aerobias en el estuario da Bahia Blanca, Argentina / Spatial and temporal distribution of aerobic bacteria in Bahia Blanca estuary, Argentina

Se establecieron 13 estaciones de muestreo en el estuario de Bahía Blanca con el objeto de realizar un estudo de base para conocer el estado bacteriológico actual de sus aguas. Durante el período comprendido entre junio 1984-octubre 1985 se realizaron 10 campañas para extraer muestras de agua subsuperficiales y a 3 m de profundidad. El análisis de varianza (ANOVA) realizado con el recuento de las bacterias heterótrofas aerobias, marinas (BM) y terrestres (BT), dio altamente significativo para las estaciones y para los meses del año. Mediante los contrastes de Scheffé y SNK, se determinaron las estaciones y los meses que dieron marcadas diferencias, en los recuentos bacterianos. La prueba F de significación no marcó diferencias entre los recuentos subsuperficiales y 3 m de cada grupo. Valores de correlación muy significativos se obtuvieron entre BM y BT en cada nivel. El patrón de comportamiento de las bacterias puede servir para detectar cambios, producidos en el estuario, por actividades humanas