Adequacy and Vitamin D in the Preoperative Period of Roux-en-Y Gastric Bypass, Bariatric Surgery, Can Protect Metabolic Health in Metabolically Healthy and Unhealthy Individuals.

Evaluating the influence of vitamin D concentrations together with preoperative metabolic phenotypes on remission of chronic noncommunicable diseases (CNCDs) after 6 months of Roux-en-Y gastric bypass (RYGB). Cross-sectional analytical study comprising 30 adult individuals who were assessed preoperatively (T0) and 6 months (T1) after undergoing RYGB. Participants were distributed preoperatively into metabolically healthy obese (MHO) and metabolically unhealthy obese (MUHO) individuals according to HOMA-IR classification and to the adequacy and inadequacy of vitamin D concentrations in the form of 25(OH)D. All participants were assessed for anthropometric characteristics, biochemical variables, and presence of CNCDs. The statistical program used was the SPSS version 21. In face of vitamin D adequacy and regardless of the metabolic phenotype classification in the preoperative period, the means found for HOMA-IR allowed us to define them as metabolically healthy 6 months after RYGB. Only those with vitamin D inadequacy with the MUHO phenotype showed better results regarding the reduction of glucose that accompanied the shift in serum 25(OH)D concentrations from deficient to insufficient. It is possible that preoperative vitamin D adequacy, even in the presence of an unhealthy phenotype, may contribute to the reduction of dyslipidemia and improvement in cholesterol. It is suggested that preoperative vitamin D adequacy in both phenotypes may have a protective effect on metabolic health.

High-accuracy detection of airway obstruction in asthma using machine learning algorithms and forced oscillation measurements.

BACKGROUND AND OBJECTIVES: The main pathologic feature of asthma is episodic airway obstruction. This is usually detected by spirometry and body plethysmography. These tests, however, require a high degree of collaboration and maximal effort on the part of the patient. There is agreement in the literature that there is a demand of research into new technologies to improve non-invasive testing of lung function. The purpose of this study was to develop automatic classifiers to simplify the clinical use and to increase the accuracy of the forced oscillation technique (FOT) in the diagnosis of airway obstruction in patients with asthma. METHODS: The data consisted of FOT parameters obtained from 75 volunteers (39 with obstruction and 36 without). Different supervised machine learning (ML) techniques were investigated, including k-nearest neighbors (KNN), random forest (RF), AdaBoost with decision trees (ADAB) and feature-based dissimilarity space classifier (FDSC). RESULTS: The first part of this study showed that the best FOT parameter was the resonance frequency (AUC = 0.81), which indicates moderate accuracy (0.70-0.90). In the second part of this study, the use of the cited ML techniques was investigated. All the classifiers improved the diagnostic accuracy. Notably, ADAB and KNN were very close to achieving high accuracy (AUC = 0.88 and 0.89, respectively). Experiments including the cross products of the FOT parameters showed that all the classifiers improved the diagnosis accuracy and KNN was able to reach a higher accuracy range (AUC = 0.91). CONCLUSIONS: Machine learning classifiers can help in the diagnosis of airway obstruction in asthma patients, and they can assist clinicians in airway obstruction identification.

Forced oscillation, integer and fractional-order modeling in asthma.

The purpose of this study was to evaluate the use of fractional-order (FrOr) modeling in asthma. To this end, three FrOr models were compared with traditional parameters and an integer-order model (InOr). We investigated which model would best fit the data, the correlation with traditional lung function tests and the contribution to the diagnostic of airway obstruction. The data consisted of forced oscillation (FO) measurements obtained from healthy (n=22) and asthmatic volunteers with mild (n=22), moderate (n=19) and severe (n=19) obstructions. The first part of this study showed that a FrOr was the model that best fit the data (relative distance: FrOr=4.3±2.4; InOr=5.1±2.6%). The correlation analysis resulted in reasonable (R=0.36) to very good (R=0.77) associations between FrOr parameters and spirometry. The closest associations were observed between parameters related to peripheral airway obstruction, showing a clear relationship between the FrOr models and lung mechanics. Receiver-operator analysis showed that FrOr parameters presented a high potential to contribute to the detection of the mild obstruction in a clinical setting. The accuracy [area under the Receiver Operating Characteristic curve (AUC)] observed in these parameters (AUC=0.954) was higher than that observed in traditional FO parameters (AUC=0.732) and that obtained from the InOr model (AUC=0.861). Patients with moderate and severe obstruction were identified with high accuracy (AUC=0.972 and 0.977, respectively). In conclusion, the results obtained are in close agreement with asthma pathology, and provide evidence that FO measurement associated with FrOr models is a non-invasive, simple and radiation-free method for the detection of biomechanical abnormalities in asthma.

Airflow pattern complexity and airway obstruction in asthma.

The scientific and clinical value of a measure of complexity is potentially enormous because complexity appears to be lost in the presence of illness. The authors examined the effect of elevated airway obstruction on the complexity of the airflow (Q) pattern of asthmatic patients analyzing the airflow approximate entropy (ApEnQ). This study involved 11 healthy controls, 11 asthmatics with normal spirometric exams, and 40 asthmatics with mild (14), moderate (14), and severe (12) airway obstructions. A significant (P < 0.02) reduction in the ApEnQ was observed in the asthmatic patients. This reduction was significantly correlated with spirometric indexes of airway obstruction [FEV(1) (%): R = 0.31, P = 0.013] and the total respiratory impedance (R = -0.39; P < 0.002). These results are in close agreement with pathophysiological fundamentals and suggest that the airflow pattern becomes less complex in asthmatic patients, which may reduce the adaptability of the respiratory system to perform the exercise that is associated with daily life activities. This analysis was able to identify respiratory changes in patients with mild obstruction with an adequate accuracy (83%). Higher accuracies were obtained in patients with moderate and severe obstructions. The analysis of airflow pattern complexity by the ApEnQ was able to provide new information concerning the changes associated with asthma. In addition, this analysis was also able to contribute to the detection of the adverse effects of asthma. Because these measurements are easy to perform, such a technique may represent an alternative and/or a complement to other conventional exams to help the clinical evaluations of asthmatic patients.

Approximate entropy as a measure of the airflow pattern complexity in asthma.

The scientific and clinical value of a measure of complexity is potentially enormous because complexity appears to be lost in the presence of illness. The changes introduced by asthma in respiratory mechanics and control of breathing may result in modifications in the airflow pattern. These changes may be interesting clinically, since they can reduce the ability of the patient to perform daily life activities. In this paper, we examine the effect of elevated airway obstruction on the complexity of the airflow pattern of asthmatic patients using the approximate entropy method (ApEnQ). This study involved 5 healthy and asthmatics with normal spirometric exam (5), mild (5), moderate (6) and severe (5) airway obstruction. A significant (p〈0.002) reduction in ApEnQ was observed in asthmatic patients. This reduction was significantly correlated with spirometric indices of airway obstruction (R=0.60; p〈0.001). These results are in close agreement with pathophysiological fundamentals, and suggest that in asthmatic patients the airflow pattern becomes less complex, which may reduce the adaptability of the respiratory system to perform exercise associated with daily life activities. Furthermore, our findings also suggest that ApEnQ may help the clinical evaluation of asthmatic patients.

Effects of airway obstruction on albuterol-mediated variations in the resistive and elastic properties of the respiratory system of patients with asthma.

OBJECTIVE: To investigate the effects of airway obstruction on albuterol-mediated variations in the resistive and elastic properties of the respiratory system of adult patients with asthma. METHODS: This study comprised 24 healthy controls and 69 patients with asthma, all of whom were nonsmokers. The patients were divided into three groups according to the severity of airway obstruction (mild, moderate or severe). Each of the three groups was divided into two subgroups according to the bronchodilator response (BR): positive (BR+) or negative (BR(-)). Airway obstruction was determined by means of spirometry, and the resistive and elastic properties were determined by means of the forced oscillation technique. These measurements were conducted before and after albuterol use (300 microg). RESULTS: The resistance at the intercept (R(0)) presented greater reductions in the groups with higher obstruction. This reduction was more evident in the BR+ subgroups than in the BR(-) subgroups (p < 0.02 and p < 0.03, respectively). There was a significant difference between the control group and the BR+ subgroup with severe obstruction (p < 0.002). The reductions in dynamic elastance (Edyn) were significantly greater in proportion to the degree of obstruction, in the BR(-) subgroups (p < 0.03), and in the BR+ subgroups (p < 0.003). The reductions in Edyn were significantly greater in the BR- subgroup with moderate obstruction (p < 0.008) and in the BR+ subgroup with severe obstruction (p < 0.0005) than in the control group. CONCLUSIONS: In patients with asthma, increased airway obstruction results in greater reductions in R(0) and Edyn after albuterol use. These reductions are greater among BR+ patients than among BR(-) patients.

Within-breath analysis of respiratory mechanics in asthmatic patients by forced oscillation.

INTRODUCTION: The within-breath analysis of respiratory mechanics by the monofrequency Forced Oscillation Technique (mFOT) is of great interest in both physiopathology studies and the diagnosis of respiratory diseases. However, there are limited data on the use of this technique in the analysis of asthma. This study evaluates within-breath mechanics of asthmatic individuals and the contribution of the mFOT in the asthma diagnosis. METHODS: Twenty-two healthy and twenty-two asthmatic subjects, including patients with mild (n=8), moderate (n=8), and severe (n=6) obstruction, were studied. Forced Oscillation Technique data were interpreted using the mean respiratory impedance (Zt), the impedance during inspiration (Zi), expiration (Ze), at the beginning of inspiration (Zii), and at expiration (Zie). The peak-to-peak impedance (Zpp) was also calculated by the subtraction of Zii from Zie. Receiver operating characteristic curves were used to determine the sensitivity (Se) and specificity (Sp) of m Forced Oscillation Technique parameters in identifying asthma. RESULTS: Respiratory impedance values were significantly higher in asthmatics: Zt (p<0.001), Zi (p<0.001), Ze (p<0.001), Zii (p<0.001), Zie (p<0.001), and Zpp (p<0.003). The best parameters for detecting asthma were Zi, Zii, and Zie (Se=90.9%, Sp=90.9%), followed by Zt and Ze. These results are in close agreement with recently published theories and pathophysiological fundamentals. CONCLUSIONS: mFOT permits a non-invasive and detailed analysis in different phases of the respiratory cycle, providing parameters that are adequate for the diagnosis of asthma with high accuracy. These results confirm the high clinical and scientific potential of this methodology in the evaluation of asthmatic patients.

Efeito da obstrução de vias aéreas nas variações das propriedades resistivas e elásticas do sistema respiratório de asmáticos, mediadas pelo uso de salbutamol / Effects of airway obstruction on albuterol-mediated variations in the resistive and elastic properties of the respiratory system of patients with asthma

OBJETIVO: Investigar os efeitos da obstrução de vias aéreas nas variações das propriedades resistivas e elásticas do sistema respiratório de asmáticos adultos mediadas pelo uso de salbutamol. MÉTODOS: Foram analisados 24 indivíduos controles e 69 asmáticos, todos não tabagistas, divididos em três grupos segundo o nível de obstrução de vias aéreas (leve, moderada e acentuada). Cada grupo foi dividido em dois subgrupos de acordo com a resposta broncodilatadora: resposta broncodilatadora positiva (RB+) ou negativa (RB-). A espirometria foi utilizada para a avaliação da obstrução, e a técnica de oscilações forçadas, para a análise das propriedades resistivas e elásticas, sendo realizadas antes e após a utilização de 300 µg de salbutamol. RESULTADOS: A resistência no intercepto (R0) apresentou maior redução nos grupos com maior obstrução. Essa redução foi mais evidente nos subgrupos RB+ do que nos RB- (p < 0,02 e p < 0,03, respectivamente). Houve diferença significativa entre o grupo controle e a o subgrupo com obstrução acentuada RB+ (p < 0,002). As reduções na elastância dinâmica (Edyn) se acentuaram significativamente com a obstrução, tanto para os subgrupos RB- (p < 0,03), quanto para os RB+ (p < 0,003). As reduções da Edyn foram significativamente maiores nos subgrupos com obstrução moderada RB- (p < 0,008) e com obstrução acentuada RB+ (p < 0,0005) do que no grupo controle. CONCLUSÕES: Em asmáticos, o aumento da obstrução de vias aéreas resulta na elevação das variações em R0 e Edyn com o uso de salbutamol. Pacientes com RB+ apresentam variações mais elevadas que indivíduos com RB-.

OBJECTIVE: To investigate the effects of airway obstruction on albuterol-mediated variations in the resistive and elastic properties of the respiratory system of adult patients with asthma. METHODS: This study comprised 24 healthy controls and 69 patients with asthma, all of whom were nonsmokers. The patients were divided into three groups according to the severity of airway obstruction (mild, moderate or severe). Each of the three groups was divided into two subgroups according to the bronchodilator response (BR): positive (BR+) or negative (BR-). Airway obstruction was determined by means of spirometry, and the resistive and elastic properties were determined by means of the forced oscillation technique. These measurements were conducted before and after albuterol use (300 µg). RESULTS: The resistance at the intercept (R0) presented greater reductions in the groups with higher obstruction. This reduction was more evident in the BR+ subgroups than in the BR- subgroups (p < 0.02 and p < 0.03, respectively). There was a significant difference between the control group and the BR+ subgroup with severe obstruction (p < 0.002). The reductions in dynamic elastance (Edyn) were significantly greater in proportion to the degree of obstruction, in the BR- subgroups (p < 0.03), and in the BR+ subgroups (p < 0.003). The reductions in Edyn were significantly greater in the BR- subgroup with moderate obstruction (p < 0.008) and in the BR+ subgroup with severe obstruction (p < 0.0005) than in the control group. CONCLUSIONS: In patients with asthma, increased airway obstruction results in greater reductions in R0 and Edyn after albuterol use. These reductions are greater among BR+ patients than among BR- patients.

Within-breath analysis of respiratory mechanics in asthmatic patients by forced oscillation

INTRODUCTION: The within-breath analysis of respiratory mechanics by the monofrequency Forced Oscillation Technique (mFOT) is of great interest in both physiopathology studies and the diagnosis of respiratory diseases. However, there are limited data on the use of this technique in the analysis of asthma. This study evaluates within-breath mechanics of asthmatic individuals and the contribution of the mFOT in the asthma diagnosis. METHODS: Twenty-two healthy and twenty-two asthmatic subjects, including patients with mild (n=8), moderate (n=8), and severe (n=6) obstruction, were studied. Forced Oscillation Technique data were interpreted using the mean respiratory impedance (Zt), the impedance during inspiration (Zi), expiration (Ze), at the beginning of inspiration (Zii), and at expiration (Zie). The peakto-peak impedance (Zpp) was also calculated by the subtraction of Zii from Zie. Receiver operating characteristic curves were used to determine the sensitivity (Se) and specificity (Sp) of m Forced Oscillation Technique parameters in identifying asthma. RESULTS: Respiratory impedance values were significantly higher in asthmatics: Zt (p<0.001), Zi (p<0.001), Ze (p<0.001), Zii (p<0.001), Zie (p<0.001), and Zpp (p<0.003). The best parameters for detecting asthma were Zi, Zii, and Zie (Se=90.9%, Sp=90.9%), followed by Zt and Ze. These results are in close agreement with recently published theories and pathophysiological fundamentals. CONCLUSIONS: mFOT permits a non-invasive and detailed analysis in different phases of the respiratory cycle, providing parameters that are adequate for the diagnosis of asthma with high accuracy. These results confirm the high clinical and scientific potential of this methodology in the evaluation of asthmatic patients.

Efeito do Flutter® VRP1 na mecânica respiratória de indivíduos saudáveis e portadores de DPOC, asma e bronquiectasia / Respiratory mechanic effects of Flutter® VRP1 in healthy subjects and COPD, asthma and bronchiectasis patients

Introdução: O Flutter® VRP1 é um dispositivo que combina pressão positiva expiratória e oscilações de alta freqüência com objetivo de manter as vias aéreas pérvias. Apesar de sua utilização rotineira na prática da fisioterapia, seu efeito na mecânicarespiratória é escasso na literatura. O presente estudo investigou o efeito, a curto prazo, do uso deste dispositvo em indivíduos saudáveis e em pacientes portadores de Doença Pulmonar Obstrutiva Crônica (DPOC), asma e bronquiectasia. Metodologia: Os pacientes foram submetidos à utilização do Flutter® VRP1 por um período de 5 a 10 minutos. Para análise da mecânica respiratória, a técnica de oscilações forçadas (FOT) e a espirometria foram realizadas antes e imediatamente após o uso do dispositivo. Resultados: O uso do Flutter® VRP1 não resultou em alterações significativas nos parâmetros avaliados pela FOT nos grupos estudados. Considerando-se a espirometria, a única variável que apresentou diferença significativa (p<0,05) foi VEF1 (L) no grupo controle. Conclusão: Com o protocolo utilizado, nos grupos de indivíduos saudáveis e de portadores de DPOC, asma e bronquiectasia, o uso do Flutter® VRP1 não introduziu modificações, a curto prazo, na mecânica respiratória.

Introduction: The Flutter® VRP1 is a device that combines expiratory positive airway pressure with high frequency oscillations to keep airway clean. In spite of the widely clinical use, the effect analyze of this device in the respiratory mechanics of obstructive patients is little. The aim of the present study was to investigate the short-term effect of the use of the Flutter® VRP1 in healthy subjects and patients with Pulmonary Disease, Chronic Obstructive (COPD), asthma and bronchiectasis.Methodology: The patients were submitted to a protocol where the Flutter® VRP1 was used for a period of 5 to 10 minutes. Changes in pulmonary mechanics were analyzed by the forced oscillations technique (FOT) and spirometry, which were performed before and immediately after the use of the device. Results: The use of Flutter® VRP1 didn’t result in significant alterations in the evaluated parameters of FOT in the studied groups. Considering spirometry, the only variable that presented significant difference (p <0.05) was VEF1 (L) in healthy group. Conclusion: With the used protocol, in the studied populationof healthy subjects and patients with COPD, asthma and bronchiectasis, the use of the Flutter® VRP1 do not introduced shortterm modifications in respiratory mechanics.