[Determining the alveolar component of nitric oxide in exhaled air: procedures and reference values for healthy persons]. / Determinación de la concentración de óxido nítrico alveolar en aire espirado: procedimiento y valores de referencia en personas sanas.

Nitric oxide (NO) production has been described using a 2-compartment model for the synthesis and movement of NO in both the alveoli and the airways. The alveolar concentration of NO (Ca(NO)), an indirect marker of the inflammatory state of the distal portions of the lung, can be deduced through exhalation at multiple flow rates. Our objective was to determine reference values for Ca(NO). The fraction of exhaled NO (Fe(NO)) was measured in 33 healthy individuals at a rate of 50mL/s; the subjects then exhaled at 10, 30, 100, and 200mL/s to calculate Ca(NO). A chemiluminescence analyzer (NIOX Aerocrine) was used to perform the measurements. The mean (SD) Fe(NO) was 15 (6)ppb. The mean Ca(NO) was 3.04 (1.30)ppb. These values of Ca(NO) measured in healthy individuals will allow us to analyze alveolar inflammatory behavior in respiratory and systemic processes.

[Assessment of differential lung function by electrical impedance tomography]. / Evaluación de la función pulmonar unilateral mediante tomografía por impedancia eléctrica.

OBJECTIVE: To compare unilateral lung function estimated by 2 methods: electrical impedance tomography (EIT) and ventilation-perfusion lung scintigraphy. PATIENTS AND METHODS: This prospective clinical study was carried out in the pulmonary function laboratory of a general hospital. Twenty patients diagnosed with lung cancer (17 men and 3 women, ranging in age from 25 to 77 years) who were candidates for lung resection underwent ventilation-perfusion lung scanning breathing a radioactive gas. Differential lung function was estimated based on images taken at 2 intercostal spaces in which ventilation and perfusion were represented by changes in bioelectrical impedance. Each lung's contribution to overall respiratory function was also calculated based on scintigraphy. RESULTS: The right lung contributed a mean (SD) of 54% (9%) of ventilation (range, 32%-71%) according to EIT. Scintigraphy similarly estimated the right lung's contribution to be 52% (10%) of total ventilation (range, 31%-80%) and 50% (9%) of perfusion (range, 37%-71%). The difference between the 2 estimates was not significant (t test), and the correlation coefficients between them were r=0.90 for ventilation and r=0.72 for perfusion (P< .05 in both cases). The analysis of agreement showed that the mean difference between the methods was 1.9% (95% confidence interval [CI], 10.5% to -6.8%) for ventilation and 3.4% (95% CI, 17.1% to -10.3%) for perfusion. CONCLUSIONS: EIT is able to estimate differential lung function as accurately as ventilation-perfusion scintigraphy.

[Risk factors for mortality in chronic obstructive pulmonary disease]. / Factores de riesgo de mortalidad en la EPOC.

OBJECTIVE: Although the factors predictive of survival in patients with chronic obstructive pulmonary disease (COPD) have been widely studied, full consensus has yet to be reached. The objective of this study was to further clarify how lung function parameters, exercise tolerance, and quality of life influence survival in patients with COPD. PATIENTS AND METHODS: This prospective study included 60 patients diagnosed with COPD. At the start of the study, patients underwent respiratory function tests, exercise testing, and 6-minute walk test. They also answered a chronic respiratory disease questionnaire to measure health-related quality of life. Follow-up lasted 7 years. RESULTS: Five of the 60 patients withdrew from the study. Twenty-six of the remaining 55 patients (47%) died during the study. Univariate Cox regression analysis showed a correlation between survival and age, degree of obstruction, inspiratory capacity, carbon monoxide diffusing capacity, and peak exercise tolerance. No correlation was found between survival and body mass index, PaO2, PaCO2, total lung capacity, residual volume, maximal respiratory pressures, 6-minute walk distance, or health-related quality of life. Age, degree of obstruction (measured as the ratio of forced expiratory volume in 1 second to forced vital capacity after administration of bronchodilator), and maximum minute ventilation in the exercise test were introduced initially in the multivariate Cox stepwise regression analysis, but only maximum minute ventilation remained in the final model (relative risk, 0.926; P< .001). CONCLUSIONS: Our findings show that peak exercise tolerance is the best predictor of survival in patients with COPD.

[Monitoring of breathing pattern at rest by electrical impedance tomography]. / Seguimiento del patrón ventilatorio en reposo mediante tomografía por impedancia eléctrica.

OBJECTIVE: Electrical impedance tomography (EIT) involves the application of a small alternating current to produce a series of chest images that can be used to monitor breathing pattern. The relation between chest images and tidal volume has not been sufficiently validated. The aim of the present study was to analyze the correlation between EIT images and the volume-time signal measured with a pneumotachometer in 13 healthy volunteers. MATERIAL AND METHODS: The following measurement devices were used: a) MedGraphics preVent Pneumotach, with special software for recording the volume-time signal (reference test), and b) EIT-4, a fourth-generation prototype unit designed by the Department of Electronic Engineering at the Universidad Politécnica de Cataluña, Spain that records the volume-time signal and produces a graphic depiction of a cross section of the thorax at the sixth intercostal space. RESULTS: The mean (SD) tidal volume measured by the pneumotachometer and the EIT-4 was 0.523 (0.102) L and 0.527 (0.106) L, respectively (P value not significant). The linear correlation coefficient between the 2 measurements was 0.923 (P=.001), and the mean of the differences between the 2 procedures was -0.003 L (95% confidence interval, -0.045 to 0.038). The greatest differences were associated with female gender, body mass index, and chest circumference. In view of these differences, a different equation based on these variables was needed for calibration of the EIT-4. CONCLUSIONS: The EIT-4 provides an alternative means of monitoring breathing pattern, although a number of issues related to the circumference of the rib cage need to be resolved.

Video-assisted sympathectomy for essential hyperhidrosis: effects on cardiopulmonary function.

BACKGROUND: Essential hyperhidrosis is characterized by overactivity of the sympathetic fibers passing through the upper-dorsal ganglia (second and third thoracic ganglia [D2-D3]), and the treatment of choice is video-assisted thoracoscopy sympathectomy. Alterations in cardiopulmonary function after treatment have been reported. STUDY OBJECTIVE: To evaluate cardiopulmonary function impairment after sympathectomy in patients with essential hyperhidrosis. DESIGN AND SETTING: Prospective controlled trial at a pulmonary function unit of a university hospital. PATIENTS: Twenty patients (2 men and 18 women) with essential hyperhidrosis. MEASUREMENTS AND RESULTS: Pulmonary function tests, including spirometry and thoracic gas volume, bronchial challenge with methacholine, and maximal exercise, were performed before and 3 months after D2-D3 sympathectomy. Video-assisted sympathectomy was performed using a one-stage bilateral procedure with electrocoagulation of D2-D3 ganglia. Pulmonary function values (spirometrics and volumes) were not statistically different in the two groups. The maximal midexpiratory flow was the only variable that showed significant changes, from 101% (SD, 26%) to 92% (SD, 27%) [p < 0.05]. Ten patients had positive bronchial challenge test results that remained positive 3 months after surgery, and 2 patients whose challenge test results were negative before surgery became positive after sympathectomy. Significant reductions in maximal heart rate (HR) and oxygen and carbon dioxide uptakes were observed during the maximal exercise test. CONCLUSIONS: Video-assisted thoracoscopy is a safe treatment, and the observed modifications in cardiopulmonary function only suggest a minimal small airway alterations in the presence of positive bronchial hyperresponsiveness and mild sympathetic blockade in HR. The clinical importance of these findings is not significant.

Use of electrical impedance tomography (EIT) for the assessment of unilateral pulmonary function.

We describe a fully automatable quantification process for the assessment of unilateral pulmonary function (UPF) by means of EIT and propose a measurement protocol for its clinical implementation. Measurements were performed at the fourth and sixth intercostal levels on a first group of ten healthy subjects (5M, 5F, ages 26-48 years) to define the proper protocol by evaluating the most common postures and ventilation modes. Several off-line processing tools were also evaluated, including the use of digital filters to extract the respiratory components from EIT time series. Comparative measures were then carried out on a second group consisting of five preoperatory patients with lung cancer (4M, IF, ages 25-77 years) scheduled for radionuclide scanning. Results show that measurements were best performed with the subject sitting down, holding his arms up and breathing spontaneously. As regards data processing, it is best to extract Fourier respiratory components. The mean of the healthy subject group leads to a left-right division of lung ventilation consistent with literature values (47% left lung, 53% right lung). The comparative study indicates a good correlation (r = 0.96) between the two techniques, with a mean difference of (-0.4+/-5.4)%, suggesting that the elimination of cardiac components from the thoracic transimpedance signal leads to a better estimation of UPF.

Maximal oxygen uptake cannot be estimated from resting lung function and submaximal exercise in patients with chronic obstructive pulmonary disease.

BACKGROUND: Maximal oxygen uptake ((V)O(2max)) obtained from incremental exercise testing is a useful indicator of limited exercise capacity. Several prediction equations have been developed to estimate (V)O(2max) in patients with chronic obstructive pulmonary disease (COPD), but agreement studies between estimated and measured (V)O(2max) are lacking. This study aims to assess agreement between the 6 estimated (V)O(2max) evaluated during maximal incremental exercise testing in male COPD patients. METHODS: Patients with stable COPD, in accordance with GOLD guidelines, were included in the study. Agreement between (V)O(2max) obtained during incremental exercise testing and (V)O(2max) obtained from 6 prediction equations were studied. To estimate (V)O(2max) from anthropometric prediction equations, lung function variables and submaximal exercise testing were used. RESULTS: Of the 60 male patients in the study, 12 were GOLD stage II, 24 GOLD stage III, and 24 GOLD stage IV. Five prediction equations underestimated the value of (V)O(2max) in relation to measured (V)O(2max) : equations 1, 2, 3, 4, and 6, by 14%, 66%, 42.2%, 35%, and 23.3%, respectively. Conversely, prediction equation 5 overestimated measured (V)O(2max) by 76.9%. Agreement between all (V)O(2max) prediction equations and measured (V)O(2max) was poor. Discrepancy between (V)O(2max) prediction equations and measured (V)O(2max) varied from 20.857 to 0.736 L/min. CONCLUSIONS: The use of lung function at rest and submaximal exercise testing is inaccurate for determining (V)O(2max) , which cannot be estimated by prediction equations in patients with stable COPD.

How to implement the family-centered model in early intervention / Cómo implementar el modelo centrado en la familia en la intervención temprana

From the results of a research aimed at improving the quality of life of families with a child with intellectual disability, the purpose of this paper is to provide a methodology for the implementation of the family centered model in early childhood intervention centers in our country. Quantitative and qualitative analyses of the collected data allow us to systematize the steps or stages that would be necessary to provide professionals and families in early intervention centers with useful tools to empower the families and to enhance the children's development. This article represents another step further from the proposals made by other researchers in other countries with different traditions and culture in the field of early intervention, and intends to reflect the characteristics of our country in terms of the history and the path of early intervention in recent decades (AU)

A partir de los resultados de una investigación encaminada a la mejora de la calidad de vida de las familias con un hijo o hija con discapacidad intelectual, el objetivo del presente trabajo es ofrecer una propuesta metodológica para la implementación del modelo centrado en la familia en los centros de atención temprana de nuestro país. Los análisis cuantitativos y cualitativos de los datos recogidos nos permiten sistematizar los pasos o fases que sería necesario seguir con el fin de proporcionar herramientas útiles a los profesionales y a las familias de los centros de atención temprana para promover el desarrollo de los niños y el empoderamiento de las familias. El artículo supone un paso adelante respecto a las propuestas realizadas por otros investigadores de otros países con tradiciones y cultura diferentes en el ámbito de la atención temprana y trata de recoger las características y la idiosincrasia de nuestro país en cuanto a la historia y la trayectoria de la atención temprana en las últimas décadas (AU)

[Bilateral dorsal sympathectomy for the treatment of primary hyperhidrosis: effects on lung function at 3 years]. / Simpatectomía dorsal bilateral en el tratamiento de la hiperhidrosis esencial: efectos a los 3 años sobre la función pulmonar.

INTRODUCTION: Primary hyperhidrosis is characterized by excessive sweating of the palms, soles, and axillae due to overactivity of the sympathetic nervous system at the level of the second and third sympathetic thoracic ganglia. The treatment of choice is bilateral dorsal sympathectomy performed using video-assisted thoracic surgery (VATS). The objective of our study was to determine whether lung function changes observed in a group of patients prior to bilateral dorsal sympathectomy performed using VATS were still evident 3 years after surgery. PATIENTS AND METHODS: Of the 20 patients studied at baseline, we were able to obtain data for 18 (3 men and 15 women; mean age, 35 y). They underwent spirometry and a bronchial challenge test with methacholine, and the fraction of exhaled nitric oxide (FE(NO)) was measured. The results were compared with those of the tests performed before surgery. RESULTS: At 3 years from baseline, we detected a statistically significant increase in forced vital capacity from a mean (SD) of 96% (10%) to 101% (11%) (P=.008), and a statistically significant decrease in midexpiratory flow rate from 3.8 (0.9)L/s to 3.5 (0.9)L/s (P=.01). The results of the bronchial challenge test with methacholine and the FE(NO) remained unchanged. CONCLUSIONS: The lung function changes detected point toward minimal, clinically insignificant small airway alterations due to sympathetic denervation following bilateral dorsal sympathectomy performed 3 years earlier.

[Measuring breathing pattern in patients with chronic obstructive pulmonary disease by electrical impedance tomography]. / Medición del patrón ventilatorio mediante tomografía por impedancia eléctrica en pacientes con EPOC.

BACKGROUND AND OBJECTIVE: The measurement of breathing pattern in patients with chronic obstructive pulmonary disease (COPD) by electrical impedance tomography (EIT) requires the use of a mathematical calibration model incorporating not only anthropometric characteristics (previously evaluated in healthy individuals) but probably functional alterations associated with COPD as well. The aim of this study was to analyze the association between EIT measurements and spirometry parameters, static lung volumes, and carbon monoxide diffusing capacity (DLCO) in a group of male patients to develop a calibration equation for converting EIT signals into volume signals. MATERIALS AND METHODS: We measured forced vital capacity (FVC), forced expiratory volume in 1 second (FEV(1)), FEV(1)/FVC, residual volume, total lung capacity, DLCO, carbon monoxide transfer coefficient (KCO) and standard anthropometric parameters in 28 patients with a FEV(1)/FVC ratio of <70%. We then compared tidal volume measurements from a previously validated EIT unit and a standard pneumotachometer. RESULTS: The mean (SD) lung function results were FVC, 72 (16%); FEV(1), 43% (14%); FEV(1)/FVC, 42% (9%); residual volume, 161% (44%); total lung capacity, 112% (17%); DLCO, 58% (17%); and KCO, 75% (25%). Mean (SD) tidal volumes measured by the pneumotachometer and the EIT unit were 0.697 (0.181)L and 0.515 (0.223)L, respectively (P<.001). Significant associations were found between EIT measurements and CO transfer parameters. The mathematical model developed to adjust for the differences between the 2 measurements (R(2)=0.568; P<.001) was compensation factor=1.81# - 0.82# height (m)# -0.004 x KCO (%). CONCLUSIONS: The measurement of breathing pattern by EIT in patients with COPD requires the use of a previously calculated calibration equation that incorporates not only individual anthropometric characteristics but gas exchange parameters as well.

Simpatectomía dorsal bilateral en el tratamiento de la hiperhidrosis esencial: efectos a los 3 años sobre la función pulmonar / Bilateral dorsal sympathectomy for the treatment of primary hyperhidrosis: effects on lung function at 3 years

Introducción La hiperhidrosis esencial se caracteriza por un exceso de sudoración en la palma de las manos, la planta de los pies y las axilas, debida a una hiperestimulación del sistema nervioso simpático que pasa a través del segundo y tercer ganglios torácicos simpáticos. El tratamiento de elección es la simpatectomía dorsal bilateral (SDB) por videotoracoscopia. El objetivo de nuestro estudio ha sido evaluar si las modificaciones en la función respiratoria halladas previamente en un grupo de pacientes intervenidos por SDB se mantenían a los 3 años de la cirugía. Pacientes y métodos Del grupo de 20 pacientes estudiados previamente, pudimos reunir a 18 (3 varones y 15 mujeres) con una edad media de 35 años. Se les realizaron una espirometría y una prueba de provocación bronquial con metacolina, y se determinó la concentración de óxido nítrico en aire espirado. Los resultados se compararon con los de las pruebas efectuadas antes de la cirugía. Resultados A los 3 años se detectó un incremento estadísticamente significativo del porcentaje de la capacidad vital forzada basal, que pasó de un valor medio (±desviación estándar) del 96±10% al 101±11% (p=0,008). Respecto a las cifras iniciales del flujo máximo mesoespiratorio, se halló un descenso estadísticamente significativo a los 3 años de la cirugía: de un valor basal de 3,8±0,9l/s se pasó a 3,5±0,9l/s (p=0,01). La prueba de provocación bronquial con metacolina y la concentración de óxido nítrico en aire espirado no experimentaron cambios a los 3 años. Conclusiones Las modificaciones en la función pulmonar indican una mínima afectación de la pequeña vía aérea, que persiste a los 3 años de la SDB, como consecuencia de la denervación simpática producida por la cirugía, pero sin ninguna significación clínica(AU)

Introduction Primary hyperhidrosis is characterized by excessive sweating of the palms, soles, and axillae due to overactivity of the sympathetic nervous system at the level of the second and third sympathetic thoracic ganglia. The treatment of choice is bilateral dorsal sympathectomy performed using video-assisted thoracic surgery (VATS). The objective of our study was to determine whether lung function changes observed in a group of patients prior to bilateral dorsal sympathectomy performed using VATS were still evident 3 years after surgery. Patients and methods Of the 20 patients studied at baseline, we were able to obtain data for 18 (3 men and 15 women; mean age, 35 y). They underwent spirometry and a bronchial challenge test with methacholine, and the fraction of exhaled nitric oxide (FENO) was measured. The results were compared with those of the tests performed before surgery. Results At 3 years from baseline, we detected a statistically significant increase in forced vital capacity from a mean (SD) of 96% (10%) to 101% (11%) (P=.008), and a statistically significant decrease in midexpiratory flow rate from 3.8 (0.9)L/s to 3.5 (0.9)L/s (P=.01). The results of the bronchial challenge test with methacholine and the FENO remained unchanged. Conclusions The lung function changes detected point toward minimal, clinically insignificant small airway alterations due to sympathetic denervation following bilateral dorsal sympathectomy performed 3 years earlier(AU)

Medición del patrón ventilatorio mediante tomografía por impedancia eléctrica en pacientes con EPOC / Measuring Breathing Pattern in Patients With Chronic Obstructive Pulmonary Disease by Electrical Impedance Tomography

Introducción. La medición del patrón ventilatorio (PV) en pacientes con enfermedad pulmonar obstructiva crónica (EPOC) mediante tomografía por impedancia eléctrica (TIE) requiere disponer de un modelo matemático de calibración que tenga en cuenta no sólo las características antropométricas (ya evaluadas en la persona sana), sino probablemente también las alteraciones funcionales propias de la enfermedad. El objetivo del presente estudio ha sido relacionar, en un grupo de pacientes (varones) con EPOC, las variables de la función pulmonar espirometría, volúmenes estáticos, transferencia de monóxido de carbono (CO) con las determinaciones de TIE y obtener una ecuación de calibración que permita convertir la señal eléctrica de la TIE en una señal de volumen.Material y métodosSe estudió a 28 pacientes volumen espiratorio forzado en el primer segundo (FEV1)/capacidad vital forzada (FVC)<70% con un equipo TIE-4 previamente validado y se compararon los resultados con los de un neumotacómetro estándar. Previamente se determinaron los siguientes parámetros: FVC, FEV1, FEV1/FVC, volumen residual, capacidad pulmonar total, capacidad de difusión de CO y coeficiente de transferencia de CO (KCO), además de las variables antropométricas habituales.ResultadosLos valores medios (±desviación estándar) de las diferentes pruebas funcionales fueron: FVC del 72±16%; FEV1 del 43±14%; FEV1/FVC del 42±9%; volumen residual del 161±44%, capacidad pulmonar total del 112±17%; capacidad de difusión de CO del 58±17%, y KCO del 76±25%. Los valores medios de volumen circulante de las determinaciones obtenidas con el neumotacómetro y la TIE fueron de 0,697±0,181 y 0,515±0,223l, respectivamente (p<0,001). Se encontraron relaciones significativas entre las medidas de la TIE y la transferencia de CO. El modelo matemático para ajustar las diferencias entre ambas determinaciones (R2=0,568; p<0,001) fue: factor de compensación=1,81 0,82×talla (m) 0,004×KCO (%). Conclusiones. La medición del PV mediante un equipo de TIE en pacientes con EPOC requiere una calibración previa que tenga en cuenta no sólo las características físicas de cada individuo, sino además la situación funcional del área de intercambio gaseoso (AU)

Background and ObjectiveThe measurement of breathing pattern in patients with chronic obstructive pulmonary disease (COPD) by electrical impedance tomography (EIT) requires the use of a mathematical calibration model incorporating not only anthropometric characteristics (previously evaluated in healthy individuals) but probably functional alterations associated with COPD as well. The aim of this study was to analyze the association between EIT measurements and spirometry parameters, static lung volumes, and carbon monoxide diffusing capacity (DLCO) in a group of male patients to develop a calibration equation for converting EIT signals into volume signals.Materials and MethodsWe measured forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC, residual volume, total lung capacity, DLCO, carbon monoxide transfer coefficient (KCO) and standard anthropometric parameters in 28 patients with a FEV1/FVC ratio of <70%. We then compared tidal volume measurements from a previously validated EIT unit and a standard pneumotachometer.ResultsThe mean (SD) lung function results were FVC, 72 (16%); FEV1, 43% (14%); FEV1/FVC, 42% (9%); residual volume, 161% (44%); total lung capacity, 112% (17%); DLCO, 58% (17%); and KCO, 75% (25%). Mean (SD) tidal volumes measured by the pneumotachometer and the EIT unit were 0.697 (0.181)L and 0.515 (0.223)L, respectively (P<.001). Significant associations were found between EIT measurements and CO transfer parameters. The mathematical model developed to adjust for the differences between the 2 measurements (R2=0.568; P<.001) was compensation factor=1.81o 0.82o× height (m)o 0.004×KCO (%).ConclusionsThe measurement of breathing pattern by EIT in patients with COPD requires the use of a previously calculated calibration equation that incorporates not only individual anthropometric characteristics but gas exchange parameters as well(AU)

Determinación de la concentración de óxido nítrico alveolar en aire espirado: procedimiento y valores de referencia en personas sanas / Determining the Alveolar Component of Nitric Oxide in Exhaled Air: Procedures and Reference Values for Healthy Persons

La producción de óxido nítrico (NO) se describe mediante un modelo bicompartimental que relaciona la producción y la movilidad de NO desde los alvéolos hacia las vías aéreas. La espiración a múltiples flujos permite deducir la concentración alveolar de NO (CaNO), marcador indirecto del estado inflamatorio de las zonas distales del pulmón. El objetivo fue determinar los valores de referencia de CaNO. En 33 individuos sanos se determinaron la concentración espirada de NO (FeNO) a 50ml/s y la CaNO a 10, 30, 100 y 200ml/s mediante un sensor de quimioluminiscencia (NIOX Aerocrine). El valor medio (± desviación estándar) de FeNO fue de 15±6ppb y de CaNO fue de 3,04±1,30ppb. Los valores de CaNO obtenidos en individuos sanos permitirán analizar el comportamiento inflamatorio alveolar en procesos respiratorios y sistémicos(AU)

Nitric oxide (NO) production has been described using a 2-compartment model for the synthesis and movement of NO in both the alveoli and the airways. The alveolar concentration of NO (CaNO), an indirect marker of the inflammatory state of the distal portions of the lung, can be deduced through exhalation at multiple flow rates. Our objective was to determine reference values for CaNO. The fraction of exhaled NO (FeNO) was measured in 33 healthy individuals at a rate of 50mL/s; the subjects then exhaled at 10, 30, 100, and 200mL/s to calculate CaNO. A chemiluminescence analyzer (NIOX Aerocrine) was used to perform the measurements. The mean (SD) FeNO was 15 (6)ppb. The mean CaNO was 3.04 (1.30)ppb. These values of CaNO measured in healthy individuals will allow us to analyze alveolar inflammatory behavior in respiratory and systemic processes(AU)

Evaluación de la función pulmonar unilateral mediante tomografía por impedancia eléctrica / Assessment of differential lung function by electrical impedance tomography

OBJETIVO: Comparar la función pulmonar unilateral (FPU) estimada mediante tomografía por impedancia eléctrica (TIE) con la misma determinación obtenida a partir de la gammagrafía de ventilación y perfusión pulmonar PACIENTES Y MÉTODOS: Se trata de un estudio clínico prospectivo, realizado en un laboratorio de función pulmonar de un hospital general. Se incluyó a 20 pacientes diagnosticados de cáncer de pulmón (17 varones y 3 mujeres, con edades comprendidas entre los 25 y los 77 años), candidatos a cirugía resectiva pulmonar, a quienes se realizó un estudio de ventilación/perfusión pulmonar con radioisótopos. La FPU se calculó a partir de imágenes en 2 espacios intercostales en las que se representaban la ventilación y la perfusión relacionadas con los cambios en la bioimpedancia eléctrica. Se determinó asimismo la participación de cada pulmón en la función global a partir de estudios isotópicos. RESULTADOS: El valor promedio ± desviación estándar de ventilación en el pulmón derecho obtenido mediante TIE fue del 54 ± 9% (rango: 32-71%). El mismo valor mediante radioisótopos fue del 52 ± 10% (rango: 31-80%) para la ventilación y del 50 ± 9% (rango: 37-71%) para la perfusión (prueba de la t de Student, p no significativa). El coeficiente de correlación entre ambas determinaciones fue de r = 0,90 (p < 0,05) para la ventilación y de r = 0,72 (p < 0,05) para la perfusión. El análisis de concordancia mostró una media de las diferencias del 1,9% (intervalo de confianza del 95%, del 10,5 al -6,8%) para la ventilación y del 3,4% (intervalo de confianza del 95%, entre el 17,1 y el -10,3%) para la perfusión. CONCLUSIONES: La TIE es capaz de cuantificar la FPU con una precisión similar a la gammagrafía de ventilación o perfusión con radioisótopos

OBJECTIVE: To compare unilateral lung function estimated by 2 methods: electrical impedance tomography (EIT) and ventilation-perfusion lung scintigraphy. PATIENTS AND METHODS: This prospective clinical study was carried out in the pulmonary function laboratory of a general hospital. Twenty patients diagnosed with lung cancer (17 men and 3 women, ranging in age from 25 to 77 years) who were candidates for lung resection underwent ventilation-perfusion lung scanning breathing a radioactive gas. Differential lung function was estimated based on images taken at 2 intercostal spaces in which ventilation and perfusion were represented by changes in bioelectrical impedance. Each lung's contribution to overall respiratory function was also calculated based on scintigraphy. RESULTS: The right lung contributed a mean (SD) of 54% (9%) of ventilation (range, 32%-71%) according to EIT. Scintigraphy similarly estimated the right lung's contribution to be 52% (10%) of total ventilation (range, 31%-80%) and 50% (9%) of perfusion (range, 37%-71%). The difference between the 2 estimates was not significant (t test), and the correlation coefficients between them were r=0.90 for ventilation and r=0.72 for perfusion (P<.05 in both cases). The analysis of agreement showed that the mean difference between the methods was 1.9% (95% confidence interval [CI], 10.5% to -6.8%) for ventilation and 3.4% (95% CI, 17.1% to -10.3%) for perfusion. CONCLUSIONS: EIT is able to estimate differential lung function as accurately as ventilation-perfusion scintigraphy

Factores de riesgo de mortalidad en la EPOC / Risk factors for mortality in Chronic Obstructive Pulmonary Disease

Objetivo: Aunque los factores que predicen la supervivencia en pacientes con enfermedad pulmonar obstructiva crónica (EPOC) han sido ampliamente estudiados, no disponemos de un consenso establecido. El objetivo de este estudio ha sido contribuir a clarificar el papel que desempeñan los parámetros de función pulmonar, tolerancia al esfuerzo y calidad de vida en la supervivencia en la EPOC. Pacientes y métodos: Se diseñó un estudio prospectivo en el que se incluyó a 60 pacientes diagnosticados de EPOC. Al inicio del estudio realizaron pruebas funcionales respiratorias, prueba de esfuerzo máximo y prueba de la marcha de 6 min, y respondieron un cuestionario de enfermedad respiratoria crónica para determinar la calidad de vida relacionada con la salud. El seguimiento de los pacientes fue de 7 años. Resultados: Se retiraron del estudio 5 de los 60 pacientes. De los 55 restantes, 26 (47%) murieron durante el estudio. El análisis univariante con regresión de Cox mostró que existía relación entre la supervivencia y la edad, el grado de obstrucción, la capacidad inspiratoria, la capacidad de difusión del monóxido de carbono y la tolerancia al ejercicio máximo; no se observó dicha relación entre la supervivencia y el índice de masa corporal, la presión arterial de oxígeno y anhídrido carbónico, la capacidad pulmonar total, el volumen residual, las presiones máximas respiratorias, la prueba de la marcha de 6 min ni la calidad de vida relacionada con la salud. En el análisis multivariante con regresión de Cox con pasos hacia adelante, en el que se introdujeron la edad, el grado de obstrucción (medido con la relación volumen espiratorio forzado en el primer segundo/capacidad vital forzada tras la administración de broncodilatador) y la ventilación minuto máxima en la prueba de esfuerzo, sólo esta última entró en el modelo final (riesgo relativo = 0,926; p < 0,001). Conclusiones: Nuestros hallazgos demuestran que la tolerancia al ejercicio máximo es el mejor predictor de supervivencia en los pacientes con EPOC

Objective: Although the factors predictive of survival in patients with chronic obstructive pulmonary disease (COPD) have been widely studied, full consensus has yet to be reached. The objective of this study was to further clarify how lung function parameters, exercise tolerance, and quality of life influence survival in patients with COPD. Patients and methods: This prospective study included 60 patients diagnosed with COPD. At the start of the study, patients underwent respiratory function tests, exercise testing, and 6-minute walk test. They also answered a chronic respiratory disease questionnaire to measure health-related quality of life. Follow-up lasted 7 years. Results: Five of the 60 patients withdrew from the study. Twenty-six of the remaining 55 patients (47%) died during the study. Univariate Cox regression analysis showed a correlation between survival and age, degree of obstruction, inspiratory capacity, carbon monoxide diffusing capacity, and peak exercise tolerance. No correlation was found between survival and body mass index, PaO2, PaCO2, total lung capacity, residual volume, maximal respiratory pressures, 6-minute walk distance, or health-related quality of life. Age, degree of obstruction (measured as the ratio of forced expiratory volume in 1 second to forced vital capacity after administration of bronchodilator), and maximum minute ventilation in the exercise test were introduced initially in the multivariate Cox stepwise regression analysis, but only maximum minute ventilation remained in the final model (relative risk, 0.926; P<.001). Conclusions: Our findings show that peak exercise tolerance is the best predictor of survival in patients with COPD

Seguimiento del patrón ventilatorio en reposo mediante tomografía por impedancia eléctrica / Monitoring of breathing pattern at rest by electrical impedance tomography

Objetivo: La tomografía por impedancia eléctrica (TIE) permite realizar un seguimiento del patrón ventilatorio a partir de una secuencia de imágenes torácicas obtenidas por la captación de una corriente alterna de baja intensidad. La relación entre las imágenes torácicas y el volumen circulante no está suficientemente validada. El propósito del presente estudio ha sido comparar, en un grupo de 13 voluntarios sanos, la correspondencia entre las imágenes de la TIE y la señal volumen/tiempo obtenida mediante un neumotacómetro. Material y métodos: Los equipos que se utilizaron para las mediciones fueron: a) MedGraphics prevent TM™ Pneumotach, implementando el software adecuado para registrar las señales volumen/tiempo (prueba de referencia), y b) TIE-4, cuarta versión de un equipo diseñado por el Departamento de Ingeniería Electrónica de la Universidad Politécnica de Cataluña, que permite tanto el registro de la señal volumen/tiempo como una representación gráfica de la sección transversal situada en el sexto espacio intercostal. Resultados: La media ± desviación estándar de volumen circulante obtenida mediante el neumotacómetro fue de 0,523 ± 0,102 l, y con la TIE-4, de 0,527 ± 0,106 l (p no significativa). El coeficiente de correlación lineal entre ambas determinaciones fue de 0,923 (p = 0,001). La media de las diferencias entre ambos procedimientos fue de -­0,003 l (intervalo de confianza del 95%, ­-0,045 a 0,038). Las mayores diferencias estaban relacionadas con el sexo femenino, el índice de masa corporal y el contorno torácico, lo que obligó a una ecuación diferente para calibrar la TIE-4 en función de estas variables. Conclusiones: La TIE-4 se presenta como un método alternativo para realizar el seguimiento del patrón ventilatorio, aunque deben resolverse aspectos relacionados con la conformación de la caja torácica

Objective: Electrical impedance tomography (EIT) involves the application of a small alternating current to produce a series of chest images that can be used to monitor breathing pattern. The relation between chest images and tidal volume has not been sufficiently validated. The aim of the present study was to analyze the correlation between EIT images and the volume­time signal measured with a pneumotachometer in 13 healthy volunteers. Material and Methods: The following measurement devices were used: a) MedGraphics preVent™ Pneumotach, with special software for recording the volume­time signal (reference test), and b) EIT-4, a fourth-generation prototype unit designed by the Department of Electronic Engineering at the Universidad Politécnica de Cataluña, Spain that records the volume­time signal and produces a graphic depiction of a cross section of the thorax at the sixth intercostal space. Results: The mean (SD) tidal volume measured by the pneumotachometer and the EIT-4 was 0.523 (0.102) L and 0.527 (0.106) L, respectively (P value not significant). The linear correlation coefficient between the 2 measurements was 0.923 (P=.001), and the mean of the differences between the 2 procedures was ­-0.003 L (95% confidence interval, -­0.045 to 0.038). The greatest differences were associated with female gender, body mass index, and chest circumference. In view of these differences, a different equation based on these variables was needed for calibration of the EIT-4. Conclusions: The EIT-4 provides an alternative means of monitoring breathing pattern, although a number of issues related to the circumference of the rib cage need to be resolved