Design and Verification of Lung Diffusion Function Detection System / 中国医疗器械杂志

A lung diffusion function detection system is designed. Firstly, the controllable collection of air, test gas source and calibration gas source was based on single-breath method measurement principle. Secondly, pulmonary diffusing capacity for carbon monoxide (DlCO) was calculated by gas concentration measured by the non-dispersive infrared sensor to measure, the gas flow measured by the differential pressure sensor, and the temperature, humidity and atmospheric pressure sensors to test and evaluate the quantitative detection and evaluation of lung diffusion function. Moreover, a preliminary verification of the lung diffusion function detection system was implemented, and the results showed that the error of the lung carbon monoxide diffusion and the alveolar volume did not exceed 5%. Therefore, the system has high accuracy and is of great value for early screening and accurate assessment of COPD.

Fisiología respiratoria: difusión de gases / Gas diffusion

El principal objetivo del sistema respiratorio es permitir un adecuado aporte de oxígeno y remoción del dióxido de carbono. Para esto, debe ocurrir una adecuada difusión de gases en la membrana alvéolo-capilar, proceso pasivo en el que el oxígeno se mueve hacia el capilar y el dióxido de carbono hacia el alvéolo. La ley de Fick establece los determinantes de la difusión, los que están dados por propiedades de la membrana alvéolo-capilar y de los gases. Las características únicas de la membrana alvéolo-capilar favorecen la difusión de gases, pero es el gradiente de presión parcial de los gases el principal determinante. El oxígeno pasa fácilmente por la membrana alvéolo-capilar y se une rápidamente a la hemoglobina, saturándola, cuando se iguala la presión parcial de oxígeno alveolar y la capilar se detiene la difusión de este gas; por lo que la difusión de oxígeno en reposo está limitada por perfusión. El dióxido de carbono difunde 20 veces más rápido que el oxígeno en la membrana alvéolo-capilar, y aunque su gradiente de presión sea menor, el equilibrio se logra aproximadamente en el mismo tiempo. La difusión del oxígeno es más lenta que la del dióxido de carbono debido a su menor solubilidad. En condiciones patológicas tanto el oxígeno como el dióxido de carbono pueden ser limitados por difusión. Para medir la capacidad de difusión la técnica más utilizada es la capacidad de difusión de monóxido de carbono, ya que este gas solo está limitado por difusión.

The main objective of the respiratory system is allowing an adequate supply of oxygen and the removal of carbon dioxide from the tissues. To achieve this, an adequate diffusion of gases must occur in the alveolus-capillary membrane, which is a passive process in which oxygen moves towards the capillary and carbon dioxide towards the alveolus. Fick's law establishes the determinants of diffusion, which are given by properties of the alveolar-capillary membrane and properties of gases. The unique characteristics of the capillary-alveolar membrane favor the diffusion of gases, but it is the partial pressure gradient of the gases the main determinant. Oxygen passes easily through the alveolar-capillary membrane and rapidly binds to hemoglobin, saturating it. When the partial pressure of alveolar oxygen is matched, the diffusion of this gas stops; therefore, the diffusion of oxygen is limited by perfusion. Carbon dioxide diffuses 20 times faster than oxygen in the capillary-alveolar membrane, and although its pressure gradient is less than oxygen, equilibrium is achieved in approximately the same time. The diffusion of oxygen is slower than that of carbon dioxide due to its lower solubility. Under pathological conditions both oxygen and carbon dioxide can be diffusion-limited. To measure the diffusion capacity, the most used technique is the carbon monoxide diffusion capacity, since this gas is only limited by diffusion.

Capacidad de difusión de monóxido de carbono, pautas para su interpretación / Diffusing capacity for carbon monoxide, guidelines for interpretation

Resumen La capacidad de difusión de monóxido de carbono (DLCO) es, después de la espirometría, la prueba de función pulmonar rutinaria y no invasiva de mayor utilidad clínica. No obstante, hay sustanciales errores de interpretación del significado fisiológico de la DLCO, de sus medidas derivadas y por consiguiente del significado clínico de sus alteraciones. Además de la utilización de diferentes nomenclaturas, otras fuentes de confusión han contribuido a cierta visión negativa de la prueba. Los aspectos técnicos de la prueba de DLCO tienen la ventaja de estar estandarizados. Pero a diferencia de lo que ocurre con otras pruebas de función pulmonar donde disponemos de valores de referencia que permiten determinar la "normalidad o anormalidad" de las mismas, es difícil aplicar esta vía de análisis en el caso de la DLCO. El hecho central en el análisis de la DLCO, el factor de transferencia para el CO (KCO), y el volumen alveolar (VA) es que para una correcta interpretación es necesario tener en cuenta el mecanismo por el cual la patología induce el cambio. Un KCO del 100% puede ser considerado normal en unas circunstancias o patológico bajo otras y, por el momento, el informe automatizado del estudio no puede discriminar. Este artículo describirá los principios de la prueba de DLCO, presentará diferentes modelos de análisis, expondrá ejemplos concretos y ofrecerá pautas para su correcta interpretación. Se considera indispensable efectuar un análisis integrado de la prueba de DLCO en relación con otras pruebas funcionales y con los datos clínicos.

Abstract The diffusing capacity for carbon monoxide (DLCO) is, after spirometry the standard and noninvasive pulmonary function test of greater clinical use. However, there are substantial errors in the interpretation of the physiological significance of the DLCO, its derived measures and, therefore the clinical significance of its alterations. In addition to the use of different nomenclatures, other sources of confusion have contributed to some negative view of the test. The technical aspects of the DLCO test have the advantage of being well standardized. But unlike what happens with other pulmonary function tests where we have reference values which allow us to determine their "normality or abnormality", it is difficult to apply this route of analysis in the case of DLCO. The central fact in the analysis of DLCO, transference factor for CO (KCO), and alveolar volume (VA) is that for a correct interpretation it is necessary to think about the mechanism by which the pathology induces change. A KCO of 100% can be considered normal in some circumstances or pathological in others and, for the moment, the automated study report cannot discriminate. This article will address the principles of the DLCO test; present different models of analysis submit concrete examples and provide guidelines for their correct interpretation. It is considered essential to carry out an integrated analysis of the DLCO test in relation to other functional tests and clinical data.

Valores de referência para a difusão do monóxido de carbono (fator de transferência) em uma amostra brasileira da raça branca / Reference values for the carbon monoxide diffusion (transfer factor) in a brazilian sample of white race

RESUMO Objetivo Derivar valores de referência em adultos brancos para a difusão do monóxido de carbono (DCO) em uma amostra de diferentes locais do Brasil por um mesmo modelo de equipamento (Sensormedics) e comparar os resultados com os derivados pelas equações de Crapo, Miller e Neder, e da proposta pelo Global Lung Initiative (GLI). Métodos Os testes foram realizados de acordo com as normas sugeridas pela ATS/ERS, em 2005, em seis cidades brasileiras, em 120 voluntários adultos de cada sexo, não fumantes, sem anemia referida e sem doenças pulmonares ou cardíacas. Os previstos foram derivados por regressões lineares e as diferenças entre os valores previstos por alguns autores e os observados no estudo atual foram calculadas. Resultados Nos homens, a idade variou de 25 a 88 anos e a estatura, de 156 a 189 cm. Nas mulheres, a idade variou de 21 a 92 anos e a estatura, de 140 a 176 cm. A DCO se correlacionou de maneira significativa positivamente com a estatura e negativamente com a idade. Os valores previstos pelas equações de Crapo, Neder e Miller foram maiores em comparação aos obtidos pelo estudo atual (p<0,01) em ambos os sexos. Nos homens, os valores não diferiram quando comparados aos calculados pelo GLI (p=0,29); nas mulheres, os valores derivados pelo GLI foram levemente maiores: 0,99 mL/min/mmHg (p<0,01). Conclusões Novos valores previstos para a DCO foram derivados em uma amostra de adultos brancos no Brasil. Os valores previstos são semelhantes aos compilados pelas equações GLI e diferem de equações propostas anteriormente.

ABSTRACT Objective To derive reference values from white race adults, for DCO in a sample from different sites in Brazil, through the same equipment model (Sensormedics), and compare the results with the derivatives from Crapo, Miller, Neder equations and from the Global Lung Initiative (GLI) proposal. Methods The tests were performed according to the norms suggested by ATS/ERS in 2005 in six Brazilian cities, with 120 adult volunteers of each gender, non-smokers, without referred anemia and without lung or cardio diseases. The expected values were derived from linear regressions and the differences between the values forecasted by some authors and the ones observed in the current study were calculated. Results Among men, the age varied between 25 and 88 years old, and the height varied between 140 and 176 cm. DCO was correlated significantly and positively with the height and negatively with the age. The values forecasted by Crapo, Neder, and Miller equations were higher in comparison with the ones obtained by the current study (p<0.01) in both genders. Among men, the values did not differ when compared to the ones calculated by GLI (p=0.29); among women, the values derived by GLI were slightly higher: 0.99 ml/min/mmHg (p<0.01). Conclusion new values forecasted for DCO were derived in a sample of white adults in Brazil. The forecasted values are similar to the ones complied by GLI equations and differ from the previously proposed equations.

Development of Prediction Equation of Diffusing Capacity of Lung for Koreans / 결핵

BACKGROUND: The diffusing capacity of the lung is influenced by multiple factors such as age, sex, height, weight, ethnicity and smoking status. Although a prediction equation for the diffusing capacity of Korea was proposed in the mid-1980s, this equation is not used currently. The aim of this study was to develop a new prediction equation for the diffusing capacity for Koreans. METHODS: Using the data of the Korean National Health and Nutrition Examination Survey, a total of 140 nonsmokers with normal chest X-rays were enrolled in this study. RESULTS: Using linear regression analysis, a new predicting equation for diffusing capacity was developed. For men, the following new equations were developed: carbon monoxide diffusing capacity (DLco)=−10.4433−0.1434×age (year)+0.2482×heights (cm); DLco/alveolar volume (VA)=6.01507−0.02374×age (year)−0.00233×heights (cm). For women the prediction equations were described as followed: DLco=−12.8895−0.0532×age (year)+0.2145×heights (cm) and DLco/VA=7.69516−0.02219×age (year)−0.01377×heights (cm). All equations were internally validated by k-fold cross validation method. CONCLUSION: In this study, we developed new prediction equations for the diffusing capacity of the lungs of Koreans. A further study is needed to validate the new predicting equation for diffusing capacity.

Trasplante pulmonar en pacientes portadores de fibrosis pulmonar: caracterización de una cohorte de 87 pacientes / Lung transplantation in 87 patients with idiopathic pulmonary fibrosis

Pulmonary fibrosis is a progressive disease. Lung transplantation is the only effective therapy for a group of patients. Objective: To evaluate results of lung transplantation for fibrosis up to a 5 years of follow up. Methodology: Retrospective review of clinical records of patients subjected to lung transplantation from Clínica Las Condes and Instituto Nacional del Tórax. Demographic data, type of transplant, baseline and post-transplant spirometry and 6 min walked distance (6MWT), early and late complications and long-term survival rate were analyzed. Results: From 1999 to 2015, 87patients with pulmonary fibrosis were transplanted, in average they were 56 years old, 56% were male, 89% of patients were subjected to a single lung transplant. 16% of them were in urgency. Baseline and 1-3-5 years for FVC were 49-73-83 and 78% of the reference values and for 6MWT were 280, 485, 531 and 468 meters respectively. Predominant complications < 1 year post-transplant were: acute rejection (30%) and infections (42%). Complications after 1 year of transplantation were chronic graft dysfunction (DCI) 57% and neoplasms (15%). The main causes of mortality > 1 year were DCI (45%) and neoplasms (11%). The estimated 1, 3 and 5 year survival rate were 84, 71 and 58% respectively. Conclusions: Lung transplantation in patients with pulmonary fibrosis improves their quality of life and survival rate. The monopulmonary technique is efficient in the long term. Acute rejection and infection were the most common early complications and chronic graft dysfunction was the prevalent long-term complication.

La Fibrosis pulmonar es una enfermedad progresiva y el trasplante constituye una terapia efectiva para un grupo de pacientes. Objetivo: Evaluar los resultados del trasplante pulmonar por fibrosis a 5 años. Metodología: Revisión retrospectiva de registros de trasplante pulmonar de la Clínica Las Condes e Instituto Nacional del Tórax. Se analizaron datos demográficos, tipo de trasplante, función pulmonar basal y post-trasplante, complicaciones precoces y tardías y sobrevida a largo plazo. Resultados: Entre 1999 y 2015 ambos centros trasplantaron 87 pacientes por fibrosis pulmonar. Los pacientes tenían una edad promedio de 56 años, 56% eran del género masculino y se usó técnica monopulmonar en 89% de ellos. 16% de los pacientes se encontraba en urgencia. Los resultados espirométricos y la distancia caminada en 6 minutos (T6 min) basales y a 1- 3 - 5 años fueron: CVF 49- 73- 83 y 78% del valor teórico y T6 min fue 280, 485, 531 y 468 metros respectivamente. Complicaciones predominantes < 1 año fueron: rechazo agudo 30% e infecciones 42%. Complicaciones > 1 año fueron: disfunción crónica del injerto (DCI) 57% y neoplasias 15%. Las causas de mortalidad > 1 año fueron DCI 45% y neoplasias 11%. La sobrevida estimada a uno, 3 y 5 años fue 84, 71 y 58% respectivamente. Conclusiones: El trasplante en pacientes con fibrosis pulmonar, permite mejorar la calidad de vida y sobrevida de estos pacientes. La técnica monopulmonar es eficiente a largo plazo. En las complicaciones precoces predominaron el rechazo agudo e infecciones y a largo plazo la DCI.

Combined pulmonary fibrosis and emphysema with pulmonary arterial hypertension: A Rare Case Report.

Combined pulmonary fi brosis and emphysema (CPFE) is a recently recognized radiologically defi ned syndrome characterized by simultaneous coexistence of both upper lobe emphysema and lower lobe pulmonary fi brosis. We present a case of CPFE in a 57-year-old male smoker who presented with dry cough, progressive breathlessness, and swelling of feet. His chest X-ray revealed bilateral lower Zone reticulonodular opacities with hyperlucent upper Zones. Pulmonary function tests showed wellpreserved lung volumes and reduced diff using capacity of the lung for carbon monoxide. High-resolution computed tomogram showed bilateral lower lobe subpleural honeycombing along with fi brosis and traction bronchiectasis with bilateral upper lobe emphysema predominantly paraseptal type. His 2D echo was suggestive of moderate pulmonary arterial hypertension.

Enfisema orbitario espontáneo tras la maniobra de Valsalva / Orbital emphysema after Valsalva maneuver. Report of one case

Orbital emphysema is a rare complication of orbital and facial trauma, involving the sinuses and occasionally the nasal cavity. Most cases occur as a result of trauma but spontaneous orbital emphysema has been reported. Clinical manifestations are often delayed until the upper airway pressure increases as when blowing or coughing. Along with the fracture, the rupture of the underlying mucosa is essential for emphysema to manifest. We report a 29-years-old male who consulted in the emergency room due to eyelid swelling after a Valsalva maneuver, a couple of hours after suffering a facial injury secondary to a fall. In the presence of eyelid emphysema, the patient underwent craniofacial imaging studies, confirming an ethmoidal lamina papyracea fracture.

An misunderstanding in traditional interpretation of D(L)CO / 中国应用生理学杂志

<p><b>OBJECTIVE</b>From the point of holistic integrative medicine, the D(L)CO depends on not only normal respiratory and circulatory functions, but also an optional matching between them. However, due to the limitation of traditional systemic physiology, the D(L)CO always be classified as lung functional parameter to be analyzed and interpreted. Because ignoring the circulatory system function, so it will certainly have some misunderstandings.</p><p><b>METHODS</b>Based on the Holistic Integrative Medicine, under the control of neurohumoral, respiratory, circulatory and metabolic systems work together, we discussed the diffusion function. We analyzed the change of D(L)CO in the patients with cardiac dysfunction, especially the heart failure.</p><p><b>RESULTS</b>The D(L)CO, CO gas,diffusion from lung circulating blood, depends on the normality of respiratory and circulatory systems and their matching. We analyzed the reasons of D(L)CO for characteristic pathophysiological changes of patients with heart failure.</p><p><b>CONCLUSION</b>The normal D(L)CO depends on a good matching of normal respiratory and circulatory systems. For heart failure, the respiratory and circulatory systems matching is poor. Due to dominant limitation of left ventricle pump function, pulmonary blood volume may slightly increased, but combination of all reduced pulmonary blood flow rate, thicked diffuse member and increased diffusion distance etc. suggest that patients with heart failure should have a decreased, rather than increased, D(L)CO.</p>

O impacto dos valores previstos nos testes de função pulmonar / The impact of predicted values in pulmonary function tests

A interpretação dos testes de função pulmonar é resultado da comparação de valores obtidos com valores previstos para um determinado indivíduo. Os valores previstos são obtidos através de equações de referência, sendo estas determinadas por dados antropométricos e demográficos dos indivíduos. A presente revisão de literatura pretende identificar quais as equações referência mais utilizadas para os testes de função pulmonar, comparar estudos entre equações com ênfase nas publicações de equações de referência brasileiras.

Lung function test interpretation is based on the comparison between values measured according to the predicted values for each individual. The predicted values come from reference equations, which depend on anthropometric and demographic data of individuals. The present review aims to identify the most commonly used reference equations for pulmonary function tests, interpret comparative studies between equations and emphasizes publications with Brazilian reference equations.

Cem anos do teste de difusão ao monóxido de carbono nas doenças pulmonares / One hundred years of carbon monoxide diffusion test in lung disease

Em 2015 fazem exatamente cem anos desde a primeira publicação a descrever um método de aferição da respiração única de permeabilidade dos gases. Atualmente, os testes são realizados por sistemas automatizados utilizando a manobra de respiração única já padronizada internacionalmente. Este artigo aborda as técnicas usadas nesta medida, as equações de normalidade existentes e como interpretar dos dados obtidos. A interpretação dos resultados obtidos devem ser feita de forma cuidadosa. Tanto doenças obstrutivas como restritivas podem causar redução da capacidade de difusão ao monóxido de carbono. Quando usado em indicações clínicas bem estabelecidas e, principalmente, quando os resultados são analisados em conjunto com a clínica, radiologia e a medida dos volumes e fluxos pulmonares, o teste da difusão pode ser uma rica ferramenta no auxílio diagnóstico e prognóstico. Os aparelhos atualmente disponíveis no mercado para realização do teste são extremamente confiáveis, provendo exames reprodutíveis e acurados, no entanto, são equipamentos caros, devendo ser importados o que dificulta a disseminação da técnica.

In 2015 make exactly one hundred years since the first report describing a single-breath method of measuring permeability of gases. Currently, tests are performed by automated systems using the single breath maneuver already internationally standardized. This article discusses the techniques used in this measure, the existing normal equations and how to interpret the data obtained. The interpretation of the results obtained should be done carefully. Both obstructive and restrictive diseases can cause reduced diffusion capacity for carbon monoxide. When used in well-established clinical indications and especially when the results are analyzed together with the clinical, radiology and the measured lung volumes and flows, the diffusion test can be a rich tool in the diagnosis and can also provide the prognosis. Devices currently available in the market for the test are extremely reliable, providing reproducible and accurate tests. However, they are expensive equipment and must be imported which hinders the spread of technology.

Estandarización de la prueba de capacidad de difusión de monóxido de carbono: Chilean Society of Respiratory Diseases guidelines / Standardization of the single-breath diffusing capacity

Since its introduction in clinical practice carbon monoxide diffusing capacity (DLCO), has been widely used in respiratory diseases, being the most common test utilized after spirometry in pulmonary function laboratories. It represents the entire diffusion process including transport through the alveolar-capillary barrier and hemoglobin binding. Its high affinity with hemoglobin and its near zero partial pressure in plasma determines that CO transfer depends specifically on diffusion. Common respiratory and cardiac diseases such as emphysema, interstitial lung diseases, lung damage by drugs, arterial pulmonary hypertension and cardiac failure, among others show a reduced DLCO. Recent theories considering red blood cells as the main factor involved in resistance to diffusion, suggest that DLCO may reflect the status of lung microcirculation. For example, in cardiac failure, DLCO does not improve in parallel with lung volume, even with cardiac stabilization or cardiac transplantation. Despite its wide utilization, DLCO measurement presents standardization and reproducibility difficulties. International guidelines and task forces recommend using representative values of the target population. After analyzing the available information a group of experts from the Pulmonary Function Commission of the Chilean Society of Respiratory Diseases has proposed guidelines for measurement techniques, quality control, equipment calibration and interpretation of results.

Desde la introducción en la práctica clínica de la prueba de difusión con monóxido de carbono (CO) a mediados del siglo pasado, su utilización ha sido ampliamente difundida en la evaluación de diversas enfermedades respiratorias, de hecho se le considera la prueba más utilizada luego de la espirometría. Desde el punto de vista conceptual aporta información global de todo el proceso de difusión, que incluye el paso a través de la barrera alvéolo capilar y su unión con la hemoglobina. Gracias a la elevada afinidad del CO por la hemoglobina y a la particularidad de que la presión parcial de CO en el plasma es prácticamente cero, la transferencia del CO depende sólo de su difusión. Patologías respiratorias y cardíacas habituales como el enfisema pulmonar, las enfermedades pulmonares intersticiales, el compromiso pulmonar por drogas neumotóxicas, la hipertensión arterial pulmonar y la insuficiencia cardíaca congestiva, entre otras, cursan con disminución de la capacidad de difusión de CO (DLCO). Un nuevo desafío plantean las hipótesis recientes que postulan que la resistencia a la difusión del monóxido de carbono depende principalmente del glóbulo rojo, por lo que ésta podría consistir en una representación de la microcirculación. Como ejemplo, en la insuficiencia cardíaca congestiva, el deterioro de la DLCO no mejora en conjunto con los volúmenes pulmonares, ni cuando estos pacientes se estabilizan o se trasplantan. Si bien se trata de una técnica de laboratorio ampliamente utilizada, aún presenta problemas de estandarización y reproducibilidad. En este documento de consenso, un grupo de estudio de la Comisión de Función Pulmonar de la Sociedad Chilena de Enfermedades Respiratorias, ha efectuado una revisión de este método, con las correspondientes proposiciones de técnicas de medición, control de calidad, calibración e interpretación.

The diagnostic utility of chest computed tomography scoring for the assessment of amiodarone-induced pulmonary toxicity

BACKGROUND/AIMS: Amiodarone is one of the most widely used antiarrhythmic agents; however, amiodarone-induced pulmonary toxicity (APT) can be irreversible and sometimes fatal. The aim of this study was to evaluate the feasibility of chest computed tomography (CT) as a diagnostic tool for APT and to assess the utility of the CT APT score as an index for predicting the severity of APT. METHODS: Patients underwent amiodarone treatment for various reasons, most often atrial fibrillation, for more than 2 years, and those that received a cumulative dose > 100 g were enrolled. A total of 34 patients who underwent chest CT between December 2011 and June 2012 were enrolled, whether or not they had clinical symptoms. The APT CT score was defined as the number of involved regions in the lung, which was divided into 18 regions (right and left, upper, middle, and lower, and central, middle, and peripheral). The CT findings were evaluated according to the total dose and duration of amiodarone treatment and the results of a pulmonary function test. Clinical symptoms and outcomes were also evaluated according to APT CT scores. RESULTS: Seven patients had positive APT CT scores (interstitial fibrosis in five, organizing pneumonia in one, and mixed interstitial fibrosis and organizing pneumonia in one), and these patients exhibited significantly lower diffusion capacity for carbon monoxide in the lungs compared with patients without an increased APT CT score (70.2% +/- 6.9% vs. 89.7% +/- 19.4%; p = 0.011). Three of the seven patients experienced overt APT that required hospital admission. CONCLUSIONS: Chest CT is a useful diagnostic tool for APT, and the APT CT score might be a useful index for assessing the severity of APT.

Dificultades en la elección de una ecuación de referencia para la interpretación de los resultados de capacidad de difusión de monóxido de carbono / Difficulties in the selection of a reference equation for the interpretation of the results of DLCO

Introduction: In the absence of national reference equations, the ATS recommends comparing the results of the diffusion capacity of healthy subjects in a representative sample of the population with international equations and choosing among them, the one that provides the lowest sum of the residues. Objective: To compare reference equations available in the literature and identify which best meets the selection criteria. Methods: We reviewed 10 reference equations, for each one we calculated the sum of the residues for a sample of 71 healthy subjects and described the characteristics that affect the variability of each one. Results: Since 1985 we have used the single breath method. Only Thompson et al prediction equations 2008 were obtained with instantaneous reading of CO. Equations with the lowest sum of residues (Miller, Roca and Cotes) include smokers and former smokers. Conclusions: We need an equation in non-smokers with methodology that ensures low variability.

Introducción: En ausencia de ecuaciones de referencia nacionales, la ATS recomienda comparar los resultados de capacidad de difusión de monóxido de carbono de sujetos sanos en una muestra representativa de la población, con ecuaciones internacionales y escoger entre estas, aquella que presente la menor suma de los residuos. Objetivo: Comparar las ecuaciones de referencia disponibles en la literatura e identificar cuál cumple mejor los criterios de selección. Método: Revisamos 10 ecuaciones de referencia; calculamos la suma de los residuos de cada una de ellas para una muestra de 71 sujetos sanos y describimos las características que inciden en la variabilidad de cada una. Resultados: Desde 1985 se ha utilizado el método de respiración única. Sólo las ecuaciones de Thompson y cols. 2008fueron obtenidas con lectura instantánea. Las ecuaciones que presentan menor suma de residuos (Miller, Roca y Cotes) incluyen fumadores y ex fumadores. Conclusiones: Es necesaria una ecuación nacional en sujetos sanos no fumadores, con metodología que asegure baja variabilidad.

Diferencias tomográficas y funcionales entre la EPOC severa relacionada con humo de leña y con cigarrillo: comparison between the wood smoke-related and smoking-related disease / Tomographic and functional findings in severe COPD

OBJETIVO: La exposición a humo de leña es factor de riesgo para EPOC. A diferencia de la EPOC por cigarrillo (EPOC-C), para un mismo nivel de obstrucción, en la EPOC por leña (EPOC-L), la DLCO está menos disminuida, sugiriendo menos enfisema. Por tanto, el objetivo de este estudio fue comparar los hallazgos en la TCAR en mujeres con EPOC-L y con EPOC- C. MÉTODOS: Veintidós mujeres con EPOC severa (VEF1/CVF < 70% y VEF1 < 50%) fueron divididas en dos grupos: las expuestas a leña (EPOC-L; n = 12) y las expuestas a cigarrillo (EPOC-C; n = 10). Se compararon los dos grupos con respecto al puntaje de enfisema y el compromiso de la vía aérea en la TCAR, las anormalidades funcionales en la espirometría, la DLCO, los volúmenes pulmonares y la resistencia específica de la vía aérea (sRaw). RESULTADOS: Los dos grupos tuvieron VEF1, sRaw e hiperinflación pulmonar similares. En el grupo EPOC-C, hubo mayor disminución de la DLCO y de la DLCO/VA y mayor puntaje de enfisema. En el grupo EPOC-L, no encontramos enfisema significativo en la TCAR. Los hallazgos principales fueron engrosamiento peribronquial, dilataciones bronquiales y atelectasias subsegmentarias. CONCLUSIONES: En pacientes con EPOC-L severa no hay enfisema en la TCAR. El hallazgo más importante es el compromiso severo de la vía aérea. La disminución de la DLCO y del VA con DLCO/VA normal es probablemente determinada por la obstrucción bronquial severa y la mezcla incompleta del gas inspirado en la maniobra de la respiración única de la prueba de difusión.

OBJECTIVE: Wood smoke exposure is a risk factor for COPD. For a given degree of airway obstruction, the reduction in DLCO is smaller in individuals with wood smoke-related COPD than in those with smoking-related COPD, suggesting that there is less emphysema in the former. The objective of this study was to compare HRCT findings between women with wood smoke-related COPD and women with smoking-related COPD. METHODS: Twenty-two women with severe COPD (FEV1/FVC ratio < 70% and FEV1 < 50%) were divided into two groups: those with wood smoke-related COPD (n = 12) and those with smoking-related COPD (n = 10). The two groups were compared regarding emphysema scores and airway involvement (as determined by HRCT); and functional abnormalities-spirometry results, DLCO, alveolar volume (VA), the DLCO/VA ratio, lung volumes, and specific airway resistance (sRaw). Results: There were no significant differences between the two groups in terms of FEV1, sRaw, or lung hyperinflation. Decreases in DLCO and in the DLCO/VA ratio were greater in the smoking-related COPD group subjects, who also had higher emphysema scores, in comparison with the wood smoke-related COPD group subjects. In the wood smoke-related COPD group, HRCT scans howed no significant emphysema, the main findings being peribronchial thickening, bronchial dilation, and subsegmental atelectasis. CONCLUSIONS: Female patients with severe wood smoke-related COPD do not appear to develop emphysema, although they do show severe airway involvement. The reduction in DLCO and VA, with a normal DLCO/VA ratio, is probably due to severe bronchial obstruction and incomplete mixing of inspired gas during the determination of single-breath DLCO.

Importancia de la corrección de la KCO informada computarizada en pacientes con volumen alveolar disminuído / Importance to adjust computerized informed KCO in patients with low alveolar volume

La disminución del factor de transferencia de monóxido de carbono (TLCO) y del Volumen Alveolar (VA) no es uniforme. Los informes de los equipos computadorizados entregan un valor de KCO que no toma en cuenta este detalle.Objetivo: Realizar el cálculo de KCO a través de la corrección de Stam (J Apply Physiol 1994) y compararlas con las informadas por el software de un equipo de laboratorio pulmonar computadorizado reconocido (Collins).Material y Método: Fueron incluídos pacientes consecutivos derivados al Laboratorio Pulmonar de la Unidad para realizar una prueba de TLCO por enfermedad intersticial pulmonar entre Enero y Junio de 2008. Se realizaron las pruebas según recomendacionesATS/ERS por el método de respiración única y con el método de toma de muestra de Ogilvie. Se analizó la KCO según lo informa el software del equipo Collins Plus/SQL System (1995Warren Collins), y luego se lo recalculó corregida según el cálculo de Stam (J Apply Physiol 1994). Se incluyó en este análisis si tenían <80% del volumen alveolar predicho. Resultados: Fueron evaluados 15 pacientes (media edad: 57.5 ± 12.9 años, sexo femenino 66.7%) con enfermedad intersticial.La media de VA fue 3.5±0.8 L(64.3±11.6%). La media de KCO informada a través del software fue 4.2± 1.3ml/min/mmHg/L. La media de KCO corregida fue 3.7 ± 1.2ml/min/mmHg/L (Δ 11.8±3.8, rango: 6.8%-21.1%). Se observó una relación lineal y negativa entre el %VA y el delta de KCO corregida/informada (r2= -0.99). La elección de diferentes tablas de valores normales de VA altera hasta 12% el valor de la misma, pero la KCO corregida se altera en grado mínimo (3%). Conclusiones: Cuando el VA está disminuído, se debe realizar la corrección del informe computadorizado de la KCO, porque se observa una diferencia promedio del 12%, sobreestimando la real KCO del paciente. Otros factores, como la tabla de valores predictivos de VA, influencia muy poco la corrección de KCO.

The decrease of the Transfer Factor of the Lung for Carbon Monoxide (TLCO) and the Alveolar Volume (VA) is not uniform. Software of lung computed machine informs the carbon monoxide transfer coefficient TLCO/VA (KCO) by calculating the ratio without adjusting for that assumption. Objectives: To calculate KCO using a correction by the Stam´s equation (J Apply Physiol1994), to compare the corrected KCO with the result informed by the software of Collins lung laboratory equipment, and to evaluate the impact of using different predictive tables of VA in the estimates of KCO. Materials: Consecutive patients with intersticial lung disease who attended the LungLaboratory to perform the TLCO between January and June 2008 were included in the study. TLCO was performed according to ATS/ERS recommendations by the single-breathand Ogilvie methods. KCO was calculated by the software of Collins Plus/SQL System (1995 Warren Collins), and then recalculated by Stam´s equation. Only patients withless than 80% of VA predictive value were included. Results: 15 patients with interstitial lung disease were evaluated (age: 57.53 ± 12.93 years old, female: 66.66%). The mean VA was 3.55 ±0.83 L (64.33 ±11.56%) and the mean KCO informed by software was 4.17 ±1.31 ml/min/mmHg/L. The corrected KCO was 3.76 ±1.33 ml/min/mmHg/L(Δ 11.84 ±3.84, range: 6.82%-21.1%). It was observed a negative and lineal relation between %VA and Δ KCO corrected/informed (R2= -0.99). The election of different tables of VA normal values distorts up to12% the individualvalues, but the corrected KCO is little modified (3%). Conclusion: When the VA is reduced, the correction of the KCO must be performed, to avoid on average a 12% overestimate. Other factors such as the election of VA predictive tables have little influence on the KCO correction.

Proposal of New Criteria for Assessing Respiratory Impairment / 결핵및호흡기질환

Social welfare services for respiratory-disabled persons in Korea are offered based on the respiratory impairment grade, which is determined by 3 clinical parameters; dyspnea, forced expiratory volume in 1 second (FEV1), and arterial oxygen tension. This grading system has several limitations in the objective assessment of respiratory impairment. We reviewed several guidelines for the evaluation of respiratory impairment and relevant articles. Then, we discussed a new grading system with respiratory physicians. Both researchers and respiratory physicians agreed that pulmonary function tests are essential in assessing the severity of respiratory impairment, forced vital capacity (FVC), FEV1 and single breath diffusing capacity (DLco) are the primarily recommended tests. In addition, we agreed that arterial blood gas analysis should be reserved for selected patients. In conclusion, we propose a new respiratory impairment grading system utilizing a combination FVC, FEV1 and DLco scores, with more social discussion included.

Spirometry and diffusion studies in patients with type-2 diabetes mellitus and their association with microvascular complications.

Background. Diabetes is a systemic disease with-well known complications involving eyes, kidneys and nerves. The presence of an extensive pulmonary microvascular circulation and abundant connective tissue raises the possibility that lung may also be a target organ in diabetes. Methods. A total of 45 subjects were included in the study. All patients were evaluated for diabetic microangiopathies: nephropathy (by 24-hour protein excretion), retinopathy (by direct ophthalmoscopy) and neuropathy (by clinical examination). The patients were divided into following three groups: Group A: patients with type-2 diabetes mellitus (DM) with evidence of microangiopathy (n=15); Group B: patients with type-2 DM without any evidence of microangiopathy (n=15); Group C: non-diabetic subjects (n=15) as controls. Glycosylated haemoglobin (HbA1C) was measured as an indicator of glycemic control. Spirometry and single-breath diffusion capacity for carbon-monoxide (DLCO) were performed on all patients using Elite Series Body Plethysmograph machine. Results. A significant reduction of diffusion capacity corrected for alveolar volume (%DL/VA) was observed in group A (p<0.001), as compared to the other groups. There were no differences among the three groups for other pulmonary functions. There was a significant correlation between DL/VA percent predicted and albuminuria (r= -0.975, p<0.001), and DL/VA percent predicted and the retinopathy (r = -0.550, p< 0.05). Conclusion. This study shows a mild reduction in diffusing capacity in patients with type-2 DM with microangiopathy.

Comparison of the oxygen diffusing capacity of the picui ground dove (Columbina picui) with other doves of Chile / Comparación de la capacidad de difusión de oxígeno de la tórtola picus (Columbina picui) con otras tórtolas de Chile

We studied the respiratory surface density and the thickness of the air-blood barrier in the Picui Ground Dove (Columbina picui), and compared it with Eared Dove (Zenaida auriculata) and Blacked-winged Ground Dove (Metropelia melanoptera), two larger species. As expected, Columbina picui BMR and VO2max showed higher values than those of the larger species according to the expected for their body size. The respiratory surface density and the thickness of the blood-air barrier were not different among the different species of doves. However C. picui showed an anatomical diffusion factor lower than M. melanoptera and Z. auriculata. Picui Ground Dove had low values of oxygen diffusion capacity, such as cursorial birds. A differential oxygen partial pressure of 7.5 Kpa, an usual value at sea level, it can hardly meet their maximal energy requirements and it means that Picui Ground Dove, would have serious limitations to live at high altitudes, which is consistent with the observation that this species inhabits lowlands and at the foot hills of the Andes.

Se estudió la densidad de superficie respiratoria y el espesor de la barrera sangre-aire en la Tortolita cuyana (Columbina picui), y se comparó con la Tórtola cordillerana (Metropelia melanoptera) y la Tórtola (Zenaida auriculata), dos especies más grandes. Como era de esperar, en C. picui el metabolismo basal y el metabolismo máximo fueron más altos que los de especies más grandes, pero de acuerdo a lo esperado para el tamaño corporal. La densidad de la superficie respiratoria y el espesor de la barrera sangre-aire no fueron diferentes entre las diferentes especies de tórtolas. Sin embargo C. picui mostró un factor de difusión anatómica inferior a M. melanoptera y Z. auriculata. C. picui tuvo valores bajos de capacidad de difusión de oxígeno, como las aves cursoriales. A una diferencia de presión parcial de oxígeno de 7,5 Kpa, un valor habitual a nivel del mar, apenas podría satisfacer sus necesidades de energía máxima y esto significa que tendría serias limitaciones para vivir a gran altura, lo cual es coherente con la observación de que esta especie habita en las tierras bajas y en la zona precordillerana de los Andes.