Perfil de pacientes evaluados con el Test de Capacidad de Difusión de Monóxido de Carbono: Una experiencia chilena

Antecedentes: La prueba de capacidad de difusión de monóxido de carbono (DLCO) es una evaluación de función pulmonar rutinaria y no invasiva clínicamente útil para determinar el estado de la función pulmonar en pacientes con trastornos crónicos como la enfermedad pulmonar intersticial difusa (EPID). Objetivo: Describir el perfil sociodemográfico y clínico de usuarios de la prueba DLCO en Valdivia, Chile. Materiales y Métodos: Estudio observacional, retrospectivo, de base documental. A partir de registros de 490 pacientes que se realizaron la prueba DLCO entre 2017 y 2019, se describen características sociodemográficas, clínicas y reporte de consumo de cigarrillo como cigarrillos/d e índice paquetes/año (IPA), comparando por sexo. Resultados: La mayor proporción de evaluados fueron mujeres (61%), con una edad mediana de 65 años, mayor en mujeres (66 vs 64 años; p = 0,0361). La mayoría consultaron por EPID (54,5%). Según estado nutricional, 38% presentó preobesidad y 24,7% obesidad I (24,7%), destacando que 40,5% de las mujeres y 33% de los hombres se encontraron en alguna categoría de obesidad. Entre quienes reportaron información de consumo de cigarrillos (n = 346, 70,6%), 14,7% (n = 51) eran consumidores actuales, con un consumo mediano de 10 cigarrillos/d, sin diferencias por sexo. Entre exfumadores (n = 144; 50% hombres/mujeres) hubo significativamente menor consumo diario (5 vs 15; p = 0,0300) y de IPA (7 vs 18; p = 0,0083) en mujeres. Conclusiones: En usuarios de DLCO el principal diagnóstico de consulta fue EPID. Destacó alta frecuencia de obesidad y tabaquismo, sin diferencia de consumo por sexo en fumadores actuales, pero sí en exfumadores.

Background: The carbon monoxide diffusion capacity test (DLCO) is a clinically useful, routine, non-invasive lung function assessment to determine the status of lung function in patients with chronic disorders such as interstitial lung disease (ILD). Aim: To describe the sociodemographic and clinical profile of users of the DLCO test in Valdivia, Chile. Materials and Methods: Observational, retrospective, documentary-based study. From the records of 490 patients who underwent the DLCO test between 2017 and 2019, sociodemographic and clinical characteristics and reports of cigarette consumption are described, such as cigarettes/d and pack-year index (PYI), comparing by sex. Results: The highest proportion of those evaluated were women (61%), with a median age of 65 years, higher in women (66 vs. 64 years; p = 0.0361). The majority consulted for ILD (54.5%). According to nutritional status, 38% presented pre-obesity and 24.7% obesity I (24.7%), highlighting that 40.5% of women and 33% of men were in some category of obesity. Among those who reported information on cigarette consumption (n = 346, 70.6%), 14.7% (n = 51) were current consumers, with a median consumption of 10 cigarettes/d, without differences by sex. Among exsmokers (n = 144; 50% men/women) there was significantly less daily (5 vs 15; p = 0.0300) and IPA (7 vs 18; p = 0.0083) consumption in women. Conclusions: In DLCO users, the main consultation diagnosis was ILD. High frequency of obesity and smoking stood out, with no difference in consumption by sex in current smokers, but yes in ex-smokers.

Lymphangioleiomyomatosis: circulating levels of FGF23 and pulmonary diffusion / Linfangioleiomiomatose: níveis circulantes de FGF23 e difusão pulmonar

ABSTRACT Objective: Lymphangioleiomyomatosis (LAM) is a rare, destructive disease of the lungs with a limited number of determinants of disease activity, which are a critical need for clinical trials. FGF23 has been implicated in several chronic pulmonary diseases. We aimed to determine the association between serum FGF23 levels and pulmonary function in a cohort of patients with LAM. Methods: This was a descriptive single-center study in which subjects with LAM and controls with unreported lung disease were recruited. Serum FGF23 levels were measured in all subjects. Clinical data, including pulmonary function testing, were retrospectively obtained from electronic medical records of LAM subjects. Associations between FGF23 levels and clinical features of LAM were explored via nonparametric hypothesis testing. Results: The sample comprised 37 subjects with LAM and 16 controls. FGF23 levels were higher in the LAM group than in the control group. In the LAM group, FGF23 levels above the optimal cutoff point distinguished 33% of the subjects who had nondiagnostic VEGF-D levels. Lower FGF23 levels were associated with impaired DLCO (p = 0.04), particularly for those with isolated diffusion impairment with no other spirometric abnormalities (p = 0.04). Conclusions: Our results suggest that FGF23 is associated with pulmonary diffusion abnormalities in LAM patients and elicit novel mechanisms of LAM pathogenesis. FGF23 alone or in combination with other molecules needs to be validated as a biomarker of LAM activity in future clinical research.

RESUMO Objetivo: A linfangioleiomiomatose (LAM) é uma doença rara e destrutiva dos pulmões com um número limitado de determinantes da atividade da doença, que são uma necessidade crítica para ensaios clínicos. O FGF23 já foi implicado em várias doenças pulmonares crônicas. O nosso objetivo foi determinar a associação entre os níveis séricos de FGF23 e a função pulmonar em uma coorte de pacientes com LAM. Métodos: Estudo descritivo unicêntrico no qual foram recrutados indivíduos com LAM e controles com doenças pulmonares não declaradas. Os níveis séricos de FGF23 foram medidos em todos os indivíduos. Os dados clínicos, incluindo testes de função pulmonar, foram obtidos retrospectivamente a partir dos prontuários eletrônicos dos indivíduos com LAM. As associações entre os níveis de FGF23 e as características clínicas da LAM foram exploradas por meio do teste de hipóteses não paramétrico. Resultados: A amostra incluiu 37 indivíduos com LAM e 16 controles. Os níveis de FGF23 foram mais altos no grupo LAM do que no grupo controle. No grupo LAM, níveis de FGF23 acima do ponto de corte ideal distinguiram 33% dos indivíduos com níveis não diagnósticos de VEGF-D. Níveis mais baixos de FGF23 estavam associados à DLCO comprometida (p = 0,04), particularmente naqueles com comprometimento isolado da difusão e sem outras alterações espirométricas (p = 0,04). Conclusões: Nossos resultados sugerem que o FGF23 está associado a alterações na difusão pulmonar em pacientes com LAM e potencialmente indicam novos mecanismos de patogênese da LAM. O FGF23 isoladamente ou em combinação com outras moléculas precisa ser validado como um biomarcador da atividade da LAM em futuras pesquisas clínicas.

Correlation between chest computed tomography findings and pulmonary function test results in the post-recovery phase of COVID-19

ABSTRACT Objective The radiological and functional lung sequelae in COVID-19 survivors remain unclear. We compared the chest computed tomography findings of COVID-19 patients with normal and abnormal pulmonary function test results in the post-recovery phase. Methods The data of consecutive patients who underwent pulmonary function tests and chest computed tomography within 14 days after recovery from COVID-19 at two medical centers between May and October 2020 were collected retrospectively. Two thoracic radiologists who were blinded to the clinical information and pulmonary function test results classified the patients according to the computed tomography features, evidence of fibrotic-like changes, and semi-quantitative quantification of the extent of pulmonary abnormalities. The clinical characteristics and computed tomography findings of patients with normal pulmonary function test results were compared with those of patients with abnormal results. Results A total of 101 COVID-19 survivors, comprising 48 ambulatory and 53 hospitalized patients, were included at a median of 95 days from initial symptom onset. Computed tomography revealed fibrotic-like changes in 10.9% of patients. A reduction in the diffusion capacity of carbon monoxide was the most common lung function abnormality (19.8%). Abnormal diffusion capacity of carbon monoxide was associated with the presence and extension of lung opacities on chest computed tomography scans and fibrotic pulmonary abnormalities. The sensitivity, specificity, and accuracy of reduced diffusion capacity of carbon monoxide for detecting fibrotic-like pulmonary changes on chest computed tomography scans were 72.7%, 87.8%, and 86.1%, respectively. Conclusion Our study suggests that the presence of an abnormal diffusion capacity of carbon monoxide in the post-recovery phase of COVID-19 is associated with a greater risk of long-term parenchymal lung disease, as evidenced by the presence of fibrotic-like changes on chest computed tomography scans, such as traction bronchiectasis and architectural distortion.

Risk factors for the prognosis of rheumatoid arthritis-associated interstitial lung disease: a multicenter retrospective clinical study / 中华风湿病学杂志

Objective:To explore the impact of clinical features, serological indicators, and pulmonary function test (PFT) on the prognosis of rheumatoid arthritis-associated interstitial lung disease (RA-ILD).Methods:Clinical data of RA-ILD patients who were diagnosed by HRCT and were followed up in Changhai Hospital or Yancheng First People's Hospital from 2011 to 2021 were collected Respiratory functional impairment of the patients was evaluated according to the changes of HRCT score and PFT, and the patients were divided into progressive group and stable group. COX survival analysis and ROC curve were used to determine the factors related to the progression of RA-ILD.Results:Finally 98 RA-ILD patients were included. The mean age of ILD onset was (62.9±12.1) years old, the median course of RA was 7.0 (1.0, 15.3)years, and the median follow-up time was 36.5 months (14.0, 79.5). There were 49 cases in the progressive group, and the clinical characteristics and laboratory tests of the two groups were compared. The results showed that: progressive time [(23(8.5,43.0)months vs 63(32.5,90.9) months, Z=-4.55, P=0.001)], HRCT score [(115(109,135) vs 111(105,116), Z=-2.70, P=0.007)], forced vital capacity(FVC) predicted [(70.1±15.7)% vs (80.8±19.7)%, t=2.12, P=0.039)], diffusing capacity of the lungs for CO(DLCO) predicted [(57.5±16.3)% vs (83.4±18.8)%, t=4.87, P=0.001)], male [(44.9% vs 18.4%, χ2=7.97, P=0.005)], UIP pattern [(36(73.5%) vs 9(18.4%), χ2=29.96, P<0.001)], RF>200 U/ml[(21(65.6%) vs 18(41.9%), χ2=4.15, P=0.042)], anti-CCP>75 U/ml [(42(91.3%) vs 35(71.4%), χ2=6.10, P=0.013], all had significantly different between the two groups. In multivariate analyses, UIP[ HR(95% CI)=3.25(1.62,6.50), P<0.001], anti-CCP antibody >75 U/ ml[ HR(95% CI)=3.85 (1.20,12.33), P=0.023] and smoking [ HR (95% CI): 5.74(1.10, 30.13), P=0.039] were significantly correlated with the progression of pulmonary fibrosis in RA-ILD patients. PFT was performed in only 44 patients with RA-ILD. The univariate analyses and ROC curve suggested that DLCO predicted [ HR (95% CI)=1.04 (1.02,1.06), P<0.001] was a significant risk factor for the progression of RA-ILD, and the area under curve (AUC) of DLCO was 0.845 [95% CI=(0.729,0.961)]. Conclusion:UIP pattern, high titer of anti-CCP antibody, smoking, and reduced DLCO predicted % may be potential predictors for poor prognosis of RA-ILD patients.

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.

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.

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.

O efeito do índice de massa corpórea na função pulmonar / The effect of body mass index on pulmonary function

Objetivo: caracterizar os volumes pulmonares, a resistência das vias aéreas (Rva) e a capacidade de difusão do monóxido do carbono (DCO) em indivíduos com índice de massa corpórea (IMC) normal, pré-obesos, obesidade classe I, obesidade classe II e obesidade classe III. Metodologia: estudo retrospectivo, quantitativo e transversal. A amostra foi constituída por 304 indivíduos de ambos os gêneros com suspeita ou diagnóstico clínico de asma, com IMC?25 kg/m2 e sem alterações nas provas funcionais respiratórias e por 95 indivíduos de ambos os gêneros, saudáveis e com IMC.

Objective: to characterize lung volumes, airway resistance (AWR), and carbon monoxide diffusion capacity (CMD) in individuals with normal, pre obese, class I obesity, class II obesity, and class III obesity body mass index (BMI). Methodology: this was a retrospective, quantitative, and cross-sectional study. The sample consisted of 304 individuals of both genders with suspicion or clinical diagnosis of asthma, with BMI ? 25 kg/m2, and without alterations in respiratory functional tests and 95 healthy and with normal BMI individuals of both genders.

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.

Test de respiración única para la capacidad de difusión de monóxido de carbono (DLCO) y su interpretación en enfermedades autoinmunes. Aplicación en la práctica clínica -Segunda Parte- / Single breath carbon monoxide diffusing capacity (DLCO) test and its interpretation in autoimmune diseases. Application in clinical practice Part -II-

El test de respiración única ha probado por si mismo ser una parte esencial del tamizaje de rutina de la función pulmonar, y de igual valor que la espirometría. A pesar de 100 años de investigación, aún no existe certeza sobre la relativa importancia de las membranas alveolo-capilares vs los eritrocitos como los pasos que sean delimitantes en el transporte global del monóxido de carbono del gas hacia la sangre, pero esto es solo un problema cuantitativo. La naturaleza esencial del test de DLCO ya ha sido elucidada, siendo F.J.W. Roughton y R.E. Forster los mayores protagonistas en esta descripción. La interpretación de la DLCO, en conjunto con la espirometría y los volúmenes pulmonares, pueden contribuir en la evaluación de enfermedades pulmonares subyacentes y, en el campo reumatológico es esencial su conocimiento puesto que ofrece la posibilidad de establecer un diagnóstico diferencial y un seguimiento cercano de los pacientes con enfermedades autoinmunes con manifestaciones pulmonares. El test de espiración única para la capacidad de difusión de monóxido de carbono, la espirometría y los gases arteriales son los test de función pulmonar más ampliamente utilizados para la evaluación y tratamiento de pacientes.

The single breath DLCO (TLCO) has proved as an essential part of the routine pulmonary function screen, similar to spirometry. In spite of nearly 100 years research, there is still concern over the relative importance of the alveolarcapillary membranes versus the red cells as rate limiting steps in the overall transfer of carbon monoxide from gas to blood, but this is only a quantitative problem. The essential nature of the DLCO has already been elucidated by F.J.W. Roughton and R.E. Forster having played the major roles. Interpreting the DLCO, in conjunction with spirometry and lung volumes assessment, may assist in diagnosing the underlying disease and in the Rheumatology field it is essential it's knowledge because it offers the possibility of establish the differential diagnosis and a close follow-up of the patients with pulmonary manifestations in autoimmune diseases.

Test de respiración única para la capacidad de difusión de monóxido de carbono (DLCO) y su interpretación en enfermedades autoinmunes. Historia y bases fisiológicas / Single breath carbon monoxide diffusing capacity (DLCO) test and its interpretation in autoimmune diseases. History and physiological basis

El test de respiración única para la capacidad de difusión de monóxido de carbono (DLCO) tiene una larga historia desde su nacimiento por Krogh y Krogh en 1909 hasta la primera publicación, describiendo una técnica estandarizada para la medición de la capacidad de difusión (DLCO) por Ogilvie en 1957. El test de DLCO fue inicialmente ideado como una herramienta fisiológica para evaluar el concepto (ahora abandonado) de que el pulmón, al igual que la vejiga natatoria de algún pez marino de agua profunda, podía secretar oxígeno en contra del gradiente normal de tensión provisto por el aire inspirado. El test de DLCO fue introducido como una prueba clínica por Marie Krogh en 1915, pero la medida nunca engranó debido a que los métodos de medición del monóxido de carbono eran muy engorrosos. En los años cincuenta con la introducción del medidor infrarrojo de monóxido de carbono (CO) (desarrollado en Alemania en la Segunda Guerra Mundial), el interés en el test de DLCO revivió y varios métodos para realizar el test de DLCO en pacientes con enfermedades pulmonares se aplicaron, usándose étodos en estado estable, la respiración única y las técnicas de reinhalación.

The single breath test of carbon monoxide (CO) uptake has a long history /from its birth by Krogh and Krogh in 1909 to the first publication describing a standardized technique for the diffusing capacity measurement (DLCO) by Ogilvie in 1957. The DLCO was devised originally as a physiological tool to test the notion (now abandoned) that the lung, like the swim bladder of some deep-sea fish, could secrete oxygen against the normal tension gradient provided by inspired air. The DLCO was introduced as a clinical test by Marie Krogh in 1915, but the measurement never caught on because methods of measuring carbon monoxide were so cumbersome. In the 1950s, with the introduction of the infra-red CO meter (developed in Germany, in World War II) interest in the DLCO revived, and several different methods for measuring DLCO in patients with pulmonary diseases were in use various steady state methods, the single breath and rebreathing techniques.

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.

Investigation on pulmonary diffusing capacity of the patients with diabetes mellitus / 中国综合临床

Objective To investigate pulmonary capillary changes in patients with diabetes mellitus. Meth-otis Fifty-eight patients with diabetes mellitus were enrolled and forty-seven healthy subjects were taken as control. Diffusion capacity of carbonmonoxide (DLCO) and pulmonary ventilatory function were measured. DM and Vc were measured in twenty-one patients and twelve healthy subjects among them. Results FEV1/FVC was (81.02± 6.40) % in patients with diabetes mellitus and ( 81.20±6.96 ) % in controls, and FEV 1% was ( 102.03±14.40) in patients with diabetes mellitus and 103.94±11.42 in controls ,with no significant difference between patients with DLCO% was ( 72.79±19.85 ) % in patients with diabetes mellitus and ( 90.60±13.25 ) % in controls with a sig-patients whose course of disease was less than ten years,and DLCO% was (64.69±17.49)% in patients with dia-betes mellitus whose course of disease is equal or more than ten years and (80.90±18.98)% in patients whose course of disease is less than ten years,with significant difference between these two groups (t = 4.435, -3. 381, 13.88)% in patients with diabetes mellitas and (83.58±26.79)% in controls with a significant difference (t = 4. 612, P < 0.001 ). Vc was ( 61.40±52.84 ) ml in patients with diabetes mellitus and ( 66.99±19.63 ) ml in con-trols with no significant difference (P > 0.05 ), and Vc% was (78.05±64. 40)% in patients with diabetes mellitus and (79.33±23.32) % in controls, with no significant difference ( P > 0.05 ). Conclusions Diffusing capacity is decreased in patients with diabetes mellitus, which is related to the course of disease . DM decline is the main cause of DLCO decrease in patients with diabetes mellitus.

Clinical Usefulness and the Accuracy of Korean Reference Equation for Diffusing Capacity / 결핵및호흡기질환

BACKGROUND: Park et al. developed the Korean reference equation for the measurement of diffusing capacity in 1985. However, the equation has not been widely used in Korea and foreign reference equations have been popularly used. We intended to compare the clinical usefulness and the accuracy of the the Korean reference equation (Park's equation) with that of the foreign equation (Burrows' equation) that is commonly used in Korea. METHODS: 1. Evaluation of clinical usefulness; Among 1,584 patients who underwent diffusing capacity (D(L)CO) at the Asan Medical Center from July to December 2006, group A subjects included 276 patients who had different interpretations of D(L)CO in trials employing Burrows' equation and Park's equation. Clinical assessment was decided by consensus of two respiratory physicians. In order to evaluate the clinical usefulness of Burrows' equation and Park's equation, agreement of clinical assessment and DLCO interpretation were measured. 2. Evaluation of accuracy; Group B subjects were 81 patients with interstitial lung disease (ILD) and 39 normal subjects. The 81 ILD patients were diagnosed following a surgical lung biopsy. The accuracy of diagnosing ILD as well as sensitivity and specificity were evaluated according to the use of the reference equations (Burrows' equation and Park's equation) for DLCO. RESULTS: Agreement between clinical assessment and interpretation of D(L)CO was 22% for the use of Burrows' equation and 78% for the use of Park's equation. The sensitivity and specificity of the Burrows' equation for diagnosing ILD were 64.2% and 100%. The sensitivity and specificity of the Park's equation for diagnosing ILD were 90.1% and 100%. The sensitivity of the Park's equation for diagnosing ILD was significantly higher than that of Burrows' equation (p<0.001). CONCLUSION: The Korean reference equation (Park's equation) was more clinically useful and had higher sensitivity for diagnosing ILD than the foreign reference equation (Burrows' equation).

Interplay between the morphometry of the lungs and the mode of locomotion in birds and mammals

We studied the lung diffusion parameters of two species of birds and two species of mammals to explore how structural and functional features may be paralleled by differences in life style or phylogenetic origin. We used two fast-flying species (one mammal and one bird), one running mammal and one bird species that flies only occasionally as models. The harmonic mean thickness of the air-blood barrier was very thin in the species we studied. An exception was the Chilean tinamou Notoprocta perdicaria, which only flies occasionally. It showed an air-blood barrier as thick as that of flightless Galliformes. We found that the respiratory surface density was significantly greater in flying species compared to running species. The estimated values for the oxygen diffusion capacity, DtO2 follow the same pattern: the highest values were obtained in the flying species, the bat and the eared dove. The lowest value was in N. perdicaria. Our findings suggest that the studied species show refinements in their morphometric lung parameters commensurate to their energetic requirements as dictated by their mode of locomotion, rather than their phylogenetic origin. The air-blood barrier appears to be thin in most birds and small mammals, except those with low energetic requirements such as the Chilean tinamou. In the species we studied, the respiratory surface density appears to be the factor most responsive to the energetic requirements of flight

Selection of Reference Equations for Lung Volumes and Diffusing Capacity in Korea / 결핵및호흡기질환

BACKGROUND: The lung volume and diffusing capacity are influenced by ethnicity. However, there are no equations for predicting the normal lung volume in the adult Korean population, and there is only one equation for diffusing capacity. The aim of this study is to select the most suitable reference equation for the Korean population. METHOD: 30 men and 33 women at Hanyang University Guri Hospital, and 27 men and 34 women at Asan Medical Center in healthy nonsmoking adults were enrolled in this study. The subject's age, gender, height, weight, lung volume by plethysmography, and diffusing capacity by a single breathing method were obtained. The most suitable equation with the lowest sum of residuals between the observed and predicted values for lung volume and diffusing capacity was selected. RESULT: At Hanyang University Guri Hospital, the equations with the lowest sum of residuals in the total lung capacity were ECSC's equation in males (sum of residual: 0.04 L) and Crapo/Morris's equation (-1.04) in women. At the Asan Medical Center, the equations with the lowest sum of residuals in the total lung capacity were Goldman/Becklake's equation in males (sum of residual: -2.35) and the ECSC's equation -4.49) in women. The equations with the lowest sum of residuals in the Diffusing capacity were Roca's equation in males (sum of residual: -13.66 ml/min/mmHg) and Park's in women (25.08) in Hanyang University Guri hospital and Park's equation in all cases in the Asan Medical Center (male: -1.65 , female: -6.46). CONCLUSIONS: Until a reference equstion can be made for healthy Koreans by sampling, ECSC's equation can be used for estimating the lung volume and Park's can be used for estimating the diffusing capacity.

Pulmonary membrane diffusing capacity and pulmonary capillary blood volume in patients with stable COPD / 上海第二医科大学学报

Objective To study the clinical significance of pulmonary membrane diffusing capacity(Dm) and pulmonary capillary blood volume(Vc) in patients with stable chronic obstructive pulmonary disease(COPD). Methods Spirometry was performed in 38 patients with stable COPD and 35 healthy individuals in resting condition.The changes of pulmonary parameters were obtained and compared between groups. Results Spirometry test revealed that the percent predicted forced expired volume in one second(FEV1),FEV1/forced volume capacity(FVC)and the percent predicted maximal ventilatory volume(MVV) were declined from stage Ⅰin patients with COPD in comparison with healthy individuals,while diffusing capacity for carbon monoxide of lung(DLCO),carbon monoxide diffusing capacity per liter of alveolar(DLCO/VA),Dm and Vc were declined from stage Ⅱ.Dm in patients with COPD of stageⅠwas sig-nificantly decreased compared with the controls,while Vc was increased compared with the controls(both P

Pulmonary function in patients with type 2 diabetes mellitus / 中国病理生理杂志

AIM: To evaluate the pulmonary function in patients with type 2 diabetes mellitus in order to identify whether the lung is a target organ of chronic pathologic changes in diabetes mellitus. METHODS: Pulmonary ventilation function and diffusion capacity were studied in 107 patients with type 2 diabetes mellitus and 61 healthy subjects matched for age and sex. Glycosylated hemoglobin (HbA1c), urine albumin excretion rate (AER), fundus examination and nerve conduction velocity were included as parameters of glycemic control and diabetic microangiopathies. RESULTS: Pulmonary ventilation function was similar in type 2 diabetic group and the control. Compared with the control, carbon monoxide diffusion capacity (DLCO) and DLCO corrected by alveolar volume (DLCO/VA) were significantly lower in type 2 diabetic group (P<0.05). DLCO and DLCO/VA were inversely correlated with microangiopathy score (r: -0.291, -0.324, respectively, P<0.01). Furthermore, DLCO/VA was negatively correlated with age and duration of diabetes mellitus (r: -0.269, -0.236, respectively, P<0.05). CONCLUSIONS: Pulmonary ventilation function is normal in patients with type 2 diabetes mellitus, but their diffusion capacity is impaired. It suggests that the lung may also be the target organ of the chronic pathologic changes of diabetes mellitus.

The Change of Lung Diffusing Capacity for Dialysis Duration and Membranes in Maintenance Hemodialysis Patients / 대한신장학회잡지

BACKGROUND: Pulmonary fibrosis is the most common pulmonary complication in patients with end stage renal disease undergoing hemodialysis. The diffusing capacity is sensitive and reliable methods for diagnosis for pulmonary fibrosis. The aim of this study was to investigate the change of diffusing capacity for dialysis duration and membranes (synthetic vs cellulosynthetic) in maintenance hemodialysis patients. METHODS: We evaluated prospectively pulmonary diffusing capacity (DLCO/VA) of the patients who had been receiving regular hemodialysis for a period of at least 3 months at Gyeongsang National University Hospital from April 1, 2002 to June 30, 2003. Seventy one patients were divided into two groups by dialysis duration: less than 24 months; more than 24 months. Also, we divided patients into two groups by dialysis membrane: cellulosynthetic membrane (Hemophan); synthetic membrane (Polysulfone). RESULTS: The diffusing capacity and dialysis durations were presented for negative correlation [r= -0.321 (p=0.01) in DLCO/VA]. According to dialysis membranes, DLCO/VA values were significantly decreased in patients in Hemophan group rather than Polysulfone Group [92.4+/-20.5% vs 107.5+/-19.3%, (p= 0.01)]. According to dialysis durtation and membranes, DLCO/VA values were significantly decreased in patients in Hemophan group rather than Polysulfone group at duration for more than 24 months [84.9+/-20.1% vs 105.2+/-20.8%, (p=0.003)]. CONCLUSION: Patients undergoing long-term maintenance hemodialysis showed a gradual reduction in lung diffusing capacity for dialysis duration. Our results suggested that lung diffusing capacity was more severely reduced in hemodialysis patients using bioincompatible membrane rather than biocompatible membrane.