Carmen Lisboa B

Prueba de caminata en seis minutos en sujetos chilenos sanos de 20 a 80 años

Background: The six minute walking distance test (6MWD) is widely used to evaluate exercise capacity in several diseases due to its simplicity and low cost. Aim: To establish reference values for 6MWD in healthy Chilean individuals. Material and methods: We studied 175 healthy volunteers aged 20-80 years (98 women) with normal spirometry and without history of respiratory, cardiovascular or other diseases that could impair walking capacity. The test was performed twice with an interval of 30 min. Heart rate, arterial oxygen saturation (with a pulse oxymeter) and dyspnea were measured before and after the test. Results: Walking distance was 576 ± 87 m in women and 644 ± 84 m in men (p < 0.0001). For each sex, a model including age, height and weight produced 6MWD prediction equations with a coefficient of determination (R2) of 0.63 for women and 0.55 for men. Conclusions: Our results provide reference equations for 6MWD that are valid for healthy subjects between 20 and 80 years old.

Selective training of respiratory muscles in patients with chronic heart failure

Background: Patients with chronic heart failure have a lower inspiratory muscle strength and fatigue endurance. Aim: To assess the effects of selective training of respiratory muscles in patients with heart failure. Patients and methods: Twenty patients with stable chronic heart failure, aged 58.3 ± 3 years with an ejection fraction of 28 ± 9%, were subjected to respiratory muscle training with threshold valves. The load was fixed in 30% of maximal inspiratory pressure (PImax) in 11 and in 10% of PImax in nine. Two sessions of 15 minutes, 6 days per week, during 6 weeks were done. Degree of dyspnea (Mahler score), maximal oxygen uptake, distance walked in 6 minutes, respiratory muscle function and left ventricular ejection fraction were measured before and after training. Results: Both training loads were associated to an improvement in dyspnea (+2.7 ± 1.8 and +2.8 ± 1.8 score points with 30% Plmax and 10% PImax respectively), maximal oxygen uptake (from 19 ± 3 to 21.6 ± 5 and from 16 ± 5 to 18.6 ± 7 ml/kg/min with 30% PImax and 10% PImax respectively, p< 0.05), PImax (from 78 ± 22 to 99 ± 22 and from 72 ± 34 to 82.3 cm H20 with 30% Plmax and 10% PImax respectively), sustained PImax (from 63 ± 18 to 90 ± 22 and from 58 ± 3 to 69 ± 3 cm H20 with 30% PImax and 10% PImax respectively), and maximal sustained load (from 120 ± 67 to 195 ± 47 and from 139 ± 120 to 192 ± 154 g with 30% PImax and 10% PImax respectively). The distance walked in 6 min only increased in subjects trained at 30% PImax (from 451 ± 78 to 486 ± 68 m). Conclusions: Selective training of respiratory muscles results in a functional improvement of patients with chronic heart failure. (Rev Med Chile 2001; 129: 133-39).

Potencia de los músculos inspiratorios en insuficiencia cardíaca crónica y en enfermedad pulmonar obstructiva crónica

BACKGROUND: The maximal pressure generated by inspiratory muscles (PIMax) is an index of their strength which is diminished in both chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF). Although inspiratory muscle power output (IMPO), which includes both strength and velocity of shortening, has been shown to be reduced in COPD, there is no information regarding IMPO in CHF. AIM: To measure IMPO in patients with CHF and COPD. PATIENTS AND METHODS: We studied 9 CHF patients with functional capacity II and III and 9 patients with severe COPD. Eight normal subjects of similar ages were included as controls. Power output was measured using the incremental threshold loading test. RESULTS: Maximal IMPO was significantly reduced in both groups of patients. Power output developed with each increasing load was also diminished, basically as a consequence of a reduction in Vinsp. The degree of dyspnea at the end of the test was greater in COPD than in CHF patients and normal subjects. For a given level of power, dyspnea was also greater in patients than in normals subjects. There was no decrease in SpO2 during the test. CONCLUSIONS: IMPO is equally reduced in COPD and CHF patients. Power output is better related to dyspnea than PIMax, probably because of the inclusion of shortening velocity.

Efecto de la prueba de la caminata de seis minutos sobre la hiperinflación pulmonar en pacientes con enfermedad pulmonar obstructiva crónica avanzada

Background: Exercise tolerance in patients with COPD is highly variable and poorly related to airways obstruction assessed by FEV1. These patients develop dynamic hyperinflation (DH) during an incremental exercise test which can be evaluated through a reduction in inspiratory capacity (IC). Aim: to evaluate: a) if the six minute walking test (6 MWD) induce DH reducing IC, b) if the reduction in IC is related to tidal expiratory flow limitation at rest (FL). Subjects and methods: Thirty eight stable COPD patients (28 FL and ten non FL during resting breathing, determined by the negative pressure technique). Inspiratory capacity was measured before and immediately after the 6 MWD test. Dyspnea, SpO2 and heart rate were measured before and after the test. Results: Inspiratory capacity was lower in FL patients as compared to patients without FL (p <0,005). Although no differences were found between groups in 6 MWD, dyspnea and HR, a significant reduction in IC after the walking test was observed only in FL patients (p <0,0001). In addition, SpO2 fell significantly (p <0,0001) after walking in the same group. Conclusions: Our results demonstrate that a moderate exercise such as the walking test induces DH and hypoxemia in patients with COPD and FL and stresses the importance of assessing DH by measuring IC in these patients (Rev Med Chile 2001; 129: 1171-78)

Beneficios clínicos y funcionales de agregar teofilina a la terapia inhalatoria con broncodilatadores de acción corta en pacientes con enfermedad pulmonar obstructiva crónica

Thirty-eight stable COPD patients who accepted to participate in thestudy approved by the Ethics Committee of our institution were studied. Using a randomized double-blindplacebo-controlled study, theophylline (250 mg) or placebo was administered twice a day for 15 days inaddition to inhaled salbutamol and ipratropium bromide. Prior to and at the end of the study, patientsunderwent: a) a spirometry to evaluate changes in dynamic pulmonary hyperinflation using slow vitalcapacity (SVC) and inspiratory capacity (IC), b) the 6 min walking distance (6 MWD); and c)measurement of maximal inspiratory and expiratory pressures. Dyspnea and quality of life (QoL) wereevaluated using appropriate questionnaires.

Etiología y biomarcadores de inflamación sistémica en las exacerbaciones leves a moderadas de la enfermedad pulmonar obstructiva crónica

Background: The etiology of acute exacerbations of chronic obstructive pulmonary disease (COPD) is heterogeneous and still under discussion. Inflammation increases during exacerbation of COPD. The identification of inflammatory changes will increase our knowledge and potentially guide therapy. Aim: To identify which inflammatory parameters increase during COPD exacerbations compared to stable disease, and to compare bacterial and viral exacerbations. Material and Methods: In 85 COPD patients (45 males, mean age 68 ± 8 years, FEV1 46 ± 17% of predicted) sputum, nasopharyngeal swabs and blood samples were collected to identify the causative organism, during a mild to moderate exacerbation. Serum ultrasensitive C reactive protein (CRP), fibrinogen and interleukin 6 (IL 6), neutrophil and leukocyte counts were measured in stable conditions, during a COPD exacerbation, 15 and 30 days post exacerbation. Results: A total of 120 mild to moderate COPD exacerbations were included. In 74 (61.7%), a microbial etiology could be identified, most commonly Mycoplasma pneumoniae (15.8%), Rhinovirus (15%), Haemophilus influenzae (14.2%), Chlamydia pneumoniae (11.7%), Streptococcus pneumoniae (5.8%) and Gram negative bacilli (5.8%). Serum CRP, fibrinogen and IL 6, and neutrophil and leukocyte counts significantly increased during exacerbation and recovered at 30 days post exacerbation. Compared to viral exacerbations, bacterial aggravations were associated with a systemic inflammation of higher magnitude. Conclusions: Biomarkers of systemic inflammation increase during mild to moderate COPD exacerbations. The increase in systemic inflammation seems to be limited to exacerbations caused by bacterial infections.

Características clínicas y funcionales según género de pacientes con enfermedad pulmonar obstructiva crónica

Resumen La prevalencia, al igual que la mortalidad de la enfermedad pulmonar obstructiva cronica(EPOC), ha aumentado en las mujeres. Esto ultimo sugiere que la enfermedad seria mas grave en elsexo femenino. El proposito de este estudio fue evaluar si existen diferencias en la gravedad segungenero en 95 pacientes (38 mujeres) con EPOC ingresados consecutivamente a un protocolo deseguimiento. Evaluamos la magnitud del tabaquismo, caracteristicas demograficas, gravedad segunVEF 1 e indice BODE y compromiso de la calidad de vida. Los resultados no demostraron diferen-cias entre hombres y mujeres en ninguno de los indices de gravedad. Sin embargo, la magnitud deltabaquismo fue inferior en las mujeres que en los hombres (35,5 ± 19,4 vs 45,7 ± 21 paquetes-ano;p = 0,02). Nuestros resultados sugieren una mayor susceptibilidad de las mujeres para desarrollarEPOC, pero no demuestran que la gravedad de la enfermedad dependa del genero. Palabras clave: EPOC, funcion pulmonar, indice BODE, genero. * Departamento de Enfermedades Respiratorias, Pontificia Universidad Catolica de Chile.** Ayudante alumno de la Escuela de Medicina, Pontificia Universidad Catolica de Chile.

Reversibilidad espirométrica en la enfermedad pulmonar obstructiva crónica: Efecto diferencial del salbutamol sobre el volumen espiratorio forzado del primer segundo y el volumen pulmonar

, indice relacionado con el aumento de losflujos espiratorios, sino que tambien midiendo loscambios que se producen en el volumen pulmo-nar. La evaluacion de los cambios de volumenpulmonar no requiere de equipos sofisticados, yaque con un simple espirometro es posible medirla capacidad vital lenta (CVL), la capacidad vitalforzada (CVF) y la capacidad inspiratoria. Sedesconoce cual es la magnitud de los cambios devolumen y cuantos pacientes podrian ser cataloga-dos como respondedores frente a los broncodila-tadores, basados solo en los cambios de volumen,ya que los trabajos que han explorado estaaproximacion adolecen de limitaciones entre lasque destacan: el caracter retrospectivo de unestudio

Proposición de nuevas ecuaciones para calcular valores espirométricos de referencia en población chilena adulta: Sociedad Chilena de Enfermedades Respiratorias (SER)

BACKGROUND To correctly interpret spirometric results, reference values should come from the same population. Current spirometric reference equations have been under scrutiny due to deficiencies to fit adequately for Chilean population, specially, for those aged over 65 years old. AIM To develop new spirometric reference values for Chilean adults, based on national studies in which spirometries were performed in healthy non-smoker adults. MATERIAL AND METHODS A standardized database of spirometric values was developed combining spirometric data collected from five population-based studies, in which healthy nonsmoker adults participated. Spirometries from 448 males aged 19 to 84 years and from 726 females aged 19 to 94 years, obtained according to guidelines from the American Thoracic and European Respiratory Societies, were analyzed. Using multiple regression models, which included height, gender, and age, the theoretical value and inferior limits of normality were calculated for 1st second (FEV1), forced vital capacity (FVC), FEV1/FVC, and forced mid-expiratory flow rate (FEF25-75). RESULTS Reference values and lower limits of normality (LLN) were constructed for Chilean adults of both genders. The new proposed set of equations had a better fit, when compared with the current reference values used in Chile. CONCLUSIONS The new spirometric references values derived from this study, fit better than currently used ones. Therefore, they should be used as new references values for Chilean adults.

Hiperinflación pulmonar en la enfermedad pulmonar obstructiva crónica: Importancia funcional y clínica

Si bien es un hecho conocido que distintas drogas broncodilatadoras son capaces de producir alivio de la disnea en ausencia de mejoria significativa del VEF1 en pacientes con EPOC avanzada, solo en los ultimos anos se ha avanzado en el conocimiento de los mecanismos por los cuales esto ocurre. La hiperinflacion pulmonar dinamica (HPD) que se produce como consecuencia de la limitacion del flujo espiratorio (LFE) en reposo, altera gravemente la mecanica del aparato respiratorio y el funcionamiento de los musculos inspiratorios en pacientes con EPOC avanzada. Los broncodilatadores, al disminuir la HPD producen alivio de la disnea, aun sin mejoria del VEF1. Los cambios en el grado de HPD pueden evaluarse con la espirometria, a traves de los cambios de la capacidad inspiratoria o de la capacidad vital, parametros que aumentan en mayor grado y mas frecuentemente que el VEF1. A diferencia de lo que ocurre con el VEF1, la magnitud de la HPD se relaciona con el grado de disnea y de intolerancia al ejercicio. Es asi, como la disminucion de la maxima capacidad de ejercicio se relaciona con la reduccion de la capacidad inspiratoria en estos pacientes. Otras intervenciones capaces de disminuir la HPD y producir alivio de la disnea con mejoria de la tolerancia al ejercicio son: la cirugia de reduccion de volumen pulmonar, la administracion de oxigeno y la ventilacion mecanica no invasiva. Se analizan los mecanismos por los cuales estas intervenciones actuan mejorando los sintomas de estos pacientes