RESUMEN

Rationale: Ventilatory demand-capacity imbalance, as inferred based on a low ventilatory reserve, is currently assessed only at peak cardiopulmonary exercise testing (CPET). Peak ventilatory reserve, however, is poorly sensitive to the submaximal, dynamic mechanical ventilatory abnormalities that are key to dyspnea genesis and exercise intolerance. Objectives: After establishing sex- and age-corrected norms for dynamic ventilatory reserve at progressively higher work rates, we compared peak and dynamic ventilatory reserve for their ability to expose increased exertional dyspnea and poor exercise tolerance in mild to very severe chronic obstructive pulmonary disease (COPD). Methods: We analyzed resting functional and incremental CPET data from 275 controls (130 men, aged 19-85 yr) and 359 Global Initiative for Chronic Obstructive Lung Disease patients with stage 1-4 obstruction (203 men) who were prospectively recruited for previous ethically approved studies in three research centers. In addition to peak and dynamic ventilatory reserve (1 - [ventilation / estimated maximal voluntary ventilation] × 100), operating lung volumes and dyspnea scores (0-10 on the Borg scale) were obtained. Results: Dynamic ventilatory reserve was asymmetrically distributed in controls; thus, we calculated its centile distribution at every 20 W. The lower limit of normal (lower than the fifth centile) was consistently lower in women and older subjects. Peak and dynamic ventilatory reserve disagreed significantly in indicating an abnormally low test result in patients: whereas approximately 50% of those with a normal peak ventilatory reserve showed a reduced dynamic ventilatory reserve, the opposite was found in approximately 15% (P < 0.001). Irrespective of peak ventilatory reserve and COPD severity, patients who had a dynamic ventilatory reserve below the lower limit of normal at an isowork rate of 40 W had greater ventilatory requirements, prompting earlier attainment of critically low inspiratory reserve. Consequently, they reported higher dyspnea scores, showing poorer exercise tolerance compared with those with preserved dynamic ventilatory reserve. Conversely, patients with preserved dynamic ventilatory reserve but reduced peak ventilatory reserve reported the lowest dyspnea scores, showing the best exercise tolerance. Conclusions: Reduced submaximal dynamic ventilatory reserve, even in the setting of preserved peak ventilatory reserve, is a powerful predictor of exertional dyspnea and exercise intolerance in COPD. This new parameter of ventilatory demand-capacity mismatch may enhance the yield of clinical CPET in the investigation of activity-related breathlessness in individual patients with COPD and other prevalent cardiopulmonary diseases.

Asunto(s)

Enfermedad Pulmonar Obstructiva Crónica , Masculino , Humanos , Femenino , Valores de Referencia , Pulmón , Disnea/etiología , Prueba de Esfuerzo , Tolerancia al Ejercicio

RESUMEN

BACKGROUND: Continuous monitoring of SpO2 throughout the 6-min walk test (6MWT) unveiled that some patients with respiratory diseases may present values across the test lower than SpO2 measured at the end of the test. Nevertheless, it remains unclear whether this approach improves the yield of walk-induced desaturation detection in predicting mortality and hospitalizations in patients with COPD. METHODS: Four hundred twenty-one subjects (51% males) with mild-very severe COPD underwent a 6MWT with continuous measurement of SpO2 . Exercise desaturation was defined as a fall in SpO2 ≥ 4%. All-cause mortality was assessed up to 6 y of follow-up and the rate of hospitalizations in the year succeeding the 6MWT. RESULTS: One hundred forty-nine subjects (35.4%) died during a mean (interquartile) follow-up of 55.5 (30.2-64.1) months. Desaturation was observed in 299/421 (71.0%). SpO2 along the test was < end SpO2 (88 [82-92]% vs 90 [84-93]%, P < .001). Desaturation detected only during (but not at the end of) the test was found in 81/421 (19.2%) participants. Multivariate Cox regression model adjusted for sex, body composition, FEV1, residual volume/total lung capacity ratio, walk distance, O2 supplementation during the test, and comorbidities retained the presence of desaturation either at the end (1.85 [95% CI 1.02-3.36]) or only along the test (2.08 [95% CI 1.09-4.01]) as significant predictors of mortality. The rate of hospitalizations was higher in those presenting with any kind of desaturation compared to those without exercise desaturation. Logistic regression analysis revealed that walking interruption and diffusing capacity of the lung for carbon monoxide predicted desaturation observed only during the test. CONCLUSIONS: O2 desaturation missed by end-exercise SpO2 but exposed by measurements during the test was independently associated with all-cause mortality and hospitalizations in subjects with COPD.

Asunto(s)

Enfermedad Pulmonar Obstructiva Crónica , Masculino , Humanos , Femenino , Prueba de Paso , Enfermedad Pulmonar Obstructiva Crónica/diagnóstico , Oxígeno , Prueba de Esfuerzo , Oximetría , Caminata

RESUMEN

Resumen: El cáncer de pulmón (CP) es la causa de muerte por enfermedad maligna más frecuente. Al momento del diagnóstico, solo el 15% de los pacientes con cáncer de pulmón continúan con vida tras 5 añosporqueeste se realizahabitualmente en estadios avanzados. El cribado de CP con tomografía axial computarizada de baja dosis (TCBD)se ha propuesto como una estrategia para reducir la mortalidad mediante su detección precoz y tratamiento temprano. Es bien conocida la relación entre el tabaco y el CP, siendo el 90% de estos cánceres atribuidos ala exposición activa o pasiva al humo del cigarrillo. Entre los factores de riesgo (FR)más importantes pero infra reconocidos, estála enfermedad pulmonar obstructiva crónica (EPOC).Recientemente,el uso de la TCBDha permitido identificar a el enfisema pulmonarcomo otro importante FR. La asociación entre estas dos enfermedades (EPOC y enfisema) potencia el riesgo de desarrollar CP, lo que convierte a los fumadores con estas patologías en dianas ideales para los programas de cribado. Sin embargo, el equilibrio entre el beneficio y el daño ocasionado por el cribadoha generado un intenso debate, por lo que el desafío se sitúa en mejorar los criterios de inclusiónde los programas de cribado, minimizando el número de falsos positivos y el sobre diagnóstico. Esta revisión pretende destacarlos puntos más importantes sobre el cribado de cáncer de pulmón y realizar algunas recomendaciones para su puesta en marcha.

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Abstract: Lung cancer (PC) is the cause of death due to more frequent malignant disease. At the time of diagnosis, only 15% of patients with lung cancer remain alive after 5 years because this is usually done in advanced stages. CP Screening with Computed Low-dose Axial Tomography (BDT) has been proposed as a strategy to reduce mortality through early detection and early treatment. The relationship between smoking and CP is well known, with 90% of these cancers attributed to active or passive exposure to cigarette smoke. Chronic obstructive pulmonary disease (COPD) is the most important but underrecognized risk factor (RF). Recently, the use of BDT has allowed lung emphysema to be identified as another major FR. The association between these two diseases (COPD and emphysema) increases the risk of developing COP, which makes smokers with these pathologies an ideal target for screening programs. However, the balance between benefit and damage caused by screening has generated intense debate, so the challenge lies in improving the criteria for inclusion of screening programs, minimizing the number of false positives and over-diagnosis. This review aims to highlight the most important points about lung cancer screening and make some recommendations for its implementation.