Capacidad vital lenta: diferencias entre la capacidad vital espiratoria y la capacidad vital inspiratoria

Resumen Introducción: La capacidad vital (VC) se puede determinar mediante la capacidad vital espiratoria (EVC) o la capacidad vital ins piratoria (IVC). Obtener el mayor volumen de VC es fundamental para la correcta interpretación de las pruebas de función pulmonar. Objetivos: Determinar las diferencias entre EVC y IVC (EVC-IVC) según el patrón ventilatorio; Caracterizar las relaciones FEV1/EVC y FEV1/IVC en la detección de obstrucción de las vías aéreas; Estudiar los efectos de realizar EVC o IVC en la detección de air trapping o de hiperinflación pulmonar. Materiales y Métodos: Estudio transversal. La muestra incluyó 388 individuos que se dividieron en 3 grupos: sanos, obstrucción de las vías aéreas y restricción pulmonar. Para detectar la obstrucción de las vías aéreas, se estudiaron las relaciones FEV1/EVC y FEV1/IVC. La presencia de air trapping o hiperinflación pulmonar se determinó mediante análisis del volumen pulmonar. As diferencias entre EVC e IVC (EVC-IVC) de acuerdo con el padrón ventilatorio fueron agrupados por clases. Resultados: En el grupo normal, 34.8% tuvo una diferencia EVC-IVC ≥ 200 ml, en el grupo de obstrucción de las vías respirato rias 28.4% y en la restricción pulmonar 22.4%, respectivamente. La relación FEV1/EVC detectó obstrucción de las vías aéreas en el 44.8% de los individuos y la relación FEV1/IVC en el 39.4%. En sujetos con obstrucción de las vías respiratorias, la maniobra de EVC determinó el air trapping en el 21.6% de los sujetos y la hiperinflación pulmonar en el 9.5%. En la maniobra de IVC, los porcentajes fueron 18.2% y 10.8%, respectivamente. Conclusiones: El EVC y el IVC no deben considerarse maniobras intercambiables, debido a las diferencias de volumen obtenidas por cada uno de ellos. Los resultados que provienen de su uso influyeron en la interpretación de la función pulmonar.

Slow Vital Capacity: Differences Between the Expiratory Vital Capacity and the Inspiratory Vital Capacity

ABSTRACT Introduction: The vital capacity (VC) can be determined by means of the expiratory vital capacity (EVC) or the inspiratory vital capacity (IVC). Obtaining the highest VC volume is essential for the correct interpretation of lung function tests. Objectives: To determine the differences between the EVC and the IVC (EVC-IVC) according to the ventilatory pattern; to characterize the FEV1/EVC and FEV1/IVC ratios when an obstruction of the airways is detected; to study the effects of the EVC or IVC on the detec tion of air trapping or lung hyperinflation. Materials and Methods: Cross-sectional study. The sample included 388 individuals divided in 3 groups: healthy, airway obstruc tion, and restrictive lung disease. In order to detect the airway obstruction, we studied the FEV1/EVC and FEV1/IVC ratios. The presence of air trapping or lung hyperinflation was determined by means of a lung volume test. The differences between the EVC and the IVC (EVC-IVC) according to the ventilatory pattern were grouped into classes. Results: In the normal group, there was an EVC-IVC difference of ≥ 200 ml in 34.8% of the individuals; in the airway obstruction group, 28.4%, and in the restrictive lung disease group, 22.4%. The FEV1/EVC ratio detected airway obstruction in 44.8% of the individuals, and the FEV1/IVC ratio in 39.4%. In patients with airway obstruction, the EVC maneuver determined the presence of air trapping in 21.6% of subjects and lung hyperinflation in 9.5%. The IVC maneuver showed 18.2% and 10.8%, respectively. Conclusions: The EVC and IVC should not be used as interchangeable maneuvers, considering the volume differences obtained with each one of them. Their results influenced the interpretation of lung function.

Contribution of flow-volume curves to the detection of central airway obstruction / Contribuicao da curva de fluxo-volume na deteccao de obstrucao da via aerea central

OBJECTIVE: To assess the sensitivity and specificity of flow-volume curves in detecting central airway obstruction (CAO), and to determine whether their quantitative and qualitative criteria are associated with the location, type and degree of obstruction. METHODS: Over a four-month period, we consecutively evaluated patients with bronchoscopy indicated. Over a one-week period, all patients underwent clinical evaluation, flow-volume curve, bronchoscopy, and completed a dyspnea scale. Four reviewers, blinded to quantitative and clinical data, and bronchoscopy results, classified the morphology of the curves. A fifth reviewer determined the morphological criteria, as well as the quantitative criteria. RESULTS: We studied 82 patients, 36 (44%) of whom had CAO. The sensitivity and specificity of the flow-volume curves in detecting CAO were, respectively, 88.9% and 91.3% (quantitative criteria) and 30.6% and 93.5% (qualitative criteria). The most prevalent quantitative criteria in our sample were FEF50%/FIF50% ≥ 1, in 83% of patients, and FEV1/PEF ≥ 8 mL . L–1 . min–1, in 36%, both being associated with the type, location, and degree of obstruction (p < 0.05). There was concordance among the reviewers as to the presence of CAO. There is a relationship between the degree of obstruction and dyspnea. CONCLUSIONS: The quantitative criteria should always be calculated for flow-volume curves in order to detect CAO, because of the low sensitivity of the qualitative criteria. Both FEF50%/FIF50% ≥ 1 and FEV1/PEF ≥ 8 mL . L–1 . min–1 were associated with the location, type and degree of obstruction. .

OBJETIVO: Verificar a sensibilidade e especificidade das curvas de fluxo-volume na detecção de obstrução da via aérea central (OVAC), e se os critérios qualitativos e quantitativos da curva se relacionam com a localização, o tipo e o grau de obstrução. MÉTODOS: Durante quatro meses foram selecionados, consecutivamente, indivíduos com indicação para broncoscopia. Todos efetuaram avaliação clínica, preenchimento de escala de dispneia, curva de fluxo-volume e broncoscopia num intervalo de uma semana. Quatro revisores classificaram a morfologia da curva sem conhecimento dos dados quantitativos, clínicos e broncoscopicos. Um quinto revisor averiguou os critérios morfológicos e quantitativos. RESULTADOS: Foram incluídos 82 doentes, 36 (44%) com OVAC. A sensibilidade e especificidade da curva de fluxo-volume na detecção de OVAC foram, respectivamente, de 88,9% e 91,3% (critérios quantitativos) e de 30,6% e 93,5% (critérios qualitativos). Os critérios quantitativos mais frequentes na amostra foram o FEF50%/FIF50% ≥ 1 em 83% e o VEF1/PFE ≥ 8 mL . L–1 . min–1 em 36% dos doentes, e ambos se relacionaram com o tipo, a localização e o grau de obstrução (p < 0,05). Houve concordância dos revisores quanto à existência ou não de OVAC. Existe relação entre o grau de obstrução e o de dispneia. CONCLUSÕES: Os critérios quantitativos devem ser sempre calculados nas curvas de fluxo-volume de forma a detectar OVAC, dado a baixa sensibilidade dos critérios qualitativos. Os critérios FEF50%/FIF50% ...