Utilidad de los estudios de función pulmonar en el niño / Utility of lung function tests in children

Pulmonary function testing in children includes a large number of methods and aspects. Children constitute a very heterogeneous group of individuals, among which are non-collaborative infants and preschoolers who represent a challenge in the development of new methods that do not require collaboration or coordination. This review attempts to achieve a comprehensive approach to pulmonary function tests in children that allow the physician working in pediatrics to get to know: their pathophysiological bases; the reasons for a request for a pulmonary function test taking into account the underlying pathophysiological process that is suspected; the study procedures; the possible clinical findings and their interpretation; the advantages and limitations of several of the tests. Information related to spirometry is developed more specifically, since it is the most widespread, accessible and widely validated methods.

El estudio de la función pulmonar (FP) en niños abarca un gran número de métodos y aspectos. La edad pediátrica en sí constituye un grupo muy heterogéneo de individuos, entre los que se encuentran los de edades más tempranas que son no colaborativos y que representan un desafío en el desarrollo de nuevos métodos que no requieran colaboración ni coordinación. En esta revisión se describirá un enfoque integral de los estudios de FP más utilizados en niños. Se mencionan sus bases fisiopatológicas; los motivos de un pedido de estudio de FP teniendo en cuenta el proceso fisiopatológico subyacente que se sospecha; los posibles hallazgos clínicos y su interpretación y las ventajas y limitaciones de varios de los test.

Validation of the GLI-2012 spirometry reference equations in Argentinian children.

AIM: The Global Lung Function Initiative (GLI) has produced spirometry reference equations for use in different ethnic groups. Previous reports have shown that the GLI equations do not adequately describe lung function in all populations and that adopting the new equations into clinical practice can increase the number of patients considered to have abnormal lung function. Therefore, before adopting these equations into local practice it is necessary to establish how well the equations represent the local population. The present study was conducted to determine how well the GLI spirometry reference equations represented the young children in Argentina, a population not included in the GLI dataset. METHODS: Spirometry was measured in 2072 healthy children (50.9% males) aged 3.0-12.4 years (mean 6.64 ± SD 1.39), with a height range of 93.0-158.5 cm and weight range from 13.1 to 54.7 kg. We used the GLI "Caucasian" and "other/mixed" race equations to create Z-scores. RESULTS: The Z-scores predicted by the Caucasian GLI equations did not differ from zero and fitted the data well. Z-scores calculated using "other/mixed race" fit less well. Using the GLI definition of low lung function (Z-score <1.65) 6.8% of our healthy population had abnormal FVC, 4.9% had abnormal FEV1, 5.9 % had abnormal FEV0.75, and 3.9% had abnormal FEF25-75 when using the "Caucasian" GLI equation. This compares well with the expected 5% below the lower limit of normal. CONCLUSION: We recommend the use of the GLI-2012 Caucasian equations for spirometry undertaken in Argentinian children.

Assessing bronchodilator response in preschool children using spirometry.

BACKGROUND: Measuring lung function, including bronchodilator response (BDR), is an integral part of asthma management in older children. While spirometry is possible in preschool-aged children, the question remains whether measuring BDR aids in asthma diagnosis in this age group. METHODS: 431 healthy children and 289 children with asthma, aged 3-5 years, were recruited from kindergartens and the pulmonology clinic in Trelew, Argentina. Spirometry was performed at visit 1 and repeated after 15 min, with children randomised to placebo or salbutamol (400 µg). Spirometry was again performed within 8 weeks at visit 2. Within-session repeatability from visit 1 and between-session reproducibility were calculated using baseline spirometry. The within-session repeatability and receiver operating characteristic curve analyses were used to determine the optimal threshold values for BDR for spirometry outcome variables measured at the first visit, and sensitivity, specificity and diagnostic accuracy were determined. RESULTS: As a group, children with asthma had lower lung function (FVC 1.11±0.12 L vs 1.01±0.15 L; FEV0.75 1.01±0.10 L vs 0.91±0.15 L) and a greater BDR (FEV0.75 group difference 8.6 (95% CI -5.0 to 14.3)%) than healthy children. BDR was best defined by change in FEV0.75; an increase of 11% showed the best balance between sensitivity (51%), specificity (88%), positive predictive value (47%) and negative predictive value (89%) for discriminating healthy from preschool-aged children with asthma. CONCLUSIONS: A negative BDR in a child suspected of having asthma makes a diagnosis of asthma less likely.

Validation of a questionnaire for asthma case identification in pre-schools in Latin America.

BACKGROUND AND OBJECTIVE: We recently developed and validated a screening questionnaire for determining which school-aged children may need further investigation to diagnose and manage asthma. In the present study we sought to extend this to pre-school aged children. METHODS: Questions from the school-aged questionnaire and literature on pre-school asthma were used to inform a focus group of parents with pre-school-aged children with asthma to develop a screening questionnaire. Parents of children attending 6 randomly selected kindergartens in Trelew, Argentina (n = 639) were invited to respond to the questionnaire. A reliability test-retest was undertaken in 187 randomly selected parents who completed the same questionnaire twice within 2-5 weeks. Clinical assessment included a standardized history and physical examination, spirometry before and after a ß-agonist inhaler, and chest X-ray. Asthma was diagnosed by the pulmonologist. RESULTS: Completed surveys were returned for 620 children, 607 of whom underwent clinical evaluation. The mean age was 4.21 years (range of 3.01-5.50) and included 82.5% white and 49.4% male children. Asthma was diagnosed in 103 (17.0%) children); 72 (69.9%) of these children did not have a previous diagnosis of asthma. The specificity, sensitivity, positive predictive value and negative predictive value of the questionnaire were 93.2%, 86.1%, 57.8% and 98.4%, respectively. CONCLUSIONS: We have demonstrated the utility of a screening questionnaire for identifying pre-school-aged children who may benefit from further assessment for asthma.

Validation of a school-based written questionnaire for asthma case identification in Argentina.

Recognition of asthma in community-based surveys can be problematic. We sought to develop and validate questionnaires that could identify elementary school-aged children likely to have asthma or who had poorly-controlled asthma. Questionnaires for parents (PQ) and students (SQ) to complete were developed using guidance on question wording from a focus group consisting of children with asthma and their parents. The gold standard for this study was a pulmonologist determination of asthma and this was used to calculate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for each question and for combinations of questions. Questionnaires were distributed to 830 children attending elementary schools in Trelew, Argentina and 96% were returned. Test-retest reliability was determined in 221 randomly selected parents and children and very good levels of agreement were seen for individual questions. Asthma was diagnosed in 92 students. Overall, the PQ was able to detect asthma better than the SQ. Optimal diagnostic ability came by combining questions from the PQ and SQ. Not surprisingly, these questionnaires had a better NPV than PPV and can be used to determine which children require further evaluation.

Increased asthma and respiratory symptoms in children exposed to petrochemical pollution.

BACKGROUND: Epidemiologic studies show statistical associations between levels of air pollutants and respiratory outcomes. OBJECTIVE: We sought to determine the effects of exposure to petrochemical pollution on the respiratory health of children. METHODS: Children aged 6 to 12 years living close to the petrochemical plants in La Plata, Argentina (n = 282), were compared with those living in a region with exposure to heavy traffic (n = 270) or in 2 relatively nonpolluted areas (n = 639). Parents answered a validated questionnaire providing health and demographic data. A random sample (n = 181) had lung function measured. Particulate matter and outdoor and indoor volatile organic compound levels were measured during 4-week study periods and reported as overall means for each study area. RESULTS: Children living near the petrochemical plant had more asthma (24.8% vs 10.1% to 11.5%), more asthma exacerbations (6.7 vs 2.9-3.6 per year), more respiratory symptoms (current wheeze, dyspnea, nocturnal cough, and rhinitis), and lower lung function (>13% decrease in FEV(1) percent predicted) than those living in other regions. Length of residence in the area was a significant risk factor, but age, sex, body mass index, proximity to busy roads and other nonpetrochemical industries, length of breast-feeding, and socioeconomic and demographic characteristics of children or their families were not. CONCLUSION: Exposure to particulate matter and volatile organic compounds arising from petrochemical plants but not from high traffic density was associated ith worse respiratory health in children.