Vilozni Daphna, Hakim Fahed, Adler Adi, Livnat Galit, Bar-Yishay Ephraim, Bentur Lea
Pediatric Pulmonary Unit, Meyer Children's Hospital, Rambam Medical Center, Haifa, Israel.
Respir Med. 2009 Jan;103(1):109-16. doi: 10.1016/j.rmed.2008.07.027. Epub 2008 Sep 19.
In a previous study we assessed the feasibility of measuring bronchial-reactivity (BHR) in young asthmatic children by the determination of PC(20)-FEV(1) along with clinical end-of-test criteria during a methacholine challenge test (MCT). The end-point was associated with a significant reduction in both flow and vital capacity values. The findings could be due to the children's loss of motivation, which may preclude use of this test. Alternatively, if it reflects air trapping during airway obstruction, it might reinforce its applicability in preschool age children.
To elucidate the mechanism of low vital capacity at PC(20)-FEV(1) in preschool age children.
Twenty-eight children (3.3-6.9 years) with recurrent respiratory symptoms.
An MCT was carried out using tripling doses (0.06-13.9 mg/ml) delivered by a dosimeter. Spirometry was measured at baseline and after each inhalation in duplicate sets. Whole body plethysmography was measured at baseline and at end-of-test (defined by clinical criteria) according to the recommendations for older populations.
Plethysmography was reliably performed by 20 children before and after MCT. At baseline, lung function was within the healthy range. At end-of-test (PC(20)-FEV(1)=4.02+/-3.47 mg/ml), the spirometry parameters and specific conductance values were markedly reduced in correlation with a significant increase in residual volume and resistance.
The study shows that diminished vital capacity is due to the increase in FRC at end-of-test. Our findings support the use of PC(20)-FEV(1) during BHR in young children and suggest that lung volume measurement by a plethysmograph may be feasible in early childhood. Larger studies should be performed to establish the clinical applicability of PC20-FEV1 determination in the preschool age.
在之前的一项研究中，我们通过在乙酰甲胆碱激发试验（MCT）期间测定PC(20)-FEV(1)以及临床测试结束标准，评估了在年轻哮喘儿童中测量支气管反应性（BHR）的可行性。终点与流量和肺活量值的显著降低相关。这些发现可能是由于儿童失去动力所致，这可能妨碍该测试的使用。或者，如果它反映了气道阻塞期间的气体潴留，那么它可能会加强其在学龄前儿童中的适用性。
阐明学龄前儿童在PC(20)-FEV(1)时肺活量降低的机制。
28名有反复呼吸道症状的儿童（3.3 - 6.9岁）。
使用剂量计以三倍剂量（0.06 - 13.9 mg/ml）进行MCT。在基线和每次吸入后以重复两组的方式测量肺功能。根据针对年长人群的建议，在基线和测试结束时（由临床标准定义）测量全身体积描记法。
20名儿童在MCT前后可靠地完成了体积描记法测量。在基线时，肺功能处于健康范围内。在测试结束时（PC(20)-FEV(1)=4.02±3.47 mg/ml），肺功能测定参数和比传导率值显著降低，同时残气量和阻力显著增加。
该研究表明，肺活量降低是由于测试结束时功能残气量增加所致。我们的发现支持在幼儿BHR期间使用PC(20)-FEV(1)，并表明通过体积描记器测量肺容积在幼儿期可能是可行的。应进行更大规模的研究以确定PC20-FEV1测定在学龄前儿童中的临床适用性。
