Alveolarization Continues during Childhood and Adolescence New Evidence from Helium-3 Magnetic Resonance
Alveolarization Continues during Childhood and Adolescence New Evidence from Helium-3 Magnetic Resonance
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DOI：
10.1164/rccm.201107-1348oc
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发表时间：
2012-01-15
影响因子：
24.7
通讯作者：
Silverman, Michael
中科院分区：
文献类型：
--
作者：
Narayanan, Manjith;Owers-Bradley, John;Silverman, Michael
基本原理：目前的假设，人类肺泡化是由3年完成的是矛盾的肺泡化在整个青春期在mammals.Objectives的新证据：我们重新审视了目前的假设，使用氦-3（He-3）磁共振（MR）评估肺泡大小非侵入性之间的7和21年，在此期间，肺体积近四倍。如果新的肺泡化不发生，肺泡大小应增加到相同的程度。方法：肺容量测定法和体积描记法在109名健康受试者年龄在7-21岁。使用（HeMR）-He-3，我们确定了两个独立的测量外围空域尺寸：在FRC的He-3的表观扩散系数（ADC）（n = 109），和氦的平均扩散距离（（X-rms）在酒吧）通过q空间分析（n = 46）。我们比较了这些参数的变化与肺生长对模型的肺扩张，没有新的alveolarization. Measures和主要结果：ADC增加0.19%，每增加1%的FRC（95%置信区间[CI]，0.13-0.25），而预期的变化，在没有新的alveolarization是0.41%（95%CI，0.31-0.52）。同样，FRC组（（X-rms）相对于条形图）的增加显著小于无新肺泡形成时的预测增加。肺泡的数量估计增加1.94倍（95%CI，1.64-2.30）在整个年龄范围studied.Conclusions：我们的观察结果是最好的解释，假设肺生长部分neoalveolarization在整个儿童和青少年。这具有重要的意义：发育中的肺具有从早期生命损伤中恢复的潜力，并对新兴的肺泡治疗做出反应。相反，药物，疾病或环境暴露可能会对整个儿童期的肺泡形成产生不利影响。
Rationale: The current hypothesis that human pulmonary alveolarization is complete by 3 years is contradicted by new evidence of alveolarization throughout adolescence in mammals.Objectives: We reexamined the current hypothesis using helium-3 (He-3) magnetic resonance (MR) to assess alveolar size noninvasively between 7 and 21 years, during which lung volume nearly quadruples. If new alveolarization does not occur, alveolar size should increase to the same extent.Methods: Lung volumes were measured by spirometry and plethysmography in 109 healthy subjects aged 7-21 years. Using (HeMR)-He-3 we determined two independent measures of peripheral airspace dimensions: apparent diffusion coefficient (ADC) of He-3 at FRC(n = 109), and average diffusion distance of helium ((X-rms) over bar) by q-space analysis (n = 46). We compared the change in these parameters with lung growth against a model of lung expansion with no new alveolarization.Measurements and Main Results: ADC increased by 0.19% for every 1% increment in FRC (95% confidence interval [CI], 0.13-0.25), whereas the expected change in the absence of neoalveolarization is 0.41% (95% CI, 0.31-0.52). Similarly, increase of ((X-rms) over bar) with FRC was significantly less than the predicted increase in the absence of neoalveolarization. The number of alveoli is estimated to increase 1.94-fold (95% CI, 1.64-2.30) across the age range studied.Conclusions: Our observations are best explained by postulating that the lungs grow partly by neoalveolarization throughout childhood and adolescence. This has important implications: developing lungs have the potential to recover from early life insults and respond to emerging alveolar therapies. Conversely, drugs, diseases, or environmental exposures could adversely affect alveolarization throughout childhood.