Liao S L, Luks F I, Piasecki G J, Wild Y K, Papadakis K, De Paepe M E
Division of Pediatric Surgery, Brown University School of Medicine, Providence, Rhode Island 02905, USA.
J Surg Res. 2000 Jul;92(1):64-70. doi: 10.1006/jsre.2000.5858.
Fetal tracheal occlusion (TO) results in varying degrees of lung growth. This study examines whether gestational age influences lung growth response following TO.
Fetal lambs (term = 145 days) underwent TO early (108 days, n = 6) or late (122 days, n = 6) in gestation. Aspirated lung fluid volume (LFV) and intratracheal pressure (ITP) were recorded daily. Two weeks after TO, the fetuses were sacrificed. Lung growth was assessed by lung weight and stereologic volumetry. Type II cellular density was assessed by computer-assisted morphometry using antisurfactant protein B antibody.
After early TO, ITP remained below 2 mm Hg for all but one of the first 5 days. In late TO, ITP rose to 4.8 +/- 1.7 mm Hg by Day 1 and remained elevated. LFV remained lower after early than after late TO (P < 0.05) for 8 days. Thereafter, pressure and volume reached similar levels in both TO groups; both were significantly higher than their respective controls (P < 0.05). Parenchymal fraction (1 - air-space fraction) was significantly smaller after late TO (22.8 +/- 1.2%) than after early TO (31.3 +/- 0.5%). Type II density was 38.0 +/- 12.4 x 10(6)/mL after early TO and 84.0 +/- 24.3 x 10(6)/mL in control (P < 0.05); the difference between late TO and control was not significant.
Late tracheal occlusion in fetal lambs caused more rapid lung growth than earlier TO, although ultimate lung size was similar in both groups. Late TO also resulted in greater air-space fraction and better preservation of the type II cell population than early TO. Late-gestation tracheal occlusion may therefore be preferable to prolonged occlusion initiated earlier.
胎儿气管阻塞（TO）会导致不同程度的肺生长。本研究旨在探讨胎龄是否会影响TO后的肺生长反应。
将胎羊（足月为145天）在妊娠早期（108天，n = 6）或晚期（122天，n = 6）进行TO。每天记录吸出的肺液量（LFV）和气管内压力（ITP）。TO两周后，处死胎儿。通过肺重量和体视学体积测量评估肺生长。使用抗表面活性蛋白B抗体通过计算机辅助形态计量学评估II型细胞密度。
早期TO后，除前5天中的1天外，ITP在所有时间均保持在2 mmHg以下。晚期TO时，ITP在第1天升至4.8±1.7 mmHg并持续升高。早期TO后LFV在8天内低于晚期TO（P < 0.05）。此后，两个TO组的压力和体积达到相似水平；两者均显著高于各自的对照组（P < 0.05）。晚期TO后的实质部分（1 - 气腔部分）显著小于早期TO后（22.8±1.2%）（31.3±0.5%）。早期TO后II型密度为38.0±12.4×10⁶/mL，对照组为84.0±24.3×10⁶/mL（P < 0.05）；晚期TO与对照组之间的差异不显著。
尽管两组最终的肺大小相似，但胎羊晚期气管阻塞比早期TO导致更快的肺生长。晚期TO还比早期TO导致更大的气腔部分和更好地保留II型细胞群体。因此，妊娠晚期气管阻塞可能比早期开始的长期阻塞更可取。
