Lang Justin A R, Pearson James T, te Pas Arjan B, Wallace Megan J, Siew Melissa L, Kitchen Marcus J, Fouras Andreas, Lewis Robert A, Wheeler Kevin I, Polglase Graeme R, Shirai Mikiyasu, Sonobe Takashi, Hooper Stuart B
The Ritchie Centre, MIMR-PHI Institute of Medical Research, Melbourne, Australia; Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia;
Monash Biomedical Imaging, Melbourne, Australia; Australian Synchrotron, Melbourne, Australia;
J Appl Physiol (1985). 2014 Sep 1;117(5):535-43. doi: 10.1152/japplphysiol.01358.2013. Epub 2014 Jul 3.
At birth, the transition to newborn life is triggered by lung aeration, which stimulates a large increase in pulmonary blood flow (PBF). Current theories predict that the increase in PBF is spatially related to ventilated lung regions as they aerate after birth. Using simultaneous phase-contrast X-ray imaging and angiography we investigated the spatial relationships between lung aeration and the increase in PBF after birth. Six near-term (30-day gestation) rabbits were delivered by caesarean section, intubated and an intravenous catheter inserted, before they were positioned for X-ray imaging. During imaging, iodine was injected before ventilation onset, after ventilation of the right lung only, and after ventilation of both lungs. Unilateral ventilation increased iodine levels entering both left and right pulmonary arteries (PAs) and significantly increased heart rate, iodine ejection per beat, diameters of both left and right PAs, and number of visible vessels in both lungs. Within the 6th intercostal space, the mean gray level (relative measure of iodine level) increased from 68.3 ± 11.6 and 70.3 ± 7.5%·s to 136.3 ± 22.6 and 136.3 ± 23.7%·s in the left and right PAs, respectively. No differences were observed between vessels in the left and right lungs, despite the left lung not initially being ventilated. The increase in PBF at birth is not spatially related to lung aeration allowing a large ventilation/perfusion mismatch, or pulmonary shunting, to occur in the partially aerated lung at birth.
出生时，向新生儿生活的转变由肺通气引发，这会刺激肺血流量（PBF）大幅增加。当前理论预测，出生后随着肺通气，PBF的增加在空间上与通气的肺区域相关。我们使用同步相衬X射线成像和血管造影术研究了出生后肺通气与PBF增加之间的空间关系。六只近足月（妊娠30天）的兔子通过剖宫产分娩，插管并插入静脉导管，然后将它们放置好进行X射线成像。在成像过程中，在通气开始前、仅右肺通气后以及双肺通气后注射碘。单侧通气增加了进入左、右肺动脉（PA）的碘水平，并显著增加了心率、每搏碘排出量、左、右PA的直径以及双肺可见血管的数量。在第6肋间空间内，左、右PA的平均灰度（碘水平的相对测量值）分别从68.3±11.6和70.3±7.5%·s增加到136.3±22.6和136.3±23.7%·s。尽管左肺最初未通气，但左、右肺血管之间未观察到差异。出生时PBF的增加在空间上与肺通气无关，这使得出生时部分通气的肺中会出现较大的通气/灌注不匹配或肺内分流。
