Sobotka K S, Ong T, Polglase G R, Crossley K J, Moss T J M, Hooper S B
The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia.
The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia Department of Obstetrics and Gynaecology, Monash University, Clayton, Australia.
Arch Dis Child Fetal Neonatal Ed. 2015 Jul;100(4):F337-43. doi: 10.1136/archdischild-2014-307319. Epub 2015 Apr 28.
At birth, an initial sustained inflation (SI) uniformly aerates the lungs, increases arterial oxygenation and rapidly improves circulatory recovery in asphyxiated newborns. We hypothesised that lung aeration, in the absence of an increase in arterial oxygenation, can increase heart rate (HR) in asphyxiated near-term lambs.
Lambs were delivered and instrumented at 139±2 days of gestation. Asphyxia was induced by umbilical cord clamping and then delaying the onset of ventilation until mean carotid arterial pressures (CAPs) had decreased <20 mm Hg. Lambs then received a single 30-s SI using nitrogen (N2; n=6), 5% oxygen (O2; n=6), 21% O2 (n=6) or 100% O2 (n=6) followed by ventilation in air for 30 min.
HR, CAP and pulmonary blood flow (PBF) were continuously recorded.
HR and PBF increased more quickly in lambs resuscitated with 100% and 21% O2 than with 5% O2 or N2. HR and PBF recovery in the 5% O2 group was delayed relative to all other oxygen SI groups. HR in 5%, 21% and 100% O2 groups reached 100 bpm before the SI was complete. HR and PBF in the N2 group did not increase until 10 s after the SI was completed and ventilation was initiated with air. CAP tended to increase quicker in all O2 groups than in N2 group.
Oxygen content during an SI is important for circulatory recovery in asphyxiated lambs. This increase in HR is likely driven by the increase in PBF and venous return to the heart.
出生时，初始持续充气（SI）可使肺均匀充气，提高动脉氧合，并迅速改善窒息新生儿的循环恢复。我们假设，在动脉氧合未增加的情况下，肺充气可增加近足月窒息羔羊的心率（HR）。
在妊娠139±2天分娩并对羔羊进行仪器植入。通过夹闭脐带诱导窒息，然后延迟通气开始时间，直到平均颈动脉压（CAP）降至<20 mmHg。然后，羔羊接受单次30秒的SI，分别使用氮气（N2；n = 6）、5%氧气（O2；n = 6）、21% O2（n = 6）或100% O2（n = 6），随后在空气中通气30分钟。
持续记录HR、CAP和肺血流量（PBF）。
用100%和21% O2复苏的羔羊，其HR和PBF的增加比用5% O2或N2复苏的羔羊更快。相对于所有其他氧气SI组，5% O2组的HR和PBF恢复延迟。5%、21%和100% O2组的HR在SI完成前达到100次/分钟。N2组的HR和PBF直到SI完成10秒后开始通气时才增加。所有O2组的CAP升高趋势均比N2组更快。
SI期间的氧含量对窒息羔羊的循环恢复很重要。HR的增加可能是由PBF和静脉回心血量的增加驱动的。
