Department of Pediatrics, State University of New York, Buffalo, New York 14214, USA.
Pediatr Res. 2009 Nov;66(5):539-44. doi: 10.1203/PDR.0b013e3181bab0c7.
The effect of oxygen concentration on lowering pulmonary vascular resistance (PVR) during resuscitation in a model of persistent pulmonary hypertension of the newborn (PPHN) is not known. PPHN was induced in fetal lambs by ductal ligation 9 d before delivery. After delivery by cesarean section, resuscitation of PPHN lambs with 21%, 50%, or 100% O2 (n = 6 each) for 30 min produced similar decreases in PVR. Lambs were then ventilated with 50% O2 for 60 min and exposed to inhaled nitric oxide (iNO, 20 ppm). Initial resuscitation with 100% O2 significantly impaired the subsequent response to iNO compared with 21% O2 (42 +/- 9% vs 22 +/- 4% decrease from baseline PVR). Finally, each lamb was randomly and sequentially ventilated with 10%, 21%, 50%, or 100% O2. PVR decreased with increased concentrations of inhaled O2 up to 50%, there being no additional decrease in PVR with 100% O2. When PVR was correlated with Pao2, the maximal change in PVR was achieved at Pao2 values <60 mm Hg. We conclude that resuscitation with 100% O2 does not enhance pulmonary vasodilation compared with 21% and 50% O2, but impairs the subsequent response to iNO in PPHN lambs. Hypoxia increases PVR but hyperoxia does not confer significant additional pulmonary vasodilation in lambs with PPHN.
在持续性肺动脉高压新生儿（PPHN）模型的复苏过程中，氧浓度对降低肺血管阻力（PVR）的影响尚不清楚。通过在分娩前 9 天结扎导管在胎羊中诱导 PPHN。通过剖腹产分娩后，用 21%、50%或 100%的 O2（n = 6 只）对 PPHN 羔羊进行 30 分钟的复苏，可使 PVR 产生相似的降低。然后，羔羊用 50%的 O2 通气 60 分钟，并暴露于吸入性一氧化氮（iNO，20ppm）。与 21%的 O2 相比，初始用 100%的 O2 复苏显著损害了随后对 iNO 的反应（从基线 PVR 降低 42 +/- 9%比 22 +/- 4%）。最后，每个羔羊随机和连续用 10%、21%、50%或 100%的 O2 通气。随着吸入 O2 浓度的增加，PVR 降低，直至达到 50%，而用 100%的 O2 则不会导致 PVR 的进一步降低。当 PVR 与 PaO2 相关时，在 PaO2 值<60mmHg 时可达到 PVR 的最大变化。我们得出结论，与 21%和 50%的 O2 相比，用 100%的 O2 复苏并不能增强肺血管扩张，但会损害 PPHN 羔羊对 iNO 的随后反应。低氧血症增加 PVR，但高氧血症在 PPHN 羔羊中不会带来显著的额外肺血管扩张。
