Optimal oxygen saturation as measured by pulse oximetry (Sp_O2) in neonatal lung injury, such as meconium aspiration syndrome (MAS) and persistent pulmonary hypertension of newborn (PPHN), is not known. Our goal was to determine the Sp_O2 range in lambs with MAS and PPHN that results in the highest brain oxygen delivery (bDO₂) and pulmonary blood flow (Qp) and the lowest pulmonary vascular resistance and oxidative stress. Meconium was instilled into endotracheal tubes in 25 near-term gestation lambs, and the umbilical cord was occluded to induce asphyxia and gasping, causing MAS and PPHN. Lambs were randomized into four groups and ventilated for 6 hours with fixed fraction of inspired oxygen (Fi_O2) = 1.0 irrespective of Sp_O2, and three groups had Fi_O2 titrated to keep preductal Sp_O2 between 85% and 89%, 90% and 94%, and 95% and 99%, respectively. Tissues were collected to measure nitric oxide synthase activity, 3-nitrotyrosine, and 8-isoprostanes. Throughout the 6-hour exposure period, lambs in the 95–99% Sp_O2 target group had the highest Qp, lowest pulmonary vascular resistance, and highest bDO₂ but were exposed to higher Fi_O2 (0.5 ± 0.21 vs. 0.29 ± 0.17) with higher lung 3-nitrotyrosine (0.67 [interquartile range (IQR), 0.43–0.73] ng/mcg protein vs. 0.1 [IQR, 0.09–0.2] ng/mcg protein) and lower lung nitric oxide synthase activity (196 [IQR, 192–201] mMol nitrite/mg protein vs. 270 [IQR, 227–280] mMol nitrite/mg protein) compared with the 90–94% target group. Brain 3-nitrotyrosine was lower in the 85–89% target group, and brain/lung 8-isoprostane levels were not significantly different. In term lambs with MAS and PPHN, Qp and bDO₂ through the first 6 hours are higher with target Sp_O2 in the 95–99% range. However, the 90–94% target range is associated with significantly lower Fi_O2 and lung oxidative stress. Clinical trials comparing the 90–94% versus the 95–99% Sp_O2 target range in term infants with PPHN are warranted.

在新生儿肺损伤（例如胎粪吸入综合征 (MAS) 和新生儿持续性肺动脉高压 (PPHN)）中通过脉搏血氧仪 (Sp _{O 2 ) 测量的最佳氧饱和度尚不清楚。}我们的目标是确定具有 MAS 和 PPHN 的羔羊的 Sp _{O 2}范围，从而导致最高的脑氧输送 (bDO ₂ ) 和肺血流量 (Qp) 以及最低的肺血管阻力和氧化应激。25只近月妊娠羔羊经气管插管灌注胎粪，封堵脐带引起窒息喘息，引起MAS和PPHN。羔羊被随机分为四组，并用固定比例的吸入氧气 (F i _{O 2}) = 1.0，与 Sp _{O 2}无关，三组分别滴定 F i _{O 2}以将导管前 Sp _{O 2}保持在 85% 和 89%、90% 和 94% 以及 95% 和 99% 之间。收集组织以测量一氧化氮合酶活性、3-硝基酪氨酸和 8-异前列烷。在整个 6 小时暴露期间，95–99% Sp _{O 2}目标组中的羔羊具有最高的 Qp、最低的肺血管阻力和最高的 bDO ₂但暴露于更高的 F i _{O 2}（0.5 ± 0.21 对比 0.29 ± 0.17）肺部 3-硝基酪氨酸更高（0.67 [四分位数间距 (IQR)，0.43–0.73] ng/mcg 蛋白质对比 0.1 [IQR，0.09–0.2] ng/mcg 蛋白质）和更低肺部一氧化氮合酶活性（196 [IQR，192-201] mMol 亚硝酸盐/mg 蛋白质对比 270 [IQR，227-280] mMol 亚硝酸盐/mg 蛋白质）与 90-94% 目标组相比。85-89% 目标组的脑 3-硝基酪氨酸较低，脑/肺 8-异前列烷水平无显着差异。在患有 MAS 和 PPHN 的足月羔羊中，前 6 小时的 Qp 和 bDO ₂较高，目标 Sp _{O 2}在 95–99% 范围内。然而，90–94% 的目标范围与显着较低的 F i _{O 2相关}和肺氧化应激。_{比较 90–94% 与 95–99% Sp O 2}目标范围在患有 PPHN 的足月婴儿中的临床试验是必要的。