低氧性新生儿持续肺动脉高压与肺血管重建发生机制

新生儿持续肺动脉高压(PPHN)为新生儿期的严重疾病,出生后肺动脉压力等于或超过体循环压力,出现动脉导管和(或)卵圆孔水平的右向左分流,导致明显的低氧血症.肺血管重建与PPHN的形成和发展过程有较强相关性,低氧引起的肺血管重建以血管壁的内膜、中膜和外膜细胞组成成分和调节机制紊乱,血管壁增厚为基本特征.该文从内皮细胞、平滑肌细胞和细胞外基质三方面来阐述低氧性PPHN与肺血管重建的关系及其可能机制.     

法舒地尔对大鼠低氧性肺动脉高压及其肺血管结构重建的影响

目的 探讨Rho激酶抑制剂法舒地尔对大鼠低氧性肺动脉高压(HPH)及其肺血管结构重建的影响.方法 采用常压间断低氧法建立大鼠HPH模型.雄性SD大鼠24只,随机均分为对照组、模型组和法舒地尔干预组.测各组大鼠平均肺动脉压力(mPAP)、平均颈动脉压力(mCAP)、右心室肥厚指数(RVHI);光镜下结合图像分析进行肺血管结构重建观察;透射电镜观察肺小动脉内皮细胞超微结构的变化.结果 ①模型组mPAP、RVHI、肺小动脉管壁厚度与外径比值(WT%)、管壁面积与管总面积比值(WA%)分别为(31.38±1.98)mmHg、0.47±0.03、(31.13±5.74)%、(54.93±3.34)%均明显高于对照组(15.25±0.91)mmHg、0.25±0.02、(13.24±2.03)%、(31.81±3.62)%,P均＜0.01;管腔面积与管总面积比值(LA%)为(45.07±3.34)%,明显低于对照组(68.20±3.62)%,P＜0.01;透射电镜显示模型组肺小动脉内皮细胞损伤明显,内皮细胞周围平滑肌细胞增生、肿胀,胶原纤维增生.②法舒地尔干预组mPAP、RVHI、WT%、WA%分别为(16.63±1.53)mmHg、0.27±0.02、(17.08±2.24)%、(37.30±3.69)%显著低于模型组(P＜0.01),LA%为(62.70±3.69)%明显高于模型组(P＜0.01).法舒地尔干预后肺小动脉内皮细胞损伤、平滑肌细胞及胶原纤维增生均明显减轻.③各组间mCAP差异无统计学意义(F=1.239,P＞0.05).结论 法舒地尔对低氧所致的肺动脉高压、右心室肥厚及肺血管结构重建具有较好的预防和逆转作用.     

Changes in expression of vascular endothelial growth factor and its receptors in neonatal hypoxia-induced pulmonary hypertension

Vascular endothelial growth factor (VEGF) is a potent mitogen with angiogenic and vasoactive properties. VEGF can bind to two types of receptors. VEGF receptor 2 (VEGFR2) is mainly responsible for the dilator response to VEGF through nitric oxide (NO) release, whereas VEGFR1 may sequestrate the ligand. We hypothesized that in neonatal hypoxia-induced pulmonary hypertension, VEGF vasodilation is reduced. The dilator response to VEGF was assessed in isolated perfused lung of 1-d-old piglets that were exposed to either normoxia or hypoxia (fraction of inspired oxygen 0.10) for 14 d. The plasma and pulmonary artery concentration of VEGF was measured by quantitative sandwich enzyme immunoassay in piglets that were exposed to either normoxia or hypoxia for 1, 3, 7, or 14 d. The expression of VEGFR1, VEGFR2, and endothelial NO synthase in pulmonary artery was measured in the same study groups using Western blot analysis. VEGF (10(-12)-10(-9) M) induces a dose-dependent relaxation in 14-d normoxic piglets, whereas vasodilation is abolished after 14 d of hypoxia. VEGF tissue concentration is increased by hypoxia. VEGFR1 expression is dramatically increased after 1, 3, and 7 d of hypoxia compared with normoxia and returns to normal afterward. VEGFR2 expression is reduced by hypoxia at 14 d. However, endothelial NO synthase expression is not affected by hypoxia compared with normoxia. In neonatal hypoxia-induced pulmonary hypertension, VEGF is increased, whereas vasodilation to VEGF is abolished. This reduced vasodilation may be due to decreased VEGFR2 expression. We speculate that sequestration by VEGFR1 may also limit, to some extent, the vascular protecting effect of VEGF, thus contributing to the pathophysiologic changes seen in neonatal hypoxia-induced pulmonary hypertension.     

亚硝酸乙酯和一氧化氮吸入治疗大鼠急性肺动脉高压的作用比较

新生儿持续性肺动脉高压(PPHN)是新生儿常见的危重症之一,病死率较高.自上世纪90年代临床使用一氧化氮(NO)吸入治疗肺动脉高压以来,发现其可选择性的舒张肺血管,临床效果显著,减少了体外膜肺(ECMO)的使用率[1].但NO易与氧或超氧离子形成毒性的氮氧化物,引起肺损伤、高铁血红蛋白血症等副作用,已受到人们的重视[2].传统的NO供体类药物如硝酸甘油、硝普钠等缺乏较好的肺血管选择性,而且长期使用容易产生耐药性[3].     

The effect of calcium antagonists on hypoxic pulmonary hypertension in the piglet

Cardiovascular responses to the calcium antagonists verapamil and nifedipine were evaluated in a piglet model of hypoxic pulmonary hypertension. All animals were mechanically ventilated and paralyzed. Cardiac output (CO), pulmonary artery (Ppa) and aortic blood pressure (AoP), pulmonary wedge pressure, right atrial pressure (Pra), and arterial blood gases were measured prior to and after pulmonary hypertension was induced by hypoxia and after administration of calcium-blocking agents. Results were compared to a control group of piglets subjected to a similar period of hypoxia. Verapamil infusion (0.15 mg/kg) resulted in a rapid decrease in Ppa, AoP and pulmonary vascular resistance (p less than 0.05) which returned to baseline values by 15 min. Nifedipine (100 micrograms/kg) resulted in a decrease in Ppa at 1 min (p less than 0.05) which remained significantly lower than controls throughout the study period. AoP declined precipitously during the same time period (p less than 0.01). No significant change in Ppa was noted when nifedipine was administered at a dose of 10 micrograms/kg. For the most part, these drugs have a transient vasodilatory action on pulmonary as well as systemic circulation in this animal model; however, they might in higher doses be associated with significant systemic hypotension. For this reason, the use of these drugs in the treatment of hypoxic pulmonary hypertension in the neonate should be approached with caution.     

Aerosolized perfluorocarbon suppresses early pulmonary inflammatory response in a surfactant-depleted piglet model.

The effect of new ventilation strategies on initial pulmonary inflammatory reaction was studied in a surfactant-depleted piglet model. Sixty minutes after induction of lung injury by bronchoalveolar lavage, piglets received either aerosolized FC77 (aerosol-PFC, 10 mL/kg/h, n = 5) or partial liquid ventilation (PLV) with FC77 at functional residual capacity volume (FRC-PLV, 30 mL/kg, n = 5), or at low volume (LV-PLV, 10 mL/kg per hour, n = 5), or intermittent mandatory ventilation (control, n = 5). After 2 h, perfluorocarbon application was stopped and intermittent mandatory ventilation continued for 6 h. After a total experimental period of 8 h, animals were killed and lung tissue obtained. mRNA expression of IL-1beta, IL-6, IL-8, and TGF-beta in porcine lung tissue was quantified using TaqMan real-time PCR and normalized to beta-actin (A) and hypoxanthine-guanine-phosphoribosyl-transferase (H). In the aerosol-PFC group, IL-1beta, IL-6, IL-8, and transforming growth factor (TGF)-beta mRNA expression in lung tissue was significantly lower than in the control group. Reduction was 95% for IL-1beta/H (p < 0.001), 73% for IL-6/H (p < 0.05), 87% for IL-8/H (p < 0.001), and 38% for TGF-beta/H (p < 0.01). A lower mRNA gene expression was also determined for IL-1beta and IL-8 when the aerosol-PFC group was compared with the LV-PLV group [91% for IL-1beta/H (p < 0.001), 75% for IL-8/H (p < 0.001)]. In the FRC-PLV group, mRNA expression of IL-1beta was significantly lower than in the control (p < 0.05) and LV-PLV (p < 0.01) group. In a surfactant-depleted piglet model, aerosol therapy with perfluorocarbon but not LV-PLV reduces the initial pulmonary inflammatory reaction at least as potently as PLV at FRC volume.     

吸入一氧化氮治疗大鼠缺氧性肺动脉高压

目的　 观察吸入一氧化氮 (NO)对慢性和急性缺氧所致大鼠肺动脉高压的作用。 方法 　分别利用雄性Wistar大鼠 3 0只 ,制备慢性和急性缺氧肺动脉高压模型。实验中监测肺动脉压、血气、高铁血红蛋白含量 (Met % )等指标。 结果 　慢性缺氧大鼠吸入 2 0 ppm、40ppmNO ,肺动脉平均压 (MPAP)由治疗前 (2 5 2± 3 5 )mmHg降到 (2 2 4± 3 5 )mmHg及 (2 1 8± 3 3 )mmHg ,而对动物体循环血压无明显影响 ;急性缺氧大鼠吸入 2 0 ppm、40 ppmNO 1hMPAP分别由缺氧时 (2 2 8± 2 7)mmHg、(2 4± 2 8)mmHg下降到 (19 6± 4 7)mmHg和 (2 0 5± 4 1)mmHg。吸入NO 4h ,2 0ppm组Met %由 (0 40± 0 3 9) %升到 (0 95±0 75 ) % ,40 ppm组由 (0 3 9± 0 3 2 ) %升到 (1 2 6± 0 49) %。肺病理组织检查显示 :2 0 ppm、40 ppm组与对照组无显著差别。 结论 　吸入NO对慢性和急性缺氧肺动脉高压具有选择性扩张肺血管的作用 ,急性缺氧大鼠持续吸入NO 4h不会引起高铁血红蛋白血症 ,对肺组织结构无重要影响     

吸入一氧化氮治疗先天性心脏病术后肺动脉高压的疗效观察

目的 探讨吸入一氧化氮(NO)治疗先天性心脏病术后肺动脉高压患儿的疗效.方法 选择32例先天性心脏病术后传统治疗无效的、难治的、反应性肺动脉高压或肺动脉高压危象患儿,吸入NO(10～25)×10-6,定时记录各项血流动力学和呼吸功能指标,定期监测二氧化氮、高铁血红蛋白含量.结果 吸入NO后,平均肺动脉压(mPAP)从(38.0±3.2)mm Hg(1 mm Hg=0.133 kPa)降至(28.0±2.1)mm Hg,肺血管阻力从(62.2±6.7)kPa/(L·S)降至(49.9±5.6)kPa/(L·S),氧合指数从(67.0±30.1)mm Hg升至(92.6±25.0)mm Hg,动脉血氧饱和度从0.78±0.14升至0.84±0.09,差异均有非常显著性(P＜0.01).吸入NO期间,二氧化氮和高铁血红蛋白含量均在安全范围.结论 NO可以明显降低先天性心脏病术后肺动脉压力和肺血管阻力,是一种安全且理想的肺血管扩张剂.     

Usefulness of a new Doppler index for assessing both ventricular functions and pulmonary circulation in newborn piglet with hypoxic pulmonary hypertension

Persistent pulmonary hypertension of the newborn is a clinical syndrome associated with a variety of cardiopulmonary diseases. Serial evaluation of pulmonary circulation and cardiac function is important, but available imaging techniques have been limited. A new Doppler index combining systolic and diastolic time intervals (the Tei index, which is a simple and noninvasive measurement) has been reported to be useful for the assessment of global cardiac function in adults and children. The purpose of this study was to test the effectiveness of the Tei index in prospectively assessing ventricular function and pulmonary circulation in a newborn piglet model with hypoxic pulmonary hypertension. One-day-old piglets (1.1-1.6 kg) were intubated and prepared for the experiments under room air and hypoxia. A complete two-dimensional Doppler echocardiographic examination was performed. Common hemodynamic variables were measured continuously throughout the study. The right ventricle (RV) Tei index under hypoxia (fraction of inspired oxygen = 0.10) was significantly higher than the value under air ventilation (medians, 0.38 versus 0.56; p < 0.05). Moreover, there was a significant correlation between RV Tei index and mean pulmonary artery pressure and positive linear correlation between individual changes in RV Tei index and changes in mPAP (r2 = 0.799, p < 0.05). We conclude that the Tei index is useful for assessing the function of the RV and the left ventricle and pulmonary circulation in a newborn piglet model with hypoxic pulmonary hypertension. These results suggest that the Tei index will become an objective method of assessing patients with persistent pulmonary hypertension of the newborn.     

Albumin mixed with meconium attenuates pulmonary dysfunction in a newborn piglet model with meconium aspiration

We hypothesized that lipids and bile acids in meconium may induce pulmonary insufficiency in newborns. Because albumin may bind these components we studied the effect of albumin on meconium-induced lung injury in piglets. We measured concentration of FFA in the meconium (110 mg dry weight/mL) and added albumin to provide a molar FFA to albumin ratio of 1:1. Newborn piglets, 0-2 d of age, artificially ventilated and exposed to hypoxemia by ventilation with 8% O2, were randomized to group A receiving meconium (n = 12) or group B receiving meconium + albumin (n = 12), 3 mL/kg intratracheally. The animals were reoxygenated for 8 h. Reoxygenation was started when mean blood pressure was <20 mm Hg or base excess was <-20 mM. Pulmonary function was assessed in parallel with pulmonary hemodynamics. From the start of reoxygenation and the next 8 h we found a significant difference (by ANOVA) between the two groups in oxygenation index (p = 0.005), with an increase from 1.6 +/- 0.2 to 6.1 +/- 6.8 (p = 0.04) in the meconium group and from 1.8 +/- 0.3 to 3.1 +/- 3.1 (NS) in meconium + albumin group. There were also significant differences (by ANOVA) between the groups in favor of the treatment group concerning need of inspired fraction of O2, mean airway pressure, dynamic compliance of the respiratory system, time constant, ventilation index, and pulmonary vascular resistance. In conclusion, albumin given concurrently with meconium significantly reduced detrimental effects of meconium aspiration in the lungs of newborn piglets.     

TBC3711, an ET(A) receptor antagonist, reduces neonatal hypoxia-induced pulmonary hypertension in piglets

The pulmonary vasculature of newborns with persistent pulmonary hypertension is characterized by active vasoconstriction and vascular remodeling. It has been suggested that endothelin-1 (ET-1), a potent vasoconstrictor and growth promoter, may be involved in the pathogenesis of persistent pulmonary hypertension of the newborn. To determine whether treatment with an ET(A) receptor antagonist can reverse pulmonary hypertension in the neonate, 1-d-old piglets were exposed to hypoxia for 3 d to induce pulmonary hypertension and then treated for the remainder of the 14 d with an orally active, nonpeptidic ET(A) antagonist (TBC3711, 22 mg x kg(-1) x d(-1)). At the end of the exposure, Hb, pulmonary artery pressure, right ventricle to left ventricle plus septum weight ratio, percentage wall thickness, ET-1 circulating levels, perfusion pressure, and dilator response to the nitric oxide (NO) donor, SIN-1 (3-morpholinosydnonimine-N-ethylcarbamide) in isolated perfused lungs were determined. Exhaled NO and hemodynamic variables were also examined in an intact anesthetized animal preparation that had undergone the same treatment. By 3 d of exposure to hypoxia, piglets had already developed significant pulmonary hypertension as estimated by their pulmonary artery pressure (24.0 +/- 1.3 mm Hg versus 14.2 +/- 3.4 mm Hg) and percentage wall thickness (26.6 +/- 5.9% versus 18.7 +/- 2.4% for vessels 0-30 microm). Whereas further exposure to hypoxia for 14 d did not enhance the increase in pulmonary artery pressure and percentage wall thickness, it did augment the right ventricle to left ventricle plus septum weight ratio (0.71 +/- 0.09 versus 0.35 +/- 0.01). ET-1 circulating levels were increased only when exposure to hypoxia was prolonged to 14 d (5.1 +/- 2.4 pg/mL versus 1.0 +/- 0.4 pg/mL). Treatment with TBC3711 from d 3 to d 14, once pulmonary hypertensive changes were established and while hypoxic exposure persisted, caused significant reduction in the right ventricle to left ventricle plus septum weight ratio (0.60 +/- 0.06), pulmonary artery pressure (20.0 +/- 4.8 mm Hg), and percentage wall thickness (18.5 +/- 3.3%) and restored the dilator response to the NO donor SIN-1. Prolonged hypoxia markedly reduced exhaled NO concentrations (0.3 +/- 0.6 ppb), although treatment of hypoxic animals with TBC3711 restored the concentration of exhaled NO (4.4 +/- 2.8 ppb) to the level of normoxic controls (4.9 +/- 3.0 ppb). Lastly, treatment with TBC3711 increased ET-1 circulating levels in both the normoxic (5.4 +/- 2.8 pg/mL) and hypoxic (13.0 +/- 6.3 pg/mL) groups. In conclusion, the specific ET(A) receptor antagonist, TBC3711, can significantly ameliorate the morphologic changes encountered in hypoxia-induced pulmonary hypertension in the newborn piglet and may improve the dilator response to NO.     

一氧化氮治疗新生儿持续肺动脉高压42例疗效观察

目的　探讨一氧化氮 (NO)吸入疗法治疗新生儿持续肺动脉高压 (PPHN)的疗效。方法　对 4 2例新生儿PPHN和呼吸衰竭患儿按解剖性血管梗阻和肺血管痉挛分为Ⅰ组和Ⅱ组 ,分别在呼吸机机械通气情况下 ,将NO气源加入呼吸机环路中 ,NO质量浓度从 2 0× 10 -6mg/L(2 0 ppm)开始 ,每经 15～ 30min无效者增加 (5～10 )× 10 -6mg/L(5～ 10 ppm) ,达到 4 0× 10 -6mg/L仍无效者停用。有效者经予吸入较高浓度NO 6h后 ,每 30min降低NO质量浓度 (5～ 10 )× 10 -6mg/L ,如患儿的PaO2 下降不超过 15 % ,可降至 6× 10 -6mg/L后维持 36～ 72h ,治疗时观察全身氧合情况的变化 ,监测心率、血压、吸入前后血高铁血红蛋白 (MHb)定量及凝血功能。结果　Ⅱ组 33例患儿中 2 7例 (81 82 % )治疗后氧合情况显著改善 ;Ⅰ组治疗后氧合情况无改善。两组心率、血压、凝血功能无明显改变 ,MHb定量的改变无临床意义。结论　低浓度短期NO吸入疗法治疗肺血管痉挛所致持续肺动脉高压有显著疗效 ,且未见明显副作用 ,但对解剖性血管梗阻所致持续肺动脉高压疗效欠佳。     

Tadalafil improves oxygenation in a model of newborn pulmonary hypertension.

OBJECTIVES: Sildenafil, a phosphodiesterase-5 inhibitor, significantly improves oxygenation when used in animal models and patients with pulmonary hypertension. Tadalafil is a new and clinically available phosphodiesterase-5 inhibitor that, aside from causing pulmonary vasodilation, has been shown to increase cardiac output in pulmonary hypertensive adults. Its hemodynamic effects on the newborn, however, have not been tested. The objective was to evaluate the effect of tadalafil on central hemodynamics and arterial oxygenation in a piglet model of acute pulmonary hypertension. DESIGN: Laboratory experiment. SETTING: University laboratory. SUBJECTS: Seven anesthetized and mechanically ventilated newborn piglets. INTERVENTIONS: Pulmonary hypertension was induced and maintained in seven anesthetized and mechanically ventilated newborn piglets following acute exposure to 11% oxygen. The experimental animals received orla tadalafil (1 mg/kg), whereas the control animals were given an equal volume of normal saline. Systemic and pulmonary hemodynamic variables were measured, and the cardiac output and ejection fraction were obtained from two-dimensional echocardiogram and Doppler measurements in all animals. Serial arterial blood gases were also obtained, and the alveolar-arterial oxygen gradient was calculated. MEASUREMENTS AND MAIN RESULTS: In contrast with the control animals, in which no significant changes were noted, in the experimental animals pulmonary arterial pressure decreased on average by 54% and cardiac output increased by 88% following tadalafil administration (p < .05). Tadalafil increased the PaO2 by 48% +/- 21% (p < .01), likely as a result of a 74% +/- 13% reduction in the alveolar-arterial oxygen gradient (p < .01). CONCLUSIONS: In a newborn animal model of acute pulmonary hypertension, oral tadalafil administration reduces pulmonary vascular resistance and increases arterial oxygenation by increasing cardiac output and reducing the lung shunt fraction. This previously untested compound deserves additional investigation in laboratory models of persistent pulmonary hypertension of the newborn.     

Weaning strategy with inhaled nitric oxide treatment in persistent pulmonary hypertension of the newborn

AIM—To determine if infants who had become dependent on inhaled nitric oxide treatment could be successfully weaned off it if FIO₂ was increased briefly during withdrawal.
METHODS—Sixteen infants admitted for conditions associated with increased pulmonary vascular resistance responded well to inhaled nitric oxide treatment with a significant increase in PaO₂ (maximum inhaled nitric oxide given 25 ppm). Weaning from inhaled nitric oxide in 5 ppm decrements was initiated once the FIO₂ requirement was less than 0.5. When patients were stable on 5 ppm of inhaled nitric oxide, the gas was then discontinued. If a patient showed inhaled nitric oxide dependence—that is, oxygen saturation fell by more than 10% or below 85%—inhaled nitric oxide was reinstated at 5 ppm and the patient allowed to stabilise for 30 minutes. At this time, FIO₂ was increased by 0.40 and weaning from inhaled nitric oxide was attempted again.
RESULTS—Nine infants were successfully weaned on the first attempt. The seven infants who failed the initial trial were all successfully weaned following the increase in FIO₂. After successful weaning, FIO₂ was returned to the pre-weaning level in mean 148(SD 51) minutes and inhaled nitric oxide was never reinstated.
CONCLUSION—Infants showing inhaled nitric oxide dependency can be successfully weaned by increasing FIO₂ transiently.

     

血管内皮生长因子A对缺氧性肺动脉高压新生大鼠肺血管重塑的影响及其机制研究

目的 探讨血管内皮生长因子A（VEGF-A）调控生存素（SVV）在缺氧性肺动脉高压（HPH）新生大鼠肺血管重塑中的作用。方法 96只新生大鼠随机分为HPH+VEGF-A组、HPH组和对照组,每组再随机分为3 d、7 d、10 d和14 d亚组,每个亚组8只大鼠。HPH+VEGF-A组和HPH组分别经气管内转染携带/不携带VEGF-A的腺病毒载体后建立HPH模型,对照组气管内注射0.9% NaCl溶液后常氧下饲养。直接测压法测定新生大鼠平均右心室收缩压（RVSP）;苏木精-伊红染色后光镜下观察肺血管形态学变化,计算肺小动脉中层血管壁厚度占肺小动脉外径的百分比（MT%）和肺小动脉中层横截面积占总横截面积的百分比（MA%）;免疫组化法检测肺组织中VEGF-A和SVV的表达水平。结果 HPH组新生大鼠平均RVSP高于同时间点对照组和HPH+VEGF-A组（P < 0.05）。缺氧7 d,HPH组出现肺血管重塑,HPH+VEGF-A组自缺氧10 d开始出现。缺氧7 d时,HPH组MT%和MA%高于对照组和HPH+VEGF-A组（P < 0.05）;缺氧10 d和14 d时,HPH组及HPH+VEGF-A组MT%和MA%均高于对照组（P < 0.05）。缺氧各时间点HPH组和HPH+VEGF-A组VEGF-A表达均高于对照组（P < 0.05）;缺氧3 d和7 d时,HPH+VEGF-A组VEGF-A表达高于HPH组（P < 0.05）。缺氧14 d时,HPH组SVV表达高于对照组（P < 0.05）;缺氧各时间点HPH+VEGF-A组SVV表达均高于对照组（P < 0.05）;缺氧3 d和7 d时,HPH+VEGF-A组SVV表达高于HPH组（P < 0.05）。结论 预防性外源性气管内给予HPH新生大鼠VEGF-A,可在缺氧早期通过上调SVV表达抑制肺血管重塑,降低肺动脉压力,为新生儿HPH肺血管重塑干预治疗提供了依据。     

Endostatin and vascular endothelial cell growth factor (VEGF) in piglet lungs: effect of inhaled nitric oxide and hyperoxia

Pulmonary hyperoxic injury manifests as widespread alveolar-epithelial and microvascular endothelial cell necrosis, resolution of which requires angiogenesis. We investigated the hypothesis that inhaled nitric oxide (iNO) and hyperoxia each decreases lung vascular endothelial growth factor (VEGF) expression but increases endostatin and that concurrent administration of both gases will show a greater effect. Piglets were randomized to breathe for 5 d room air (RA); RA + NO (RA + 50 ppm NO), O(2) (hyperoxia, F(I)O(2) >0.96), O(2) + NO, or O(2) + NO + REC (O(2) + NO plus recovery in 50% O(2) for 72 h. After the piglets were killed, we measured lung capillary leak, VEGF mRNA, VEGF, and endostatin protein in homogenates, plasma, and lavage. VEGF mRNA decreased significantly with O(2) and O(2) + NO compared with breathing RA (p < or = 0.05). VEGF protein declined in the experimental groups with a significant reduction in the recovery group compared with the RA group (p < or = 0.05). Similar but more dramatic, endostatin declined in all groups relative to the RA group (p < 0.001). Lavage fluid VEGF protein and lung capillary leak rose significantly with O(2) and O(2) + NO compared with RA, but endostatin was unchanged. At 72 h of recovery from hyperoxia, VEGF mRNA and lavage fluid VEGF but not lung VEGF protein had normalized. Hyperoxia and iNO suppresses lung endostatin expression, but iNO unlike hyperoxia alone does not alter lung VEGF production. Hyperoxia paradoxically raises lavageable VEGF levels. This latter effect and that on VEGF mRNA level but not protein is abrogated by recovery in reduced F(I)O(2) for 72 h.     

先天性心脏病重度肺动脉高压性质的综合评价

目的探讨先天性心脏病（简称先心病）合并重度肺动脉高压患儿器质性肺动脉高压（简称肺高压）的诊断标准。方法３７例经手术治疗后早期肺动脉压力降至正常的患儿作为动力性肺高压组；７例经手术治疗后仍持续性肺动脉高压及６例临床诊断为器质性肺高压而未予手术的共１３例患儿作为器质性肺高压组，对比两组心导管检查血液动力学指标。结果两组肺血管阻力、肺小动脉楔压、肺循环血流量与体循环血流量之比（Ｑｐ／Ｑｓ）及降主动脉血氧饱和度（ＳａＯ２）差异均有显著意义，如按年龄大于２岁、肺动脉阻力＞７２ｋＰａ·ｓ－１·Ｌ－１（９Ｗｏｏｄ单位）、肺小动脉楔压≤１．６ｋＰａ（１２ｍｍＨｇ）、Ｑｐ／Ｑｓ＜２和动脉血氧饱和度＜０．９０作为临床诊断器质性肺高压的指标，则本组动力性肺高压组仅有５．４％的患儿符合上述指标３项或３项以上，而器质性肺高压组所有病例均符合上述指标３项或３项以上。结论先心病合并重度肺动脉高压存在上述５项指标中３项或３项以上，高度提示患儿存在器质性肺动脉高压     

The effect of inhaled nitric oxide therapy on thromboelastogram in newborns with persistent pulmonary hypertension

Studies about the effects of inhaled nitric oxide (iNO) on bleeding time and platelet aggregation in newborns are limited in number and have inconclusive results. Thromboelastogram (TEG) shows the combined effects of coagulation factors and platelet functions. In this preliminary study, we aimed to evaluate the effects of iNO on coagulation using TEG in newborns with persistent pulmonary hypertension (PPH). TEG assays were performed in 10 term infants receiving iNO treatment for PPH and 32 healthy term infants. Samples of the iNO group were collected before and during iNO. Clot reaction time (R), clot kinetics (K), maximum amplitude (MA), and alpha angle were obtained from the TEG tracing. TEG-R values were statistically higher during iNO treatment (7.75?±?3.34) when compared to the values before iNO (4.83?±?1.38) and the healthy controls (3.75?±?0.98). The alpha angle was lower in iNO treated infants at both periods (before iNO, 55.33?±?8.58; during iNO, 42.90?±?18.34) compared to the control group (64.95?±?6.88). MA values before iNO treatment were the lowest (44.43?±?14.09) and improved with the iNO treatment (48.40?±?9.49) despite still being lower compared to the controls (53.67?±?5.56). Conclusion: Both PPH and iNO may negatively effect in vitro coagulation tests. Therefore, newborns with PPH requiring iNO treatment should be closely monitored for coagulation problems.     

Variable oxygenation response to inhaled nitric oxide in severe persistent pulmonary hypertension of the newborn

The causes of variable responsiveness to inhaled nitric oxide (NO) in Persistent Pulmonary Hypertension of the Newborn (PPHN) are unknown. The changes in the severity of respiratory failure after the onset of inhaled NO (maximal dose 20ppm) were studied in 13 consecutive neonates with severe PPHN. Response was defined as a sustained decrease of alveolar-arterial oxygen gradient (AaD0₂) by > 20%, or a decrease in oxygenation index (OI) by > 40%. Six neonates had a rapid response within 30min, three had an intermediate response within 8h, and three had a delayed response within 12 h after the onset of NO. Three infants with birth asphyxia responded rapidly to inhaled NO. One infant with sepsis did not respond, and two with suspected sepsis had a delayed response. The infants with Meconium Aspiration Syndrome and idiopathic PPHN had a variable response time. Twelve neonates required 4 to 14 days of mechanical ventilation and survived. Infants with PPHN may benefit from a trial of inhaled NO therapy that exceeds 30min. The variability of the response time to inhaled NO is likely to be multifactorial and dependent on the disease process associated with PPHN.