早期连续性血液净化在肠穿孔腹膜炎模型中改善全身炎症状况的作用

目的 观察早期连续性血液净化对幼猪肠穿孔腹膜炎诱导的全身炎症反应综合征(SIRS)的疗效,旨在探索新生儿肠穿孔腹膜炎治疗的新方法.方法 12只上海种小白猪,体重7～9 kg,雌雄不限.随机分为对照组(n=6)和治疗组(n=6).以盲肠手术穿孔诱导全身炎症反应综合征(SIRS),造模成功后治疗组行连续静脉-静脉血液透析滤过(CVVHDF)8 h.成模后,治疗2、4、8、16 h分别记录二组动物基础状态的心率、呼吸、血压、体温、外周血细胞计数和血气分析,采血检测TNF-α、IL-1β和IL-6含量.结果 所有动物经造模后4～6 h内均达SIRS标准.经分组行CVVH-DF 8h后,观察指标有明显变化的是:CVVHDF组的心率、呼吸、血压、血清TNF-α水平均较对照组明显降低(P＜0.05),而血清IL-6在CVVHDF组则较对照组升高(P=0.04).血氧分压、血细胞计数和血清IL-1β水平的变化在二组中无显著性差异.结论 本组动物实验的资料显示,在幼猪肠穿孔腹膜炎模型中,治疗的早期采用CVVHDF,可降低部分炎因子反应,对稳定SIRS动物的血流动力学有益处,但对SIRS的部分指标改善不显著.     

Impact of room air resuscitation on early growth response gene-1 in a neonatal piglet model of cerebral hypoxic ischemia

Early growth response gene-1 (Egr-1) is up-regulated by hypoxia-ischemia (HI) and reactive oxygen species (ROS) in adult animals, functioning as a master switch in inflammation and thrombogenesis. We hypothesized that resuscitation from HI with 100% O2 would result in greater Egr-1 expression, ROS, and cell death (CD) in the brains of newborn piglets than 21% O2. Two control groups breathed 21% O2 for 1 h followed by 21% or 100% O2 for 1 h. Two HI groups underwent carotid artery occlusion and breathed 8-12% O2 for 1 h followed by occlusion release and 21% or 100% O2 for 1 h. Brain Egr-1 mRNA and protein were analyzed via quantitative PCR and Western blot. CD and ROS were measured by fluorescence microscopy. Egr-1 mRNA expression increased throughout the brain in response to HI with regional heterogeneity, but protein levels did not. Resuscitation with 100% oxygen did not cause any additional Egr-1 mRNA, Egr-1 protein, CD, or ROS production as compared with 21% oxygen. There was no difference in physiologic recovery after HI with room air compared with 100% O2 resuscitation. However, 100% O2 administration was associated with increased CD in the brainstem independent of HI. Therefore, 100% O2 may have been toxic to some brainstem cells and potentially have significance in long-term neurologic sequelae seen after neonatal HI/resuscitation. Egr-1 protein levels may be tightly regulated in an attempt to diminish neurotoxicity or to enhance plasticity at this stage of development.     

A novel inhaled organic nitrate that affects pulmonary vascular tone in a piglet model of hypoxia-induced pulmonary hypertension

Persistent pulmonary hypertension of the newborn is characterized by elevated pulmonary vascular resistance after birth leading to right-to-left shunting and systemic arterial hypoxemia. Inhaled nitric oxide (NO) is effective in reducing the need for extracorporeal membrane oxygenation, but it has potential toxicities, especially in an oxygen-rich environment. A number of other NO-based molecules have been given by inhalation, but their structure-function relationships have not been established. Recent studies have raised the idea that toxic and beneficial properties can be separated. We synthesized a novel organic nitrate [ethyl nitrate (ENO2)], tested it in vitro, and administered it to hypoxic piglets. ENO2 lowered pulmonary artery pressure and raised the Po2 in arterial blood but did not alter systemic vascular resistance or methemoglobin levels. In addition, we tested the effect of ENO2 in the presence of the thiol glutathione, both in vivo and in vitro, and found its action to be enhanced. Although ENO2 is less potent than inhaled NO on a dose-equivalency basis, pretreatment of hypoxic animals with glutathione, which may be depleted in injured lungs, led to a markedly enhanced effect (largely mitigating the difference in potency). These results suggest that ENO2 may hold promise as a safe alternative to NO, particularly in hypoxemic conditions characterized by thiol depletion.     

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.     

小儿全身炎症反应综合征早期敏感炎症因子的研究

目的研究筛选小儿全身炎症反应综合征(SIRS)早期敏感炎症因子指标,为今后的合理早期干预提供理论依据。方法用化学发光酶免疫分析法(CLEIA)测定SIRS患儿血白介素1β(IL-1β),白介素-6(IL-6),白介素-8(IL-8),肿瘤坏死因子-α(TNFα-),采用酶联免疫吸附比色法(ELISA)测定血白介素-10(IL-10),白介素-13(IL-13)。结果SIRS患儿与对照组比较血TNFα-明显升高,血IL-6阳性率明显升高,有显著性差异(P<0.05),其他指标则无统计学意义(P>0.05)。结论血清TNFα-和IL-6是SIRS早期检测敏感指标。     

Alveolar recruitment promotes homogeneous surfactant distribution in a piglet model of lung injury.

Uneven distribution of exogenous surfactant contributes to a poor clinical response in animal models of respiratory distress syndrome. Alveolar recruitment at the time of surfactant administration may lead to more homogeneous distribution within the lungs and result in a superior clinical response. To investigate the effects of three different volume recruitment maneuvers on gas exchange, lung function, and homogeneity of surfactant distribution, we studied 35 newborn piglets made surfactant deficient by repeated airway lavage with warm saline. Volume recruitment was achieved by either a temporal increase in tidal volume or an increase in end-expiratory pressure during surfactant administration, yielding an increase in dynamic compliance of the respiratory system of 77% in the first group and an increase in functional residual capacity of 108% in the second group. A third group of piglets (all n = 7) received a combination of both volume recruitment maneuvers, with increases in dynamic compliance of the respiratory system of 100% and in functional residual capacity of 192%. Those animals subjected to increased tidal volume showed an improved surfactant response in terms of oxygenation, ventilation, lung volumes, lung mechanics, and homogeneity of surfactant distribution. Increased end-expiratory volume augmented the surfactant effect only to some extent. The combination of both volume recruitment maneuvers, however, needed lung volumes beyond total lung capacity (approximately 56 mL/kg), thus probably inducing early sequelae of ventilator-induced lung injury. We conclude that volume recruitment by means of increased tidal volumes at the time of surfactant administration leads to a superior surfactant effect owing to more homogeneous surfactant distribution within a collapsed lung.     

Conventional vs high-frequency jet ventilation in a piglet model of meconium aspiration: comparison of pulmonary and hemodynamic effects

The pulmonary and cardiovascular effects of high-frequency jet (HFJV) and conventional (CV) ventilation were evaluated in a piglet model of meconium aspiration. A mixture of 20% human meconium and 0.9% saline solution was instilled deep into the trachea of 10 piglets, after which either HFJV or CV was administered for 4 hours. Arterial blood gases, cardiac output, mean pulmonary and systemic arterial pressures, pulmonary and systemic vascular resistances, and pulmonary mechanics were compared between groups. During the 4 hours of ventilation, PaO2 and PaCO2 were not statistically different between groups. The peak inspiratory pressure necessary to maintain PaCO2 in the preset range was approximately half as much in the HFJV group as in the CV group (P less than 0.002). Mean airway pressure was lower in the HFJV group only during the second hour (P less than 0.03). Cardiac output, mean aortic and pulmonary artery pressures, systemic and pulmonary vascular resistance, dynamic lung compliance, and pulmonary resistance were not statistically different between groups. Our results suggest that HFJV may be more effective than CV in the early stages of meconium aspiration syndrome because HFJV allows more efficient ventilation and adequate oxygenation at lower peak inspiratory pressures.     

Dexamethasone treatment attenuates pulmonary injury in piglet meconium aspiration

To investigate the pulmonary effects of steroid treatment in neonates with meconium aspiration, 25 10- to 12-d-old piglets were studied for 6 h after an intratracheal bolus of human meconium. Dexamethasone (0.5 mg/kg) was given in two treatment schedules, either 1 h before (n = 6) or 1 h after meconium instillation (n = 8). Eight piglets served as controls. Three additional piglets were given dexamethasone without meconium instillation. Pulmonary hemodynamics and oxygenation were followed, and lung tissue samples investigated for signs of inflammation and ultrastructural injury, including apoptosis. Pulmonary artery pressure and vascular resistance increased after meconium instillation, but this rise was significantly prevented after prophylactic dexamethasone. This treatment also improved the acutely deteriorated oxygenation of the piglets after meconium insufflation. Prophylactic, but not early, dexamethasone treatment further protected the lungs from the ultrastructural changes caused by meconium instillation. Additionally, the increase of apoptotic epithelial cell deaths was significantly prevented by both dexamethasone treatments. These results show that prophylactic dexamethasone treatment significantly attenuates the early pulmonary hemodynamic deterioration and structural lung damage caused by meconium aspiration. Further studies on the apoptosis-inhibiting effect of dexamethasone administration in neonatal lungs exposed to heavy meconium are warranted.     

Comparison of effects of perflubron and surfactant lung lavage on pulmonary gas exchange in a piglet model of meconium aspiration

In a piglet model of meconium aspiration we compared lavage with surfactant with that with perflubron (PFOB) and a control group. A human meconium suspension was instilled into piglets which were randomized in 3 (n = 6 each) groups. After lung injury, the control group was ventilated with high-frequency oscillatory ventilation (HFOV) without suctioning and lavage. A second group was lavaged with 10 ml/kg diluted surfactant, a third with 10 ml/kg pre-oxygenated PFOB. Thereafter, the animals of both groups were ventilated with HFOV. After lung injury by instillation of meconium, no further improvement in oxygenation was possible in animals of the control group and 3 piglets died during the ventilation. The subjects of the surfactant group improved promptly, and at the end of the study the arterial pO(2) was significantly better than immediately after injury as compared with the other groups. Lavage with PFOB had intermediate effects in gas exchange and oxygenation compared to surfactant lavage. No differences were observed in arterial blood pressure and heart rate as well as in histological lung injury score between all groups. Lavage with exogenous surfactant as well as with PFOB improve pulmonary gas exchange in a piglet model of meconium aspiration.     

Aerosolized iloprost in the treatment of pulmonary hypertension in extremely preterm infants: a pilot study

BACKGROUND: In premature infants with preterm prolonged rupture of membranes, death after birth is often due to persistent pulmonary hyper-tension. PATIENTS: Aerosolized iloprost was used to treat pulmonary hypertension due to prolonged preterm rupture of fetal membranes (7-56 days) in four extremely low-birthweight neonates (23-25 weeks' gestation, weight 448-645 g) under spontaneous breathing supported by nasal continuous positive airway pressure. METHOD: Inhalation dose was 2 microg/kg b.w. and between 44 and 65 inhalations were performed in each patient starting within the first hour of life over a total of several days. Single inhalations lasted 5 min and were not repeated until 60 min had elapsed. RESULTS: After the first inhalation, the PaO2/FiO2 mean ratio increased from 65 (range 35-114) to 194 (148-250) mmHg and oxygenation requirements decreased within the next 7 days. Echocardiography similarly showed reduction in pulmonary resistance. We observed no severe side effects on blood pressure or prolonged bleeding time during inhalation. CONCLUSIONS: Iloprost inhalation might therefore be an additional treatment for improving oxygenation in cases of persistent pulmonary hypertension in extremely low-birthweight infants under spontaneous breathing. Further randomized clinical studies are required to establish the role of iloprost in this setting.     

Pentoxifylline reduces regional inflammatory and ventilatory disturbances in meconium-exposed piglet lungs

Neonatal meconium aspiration frequently produces severe respiratory distress, which is associated with patchy pulmonary neutrophil influx and inflammatory injury. To examine the effects of pentoxifylline (PTX), a potent anti-inflammatory agent, on regional pulmonary inflammation and ventilation after meconium aspiration, we studied 17 anesthetized and ventilated neonatal piglets (age <2 d) for 12 h. After unilateral intrapulmonary instillation of meconium, PTX treatment was started in nine animals, and eight untreated animals served as controls. Bronchoalveolar lavage (BAL) fluid and lung tissue were studied for inflammatory variables at the end of the study, and changes in regional ventilation were serially analyzed with a dynamic pulmonary x-ray imaging method. Meconium insufflation increased BAL fluid total cell, neutrophil, and macrophage counts and tumor necrosis factor-alpha (TNF-alpha) and protein concentrations as well as lung tissue myeloperoxidase activity in the instilled lungs, compared with the noninstilled side. PTX treatment prevented the increase of BAL fluid alveolar macrophage count and TNF-alpha and protein concentrations in the meconium-instilled lungs but had no significant effect on the pulmonary neutrophil accumulation. Ventilation of the meconium-insulted lung was initially disturbed similarly in both study groups, but PTX administration prevented the sustained local ventilatory perturbation at 4, 6, and 12 h after meconium instillation. The results thus indicate that PTX treatment may attenuate meconium-induced regional ventilation derangements, mainly through its effects on local alveolar macrophages and TNF-alpha production as well as alveolocapillary permeability rather than via significant prevention of accumulation of active neutrophils in the insulted lungs.     

Elevated inflammatory mediators and pulmonary hypertension after applying an extracorporeal circuit in a neonatal sepsis model

Purpose  

We aimed to study the changes in cytokines, oxidative mediators, and pulmonary blood pressure in a neonatal sepsis model when applying an extracorporeal circuit (ECC).     

Aerosolized iloprost therapy in an infant with chronic pulmonary hypertension after a neonatal arterial switch operation]

The treatment of chronic pulmonary hypertension with prostacyclin in children is prone to severe complications due to mandatory long-term venous therapy. Inhaled iloprost has been evaluated in adult patients with good preliminary results. CASE REPORT: We report our experience of the use of aerosolized iloprost in an infant treated for pulmonary hypertension associated to a right ventricular failure, which occurred after a neonatal arterial switch operation for transposition of the great arteries. For nine months, hemodynamic and functional status improved and the quality of life was satisfactory at home. CONCLUSION: If further experiences and studies support this observation, aerosolized iloprost could be an alternative to prostacyclin venous therapy in treating children with chronic pulmonary hypertension.     

High frequency oscillatory ventilation suppresses inflammatory response in lung tissue and microdissected alveolar macrophages in surfactant depleted piglets

The impact of high frequency oscillatory ventilation (HFOV) compared with intermittent mandatory ventilation (IMV) on oxygenation and pulmonary inflammatory response was studied in a surfactant depleted piglet model. After establishment of lung injury by bronchoalveolar lavage, piglets either received HFOV (n =5) or IMV (control; n = 5) for eight hours. PaO(2) was higher and mean pulmonary arterial pressure (MPAP) was lower with HFOV (HFOV versus control, mean +/- SEM; endpoint PaO(2): 252 +/- 73 versus 68 +/- 8.4 mm Hg; p < 0.001; MPAP: 22 +/- 2.3 versus 34 +/- 2.5 mm Hg; p < 0.01). mRNA expression of interleukin (IL)-1 beta, IL-6, IL-8, IL-10, TGF-beta 1, Endothelin-1, and adhesion molecules (E-selectin, P-selectin, ICAM-1) in lung tissue was quantified by real time PCR normalized to beta-actin and hypoxanthine-guanine-phosphoribosyl-transferase (HPRT). mRNA expression of all cytokines and adhesion molecules/HPRT was higher in controls (e.g.: HFOV versus control, mean +/- SEM; IL-1 beta/HPRT: 1.6 +/- 0.3 versus 23.1 +/- 8.6 relative units (RU), p < 0.001; IL-8/HPRT: 8.5 +/- 2.0 versus 63.5 +/- 15.2 RU, p < 0.001). IL-8/HPRT gene expression was quantified in microdissected single cells. With HFOV, IL-8 gene expression was highly reduced in alveolar macrophages: 10 +/- 3.4 copies IL-8 mRNA/copy HPRT mRNA versus 356 +/- 142; p < 0.05 (bronchiolar epithelial cells: 33 +/- 16 versus 208 +/- 108; alveolar septum: 2.1 +/- 1.3 versus 26 +/- 11; bronchiolar smooth muscle cells: 1.3 +/- 0.3 versus 2.8 +/- 1.0; vascular smooth muscle cells: 0.7 +/- 0.3 versus 1.1 +/- 0.4). In conclusion, HFOV improved oxygenation, reduced pulmonary arterial pressure and attenuated pulmonary inflammatory response.     

新生猪多器官功能障碍综合征模型建立的实验研究

目的：探讨采用盲肠结扎加穿孔(CLP)建立新生猪多器官功能障碍综合征(MODS)模型的方法及实验与临床意义。方法：选用健康长白新生猪14只,随机分成实验组(E组,n=9)和对照组(C组,n=5),实验组施行盲肠结扎加穿孔(CLP)制成MODS动物模型,对照组只行剖腹和盲肠探查术。动态观察两组血清生化指标(ALT,AST,ALB,BUN,Cr,CKMB,lac)及血小板、血气分析(PaO2,PaCO2)的变化,通过光镜观察动物各重要生命器官组织形态学变化。结果：与对照组相比,实验组动物在CLP后血ALT,AST,BUN,Cr,CKMB,lac24h即已开始升高,48～96h明显升高,48h时ALT为83.0±9.3U/L、AST为348.8±132.9U/L、BUN为10.5±2.5mmol/L、Cr为79.2±9.0μmol/L、CKMB为5152.0±1857.8U/L、lac为12.3±4.0mmol/L(P<0.01),96h后开始有所降低,但仍高于0h;ALB24h后开始降低,各时间点均低于对照组,但差异无显著性;血小板24h开始降低,96h与0h比较差异有显著性;PaO2和PaCO248h时实验组与对照组差异有非常显著性(P<0.01);实验组动物死亡率与对照组差异有显著性(P<0.05),MODS的发生率为56%。实验组动物肺、肝、心、肾、胃肠道等器官均有不同程度的病理改变。结论：CLP诱发了新生猪多个器官的功能障碍,该实验可用于新生动物MODS模型的探讨。     

Effect of level of circular myotomy on oesophageal function in a piglet model

Oesophageal continuity is often difficult to obtain in long-gap oesophageal atresia, and a circular myotomy may be required to achieve oesophageal anastomosis. This study compared the effects of upper and lower segmental circular myotomy on oesophageal stricture formation, oesophageal motility, and the development of gastro-oesophageal reflux (GOR) in a piglet model. Group I underwent mid-oesophageal resection with upper segment myotomy (14); group II mid-oesophageal resection with lower segment myotomy (8); and group III oesophageal transection and anastomosis without resection (6). Normal motility data were obtained from 8 unmanipulated piglets. The incidence of stricture formation was high in all operated groups. Pseudodiverticula developed in all piglets after proximal myotomy, but not after transection or distal myotomy. Lower oesophageal sphincter pressure and mean amplitude of upper oesophageal contractions were similar after operation in all groups and in controls. GOR (number of reflux episodes/24 h, number of episodes of reflux lasting more than 5 min, and fraction of time pH less than 4.0) was worse after operation compared to controls. Within each group most manometric parameters and GOR worsened with time. We found no evidence that the level of circular myotomy (upper or lower) resulted in any significant difference in stricture rate, oesophageal motility, or severity of GOR. Given the difficulty of performing an upper myotomy in long-gap atresia, where the upper segment is often very short and pseudodiverticulum formation is common, a lower-segment circular myotomy would appear to be a reasonable alternative.     

Utility and limitations of near-infrared spectroscopy during cardiopulmonary bypass in a piglet model

Near-infrared spectroscopy assessment of cytochrome oxygenation could be a valuable technique to monitor cerebral intraneuronal oxygen delivery during cardiopulmonary bypass. However, the validity of the cytochrome signal has been questioned as it could easily be overwhelmed by the Hb signal. Five- to six-week-old control piglets (n = 5) underwent cardiopulmonary bypass at 37 degrees C. Study animals (n = 10) received 100 mg/kg of sodium cyanide to uncouple cytochrome from HB: Hematocrit was then decreased in steps of 5% from 35 to 5% with crystalloid hemodilution. In study piglets, the initiation of cardiopulmonary bypass was associated with oxygenated Hb increasing from 0 to 62.9 +/- 25.6 microM times the differential path-length factor, and oxidized cytochrome a,a3 increasing to 1.9 +/- 1.8 microM times the differential path-length factor. Cyanide caused oxygenated Hb to increase further to 132.3 +/- 48.9 microM times the differential path-length factor, and oxidized cytochrome c decreased to -7.0 +/- 2.6 microM times the differential path-length factor as anticipated, confirming uncoupling of electron transport. However, hemodilution subsequently resulted in linear decreases in oxidized cytochrome a,a3 (F = 8.57, p < 0.001) suggesting important cross-talk between the Hb and cytochrome signals as cytochrome is only intracellular. In control piglets, tissue oxygenation index showed a positive correlation with pump flow (r = 0.986, p = 0.013). The cytochrome signal as presently measured by near-infrared spectroscopy is highly dependent on hematocrit.     

微剂量肝素早期干预对危重新生儿伴全身炎症反应综合征预后的影响

目的观察早期使用微剂量肝素对危重新生儿伴全身炎症反应综合征(SIRS)的治疗效果及预后的影响。方法对符合诊断标准的84例新生儿SIRS患儿随机分组进行前瞻性对照研究,对照组39例,给予原发病及保护重要脏器等常规治疗;治疗组45例,在常规治疗基础上早期加用微剂量肝素皮下注射按5～10U/kg,6h1次,共用3d。结果两组治疗前后比较,治疗后血小板计数明显升高,CRP、D-D水平明显下降。治疗组与对照组比较,SIRS的持续时间缩短(χ2=5.655,P=0.017),多脏器功能不全(MODS)发生率有显著减少、病死率均明显降低(P<0.05)。结论微剂量肝素早期干预可缩短新生儿SIRS持续时间,降低MODS的发生率及病死率。     

微剂量肝素早期干预对危重新生儿伴全身炎症反应综合征预后的影响

目的 观察早期使用微剂量肝素对危重新生儿伴全身炎症反应综合征（SIRS）的治疗效果及预后的影响.方法 对符合诊断标准的84例新生儿SIRS患儿随机分组进行前瞻性对照研究,对照组39例,给予原发病及保护重要脏器等常规治疗;治疗组45例,在常规治疗基础上早期加用微剂量肝素皮下注射按5～10 U/kg,6 h 1次,共用3 d.结果 两组治疗前后比较,治疗后血小板计数明显升高,CRP、D-D水平明显下降.治疗组与对照组比较,SIRS的持续时间缩短（χ2=5.655,P=0.017）,多脏器功能不全（MODS）发生率有显著减少、病死率均明显降低（P＜0.05）.结论 微剂量肝素早期干预可缩短新生儿SIRS持续时间,降低MODS的发生率及病死率.