急性肺损伤家兔部分液体通气疗效的实验研究

目的　观察部分液体通气 (partialliquidventilation ,PLV)治疗肺灌洗诱导的急性肺损伤 (acutelungin jury ,ALI)家兔时 ,肺气体交换及血流动力学变化。方法　 12只成年健康新西兰兔 ,麻醉后气管切开生理盐水反复肺内灌洗 ,直至动脉氧分压 (PaO2 ) <10 0mmHg(13 33kPa)达 1h ,即为ALI。随机分为部分液体通气组及对照组 ,对照组以呼吸机行常规机械通气 ,PLV组动物于ALI后气管内灌入氟碳化合物 (FC32 80 ,3M) 15ml/kg ,补充剂量 4ml/(kg·h) ,每小时记录各参数 ,4h处死动物。结果　部分液体通气组PaO2 及动脉血氧饱和度 (SpO2 )显著改善 ,PaCO2 显著降低 ,而血流动力学在整个试验过程中基本维持恒定。结论　以氟碳化合物为呼吸媒介的部分液体通气可明显改善肺灌洗诱导的急性肺损伤家兔的肺气体交换 ,对血液动力学无明显影响。     

Interfacial Properties as Stability Predictors of Lecithin-Stabilized Perfluorocarbon Emulsions

ABSTRACT

The purpose of this study was to determine whether the addition of small quantities of minor lecithin components (phosphatidylinositol, phosphatidic acid, lysophosphatidylethanolamine, and cholesterol) and Pluronic F68 to lecithin could improve the stability of lecithin-stabilized perfluorocarbon emulsions. Attempts were made to correlate emulsion stability with interfacial properties (tension and charge). Dynamic interfacial tension was determined using a Teflon Wilhelmy plate method [reported previously (1)]. Emulsions were prepared by microfluidization. Microelectrophoresis was used to measure emulsion droplet charge, and photon correlation spectroscopy and Coulter analysis were used to determine emulsion stability as a function of droplet size. Thermal kinetic accelerated stability testing was conducted. Various droplet size parameters were used to compare emulsion stabilities, and an overall stability ranking, based on these parameters, was obtained for each emulsion. Small quantities of additives altered emulsion stability and these data were correlated with interfacial properties and initial droplet diameters. The addition of cholesterol to lecithin resulted in the most stable perfluorocarbon emulsion.     

部分液体通气对无心跳供体肺的保护作用

目的 观察部分液体通气对无心跳供体(NHBD)肺的保护作用.方法 36只清洁级SD大鼠随机分为3组:氧气组(C组)、盐水组(B组)和部分液体通气组(A组).建立NHBD肺模型后行机械通气2h并监测大鼠气道压,2h后测量P-V曲线,切除大鼠左肺下叶,观察供体肺病理特点.行右肺支气管灌洗,测量灌洗液中肺表面活性物质相关蛋白B、C(SP-B、SP-C)的浓度.切除大鼠右肺上叶,并进一步行SP-B、SP-C的实时定量聚合酶链反应(Real-time PCR)检测.结果 A组大鼠动态顺应性和静态顺应性在2h热缺血期间都优于B和C组(P＜0.05);病理组织评分A组优于B组和C组(P＜0.05);肺泡灌洗液酶联免疫吸附试验(ELISA)检测和肺组织的Real-time PCR检测说明SP-B和SP-C蛋白和RNA含量差异有统计学意义,其中A组含量明显高于B组和C组(P＜0.05).结论 部分液体通气可以对热缺血期间供肺的肺功能和肺组织起到很好的保护作用,并对SP-B和SP-C有较好的保护作用.     

Reperfusion injury after critical intestinal ischemia and its correction with perfluorochemical emulsion ＂perftoran＂

AIM: To investigate the anti-ischemic properties of perfluorochemical emulsion "perftoran" in mesenteric region. METHODS: Experiments were conducted on 146 nonlinear white male rats weighing 200-350 g. Partial critical intestinal ischemia was induced by thorough atraumatic strangulation of 5-6 cm jejunal loop with its mesentery for 90 min. Global critical intestinal ischemia was made by atraumatic occlusion of the cranial mesenteric artery (CMA) for 90 min also. Perftoran (PF, 0.8-1.0 mL per 100 g) in experimental groups or 0.9% sodium chloride in control groups was injected at 75 min of ischemic period. Mean systemic arterial blood pressure (BPM) registration, intravital microscopy and morphological examination of ischemic intestine and its mesentery were performed in both groups. RESULTS: During 90 min of reperfusion, BPM progressively decreased to 27.3±7.4% after PF administration vs 38.6±8.0% in the control group of rats with partial intestinal ischemia (NS) and to 50.3±6.9% vs 53.1±5.8% in rats after global ischemia (NS). During the reperfusion period, full restoration of microcirculation was never registered; parts with restored blood flow had leukocyte and erythrocyte stasis and intra-vascular clotting, a typical "non-reflow" phenomenon. The reduction of mesenteric 50-400 μm feeding artery diameter was significantly less in the PF group than in the control group (24±5.5% vs 45.2±3.6%, P<0.05) 5 min after partial intestinal ischemia. This decrease progressed but differences between groups minimized at the 90th min of reperfusion (41.5±4.2% and 50.3±2.8%, respectively). In reperfusion of rat's intestine, a significant mucosal alteration was registered. Villous height decreased 2.5-3 times and the quantity of crypts decreased more than twice. In the group of rats administered PF, intestinal mucosal layer was protected from irreversible post-ischemic derangement during reperfusion. Saved cryptal epithelial cells were the source of regeneration of the epithelium, which began to cover renewing intestinal villi after 24 h of blood flow restoration. View of morphological alterations was more heterogeneous in CMA groups. CONCLUSION: Systemic administration of perftoran promotes earlier and more complete structural regeneration during reperfusion in rats after partial and global critical intestinal ischemia.     

Ⅱ号氟碳代血液在大鼠体内蓄积的病理形态学观察

本文用Ⅱ号氟碳代血液连续静脉输入大白鼠后,在1年时间内对各脏器作了病理形态学的动态观察。观察结果表明,氟碳颗粒主要蓄积在网状内皮系统丰富的肝、脾中,镜下表现为泡沫细胞,因此,肝、脾的重量变化和泡沫细胞的消长可以作为氟碳颗粒在体内蓄积的指标。本实验在输注Ⅱ号氟碳代血液后1年,肝、脾的重量已基本上恢复正常,但泡沫细胞尚未完全消失。在体内蓄积的氟碳颗粒对各脏器的结构和功能并无毒性损害作用。     

Hepatocyte function in a radial-flow bioreactor using a perfluorocarbon oxygen carrier

The aims of this study were, first, to indicate the metabolic activity of hepatocytes in a radial-flow polyurethane foam matrix bioreactor relative to monocultures, and second, to evaluate the effect on the hepatocytes of including a synthetic perfluorocarbon (PFC) oxygen carrier to the recirculating medium. The efficient O2-carrying ability of PFCs may be beneficial to bioreactors employed in stressed cellular environments. Thus, they may also be useful in the treatment of an acute liver failure patient with a bioartificial liver support system (BALSS). Data on the function of three-dimensional (3-D) hepatocyte cultures exposed to emulsified PFCs are lacking. RESULTS: the metabolic functions of the 3-D hepatocyte cultures were improved relative to monocultures. Three-dimensional cultures with and without PFC behaved similarly, and no adverse effects could be detected when PFC was included in the recirculating medium. The addition of PFC significantly improved lidocaine clearance possibly due to the presence of higher O2 tension in the medium. Imaging indicated that large aggregates formed and that seeding had followed flow through the matrix. Simulations indicated first, that the cell numbers used in this study had been insufficient to challenge the bioreactor O2 supply explaining the similarity in performance of the 3-D cultures, and second, that the benefit of adding PFC would be more pronounced at the cell densities likely to be used in a BALSS bioreactor.     

部分液体通气对吸入性损伤犬肺组织病理学的影响

目的 研究部分液体通气(PLV)对吸入性损伤犬肺组织病理学的影响。方法 将16只犬经蒸气吸入造成吸入性损伤模型，并随机分为对照组和治疗组。所有动物行机械通气，伤后1．5h PLV治疗组给予氟碳，剂量为12mL／kg，伤后3h放血致死动物，取肺组织分别进行光镜和电镜下的组织病理学观察。结果 与对照组比较，PLV治疗组肺组织充血、水肿、中性粒细胞浸润明显减轻，血管内皮细胞和肺泡细胞损伤轻。结论 PLV能减轻吸人性损伤的肺组织损伤，具有抗炎作用。     

Hemodynamic effects of partial liquid ventilation with perfluorocarbon in acute lung injury

Objective To assess the effect of partial liquid ventilation with perfluorocarbons on hemodynamics and gas exchange in large pigs with induced acute lung injury (ALI).Design Randomized, prospective, double-control, experimental study.Setting Experimental intensive care unit of a university.Materials Eighteen large pigs (50±5 kg body weight) with an average anterior posterior thoracic diameter of 24 cm and induced acute lung injury.Interventions All animals were surfactant depleted by lung lavage to aP _aO₂ below 100 mmHg and randomized to receive either perflubron (n=6) or saline (n=6) in five intratracheal doses of 5 ml/kg at 20-min intervals, or no instillation (n=6).Measurements and results In all animals heart rate, arterial pressures, pulmonary pressures, cardiac output and blood gases were recorded at 20-min intervals. There was no deleterious effect on any hemodynamic parameter in the perflubron group, whereas systolic and mean pulmonary arterial pressure values showed a persistent decrease after the first 5 ml/kg of perflubron, from 48.7±14.1 to 40.8±11.7 mmHg and from 39.7±13.2 to 35.2±12.0 mmHg, respectively. Perflubron resulted in a significant (ANOVAP<0.01), dose-dependent increase inP _aO₂ values from 86.3±22.4 to a maximum of 342.4±59.4 mmHg at a dose of 25 ml/kg; the other groups showed no significant increase inP _aO₂.Conclusions Tracheal instillation of perflubron in induced ALI results in a dose-dependent increase inP _aO₂ and has no deleterious effect on hemodynamic parameters.     

Molecular imaging with targeted perfluorocarbon nanoparticles: quantification of the concentration dependence of contrast enhancement for binding to sparse cellular epitopes

Targeted, liquid perfluorocarbon nanoparticles are effective agents for acoustic contrast enhancement of abundant cellular epitopes (e.g., fibrin in thrombi) and for lower prevalence binding sites, such as integrins associated with tumor neovasculature. In this study, we sought to delineate the quantitative relationship between the extent of contrast enhancement of targeted surfaces and the density (and concentration) of bound perfluorocarbon (PFC) nanoparticles. Two dramatically different substrates were utilized for targeting. In one set of experiments, the surfaces of smooth, flat, avidin-coated agar disks were exposed to biotinylated nanoparticles to yield a thin layer of targeted contrast. For the second set of measurements, we targeted PFC nanoparticles applied in thicker layers to cultured smooth muscle cells expressing the transmembrane glycoprotein "tissue factor" at the cell surface. An acoustic microscope was used to characterize reflectivity for all samples as a function of bound PFC (determined via gas chromatography). We utilized a formulation of low-scattering nanoparticles having oil-based cores to compete against high-scattering PFC nanoparticles for binding, to elucidate the dependence of contrast enhancement on PFC concentration. The relationship between reflectivity enhancement and bound PFC content varied in a curvilinear fashion and exhibited an apparent asymptote (approximately 16 dB and 9 dB enhancement for agar and cell samples, respectively) at the maximum concentrations (approximately 150 microg and approximately 1000 microg PFOB for agar and cell samples, respectively). Samples targeted with only oil-based nanoparticles exhibited mean backscatter values that were nearly identical to untreated samples (<1 dB difference), confirming the oil particles' low-scattering behavior. The results of this study indicate that substantial contrast enhancement with liquid perfluorocarbon nanoparticles can be realized even in cases of partial surface coverage (as might be encountered when targeting sparsely populated epitopes) or when targeting surfaces with locally irregular topography. Furthermore, it may be possible to assess the quantity of bound cellular epitopes through acoustic means.     

Distribution of pulmonary blood flow in the perfluorocarbon-filled lung

Objective: Partial liquid ventilation (PLV) improves gas exchange in animal studies of lung injury. Perfluorocarbons (PFCs) are heavy liquids and are therefore preferentially delivered to the most dependent areas of lung. We hypothesised that improved oxygenation during PLV might be the consequence of a redistribution of pulmonary blood flow away from poorly ventilated, dependent alveoli, leading to improved ventilation/perfusion (V/Q) matching. This study investigated whether partially filling the lung with PFC would result in a redistribution of pulmonary blood flow.¶Design: Prospective experimental study.¶Setting: Hospital research institute laboratory.¶Participants: Six anaesthetised pigs without lung injury.¶Interventions: Animals were anaesthetised and ventilated (gas tidal volume 12 ml/kg, PEEP 5, FIO₂ 1.0, rate 16). Whilst the pigs were maintained in the supine position, regional pulmonary blood flow was measured during conventional gas ventilation and repeated during PLV. Flow to regions of lung was determined by injection of radioactive microspheres (Co⁵⁷, Sn¹¹³, Sc⁴⁶). Measurements were performed with ventilation held at end-expiratory pressure and, in two PLV animals only, repeated with ventilation held at peak inspiratory pressure.¶Results: During conventional gas ventilation, blood flow followed a linear distribution with the highest flow to the most dependent lung. In the lung partially filled with PFC a diversion of blood flow away from the most dependent lung was seen (p = 0.007), resulting in a more uniform distribution of flow down the lung (p = 0.006). Linear regression analysis (r ² = 0.75) also confirmed a difference in distribution pattern. On applying an inspiratory hold to the liquid-containing lung, blood flow was redistributed back towards the dependent lung.¶Conclusions: Partially filling the lung with PFC results in a redistribution of pulmonary blood flow away from the dependent region of the lung. During PLV a different blood flow distribution may be seen between inspiration and expiration. The clinical significance of these findings has yet to be determined.