Ventilatory strategies in patients with sepsis and respiratory failure

Patients with sepsis may require mechanical ventilation due to the acute respiratory distress syndrome (ARDS). It has become increasingly accepted that mechanical ventilation can contribute to lung injury in these patients. The modern concept of ventilator-induced lung injury is described in the context of alveolar over-distention (volutrauma), alveolar de-recruitment (atelectrauma), and biochemical injury and inflammation to the lung parenchyma (biotrauma). To avoid over-distention lung injury, the tidal volume should be set at 6 mL/kg predicted body weight and plateau pressure should be limited to 30 cm H₂O. This has been shown to afford a survival benefit. Although setting positive end-expiratory pressure (PEEP) to zero is likely harmful during mechanical ventilation of patients with ARDS, evidence is lacking for a survival benefit if a high PEEP level is set compared with a modest level of PEEP. Although adjunctive measures such as recruitment maneuvers, prone position, and inhaled nitric oxide may improve oxygenation, evidence is lacking that these measures improve survival.     

急性呼吸窘迫综合征家兔肺不同区域有效血流灌注变化及肺保护性通气对其的影响

目的 通过观察家兔急性呼吸窘迫综合征(ARDS)模型肺不同区域有效血流灌注变化及肺保护性通气对其的影响,探讨ARDS所致严重低氧血症的发生机制。方法 采用静脉注射油酸的方法建立家兔ARDS模型,应用PIM-Ⅱ激光多普勒血流灌注扫描仪观察不同肺通气模式[(大潮气、小潮气 外源性呼气末正压(PEEP)、大潮气 俯卧位、俯卧位 小潮气 PEEP]下肺不同区域(肺上区、肺下区腹侧和肺下区背侧)局部有效血流灌注及动脉血气指标的变化。结果 家兔静脉注射油酸后,(1)肺不同区域氧合指数明显下降,应用肺保护性通气(小潮气 PEEP,俯卧位 小潮气 PEEP)后氧合指数明显改善;(2)肺不同区域局部有效血流灌注均有不同程度的下降,以肺下区背侧最为明显,肺下区腹侧次之,肺上区变化最小,应用肺保护性通气后,小潮气 PEEP对改善肺下区背侧胸膜下肺局部有效血流灌注的效果不如俯卧位 小潮气 PEEP。结论小潮气 PEEP、俯卧位 小潮气 PEEP均可良好改善肺局部有效血流灌注,其中俯卧位 小潮气 PEEP效果尤为明显;右-左分流导致的肺内分流可能是ARDS发生严重进行性低氧血症的主要原因之一。     

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??Abstract??Mechanical ventilation is still one of the main treatment measures of acute respiratory distress syndrome (ARDS).From the traditional high tidal volume ventilation (10 ~ 15 mL/kg) to the current use of lung protective ventilation strategies??low tidal volume ventilation (VT)??positive end-expiratory pressure (PEEP)??airway pressure release ventilation (APRV)??bilevel positive airway pressure(BIPAP)??considerable progress has been made.In addition to the well-known conventional mechanical ventilation modes and methods??there are many non-standard mechanical ventilation modes and methods??such as prone position ventilation??neurally adjusted ventilatory assist (NAVA)??extracorporeal membrane oxygenation (ECMO)??high-frequency ventilation and etc.All these measures produce unique effects on the treatment of ARDS.     

Lung recruitment maneuvers in acute respiratory distress syndrome

In the experimental setting, repeated derecruitments of the lungs of ARDS models accentuate lung injury during mechanical ventilation, whereas open lung concept strategies can attenuate the injury. In the clinical setting, recruitment manuevers that use a continuous positive airway pressure of 40 cmH2O for 40 secs improve oxygenation in patients with early ARDS who do not have an impairment in the chest wall. High intermittent positive end-expiratory pressure (PEEP), intermitent sighs, or high-pressure controlled ventilation improves short-term oxygenation in ARDS patients. Both conventional and electrical impedance thoracictomography studies at the clinical setting indicate that high PEEP associated with low levels of pressure control ventilation recruit the collapsed portions of the ARDS lungs and that adequate PEEP levels are necessary to keep the ARDS lungs opened allowing a more homogenous ventilation. High PEEP/low tidal volume ventilation was seen to reduce inflammatory mediators in both bronchoalveolar lavage and plasma, compared to low PEEP/high tidal volume ventilation, after 36 hours of mechanical ventilation in ARDS patients. Recruitment maneuvers that used continuous positive airway pressure levels of 35-40 cmH2O for 40 secs, with PEEP set at 2 cmH2O above the lower inflection point of the pressure-volume curve, and tidal volume < 6 mL/kg were associated with a 28-day intensive care unit survival rate of 62%. This contrasted with a survival rate of only 29% with conventional ventilation (defined as the lowest PEEP for acceptable oxygenation without hemodynamic impairment with a tidal volume of 12 mL/kg), without recruitment manuevers (number needed to treat = 3; p < 0.001). In the near future, thoracic computed tomography associated with high-performance monitoring of regional ventilation may be used at the bedside to determine the optimal mechanical ventilation of the ARDS keeping an opened lung with a homogenous ventilation.     

肺保护性通气对严重胸外伤致急性呼吸窘迫综合征疗效的影响研究

目的探讨小潮气量（LTV）加呼气末正压（PEEP）机械通气（MV）治疗严重胸外伤致急性呼吸窘迫综合征（ARDS）的疗效。方法以28例常规潮气量（8～12ml/kg）MV为对照组,30例小潮气量（5～7ml/kg）加用PEEP的MV模式为观察组,比较两组血气,RR、HR、MAP、CVP、呼吸机所致肺损伤（VILI）、多脏器功能不全（MODS）发生率及ARDS病死率。结果两组PaO2差异无显著性意义;观察组PaCO2高于对照组;观察组出现6例VILI、4例MODS及死亡3例,对照组13例VILI、7例MODS、死亡5例。结论在ARDS治疗中采用小潮气量加PEEP及允许范围内高碳酸血症（PHC）的肺保护性通气策略,可明显改善缺氧,减少VILI发生,从而降低病死率。     

Personalizing mechanical ventilation for acute respiratory distress syndrome

Lung-protective ventilation with low tidal volumes remains the cornerstone for treating patient with acute respiratory distress syndrome (ARDS). Personalizing such an approach to each patient’s unique physiology may improve outcomes further. Many factors should be considered when mechanically ventilating a critically ill patient with ARDS. Estimations of transpulmonary pressures as well as individual’s hemodynamics and respiratory mechanics should influence PEEP decisions as well as response to therapy (recruitability). This summary will emphasize the potential role of personalized therapy in mechanical ventilation.     

急性呼吸窘迫综合征的容许性高碳酸血症的机械通气治疗

急性呼吸窘迫综合合征（ＡＲＤＳ）机械通气治疗的探索。方法观察了１０例ＡＲＤＳ患者。为了减低吸气末气道压力（ｐｐｌａｔ），减少肺气压伤，应用较低的潮气量（ＶＴ，ｘ＝６．５ｍｌ／ｋｇ），依靠自身肾脏代偿功能，容许一定限度的呼吸性酸中毒（简称呼酸）存在（ｐＨ≥７．１９）。在维持动脉血氧分压（ＰａＯ２）７．３ｋＰａ（１ｋＰａ＝７．５ｍｍＨｇ）左右情况下，尽量使用低水平吸氧浓度（ＦｉＯ２，ｘ＝０．５１）及呼气示正压（ＰＥＥＥＰ，ｘ＝０．９２ｋＰａ）（１ｋＰａ＝１０．２ｃｍＨ２Ｏ）。结果７例存活，其中３例在机械通气期间出现过呼酸，２例出现肺气压伤。结论在ＡＲＤＳ机械通气治疗中，使用较低ＶＴ及容许一定限度呼酸存在是值得重视的新观点，应在临床上进一步探索     

Best compliance during a decremental, but not incremental, positive end-expiratory pressure trial is related to open-lung positive end-expiratory pressure: a mathematical model of acute respiratory distress syndrome lungs

A mathematical model of the acute respiratory distress syndrome (ARDS) lung, incorporating simulated gravitational superimposed pressure and alveolar opening and closing pressures, was used to study the mean tidal pressure-volume (PV) slope ("effective compliance") during incremental and decremental positive end-expiratory pressure (PEEP) trials with constant tidal volume (VT) "ventilation." During incremental PEEP, the PEEP giving maximum mean tidal PV slope did not coincide with "open lung PEEP" (minimum PEEP preventing end expiratory collapse of 97.5% of alveoli inflated at end-inspiration), and it varied greatly with varying VT and "lung mechanics." Incremental PEEP with a low VT tests recruitment by the peak pressure, not prevention of collapse by PEEP. During decremental PEEP with a low VT, maximum mean tidal PV slope occurred with PEEP 2-3.5 cm H2O below open-lung PEEP, unless closing pressure was high. High VT, high "specific compliance," and high opening pressures caused slightly greater underestimation of open-lung PEEP. Maximum mean tidal PV slope was always higher (e.g., 93.7 versus 16.69 ml/cm H2O), and the variation in PV slope with PEEP was greater, during decremental PEEP. The maximum PV slope during a decremental PEEP trial with a low VT may be a useful method to determine open-lung PEEP in ARDS, and should be studied clinically.     

Extracorporeal lung assist in severe respiratory failure and ARDS. Current situation and clinical applications

Despite improvements in ventilation support techniques, lung protection strategies, and the application of new support treatment, acute respiratory distress syndrome continues to have a high mortality rate. Many strategies and treatments for this syndrome have been investigated over the last few year. However, the only therapeutic measure that has systematically shown to be able to improve survival is that of low volume lung protective ventilation. Thus, using a low tidal volume prevents added lung damage by the same mechanical ventilation that is essential for life support. In this context, the use of extracorporeal lung assist systems is considered an exceptional use rescue treatment in extreme cases. On the other hand, it could be a potentially useful complementary method for an ultra-protective ventilation strategy, that is, by using even lower tidal volumes. The currently available extracorporeal lung assist systems are described in this article, including high flow systems such as traditional extracorporeal membrane oxygenation, CO₂ removal systems (interventional lung assist or iLA, with or without associated centrifugal pumps), and the new low flow and less invasive systems under development. The aim of this review is to update the latest available clinical and experimental data, the indications for these devices in adult respiratory distress syndrome (ARDS), and their potential indications in other clinical situations, such as the bridge to lung transplantation, multiple organ dysfunction syndrome, or COPD.     

Recruitment maneuvers in three experimental models of acute lung injury. Effect on lung volume and gas exchange

Recruitment maneuvers (RM), consisting of sustained inflations at high airway pressures, have been advocated as an adjunct to mechanical ventilation in acute respiratory distress syndrome (ARDS). We studied the effect of baseline ventilatory strategy and RM on end-expiratory lung volume (EELV) and oxygenation in 18 dogs, using three models of acute lung injury (ALI; n = 6 in each group): saline lavage (LAV), oleic acid injury (OAI), and intratracheal instillation of Escherichia coli (pneumonia; PNM). All three models exhibited similar degrees of lung injury. The PNM model was less responsive to positive end-expiratory pressure (PEEP) than was the LAV or OAI model. Only the LAV model showed an oxygenation response to increasing tidal volume (VT). After RM, there were transient increases in Pa(O(2)) and EELV when ventilating with PEEP = 10 cm H(2)O. At PEEP = 20 cm H(2)O the lungs were probably fully recruited, since the plateau airway pressures were relatively high ( approximately 45 cm H(2)O) and the oxygenation was similar to preinjury values, thus making the system unresponsive to RM. Sustained improvement in oxygenation after RM was seen in the LAV model when ventilating with PEEP = 10 cm H(2)O and VT = 15 ml/kg. Changes in EELV correlated with changes in Pa(O(2)) only in the OAI model with PEEP = 10 cm H(2)O. We conclude that responses to PEEP, VT, and RM differ among these models of ALI. RM may have a role in some patients with ARDS who are ventilated with low PEEP and low VT.     

Successful treatment of a critically ill patient with acute respiratory distress syndrome from COVID-19 using mechanical ventilation strategy with low levels of positive end-expiratory pressure: A CARE-compliant case report

Introduction:Acute respiratory distress syndrome (ARDS) secondary to COVID-19 is different from the ARDS caused by other infections. Conventional mechanical ventilation strategies using high levels of PEEP may not be beneficial and can even be harmful to patient with ARDS from COVID-19. So the ventilation strategies should be adjusted in order to improve the pulmonary ventilation function and oxygenation status, and outcomes of the patient.Patient concerns:Herein, we present a 76-year-old male patient with ARDS secondary to COVID-19. We describe our experience with mechanical ventilation strategy and the changes in respiratory mechanics in the patient during treatment.Diagnosis:The patient had tested positive for coronavirus (COVID-19) in nucleic acid test. Chest CT showed multiple ground glass shadows in both lungs.Interventions:The patient received mechanical ventilation with low tidal volume and low PEEP.Outcomes:After treatment, the patients condition, as well as oxygenation status was improved, and he tested negative for the coronavirus several times.Conclusion:This case demonstrated that the low tidal volume with low levels of PEEP ventilation strategy may be more suitable for ARDS from COVID-19.     

ARDSnet ventilatory protocol and alveolar hyperinflation: role of positive end-expiratory pressure

RATIONALE: In patients with acute respiratory distress syndrome (ARDS), a focal distribution of loss of aeration in lung computed tomography predicts low potential for alveolar recruitment and susceptibility to alveolar hyperinflation with high levels of positive end-expiratory pressure (PEEP). OBJECTIVES: We tested the hypothesis that, in this cohort of patients, the table-based PEEP setting criteria of the National Heart, Lung, and Blood Institute's ARDS Network (ARDSnet) low tidal volume ventilatory protocol could induce tidal alveolar hyperinflation. METHODS: In 15 patients, physiologic parameters and plasma inflammatory mediators were measured during two ventilatory strategies, applied randomly: the ARDSnet and the stress index strategy. The latter used the same ARDSnet ventilatory pattern except for the PEEP level, which was adjusted based on the stress index, a monitoring tool intended to quantify tidal alveolar hyperinflation and/or recruiting/derecruiting that occurs during constant-flow ventilation, on a breath-by-breath basis. MEASUREMENTS AND MAIN RESULTS: In all patients, the stress index revealed alveolar hyperinflation during application of the ARDSnet strategy, and consequently, PEEP was significantly decreased (P < 0.01) to normalize the stress index value. Static lung elastance (P = 0.01), plasma concentrations of interleukin-6 (P < 0.01), interleukin-8 (P = 0.031), and soluble tumor necrosis factor receptor I (P = 0.013) were significantly lower during the stress index as compared with the ARDSnet strategy-guided ventilation. CONCLUSIONS: Alveolar hyperinflation in patients with focal ARDS ventilated with the ARDSnet protocol is attenuated by a physiologic approach to PEEP setting based on the stress index measurement.     

肺泡复张后不同呼气末正压和潮气量调节策略对防止肺泡再萎陷效果的实验研究

目的探讨肺泡复张(RM)后再萎陷的机制以及呼气末正压(PEEP)和潮气量(VT)的调节策略。方法健康杂种犬18只,建立油酸所致急性呼吸窘迫综合征(ARDS),行容量控制通气(VCV)、PEEP 16 cm H2O、VT10 m l/kg、通气频率(RR)30次/m in,稳定后作为基础状态(0 m in)。以压力控制通气[气道峰压(PIP)50 cm H2O,PEEP 35 cm H2O,持续60 s]行RM,然后随机分为小VT中等PEEP组(LVMP组,VT10 m l/kg、PEEP 16 cm H2O、RR 30次/m in),小VT低PEEP组(LVLP组,VT10 m l/kg、PEEP 10 cm H2O、RR 30次/m in)和中等VT低PEEP组(MVLP组,VT15 m l/kg、PEEP 10cm H2O、RR 20次/m in)。观察4 h后处死动物,行支气管肺泡灌冼。监测氧合、呼吸力学、血流动力学及肺损伤指标。结果(1)LVMP、LVLP、MVLP组低位拐点(LIP)分别为(16.0±1.3)、(15.8±3.0)、(16.3±1.9)cm H2O。(2)在RM后30、60 m in,LVMP组动脉血氧分压(PaO2)[(371±64)、(365±51)mm Hg]显著高于LVLP组[(243±112)、(240±108)mm Hg]及MVLP组[(242±97)、(232±87)mm Hg,P均<0.05],但直至RM后4 h 3组比较差异无统计学意义;LVLP与MVLP组在RM后各个时间点的PaO2与基础状态比较差异均无统计学意义;MVLP组的通气功能较其他两组显著改善。(3)与基础状态比较,RM后LVMP组平均动脉压(mABP)显著降低,平均肺动脉压(mPAP)显著增加,而其他两组mABP保持稳定,mPAP降低。(4)与基础状态比较,3组PIP和气道平台压(Pp lat)在RM后均显著降低,呼吸系统静态顺应性(Cst)显著改善。在RM后同一时间点比较,MVLP组PIP、Pp lat和Cst均显著好于LVMP组。MVLP组与LVLP组相比,Cst有增加趋势。(5)在相同部位的支气管肺泡灌冼液中,肺损伤指标在各组之间无显著差异。结论与LIP相近的高PEEP有助于防止复张肺泡的再萎陷,但对血流动力学和呼吸力学产生不利影响;早期应用RM能有效“节约”PEEP,并为上调VT提供了较肺泡复张之前更大的空间。     

Tidal volume reduction in patients with acute lung injury when plateau pressures are not high

Use of a volume- and pressure-limited mechanical ventilation strategy improves clinical outcomes of patients with acute lung injury and acute respiratory distress syndrome (ALI/ARDS). However, the extent to which tidal volumes and inspiratory airway pressures should be reduced to optimize clinical outcomes is a controversial topic. This article addresses the question, "Is there a safe upper limit to inspiratory plateau pressure in patients with ALI/ARDS?" We reviewed data from animal models with and without preexisting lung injury, studies of normal human respiratory system mechanics, and the results of five clinical trials of lung-protective mechanical ventilation strategies. We also present an original analysis of data from the largest of the five clinical trials. The available data from each of these assessments do not support the commonly held view that inspiratory plateau pressures of 30 to 35 cm H2O are safe. We could not identify a safe upper limit for plateau pressures in patients with ALI/ARDS.     

The protective effects of glutamine in a rat model of ventilator-induced lung injury

Background

The mortality rate of patients with acute respiratory distress syndrome (ARDS) is still high despite the use of protective ventilatory strategies. We sought to examine the pharmacological effects of glutamine (GLN) in a two-hit model of endotoxin-induced inflammation followed by ventilator-induced lung injury (VILI). We hypothesized that the administration of GLN ameliorates the VILI.

Methods

Sprague-Dawley rats were anesthetized and given lipopolysaccharide (LPS) intratracheally as a first hit to induce lung inflammation, followed 24 h later by a second hit of mechanical ventilation (MV) with either low tidal volume (6 mL/kg) with 5 cmH₂O of positive end-expiratory pressure (PEEP) or high tidal volume (22 mL/kg) with zero PEEP for 4 h. GLN or lactated Ringer’s solution as the placebo was administered intravenously 15 min prior to MV.

Results

In the LPS-challenged rats ventilated with high tidal volume, the treatment with GLN improved lung injury indices, lung mechanics and cytokine responses compared with the placebo group.

Conclusions

The administration of GLN given immediately prior to MV may be beneficial in the context of reducing VILI.     

10例高甘油三酯血症性急性胰腺炎合并急性呼吸窘迫综合征的呼吸支持特点分析

摘要 目的：分析10例高甘油三酯血症性急性胰腺炎（HTG-AP）合并急性呼吸窘迫综合征（ARDS）患者的临床特征及呼吸支持治疗方式。方法：选取10例 HTG-AP 合并 ARDS 患者为研究对象，其中单纯使用高流量氧疗(HFNO)4例为HFNO组，使用有创机械通气（IMV）6例为IMV组。比较2组人口学资料、体重指数、呼吸频率、实验室检查、肺部及腹部特征、呼吸支持参数等。结果：IMV组患者中3例入ICU时立即接受IMV，另3例由HFNO或无创呼吸机辅助通气（NIV）失败后转为IMV。10例HTG-AP合并ARDS中男性8例，IMV组中肥胖5例，HNFO组1例；与HFNO组比较，IMV组年龄更小[(36.7±6.3)岁 vs (49.8±10.2)岁，P=0.035]、膀胱压较高[(30.33±6.22)cmH2O vs (23.25±1.5)cmH2O，P=0.038]、呼吸频率明显更快 [(45.67±5.75）次/min vs (34.75±3.69)次/min,P=0.01]。腹部CT均示急性胰周液体积聚，急性坏死物积聚3例（IMV组1例，HFNO组2例）；胰腺假性囊肿2例，均为IMV组；包裹性坏死2例(2组各1例)。胸片或胸部CT均示双肺渗出并双下肺背侧含气不全。呼吸支持治疗：IMV均采用肺保护性通气策略，压力辅助/控制模式，压力支持为10~14cmH2O,目标潮气量控制为6~8mL/kg预测体重（PBW），呼气末正压（PEEP）大部分予以10~14cmH2O；HFNO组患者给予氧流量40~60L/min，吸氧浓度40%~60%。所有患者经治疗后均成功脱机，好转出院。结论：HFNO及IMV是HTG-AP合并ARDS患者有效呼吸支持方式，通常患者合并肥胖、气促明显、腹内高压时，IMV常需予以较高PEEP水平的肺保护性通气。     

The role of cytokines during the pathogenesis of ventilator-associated and ventilator-induced lung injury

Mortality rates from acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) range from 30 to 65%. Although mechanical ventilation (MV) may delay mortality in critically ill patients with ALI/ARDS, it may also cause a lung injury that further promotes and perpetuates ALI/ARDS and multiorgan dysfunction syndrome (MODS). Recent studies have demonstrated that lung protective strategies of MV, as compared with the injurious strategy of conventional MV (CMV) can reduce absolute mortality rates during ALI/ARDS. The protective strategies limit tidal volumes and peak/plateau pressures while maximizing positive end-expiratory pressure. The injury to the lung by CMV is characterized histologically by edema, leukocyte extravasation, and endothelial and epithelial damage. Both human and animal studies suggest that alveolar cell deformation from CMV leads to the release of cytokines/chemokines which orchestrate the extravasation, activation, and recruitment of leukocytes, causing ventilator-associated lung injury (VALI) and ventilator-induced lung injury (VILI). Moreover, VALI/VILI can perpetuate the chronic inflammatory response during ALI/ARDS and MODS. This article explores the role of cytokines/chemokines during the pathogenesis of VALI/VILI.     

Ventilatory Management of ALI/ARDS

Acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) describe syndromes of diffuse parenchymal lung injury resulting from a variety of inflammatory triggers. The pathophysiological consequences include stiff, low-compliance lungs with impaired gas exchange. Importantly, there is often marked heterogeneity of disease. Positive pressure ventilation must therefore not only focus on recruiting and ventilating diseased units but must also avoid injuring healthy units. To this end, the goals of mechanical ventilatory support of ALI and ARDS have shifted over the last decade to providing smaller (and thus less injurious) tidal volumes and accepting consequently lower arterial values for PaO(2) and the development of respiratory acidosis. This has resulted in significant improvements in outcomes. Future developments will need to further refine this lung protective concept.     

New modalities of mechanical ventilation: high-frequency oscillatory ventilation and airway pressure release ventilation

Management of acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) is largely supportive, with the use of mechanical ventilation being a central feature. Recent advances in the understanding of ALI/ARDS and mechanical ventilation have revealed that lung-protective ventilation strategies may attenuate ventilator-associated lung injury and improve patient morbidity/mortality. High-frequency oscillatory ventilation and airway pressure release ventilation are two novel alternative modes of ventilation that theoretically fulfill the principles of lung protection and may offer an advantage over conventional ventilation for ALI/ARDS.     

肺保护性通气对急性呼吸窘迫综合征兔肺部炎症反应的影响

目的　观察肺保护性通气对急性呼吸窘迫综合征 (ARDS)家兔肺部炎症反应的影响。方法　生理盐水肺泡灌洗法复制ARDS家兔模型 ,将 36只家兔随机分为 6组 :(1)正常对照组 (N组 ) ,(2 )ARDS模型组 (M组 ) ,(3)小潮气量 (VT) 最佳呼气末正压 (PEEP)组 (A组 ) ,(4)常规VT 最佳PEEP组 (B组 ) ,(5 )小VT 高PEEP组 (C组 ) ,(6 )高VT 零PEEP组 (D组 )。机械通气 4h后测定肺组织湿/干重比 (W/D) ,迁移率改变电泳法 (EMSA)测定肺组织核因子κB(NF κB)活性 ,逆转录 聚合酶链反应(RT PCR)检测肺组织中肿瘤坏死因子α(TNF α)和白细胞介素 10 (IL 10 )mRNA表达 ,酶联免疫吸附测定 (ELISA)检测肺组织TNF α及IL 10浓度。结果　A组肺组织W/D为 5 6± 1 1,不但显著低于B组(6 6± 0 8)和D组 (6 9± 1 0 ) ,而且也显著低于C组 (6 6± 1 0 ,P均 <0 0 5 ) ,但与M组 (5 8± 0 5 )比较差异无显著性 (P >0 0 5 )。A组肺组织NF κB活性 (331± 113)显著低于B组 (45 5± 6 3)、C组 (478±74 )和D组 (6 4 5± 16 2 ,P均 <0 0 5 ) ,其中D组NF κB活性最高。与A组比较 ,B、C和D组肺组织TNF α及IL 10mRNA表达及浓度显著增高 ,其中D组TNF α和IL 10mRNA表达及其浓度在各组中最高。肺组织髓过氧化物酶 (MPO)及丙二醛 (MDA)含