对意外或自主拔管患者的研究显示，接受完全机械通气患者的23％和开始撤机过程患者的69％并不需要重新插管，这表明机械通气患者的撤机存在被延迟的倾向，致使患者承受不必要的痛苦，增加了并发症的发生率和医疗费用。撤机过程所耗费的时间占机械通气整个时间的40％~50％ 。Esteban等的研究证明：延长通气时间增加病死率。在美国，机械通气的费用约2 000美元／d，延长通气者占总机械通气患者的6％，但却消耗ICU资源的37％。我国的撤机现状与之类似，日益增多的撤机困难患者占用各ICU的有限资源，成为医疗费用和床位周转的沉重负担。机械通气撤离的研究亟待加强。
机械通气领域目前有几大争论, 涉及在机械通气中基本的也是十分重要的问题, 复习和深入探讨这些问题, 对了解机械通气近年的研究进展, 指导机械通气的临床实践很有意义。
过去10 多年来, 急性呼吸窘迫综合征( ARDS) 的基础和临床研究取得了巨大进展, 也暴露了目前临床上正在应用的ARDS 诊断标准的重要缺陷。近年来已经有多组学者提出了重新制订ARDS 诊断标准的建议。为今后更好开展前瞻性多中心随机对照研究( RCT) , 也迫切需要一个诊断新标准来统一和规范病例的选择。
Objective To investigate the influence of chronic alcohol ingestion on the severity of acute lung injury (ALI) induced by oleic acid and lipopolysaccharide (LPS).Methods Thirty-two SD rats were randomly administrated with alcohol or water for 6 weeks，then instilled with oleic acid and LPS to induce ALI or with normal saline as control.Thus the rats were randomly divided into two injury groups [ethanol group and water group] and two control groups [ethanol group and water group] (n=8 in each group). PaO2,Wet to dry lung weight ratio (W/D)，levels of γ-glutamylcysteinylglycine (GSH) and malonaldehyde (MDA) in the lung tissue were measured.Results Compared to corresponding control groups，the PaO2 and GSH significantly decreased，and the lung W/D and MDA level were significantly increased in the injury groups (all Plt;0.05).In the injury groups，the changes of above parameters were more significant in the alcohol group than thoe in the water group (all Plt;0.05)，except the lung W/D with no significant difference.Conclusion Chronic ethanol ingestion was relevalent to oxidation/ antioxidation imbalance and more severe lung injury in rats with severe septic after trauma,which suggests that chronic alcohol abuse could increase the severity of acute lung injury.
Objective To investigate the gene expression of beta-defensin-4 (mBD-4) and mBD-6 in acute lung injury (ALI) mouse.Methods Sixty adult mice were randomly divided into a control group and a ALI group.ALI was induced by intraperitoneal injection of lipopolysaccharide (LPS) in the ALI group.The control group was treated with same dose of normal saline.The lung tissues were harvested at different time point after stimulation.The expression of mBD-4 and mBD-6 mRNA was measured by real-time quantitative reverse transcription polymerase chain reaction.DNA sequencing was used to confirm the specificity of mBD-4 and mBD-6 cDNA fragment.Results There were no obvious mBD-4 and mBD-6 mRNA expression in mouse lung in the control group at all time points and ALI 6 h group.In the ALI group a marked increasing expression was found on 12 h，1 d and 3 d after LPS stimulation.The mBD-4 mRNA expression was significant higher in the ALI groups of 1 d and 3 d points than that of ALI 12 h group with no obvious difference between each other.There were no significant differences of mBD-6 mRNA expression between ALI groups of 12 h，1 d and 3 d points Conclusion mBD-4 and mBD-6 mRNA is not constitutive expressed in mouse lung and show a up-regulative expression pattern after ALI.
Objective To study the effects of two different tidal volume mechanical ventilation on lipopolysaccharide( LPS) -induced acute lung injury( ALI) , and explore the effects of glutamine on ALI.Methods Thirty male Sprague-Dawley rats were randomly divided into three groups. After anesthesia and tracheotomy were performed, the rats were challenged with intratracheal LPS ( 5mg/kg) and received ventilation for 4 hours with small animal ventilator. Group A received conventional tidal volume, while groupB received large tidal volume. Group C received large tidal volume as well, with glutamine injected intravenously 1 hour before ventilation. Arterial blood gases were measured every one hour. 4 hours later, the rats were killed by carotid artery bleeding. The total lung wetweightwas measured and lung coefficient ( total lung wet weight /body weight ×100) was counted. WBCs and neutrophils in BALF were counted. Protein concentration, TNF-α, IL-6, and cytokine-induced neutrophil chemoattractant-1 ( CINC-1) levels in BALF,myeloperoxidase ( MPO) , and superoxide dismutase ( SOD) levels in the lung were assayed respectively.Results PaO2 and SOD levels decreased more significantly in group B than those of group A. The lung coefficient, WBCs, neutrophils, protein, TNF-α, IL-6, and CINC-1 levels in BALF, MPO levels in lung increased more significantly in group B than those of group A. PaO2 and SOD levels were significantly higher in group C than those of group B. The lung coefficient, WBCs, neutrophils, protein, TNF-α, IL-6, and CINC-1 levels in BALF,MPO levels in lung were significantly lower in group C than those of group B. Conclusion Large tidal volume mechanical ventilation aggravates LPS-induced ALI, and glutamine has obviouslyprotective effects.
Objective To determine the risk factors for acute lung injury（ALI） early after orthotopic liver transplantation.Methods The perioperative clinical data of all 275 patients who had undergone orthotopic liver transplantation were analysed retrospectively.Several statistically significant risk factors were screened out with univarite analysis，then independent risk factors were determined with multivariate stepwise logistic regression analysis.Results Of the all 275 patients，the morbidity of ALI was 9.8% with a mortality of 22.2%.Univariate analysis showed that the occurrence of ALI was associated with preoperative infection，severe hepatitis，renal dysfunction，massive blood transfusion in operation，long non-hepatic period and long cold ischemic time.Multivarite stepwise logistic regression analysis revealed that the independent risk factors for ALI were massive blood transfusion in operation（OR=12.12，95%CI 0.958-25.364），longer non-hepatic period（OR=1.23，95%CI 1.034-1.410） and longer cold ischemic time（OR=22.35，95%CI 1.266-43.421）.Conclusion Massive blood transfusion in operation，long non-hepatic period and long cold ischemic time were independent risk factors for ALI early after orthotopic liver transplantation.
Objective To study the effects of hyperoxia on ventilator-induced lung injury（VILI） in rats.Methods 48 healthy male SD rats were randomly divided into four groups：Group A received conventional mechanical ventilation（VT=8 mL/kg） with room air，Group B received the same tidal volume as group A with 100% O2，Group C received large tidal volume（VT=40 mL/kg） with room air，group D received the same tidal volume as group C with 100% O2.Arterial blood gases were measured every one hour and oxygenation index（PaO2/FiO2） was calculated.The changes of lung histopathology were assessed by HE staining and observed under light microscope.Wet-to-dry weight ratio（W/D） of left lung，neutrophils and white blood cell（WBC） counts in BALF were measured.TNF-α，IL-1β，and MIP-2 levels in BALF，malondialdehyde（MDA），myeloperoxidase（MPO），and superoxide dismutase（SOD） levels in the lung were assayed，respectively.Results Compared with the Group C，the Group D demonstrated more infiltrating neutrophils in the lung and more destructive changes in the alveolar wall.Meanwhile，the oxygenation index decreased，the WBC and neutrophils counts in BALF increased，and the W/D of left lung was higher in the Group D with significant differences compared with the Group C.Moreover，the BALF levels of TNF-α，IL-1β and MIP-2，the lung levels of MDA increased，and the lung levels of SOD decreased significantly in the Group D compared with those in the Group C.There were no statistical significant differences between the Group B and Group A in all parameters except that MDA levels increased and SOD levels decreased significantly in the Group B.Conclusion Hyperoxia can increase lung injury induced in large tidal volume ventilation in rats，but has mininmal effects in conventional mechanical ventilation.
Objective To explore the expression and effect of heme oxygenase-1 ( HO-1) in ventilator-induced lung injury. Methods Twenty-four New Zealand rabbits were randomly assigned to three groups, ie. a conventional ventilation + PEEP group( C group) , a ventilator-induced lung injury group( VILI group) , and a VILI + HO-1 inducer hemin group( Hm group) .Western blot and immunohistochemistry assay were used to investigate the expression of HO-1 protein. Blood gas analysis, lung wet /dry ratio, lunghistopathology and lung injury score were used to evaluate lung injury. Results HO-1 protein expression significantly increased in the VILI group compared with the C group. HO-1 was found mainly in alveolar epithelial cells and vascular endothelial cells, as well as in alveolar macrophages and neutrophils. Compared with the VILI group, HO-1 protein and PaO2 /FiO2 increased, while lung wet/dry ratio and lung injury score decreased in the Hmgroup significantly( P lt;0. 05) . Conclusion High HO-1 expression can alleviate lung injury from large tidal volume ventilation, implying its protective role in lung pathogenesis.
Ojective To establish a rat model of hyperoxia induced acute lung injury. Methods Eighty healthy male SD rats were randomly divided into an air group and a hyperoxia group ( ≥95% O2 ) .Each group was further divided into 12 h, 24 h, 36 h, 48 h, 60 h subgroups. Arterial blood gas was monitored. Lung tissue was sampled for evaluation of lung wet to dry ratio, lung index, and pulmonary permeation index. Bronchoalveolar lavage fluid ( BALF) was collected for measurement of lactatedehydrogenase ( LDH) activity and white blood cell count ( WBC) . Results After hyperoxia exposure for 48 ～60 h, lung pathology showed alveolar structure disruption, lung parenchyma wrath bleeding and edema.Lung wet to dry ratio, lung index, pulmonary permeation index, LDH and WBC in BALF all increased significantly, peaked at 48 h and remained at high level at 60 h while PaO2 dropped progressively.Conclusion Exposure to ≥ 95% O2 for 48 ～60 h can successfully establish the rat model of hyperoxia induced acute lung injury.