急性呼吸窘迫綜合征( ARDS) 本身即為呼吸系統的急危重癥, 80% 以上ARDS 患者需要氣管插管和機械通氣 。 凡屬嚴重ARDS 的患者, 均有應用挽救性治療( rescue therapies) 的適應證。
過去10 多年來, 急性呼吸窘迫綜合征( ARDS) 的基礎和臨床研究取得了巨大進展, 也暴露了目前臨床上正在應用的ARDS 診斷標準的重要缺陷。近年來已經有多組學者提出了重新制訂ARDS 診斷標準的建議。為今后更好開展前瞻性多中心隨機對照研究( RCT) , 也迫切需要一個診斷新標準來統一和規范病例的選擇。
對意外或自主拔管患者的研究顯示，接受完全機械通氣患者的23％和開始撤機過程患者的69％并不需要重新插管，這表明機械通氣患者的撤機存在被延遲的傾向，致使患者承受不必要的痛苦，增加了并發癥的發生率和醫療費用。撤機過程所耗費的時間占機械通氣整個時間的40％~50％ 。Esteban等的研究證明：延長通氣時間增加病死率。在美國，機械通氣的費用約2 000美元／d，延長通氣者占總機械通氣患者的6％，但卻消耗ICU資源的37％。我國的撤機現狀與之類似，日益增多的撤機困難患者占用各ICU的有限資源，成為醫療費用和床位周轉的沉重負擔。機械通氣撤離的研究亟待加強。
機械通氣領域目前有幾大爭論, 涉及在機械通氣中基本的也是十分重要的問題, 復習和深入探討這些問題, 對了解機械通氣近年的研究進展, 指導機械通氣的臨床實踐很有意義。
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 investigate the effects of recombinant human erythropoietin ( rHuEPO) on expressions of Bax and Bcl-2 proteins in hyperoxia-induced lung injury of adult rats. Methods Fortyeight healthy male SD adult rats were randomly divided into six groups. The control group ( 0 h) breathed with room air. The rHuEPO intervention group was put into oxygen chamber and breathed with 100% O2 for 96 h plus intraperitoneal injection of rHuEPO (1000 U/kg) daily. Other four groups were put into oxygen chamber and breathed with 100% O2 for 24, 48, 72 and 96 h respectively. Arterial blood gases were measured to calculate oxygenation index. Wet-to-dry weight ratios of left lung were measured. The contents of TNF-α and IL-1β in bronchoalveolar lavage fluid (BALF) were assayed with radioimmunoassay. The expressions of Bax and Bcl-2 proteins in the lung were determined withWestern blot and immunohistochemisty. The changes of lung histopathology were assessed by hematoxylin and eosin stain and observed under light microscope. Results After breathing 100% O2 , the oxygenation index decreased gradually and reached minimal value at 96 h. The wet-to-dry weight ratio of left lung increased gradually and reached maximal value at 96 h. The contents of TNF-α and IL-1β in BALF reached maximal value at 48 h and then decreased gradually. The expression of Bax protein increased, but the expression of Bcl-2 protein decreased gradually in the lung. Compared with the 96 h group, the oxygenation index was higher, wet-to-dry weight ratio and contents of TNF-α and IL-1β in BALF decreased, the expression of Bax protein decreased, and the expression of Bcl-2 protein increased in the lung of the rHuEPO group. Conclusion rHuEPO can attenuate hyperoxia-induced lung injury of adult rats by down-regulating expression of Bax protein and up-regulating expression of Bcl-2 protein.
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.