犬油酸型呼吸窘迫综合征时肺泡毛细血管通透性的变化及…

采用多指示剂衡释曲线动态观察犬油酸型呼吸窘迫综合征（ＲＤＳ）模型的肺泡毛细血管通透性、血管外肺水和心输出量，并与相应的血气、Ｘ线胸片及病理组织学检查进行对比，结果表明：实验犬注入油酸后肺泡毛细血管的通透性立即明显增高，且发生时间明显早于血管外肺水，血气和胸片和改变，与ＲＤＳ的早期病理改变相对应。作者认为：测定肺泡毛细血管通透性有可能作为一种诊断ＲＤＳ的早期敏感指标。     

ARDS机械通气治疗进展

机械通气是急性呼吸窘迫综合症(ＡＲＤＳ)最重要的治疗手段之一 ,随着对ＡＲＤＳ病理生理学认识的不断深入以及ＡＲＤＳ机械通气实验与临床研究的广泛开展 ,对ＡＲＤＳ机械通气治疗策略有了一些新的进展 ,可能有助于提高机械通气的治疗效果 ,改善ＡＲＤＳ的治疗。1　既往对ＡＲＤＳ病理生理的认识及机械通气策略　　既往认为ＡＲＤＳ主要的病理生理特点是 :①肺泡上皮和肺毛细血管内皮受损致通透性增加 ,含蛋白质的液体渗出到肺间质和肺泡腔导致非心源性肺水肿。②肺泡Ⅱ型上皮细胞受损 ,肺表面活性物质减少 ,使肺泡早期关闭 ,容量变小 ,导…     

急性呼吸窘迫综合征诊断标准与治疗方案

１急性呼吸窘迫综合征（ＡＲＤＳ）的概念及诊断标准 ＡＲＤＳ是指由心源性以外的各种肺内外致病因素导致的急性、进行性缺氧性呼吸衰竭。急性肺损伤（ＡＬＩ）和ＡＲＤＳ具有性质相同的病理生理改变,严重的ＡＬＩ被定义为ＡＲＤＳ。ＡＬＩ／ＡＲＤＳ的病理基础是,由不同原发病引发的多种炎症细胞（巨噬细胞、中性粒细胞及淋巴细胞等）及炎性介质（氧自由基、肿瘤坏死因子、白细胞介素等）介导的肺脏局部炎症反应和炎症反应失控所致的弥漫性肺泡上皮细胞和肺毛细血管内皮细胞损伤。其主要病理特征为肺微血管通透性增高,导致肺泡渗出液中…     

急性呼吸窘迫综合征患者肺组织Fas/FasL系统表达的变化及其意义

目的：探讨细胞凋亡在急性呼吸窘迫综合征（ＡＲＤＳ）发病中的作用及基因调控机制,为进一步阐明ＡＲＤＳ的发病机制和在细胞凋亡水平防治本病提供理论依据。方法：ＡＲＤＳ组９例,对照组５例,采用ＴＵＮＥＬ法以及免疫组化技术观察ＡＲＤＳ患者肺组织Ｆａｓ／ＦａｓＬ系统表达及细胞凋亡的变化。结果：ＡＲＤＳ早期患者肺组织细胞凋亡率较对照组明显增加,且主要表现为肺泡上皮和肺血管内皮细胞凋亡增加;Ｆａｓ抗原、ＦａｓＬ在ＡＲＤＳ早期患者肺组织表达明显上调,并且Ｆａｓ、ＦａｓＬ表达的增加与肺组织细胞凋亡增加呈平行关系。结论：肺泡上皮和肺血管内皮细胞凋亡增加和Ｆａｓ／ＦａｓＬ系统活化可能参与临床ＡＲＤＳ早期的发病。     

肺表面活性物质治疗急性呼吸窘迫综合征的实验研究

目的：观察外源性肺表面活性物质（ＰＳ）对实验性急性呼吸窘迫综合征（ＡＲＤＳ）的疗效。方法：１８只新西兰白兔油酸诱发ＡＲＤＳ后，９只在机械通气基础上经气道滴入猪ＰＳ（１００ｍｇ／ｋｇ，为ＰＳ组），另外９只给于单纯机械通气作为对照组，均观察４小时。于动物实验的基础状态、治疗前及治疗后１小时、２小时、４小时测定肺功能残气量（ＦＲＣ）、动脉血气和肺泡动脉血氧分压差〔Ｐ（Ａ－ａ）Ｏ２〕。实验结束时观察肺病理形态并测定肺泡容积密度（ＶＶ）。结果：治疗后，对照组ＦＲＣ和动脉血氧分压（ＰａＯ２）／氧浓度（ＦｉＯ２）比值（ＯＩ）呈下降趋势，而ＰＳ组ＦＲＣ和ＯＩ明显高于治疗前和同时间点的对照组（Ｐ＜０．０５或Ｐ＜０．０１），Ｐ（Ａ－ａ）Ｏ２明显低于治疗前和同时间点的对照组（Ｐ＜０．０５或Ｐ＜０．０１）。病理形态观察见对照组广泛性肺不张、肺泡和间质水肿、出血和炎性细胞浸润，ＰＳ组上述改变较轻，ＶＶ增加（Ｐ＜０．０１）。结论：外源性肺表面活性物质对兔油酸型ＡＲＤＳ模型有一定的治疗效果     

血管外肺水与肺血管通透性指数在急性呼吸窘迫综合征的研究进展

急性呼吸窘迫综合征（acute＆amp;respiratory＆amp;distress＆amp;syndrome,ARDS）是在严重感染、休克、创伤及烧伤等疾病的过程中,肺毛细血管内皮细胞和肺泡上皮细胞损伤,导致急性低氧性呼吸功能不全或衰竭。其病理生理特征为因肺泡膜通透性增加引起的渗出性肺水肿。 ARDS具有高患病率、高死亡率、临床预后差等特点,其死亡率高达35%～45%[1]。早期诊断ARDS非常困难,目前ARDS的临床诊断标准主要有1994年欧美联席会议标准[2]和2012年柏林定义[8],但两个标准中并没有一项直接体现ARDS病理生理过程中的肺水量化标准,这一缺陷可能会影响ARDS诊断的敏感性和特异性。随着脉搏指示剂连续心排血量监测（pulseC indicator＆amp;continous＆amp;output, PiCCO）技术的进步,用经肺热稀释法测得的血管外肺水指数（extravascularClungCwaterCindex,EVLWI）和肺血管通透性指数（pulmonaryCvascularCpermeabilityC index,PVPI）能较好地反映ARDS毛细血管通透性改变的特征性病理生理过程,对ARDS的早期诊断、早期干预及鉴别诊断等方面有重要意义。本次研究就血管外肺水（extravascularClungCwaterC,EVLW）和PVPI在ARDS的研究进展作一综述。     

成人呼吸窘迫综合征研究进展

成人呼吸窘迫综合征研究进展潍坊医学院附属青州医院内科（２６２５００）张忠山东昌邑市人民医院孙成友成人呼吸窘迫综合征（ＡＲＤＳ）系指多种原发疾病过程中发生的急性进行性缺氧性呼吸衰竭。其病理生理改变为弥漫性肺损伤，肺微血管壁通透性增加和肺泡群萎陷，导致肺...     

严重脓毒症患者血管外肺水的监测价值与研究现状

脓毒症所致的多器官功能障碍中,肺脏是最易受损伤的靶器官。脓毒症相关性ARDS/ALI的发病机制复杂,迄今为止其发病机制尚未完全阐明〔1〕。其基本病理生理改变是肺泡-毛细血管屏障功能障碍所致通透性升高,表现为肺血管内液体渗出增加形成血管外肺水（extravascular lung water,EVLW）的聚集。EVLW增加引起的严重通     

急性呼吸窘迫综合征的动物模型

急性呼吸窘迫综合征（ＡＲＤＳ）系多种原发疾病如休克、创伤、严重感染、误吸等疾病过程中发生的急性进行性缺氧性呼吸衰竭。其主要病理生理改变为弥漫性肺损伤、肺微血管壁通透性增加和肺泡群萎陷，导致肺内血液分流增加和通气／血流比失衡，临床表现为严重的不易缓解的...     

丹参对ARDS大鼠肺损伤的治疗保护和对肺泡巨噬细胞分泌细胞因子的 …

目的 了解丹参对大鼠血气改变和肺系数以及影响对肺泡巨噬细胞分泌肿瘤坏死因子，白介素－１的调节作用。方法 静注油酸制造ＡＲＤＳ大鼠模型为油酸组，静注生理盐水作对照组，静注油酸同时以丹参灌胃为治疗组。静注油酸及生理盐水６小时后，测定左心ＰａＯ２，ＰａＣＯ２及肺系数。分离增减各组大鼠肺泡巨噬细胞，采用ＭＴＴ法测定ＴＮＦα ＩＬ－１。     

单指示剂法与重力法测定急性呼吸窘迫综合征犬血管外肺水的比较研究

目的 比较单指示剂法与重力法测定不同急性呼吸窘迫综合征（ARDS）模型犬血管外肺水（EVLW）的差异。方法 33只犬按随机数字表法分成对照组、油酸静脉注射复制ARDS模型组（油酸组）和盐酸吸入复制ARDS模型组（盐酸组）。用单指示剂法测定ARDS成模前、成模时及成模后10hEVLW；成模后10h处死动物，用重力法（金标准）测定EVLW；并监测血流动力学、血气分析和呼吸力学指标变化。结果 单指示剂法和重力法测定的EVLW呈显著正相关（r=0．8820，P〈0．05）；与重力法相比，单指示剂法测定的EVLW显著增高。对照组单指示剂法和重力法测定的EVLW呈显著正相关（r=0．9870，P〈0．05）；油酸组单指示剂法和重力法测定的EVLW呈显著正相关（r=0．9360，P〈0．05）;盐酸组单指示剂法和重力法测定的EVLW呈显著正相关（r=0．7950，P〈0．05），但其相关性较前两组差。ARDS10h时，盐酸组肺内分流和动脉血二氧化碳分压显著高于油酸组（P〈0．05）。而氧合指数却显著低于油酸组（P〈0．05）。结论 单指示剂法与重力法测定ARDS的EVLW有正相关性，但不同原因导致的ARDS其相关性不同。     

Inhibition of angiotensin-converting enzyme by perindopril diacid in canine oleic acid pulmonary edema

To test the hypothesis that angiotensin II could be a mediator of acute lung injury, we studied the effects of perindopril diacid, a new angiotensin-converting enzyme inhibitor, on hemodynamics, blood gases, lung mechanics, and extravascular lung water (EVLW). Twenty-four dogs were anesthetized, paralyzed and ventilated with a fraction of inspired oxygen of 0.4 in which pulmonary edema was induced by 0.1 ml/kg iv oleic acid. Perindopril diacid (1 mg/kg) was administered iv either before (eight dogs) or 100 min after (eight dogs) oleic acid injection. In the control group (eight dogs) not treated with perindopril diacid, 150 min after oleic acid injection, PaO2 changed from 193 +/- 7 (mean +/- SEM) to 55 +/- 4 torr, venous admixture from 3 +/- 1% to 52 +/- 5%, cardiac index from 4.1 +/- 0.3 to 3.1 +/- 0.3 L/min X m2, mean pulmonary artery pressure from 13 +/- 1 to 17 +/- 1 mm Hg, dynamic compliance from 90 +/- 8 to 46 +/- 7 ml/cm H2O, and EVLW from 165 +/- 25 to 750 +/- 92 ml/m2. Administration of perindopril diacid reduced systemic BP by 20% but did not affect other hemodynamic variables, blood gases, or dynamic compliance. Maximum increases in EVLW were from 169 +/- 16 to 615 +/- 54 ml/m2 in the pretreated group and from 188 +/- 23 to 675 +/- 56 ml/m2 in the treated group (no significant difference from the control group). However, pretreatment with perindopril diacid significantly (p less than .05) slowed the rise in EVLW, which was lower 60 and 90 min after oleic acid injection compared to untreated dogs. Plasma renin activity and angiotensin I concentration increased after oleic acid injection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Abdomen release in prone position does not improve oxygenation in an experimental model of acute lung injury

OBJECTIVE: To analyze the effect of abdomen release in the prone position on oxygenation in an experimental model of acute lung injury. DESIGN: Experimental randomized controlled study. SETTING: Experimental laboratory of a tertiary university hospital. PARTICIPANTS: Mixed-breed adolescent pigs weighing between 25-31 kg. INTERVENTIONS: Thirty minutes after pulmonary edema was produced with oleic acid, the animals were turned prone and randomized into two groups: group I or control (n = 9), lying directly on the operating table; and group II (n = 11) with abdomen release, with positioning rolls under the upper part of the chest wall and the pelvis to allow free movement of the abdomen. MEASUREMENTS AND RESULTS: The gas exchange, respiratory mechanics, hemodynamics, intra-abdominal pressure (IAP) and the extravascular lung water (EVLW), determined by double indicator dilution method (DI), were recorded at baseline (time 0) and at 30, 60, 90, 120 and 150 min. The PaO2/FIO2 increased in both groups at 30 min after the pigs were placed in the prone position (time 60) and then decreased progressively until the end of the experimental period, with no statistical differences between the groups at any time (73.1 +/- 14.5 vs 79.5 +/- 14.9 at 150 min). Abdomen release was not associated with changes in the respiratory mechanics, EVLW or intra-abdominal pressure. CONCLUSIONS: Abdomen release in prone position does not improve oxygenation in an experimental model of acute lung injury.     

Compared effects of selected colloids on extravascular lung water in dogs after oleic acid-induced lung injury and severe hemorrhage

While the hemodynamic effects of hydroxyethyl starch (HES) have been reported, the effect of this material upon extravascular lung water (EVLW) has not been investigated. Twenty mongrel dogs were subjected to both an oleic acid-induced lung injury and a 2-h period of hemorrhagic shock (MAP = 40 mm Hg). After reinfusion of shed blood, 5 dogs in each of 4 groups were given either 0.5 L of lactated Ringer's solution or 0.5 L of 5% albumin, 6% dextran 75, or 6% HES. Lactated Ringer's solution was then given in sufficient quantity to keep the wedge pressure (WP) at 12-15 mm Hg and PaO2, P(A-a)O2, cardiac index (CI) and oxygen delivery were determined. EVLW was measured by thermal-green dye double-indicator technique with an Edwards Lung Water Computer (American Edwards Laboratories, Santa Ana, CA). Mean baseline EVLW was 6.9 +/- 0.3 ml/kg. Mean EVLW rose to 11.5 +/- 1.9 ml/kg after oleic acid. One h after reinfusion, EVLW increased to 40.5 +/- 4 ml/kg in the dogs given only lactated Ringer's solution and to 39.5 +/- 1.5 ml/kg in the dextran group. EVLW was 25.5 +/- 3 ml/kg in the HES dogs, and 29.5 +/- 2 ml/kg in the group given albumin. Differences between albumin and lactated Ringer's solution and between the HES and lactated Ringer's groups were significant (p less than 0.02 and p less than 0.05). Measurements of oxygen, ventilation, CI, and oxygen delivery were not significantly different between the albumin and HES subjects.     

CT在油酸致兔急性呼吸窘迫综合征早期诊断中的应用

目的 通过CT测定油酸性急性呼吸窘迫综合征(ARDS)兔病程中不同病变区域肺容积的变化,探讨CT早期诊断ARDS的价值.方法 健康成年大耳白兔20只,随机(随机数字法)分为对照组和油酸组,每组10只.于江苏大学附属人民医院CT室,采用静脉注射油酸法(0.1 mL/kg)制作ARDS模型.动态监测动脉血气,于造模前(T_o)、200 mmHg＜氧合指数(OI)≤300 mmHg(T_1)、OI≤200mmHg(T_2)三个时点对所有实验兔行胸部X线、CT检查,同时应用CT机载软件测定实验兔不同病变肺区百分比.观察并评价实验过程中不同病变区域肺容积的动态变化情况,比较肺容积的改变与OI的动态变化的相关性以及同一时点胸部X线片、CT的影像学表现.同时观察实验兔肺湿千重比及病理改变.数据采用两样本均数比较的t检验及重复测量数据的方差分析,两参数间的相关性分析采用等级相关分析法.结果 (1)T_1,T_2时点油酸组兔不通气肺区百分比[T_1(19.30±2.34)%,T_2(26.47±1.89)%]、通气不良肺区百分比[T_1(28.08±2.70)%,T_2(37.40±1.78)%]明显高于对照组(P＜0.01),通气正常肺区[T_1(47.38±3.19)%,T_2(30.82 4±3.25)%]显著低于对照组[T_1(79.12±1.25)%,T_2(78.24±1.84)%](P＜0.01),油酸组不通气、通气不良、通气正常肺区百分比不同时点比较差异具有统计学意义(P＜0.01),通气过度肺区百分比无明显变化(P＞0.05);(2)油酸组兔不同时点不通气、通气不良肺区百分比与氧合指数均呈负相关(-0.745～-0 636)(P＜0.05),通气正常肺区百分比与氧合指数呈正相关(0.742～0.842)(P＜0.05);(3)油酸组兔同时点胸部影像学表现CT较X线胸片早且显著;(4)油酸组免肺组织干/温质量比(W/D)明显高于对照组(分别为6.25±0.32,4.89±0.30),差异有统计学意义(P＜0.01).结论 油酸所致ARDS兔肺部影像学表现CT较X线胸片早且显著,同时通过CT测定模型兔肺容积的变化,可量化病情程度,有助于ARDS的早期诊断.     

床旁肺部超声对ICU急性呼吸窘迫综合征的临床价值

目的：探讨床旁肺部超声(LUS)对ICU急性呼吸窘迫综合征(ARDS)的临床价值。方法：将60例疑似ARDS患者分别进行血气分析、胸部CT以及LUS检查,确诊ARDS40例,分析LUS诊断ARDS的敏感度、特异性及准确率,以LUS评分=18分为截断值,绘制LUS诊断ARDS的ROC曲线,并计算曲线下面积。根据“柏林标准”将ARDS患者分为A组(非重度)、B组(重度)两组,比较两组患者的LUS评分、EVLW以及APACHE II评分,并做相关性分析。根据预后将患者分为C组(死亡)与D组(生存),记录并比较两组的LUS评分、EVLW以及APACHE II评分。结果：LUS诊断ARDS的敏感度,特异性及准确率分别87.5%,75.0%及83.3%,曲线下面积是0.957,标准误是0.014,可信区间是0.029~0.985。重度组LUS评分、EVLW以及APACHE II评分明显高于非重度组 (P<0.05), LUS结果与EVLW数值呈正相关(r= 0.763,P<0.05),LUS结果与APACHE II评分呈正相关(r= 0.593 ,P<0.05)。死亡组LUS评分、EVLW数值及APACHE II评分均明显高于生存组 (P均<0.05)。结论：LUS可以准确诊断ARDS、判断病情并评估预后,具有良好的临床价值。     

Accuracy of the double indicator method for measurement of extravascular lung water depends on the type of acute lung injury

OBJECTIVE: The double indicator method is sensitive to alterations in the distribution of pulmonary blood flow. This distribution is influenced by the type of lung injury. The aim of this study was to compare measurements of lung water by the double indicator method with measurements obtained by gravimetry in a direct lung injury model induced by tracheal instillation of hydrochloric acid and in an indirect lung injury model induced by the intravenous injection of oleic acid. DESIGN: Prospective, randomized laboratory study. SETTING: Animal research laboratory. SUBJECTS: Forty-two female pigs (28+/-3 kg). INTERVENTIONS: Pigs were anesthetized and ventilated and were allocated into three groups: control (n = 6), hydrochloric acid (4 mL/kg intratracheally, n = 24), or oleic acid (0.1 mL/kg intravenously, n = 12). MEASUREMENTS AND MAIN RESULTS: Hydrochloric acid instillation or oleic acid injection resulted in a similar hypoxemia and induced a two- to three-fold increase in extravascular lung water (EVLW) by gravimetry (EVLWG) at 3 hrs compared with controls. In the oleic acid group, there was a significant correlation between EVLWG and EVLW by double indicator method (EVLWDI; r =.88, p <.0001). The bias for EVLWDI - EVLWG measurements was -5.2 mL/kg (95% confidence interval, -5.7 to -4.7 mL/kg) with 95% limits of agreement of -7 to -3.4 mL/kg. In the hydrochloric acid group, there was no significant correlation between EVLWDI and EVLWG values, and the double indicator method failed to detect pulmonary edema in 65% of the animals (EVLWDI <8 mL/kg). The bias was -7.9 mL/kg (95% confidence interval, -9.3 to -6.5 mL/kg) with 95% limits of agreement of -14.4 to -1.4 mL/kg. CONCLUSIONS: The double indicator method is useful for evaluation of pulmonary edema in indirect lung injury, as induced by oleic acid, but produces misleading values in direct lung injury, as produced by hydrochloric instillation.     

Assessment of current methods quantitating extravascular lung water and pulmonary aeration in inhomogeneous lung injury: an experimental study

BACKGROUND: Single transpulmonary thermodilution (STTD) is a widely recognized technique for the quantification of extravascular lung water (EVLW). However, the accuracy of STTD can be substantially reduced in acute lung lesion (ALL) characterized by inhomogeneous distribution of edematous zones and major ventilation-perfusion mismatch. Quantitative computed tomography (CT) may be a helpful clinical adjunct allowing an assessment of pulmonary gas and tissue content. The purpose of the study was to compare the tissue volume index, as estimated by spiral CT (TVICT), with EVLW indices determined with STTD (EVLWISTTD), thermal-dye dilution (EVLWITDD), and postmortem gravimetry (EVLWIG) before and after oleic acid-induced ALL in sheep. MATERIALS: Eleven yearling sheep were randomly assigned to either an oleic acid (OA) group receiving an infusion of OA in a dose of 0.08 ml/kg i.v. or to a control group. The day before and immediately after the experiment, sheep underwent CT examinations. Pulmonary and systemic hemodynamics, oxygenation, EVLWISTTD and EVLWITDD were recorded. Linear regression analysis was used to assess the relationships between EVLWISTTD, EVLWITDD, EVLWIG, and TVICT (syngo PulmpCT, Siemens, Germany). RESULTS: OA caused 5- and 7-fold increments in poorly and nonaerated lung volumes, respectively, and increased total lung volume and TVICT, EVLWISTTD, EVLWITDD, and TVICT demonstrated a close agreement with EVLWIG (r = 0.86, 0.90, and 0.97, respectively; p < 0.001). TVICT overestimated reference EVLWIG values to the greatest extent. CONCLUSION: In a sheep model of OA-induced ALL, pulmonary tissue volume as estimated by quantitative CT closely correlates with EVLWI measured by dilutional methods and postmortem gravimetry.     

Low molecular weight dextran attenuates increase in extravascular lung water caused by ARDS

We studied the effect of low molecular weight dextran (mean molecular weight 40,000, Dextran 40; LMD) on the accumulation of extravascular lung water (EVLW), and also on hemodynamics and blood gases, in the oleic acid (OA)-injured lung in pentobarbital anesthetized rats. Starting just before the OA injection (0.01 mL/kg via femoral vein), 10% LMD in lactated Ringer's solution was infused throughout the experiment (5 mL/kg/h) instead of lactated Ringer's solution. OA caused acute lung injury leading to decreased oxygenation (PaO2: 87 +/- 11 mmHg versus control group 128 +/- 11) and an increased permeability of the alveolar-capillary membrane, as shown by increases in EVLW (4.89 +/- 0.54 versus control group 4.07 +/- 0.14), and albumin leakage (0.043 +/- 0.015 versus control group 0.010 +/- 0.004). LMD protected against the increase in EVLW (4.14 +/- 0.10) and the hypoxemia (112 +/- 19 mmHg), but it did not reduce the albumin leakage into the alveolar space (0.052 +/- 0.009). These data suggest that LMD may limit the fluid accumulation that is secondary to OA-induced lung injury.     

Immediate application of positive-end expiratory pressure is more effective than delayed positive-end expiratory pressure to reduce extravascular lung water

OBJECTIVE: To determine by the measurement of extravascular lung water (EVLW) whether the timing of positive-end expiratory pressure (PEEP) application influences the intensity of lung injury. DESIGN: Animal experimental study. SETTING: Animal experimental laboratory. SUBJECTS: Mixed-breed pigs (n = 18), aged 4 to 5 mos, weighing 25 to 30 kg. INTERVENTIONS: The animals were anesthetized and tracheotomized, after which a permeability pulmonary edema was instigated by infusing oleic acid (0.1/kg) into the central vein. All animals were then randomly divided into three groups. In group 1 (n = 5), 10 cm H2O of PEEP was applied immediately after the oleic acid infusion and maintained throughout the 6 hrs of the experiment. Group 2 (n = 7) received the same level of PEEP 120 mins after the insult for 4 hrs. Group 3 (n = 6), the control group, was ventilated without PEEP for the six hrs of the experiment. MEASUREMENTS AND MAIN RESULTS: At the end of the experiment, EVLW was calculated by gravimetric method. EVLW in group 1 (11.46+/-2.00 mL/kg) was significantly less than in group 2 (19.12+/-2.62 mL/kg) and group 3 (25.81+/-1.57 mL/kg), (p<.0001). Oxygenation also showed important differences by the end of the experiment when the Pao2/Fio2 ratio was significantly better in group 1 (467+/-73) than in group 2 (180+/-82) and group 3 (39+/-9), (p<.0001). CONCLUSIONS: The application of 10 cm H2O of PEEP reduces EVLW in a time-dependent manner and maximum protective effect is achieved if it is applied immediately after lung injury production.