俯卧位机械通气治疗肺内/外源性急性呼吸窘迫综合征的比较研究

目的探讨俯卧位机械通气对肺内／外源性急性呼吸窘迫综合征（ARDS）的治疗作用。方法2001年1月-2004年2月华北煤碳医学院附属开滦医院重症监护治疗病房（ICU）收治42例ARDS患者，按ARDS病原不同分为肺内源性ARDS组（ARDSp）和肺外源性ARDS组（ARDSexp）。两组均早期予以俯卧位机械通气治疗。记录仰卧位及俯卧位2h和4h的动脉血气分析、呼吸频率（RR）、吸入氧浓度（FiO2）、氧合指数（PaO2／FiO2）、胸肺顺应性（C）、潮气量（VT）、气道阻力（Raw）的变化。5例患者进行了两种体位的胸部CT比较。结果俯卧位机械通气后，两组患者FiO2减少。RR减慢。PaO2／FiO2、动脉血氧饱和度（SaO2）、Raw均显著增加。ARDSexp组VT明显高于同时间点ARDSp组；而动脉血pH和动脉血二氧化碳分压（PaCO2）则无明显变化；ARDSp组与ARDSexp组同时间点比较，PaO2／FiO2显著增加；ARDSp组应用俯卧位机械通气改善氧合的有效率为65％，ARDSexp组为68％，二者比较差异无显著性；胸部CT显示俯卧位后原背侧渗出性改变有所改善。原腹侧正常肺组织出现渗出性改变。结论无论是ARDSp组还是ARDSexp组。俯卧位机械通气均能显著改善PaO2／FiO2，是ARDS患者早期支持治疗的重要而有效的手段。     

肺复张策略治疗肺内/外源性急性呼吸窘迫综合征比较研究

目的 对比研究肺复张策略（RM）对肺内／外源性急性呼吸窘迫综合征（ARDSp／ARDSexp）的影响。方法 选择37例ARDS机械通气的患者，其中ARDSp16例，ARDSexp21例，在非肌肉松弛状态下，采用高水平持续气道正压通气（CPAP），CPAP压力升至30cmH2O（1cmH2O=0．098kPa），屏气时间维持30s，然后在5～10s内将CPAP水平下调至治疗前的呼吸支持条件。结果 肺复张后与复张前比较，两组心率变化在RM过程中差异无显著性，两组RM后2min平均动脉压均明显升高（P均〈0．05），两组中心静脉压仅在RM后30s明显增高（P均〈0．05），气道峰压、平台压、平均气道压在30s均明显增加（P均〈0．05）;两组动态肺顺应性RM后30s均明显下降（P均〈0．05），ARDSexp组RM后5、15和30min较复张前均明显增加（P均〈0．05）。ARDSp组RM后10、30min和1h氧合指数与治疗前比较差异均有显著性（P均〈0．05），ARDSexp组RM后10min、30min、1h、2h氧合指数与治疗前比较差异均有显著性（P均〈0．05）。结论 以肺间质水肿为主要改变的ARDSexp对RM的反应要比以肺实变为主要改变的ARDSp效果好。     

高呼气末正压加肺复张治疗急性呼吸窘迫综合征

目的 评价高呼气末正压(PEEP)加肺复张(RM)治疗急性呼吸窘迫综合征(ARDS)的临床疗效和安全性.方法 选择2008年6月至2010年5月贵阳医学院附属医院内科重症监护病房(MICU)收治的ARDS患者38例,按信封法随机分为RM组和非RM组,每组19例.两组均采用压力支持通气(PSV)模式行机械通气,尽可能在吸入氧浓度(FiO2)＜0.60时达到目标氧合的最小PEEP水平,限制平台压≤30 cm H2O(1 cm H2O=0.098 kPa).RM时FiO2调至1.00,压力支持水平调至0,将PEEP升至40 cm H2O,持续30 s后再降低,8 h 1次,连续5 d.记录基础状态和5 d内的机械通气参数、血气分析结果及生命体征,比较两组氧合改善和肺损伤指标变化,观察RM的不良反应和气压伤发生率.结果 ①两组患者基础状态及机械通气参数均无明显差异.②两组动脉血氧分压(PaO2)和氧合指数(PaO2/FiO2)均明显改善,且RM组明显优于非RM组[PaO2(mm Hg,1 mm Hg=0.133 kPa)2 d:85.8±21.3比73.5±18.7,3 d:88.6±22.8比74.3±19.8,4 d:98.8±30.7比79.3±19.3,5 d:105.5±29.4比84.4±13.8;PaO2/FiO2(mm Hg)4 d:221.8±103.5比160.3±51.4,5 d:239.6±69.0比176.8±45.5,均P＜0.05].③两组呼出气冷凝液(EBC)中过氧化氢(H2O2)和白细胞介素-6(IL-6)水平均呈下降趋势,RM组下降幅度更明显[5 d时H2O2(μmol/L):0.04±0.02比0.10±0.03;IL-6(ng/L):4.12±2.09比9.26±3.47,均P＜0.05].④两组均无气压伤发生,心率无明显变化,无心律失常发生,中心静脉压和平均动脉压无明显变化.结论 高PEEP加RM可增加气体交换,改善氧合,减少呼吸机相关性肺损伤(VALI).应用RM比较安全,耐受性好,临床观察未见低氧血症、气压伤和血流动力学异常.

Abstract：

Objective To investigate the clinical effects and safety degree of high positive endexpiratory pressure (PEEP) combined with lung recruitment maneuver (RM) in patients with acute respiratory distress syndrome (ARDS). Methods Thirty-eight patients in medical intensive care unit (MICU) of Affiliated Hospital of Guiyang Medical College suffering from ARDS admitted from June 2008 to May 2010 were enrolled in the study. With the envelope method they were randomized into RM group and non-RM group, with n= 19 in each group. All patients received protective ventilation: pressure support ventilation (PSV) with plateau pressure limited at 30 cm H2O (1 cm H2O=0. 098 kPa) or lower. PEEP was set at the minimum level with fraction of inspired oxygen (FiO2) ＜0. 60 and partial pressure of arterial oxygen (PaO2) kept between 60 and 80 mm Hg (1 mm Hg=0. 133 kPa). RM was conducted by regulating FiO2 to 1.00, support pressure to 0, PEEP increased to 40 cm H2O and maintained for 30 seconds before lowering, and this maneuver was repeated every 8 hours for a total of 5 days. Base status, ventilation parameters, blood gas analysis and vital signs were obtained at baseline and for the next 5 days. Oxygenation status and lung injury indexes were compared between RM group and non-RM group, the adverse effects of (PaO2/FiO2) were both increased in RM group and non-RM group, but the values were higher in RM group [PaO2 (mm Hg) 2 days: 85.8± 21.3 vs. 73. 5± 18. 7, 3 days : 88. 6± 22. 8 vs. 74. 3 ±19. 8, 4 days : 98. 8 ±30. 7 vs. 79. 3±19. 3, 5 days: 105.5±29.4 vs. 84. 4±13. 8; PaO2/FiO2(mm Hg) 4 days: 221.8±103. 5 vs.interleukin-6 (IL-6) concentration in exhaled breath condensate (EBC) decreased in both groups but lower in RM group with significant difference [5 days H2O(μmol/L): 0. 04 ± 0. 02 vs. 0.10 ± 0.03 ; IL-6 (ng/L):No significant changes in heart rate were found during RM. Central venous pressure and mean arterial pressure remained unchanged after RM. Conclusion High level PEEP combined with RM can improve gas exchange and oxygenation, decrease ventilator associated lung injury (VALI). RM was safe and had good tolerance, no hypoxemia, barotrauma and hemodynamic instability were observed.     

肺复张通气策略在急性呼吸窘迫综合征治疗中的临床应用

【目的】探讨肺复张通气策略治疗急性呼吸窘迫综合征（ARDS）的疗效和风险。【方法】随机将ARDS患者分成对照组和治疗组，对照组在常规治疗的基础上，应用PB760呼吸机采用小潮气量和最佳呼吸末正压（PEEP）的肺保护性通气策略进行机械通气，治疗组在对照组的机械通气治疗基础上再应用肺复张策略。记录肺复张前及肺复张后12h、24h、72h的氧合指数（PaO2／FiO2）、动脉二氧化碳分压（PaCO2）以及是否出现气压伤等并进行对比分析。【结果】治疗组与对照组比较在肺复张后12h、24h、72h的氧合指数（PaO2／FiO2）均明显改善（P〈0．05）、PaCO2均明显降低（P〈0．01），两组气压伤发生率差异无显著性（P〉0．05）。【结论】采用小潮气量和最佳PEEP联合肺复张策略治疗ARDS是安全有效的。     

最佳氧合法导向的PEEP对ARDS绵羊血流动力学和气体交换的影响

目的 探讨最佳氧合法导向的呼气末正压（PEEP）对急性呼吸窘迫综合征（ARDS）绵羊血流动力学和气体交换的影响。方法 肺泡灌洗法复制绵羊ARDS模型（n=6）,在充分肺复张的基础上,利用最佳氧合法滴定最佳PEEP。并维持通气2h。观察基础状态（PEEP 5 cmH2O）、ARDS模型稳定（PEEP 5cmH2O）和最佳PEEP维持通气2h的血流动力学、气体交换和呼吸力学变化。结果 最佳氧合法滴定的最佳PEEP为（18±2）cmH2O。与ARDS模型比较,最佳PEEP维持通气期间心率（HR）、平均动脉压（MAP）、心脏指数（CI）、每搏指数（SVI）、中心静脉压（CVP）、平均肺动脉压（MPAP）、肺动脉嵌顿压（PAWP）和肺循环阻力指数（PVRI）差异无统计学意义（P〉0．05）,CVP、MPAP、PAWP和PVRI较基础状态明显升高（P〈0．05）。与ARDS模型稳定时比较,最佳PEEP维持通气期间动脉血二氧化碳分压（PaCO2）明显降低（P〈0．05）,氧合指数（PaO2／FiO2）和氧输送（DO2I）显著升高（P〈0．05）,肺内分流率（Qs／Qt）明显改善（P〈0．05）,且PaCO2、PaO2／FiO2、DO2I和Qs／Qt均接近基础状态（P〉0．05）。与ARDS模型稳定时比较,最佳PEEP维持通气期间的平均气道压（Pm）明显升高（P〈0．05）、平台压力（Pplat）无明显变化（P〉0．05）、肺动态顺应性（Cdyn）明显增加（P〈0．05）。结论 最佳氧合法导向的PEEP能有效地减少ARDS绵羊的肺内分流、改善氧合和肺顺应性,对血流动力学无明显影响。     

控制性低通气低呼气末正压通气机械呼吸支持在创伤性成人呼吸窘迫综合征中的应用

目的改进机械治疗创伤性成人呼吸窘迫综合征（ARDS）的方法,将控制性低通气呼气末正压通气机械呼吸支持应用于创伤性APRS患者,探讨其效果。方法将30例创伤性ARDS的患者随机分组,对照组15例,按常规大潮气量（10—15ml／kg）、呼气末正压通气（PEEP）高水平（8—12cmH2O）正压机械通气。实验组15例,给予低潮气量（6—10ml／kg）,低PEEP水平（5—8cmH2O）正压机械通气。观察两组机械通气前和通气后2h的氧合指数（PaO2／FiO2）、pH值变化及患者呼吸频率（RR）。结果两组机械通气前的PaO2／FiO、pH值、RR比较差异均无统计学意义（P〉0．05）;治疗后实验组PaO2／FiO2为（270．59±15．63）mmHg,pH值为（7．35±0．26）,RR为（24±2．74）次／min,与治疗前以上三项（159．48±11．47）mmHg,（7．41±0．17）,（3S±3．41）次／min比较差异均有统计学意义（t分别为2．63,2．33,2．56;P〈0．05）;与对照组治疗后上述三项（246．17±14．89）mmHg,（7．38±0．03）,（28±3．56）次／min比较,差异均有统计学意义（t分别为2．31,2．19,2．24;P〈0．05）。实验组较对照组改善更为明显（P〈0．05）。治疗期间实验组死亡3例,对照组死亡7例,差异有统计学意义（χ^2=3．74,P〈0．05）。结论控制性低通气低PEEP机械呼吸支持对创伤性ARDS效果较高PEEP更为理想,能明显改善低创伤性ARDS患者各项生理指标,降低患者的病死率。     

体外膜肺氧合治疗急性呼吸窘迫综合征的临床疗效观察

目的 探讨体外膜肺氧合(ECMO)治疗急性呼吸窘迫综合征(ARDS)患者的临床疗效和安全性.方法 6例ARDS患者在机械通气治疗无明显效果后,予以ECMO辅助治疗.比较ECMO治疗前后氧合、呼气末正压(PEEP)水平和吸入氧浓度(FiO2)的变化,观察ECMO的不良反应.结果 应用ECMO辅助治疗后,6例患者脉搏血氧饱和度(SpO2)升高(从0.45 ～ 0.92升至0.94～ 1.00),PEEP(cm H2O,1 cm H2O =0.098 kPa)和FiO2降低(PEEP从10.0～22.0降至4.0～15.0;FiO2从1.00降至0.30～0.60).2例危重症甲型H1N1流感肺炎患者死于休克,1例危重症甲型H1N1流感肺炎和1例肺炎克雷伯杆菌肺炎患者因病情恶化放弃治疗,1例巨细胞病毒肺炎、1例鲍曼不动杆菌肺炎患者顺利恢复出院.主要并发症为出血、溶血.结论 ECMO可增加气体交换,改善氧合,部分替代肺的功能.ARDS患者如果机械通气治疗无效,宜及早使用ECMO辅助.     

肺复张对急性呼吸窘迫综合征患者血管外肺水的影响

目的 探讨肺复张(RM)策略对急性呼吸窘迫综合征(ARDS)患者血管外肺水(EVLW)的影响.方法 采用随机对照病例研究方法,将20例ARDS患者随机分为RM组和对照组.按肺保护性通气策略的原则给患者进行机械通气;用双水平气道正压(BIPAP)通气模式进行RM,每8 h重复1次,连续7 d或至脱机前;除RM外,其余治疗两组相同.记录患者的基线资料和每日RM结束后的EVLW、血管外肺水指数(EVLWI)、呼吸力学参数、氧合指数(PaO2/FiO2)、中心静脉压(CVP)、血浆胶体渗透压(COP)以及糖皮质激素、肾上腺素能药物用量和24 h液体出入量平衡等影响EVLW各因素的数值.结果 RM组和对照组EVLW、EVLWI随时间延长呈逐渐降低趋势,但两组间比较差异无统计学意义(P均>0.05).两组间CVP、COP和去甲肾上腺素、氢化可的松用量比较差异均无统计学意义(P均>0.05);RM组多巴胺用量在4 d时明显少于对照组(P<0.05);液体出入量平衡RM组7 d时为负平衡,对照组则为正平衡(P<0.05).RM组平均气道压(Pmean)的均值[(18.8±3.2)cm H2O(1 cm H2O=0.098 kPa)]和肺准静态顺应性(Cstat)的均值[(36.5±14.5)ml/cm H2O]均明显高于对照组[(16.6±3.9)cm H2O和(29.3±12.0)ml/cm H2O,P均<0.05];其中RM组5 d时Cstat大于2 d和3 d时(P均<0.05).两组间PaO2/FiO2比较则未见明显差异(P均>0.05).结论 针对ARDS患者实施的RM治疗并没有明显影响EVLW,而仅起到了改善肺呼吸力学特征的作用.本研究中所涉及的影响肺水的因素并未影响肺水的形成和清除.     

小儿急性肺损伤/急性呼吸窘迫综合征肺功能变化的临床研究

目的：了解小儿急性肺损伤／急性呼吸窘迫综合征（ALI／ARDS）肺功能的变化。方法：20例符合AU／ARDS诊断标准的机械通气病人作为肺损伤组（Au组），同期机械通气而无肺损伤病人20例作为对照组（NALI组）。入选同时记录病人的临床资料及呼吸机参数、血气指标。结果：本研究40例全身炎症反应综合征（SIRS）病人中合并多器官功能不全综合征（MODS）10例（25．0％），其中ALI组7例（7／40，占病人的17、5％），NALI组3例（3／40，占病人的7、5％），本组病人死亡7例（占17、5％），其中Au组死亡5例（占12．5％），NALI组死亡2例（占5．0％），所有死亡病例均并发MODS。Au组肺顺应性（Cst）、氧合指数（PaO2/FiO2）与NALI组比较明显降低，而肺内分流（Qs／Qt）明显高于NAu组（P〈0、01）。发生Au的病人机械通气参数吸气峰压（PIP）、平均气道压（Pmean）、呼气末正压（PEEP）明显增高，与NAu组比较差异有显著性（P〈0．01）。结论：对小儿SIRS／MODS早期监测肺功能的改变．早期诊断和及时干预ALI,阻止MODS的发生、进展．对降低危重儿死亡率有重要意义．     

急性呼吸窘迫综合征患者机械通气时内源性呼气末正压的测定及其意义

目的:研究急性呼吸窘迫综合征(ARDS)患者机械通气时内源性呼气末正压的发生率,探讨内源性呼气末正压的临床意义.方法:前瞻性应用德尔格Evita 4和Evita 2 dura呼吸机测定34例ARDS患者机械通气时内源性呼气末正压.结果:34例急性呼吸窘迫综合症患者机械通气时内源性呼气末正压发生率为100%,内源性呼气末正压范围为2～15 cm H2O,平均为5.41±2.12 cm H2O,随着病情好转,内源性呼气末正压下降.结论:ARDS患者机械通气时普遍存在内源性呼气末正压,故此对ARDS患者机械通气时随时要注意内源性呼气末正压,减少气压伤的发生率.     

肺复张对急性呼吸窘迫综合征患者呼吸力学及血管外肺水指数的影响

目的 探讨肺复张(RM)对急性呼吸窘迫综合征(ARDS)患者呼吸力学及血管外肺水指数(EVLWI)的影响.方法 采用随机对照病例研究方法,选择30例ARDS患者,随机(随机数字法)分为RM组和Non-RM组.RM组:保护性肺通气稳定后0.5 h开始RM治疗,每12 h重复1次RM,连续3d.Non-RM组:保护性肺通气治疗,不使用RM.收集两组患者治疗前、治疗12 h,24 h,48 h,72 h各时间点氧合指数(PaO2/FiO2)、气道峰压(PIP)、气道平台压(Pplat)、静态肺顺应性(Cst)及EVLWI数据;监测RM前后血流动力学变化.数据处理采用单因素方差分析、成组t检验和Fisher确切概率法.结果 ①治疗后两组患者PaO2/FiO2均呈上升趋势,在12 h,24 h,48 h,72 h同时间点比较RM组高于NonRM组(P＜0.05);PIP、Pplat值在治疗后均呈下降趋势,RM组低于Non-RM组(P＜0.05),Cst在治疗后呈升高趋势,RM组高于Non-RM组(P＜0.05).②治疗后两组EVLWI均呈下降趋势,组内各时间点比较差异有统计学意义(F值分别为22.392、8.147,均P＜0.01);在12 h,24 h,48 h,72 h同时间点两组EVLWI比较,RM组低于Non-RM组(P＜0.05或P＜0.01).③RM时有一过性血流动力学变化,与RM前比较差异有统计学意义(P＜0.01),但RM结束后120 s与RM前比较差异无统计学意义(P＞0.05).结论 RM可以减少ARDS患者EVLWI,改善肺氧合及肺顺应性,对血流动力学影响短暂.     

Effects of recruitment maneuvers in patients with acute lung injury and acute respiratory distress syndrome ventilated with high positive end-expiratory pressure

Objective: Positive end-expiratory pressure (PEEP) and recruitment maneuvers (RMs) may partially reverse atelectasis and reduce ventilation-associated lung injury. The purposes of this study were to assess a) magnitude and duration of RM effects on arterial oxygenation and on requirements for oxygenation support (Fio2/PEEP) in patients with acute lung injury and acute respiratory distress syndrome (ALI/ARDS) receiving ventilation with low tidal volumes and high levels of PEEP; and b) frequency of adverse respiratory and circulatory events attributable to RMs. Design: Prospective, randomized, crossover study. Setting: Thirty-four intensive care units at 19 hospitals. Patients: Seventy-two patients with early ALI/ARDS. Baseline PEEP and Fio2 were 13.8 +/- 3.0 cm H2O and 0.39 +/- 0.10, respectively (mean +/- sd). Interventions: We conducted RMs by applying continuous positive airway pressure of 35-40 cm H2O for 30 secs. We conducted sham RMs on alternate days. We monitored oxyhemoglobin saturation by pulse oximetry (SpO2), Fio2/PEEP, blood pressure, and heart rate for 8 hrs after RMs and sham RMs. We examined chest radiographs for barotrauma. Measurements and Main Results: Responses to RMs were variable. Greatest increments from baseline SpO2 within 10 mins after RMs were larger than after sham RMs (1.7 +/- 0.2 vs. 0.6 +/- 0.3 %, mean +/- SEM, p < .01). Systolic blood pressure decreased more +/- 1.1 mm Hg, p < .01). Changes in Fio2/PEEP requirements were not significantly different at any time after RMs vs. sham RMs. Barotrauma was apparent on first radiographs after one RM and one sham RM.Conclusions: In ALI/ARDS patients receiving mechanical ventilation with low tidal volumes and high PEEP, short-term effects of RMs as conducted in this study are variable. Beneficial effects on gas exchange in responders appear to be of brief duration. More information is needed to determine the role of recruitment maneuvers in the management of ALI/ARDS.     

不同肺复张模式对急性呼吸窘迫综合征患者呼吸功能及血管外肺水指数的影响

目的探讨控制性肺膨胀(SI)和压力控制(PCV)两种肺复张(RM)对急性呼吸窘迫综合征(ARDS)患者呼吸力学及血管外肺水指数(EVLWI)的影响。方法采用随机对照病例研究方法,选择30例ARDS患者,随机分为SI组和PCV组,每组15例。SI组:保护性肺通气稳定0.5h后呼吸机模式改为持续正压通气(3.92kPa),持续40s;PCV组:呼吸机模式改为PCV,吸气压力(Pessure above PEEP,1.96kPa),I∶E=1∶1,持续2min。肺复张结束后,2组均恢复呼吸机基础参数。每12h重复1次RM,连续3d。收集2组患者治疗前,治疗12、24、48、72h各时间点氧合指数(PaO2/FiO2)、气道峰压(PIP)、气道平台压(Pplat)、静态肺顺应性(Cst)及EVLWI;监测每次RM前后血流动力学变化。结果 1)治疗后2组患者PaO2/FiO2、Cst均呈上升趋势(P<0.05或P<0.01),PIP、Pplat值在治疗后均呈下降趋势,但在各时间点2组比较差异无统计学意义(P>0.05)。2)治疗后2组EVLWI均呈下降趋势(P<0.01),但各时间点2组比较差异无统计学意义(P>0.05)。3)2组患者在肺复张时平均动脉压、心脏指数下降,心率、中心静脉压升高,与复张前比较差异有统计学意义(P<0.01),PCV组上述指标波动幅度及持续时间均低于SI组,在肺复张时、复张后2min、复张后5min上述指标比较差异有统计学意义(P<0.01)。结论 SI与PCV两种肺复张均能改善肺氧合及肺顺应性,减少ARDS患者EVLWI,PCV肺复张对血流动力学影响低于SI。     

老年患者重大手术后肺复张疗效观察

目的 观察肺复张(RM)对老年患者重大手术后肺不张及肺部感染的预防作用并评价其安全性.方法 选择2007年2月-2008年2月北京空军总医院重症加强治疗病房(ICU)收治的70岁以上老年患者40例,均为重大手术后,全麻手术持续6 h以上,麻醉、肌松状态入ICU,均为有创动脉压监测.随机分为RM试验组和非RM对照组,RM条件为吸入氧浓度0.60,呼吸频率20次/min,潮气量5 ml/kg,呼气末正压25 cm H2O(1 cm H2O=0.098 kPa),吸呼比1∶2,持续30 s,1 h后重复1次.记录RM前、后2 min及RM实施过程中心率(HR)、中心静脉压(CVP)、平均动脉压(MAP)、气道平台压(Pplat)、脉搏血氧饱和度(SpO2)的变化;RM前及末次RM 1 h后进行动脉血气分析;观察两组患者肺不张及肺部感染发生情况.结果 ①RM操作中HR、MAP、CVP有显著变化(P均<0.05),但未影响循环功能.②RM后2 min CVP迅速恢复,RM操作前后比较HR、MAP、CVP、SpO2变化不明显(P均>0.05);RM后Pplat显著降低(P<0.05).③RM组实施RM后肺不张、肺部感染的发生率均显著低于非RM组(P均<0.05).④RM后氧合指数较前变化明显(P<0.05).结论 RM可预防老年患者重大手术后肺不张及肺部感染的发生,RM在老年患者中使用较安全,并可明显改善老年患者氧合指数.     

Recruitment maneuvers in acute respiratory distress syndrome: The safe way is the best way

Acute respiratory distress syndrome(ARDS) represents a serious problem in critically ill patients and is associated with in-hospital mortality rates of 33%-52%. Recruitment maneuvers(RMs) are a simple, low-cost, feasible intervention that can be performed at the bedside in patients with ARDS. RMs are characterized by the application of airway pressure to increase transpulmonary pressure transiently. Once non-aerated lung units are reopened, improvements are observed in respiratory system mechanics, alveolar reaeration on computed tomography, and improvements in gas exchange(functional recruitment). However, the reopening process could lead to vascular compression, which can be associated with overinflation, and gas exchange may not improve as expected(anatomical recruitment). The purpose of this review was to discuss the effects of different RM strategies- sustained inflation, intermittent sighs, and stepwise increases of positive end-expiratory pressure(PEEP) and/or airway inspiratory pressure- on the following parameters: hemodynamics, oxygenation, barotrauma episodes, and lung recruitability through physiological variables and imaging techniques. RMs and PEEP titration are interdependent events for the success of ventilatory management. PEEP should be adjusted on the basis of respiratory system mechanics and oxygenation. Recent systematic reviews and meta-analyses suggest that RMs are associated with lower mortality in patients with ARDS. However, the optimal RM method(i.e., that providing the best balance of benefit and harm) and the effects of RMs on clinical outcome are still under discussion, and further evidence is needed.     

俯卧位通气联合呼气末正压治疗急性呼吸窘迫综合征家猪的疗效研究

目的 探讨俯卧位通气联合呼气末正压(PEEP)治疗急性呼吸窘迫综合征(ARDS)的疗效及其机制.方法 12头家猪静脉注射油酸建立ARDS模型,分为仰卧位组和俯卧位组,均给予0(ZEEP)、10(PEEP10)、20 cm H2O(PEEP20,1 cm H2O=0.098 kPa)PEEP的机械通气15 min,监测家猪血流动力学、肺气体交换和呼吸力学指标;处死动物观察肺组织病理学变化.结果 俯卧位组ZEEP、PEEP10时氧合指数(PaO2/FiO2)明显优于仰卧位组[ZEEP:(234.00±72.55)mm Hg比(106.58±34.93)mm Hg,PEEP10:(342.97±60.15) mm Hg比(246.80±83.69)mm Hg,1 mm Hg=0.133 kPa,P均<0.05];PEEP20时两组PaO2/FiO2差异无统计学意义(P>0.05).PEEP10时两组肺复张容积(RV)差异无统计学意义(P>0.05);但PEEP20时俯卧位组RV显著高于仰卧位组[(378.55±101.80)ml比(302.95±34.31)ml,P<0.05].两组间心率(HR)、平均动脉压(MAP)、心排血指数(CI)、呼吸系统顺应性(Cst)及动脉血二氧化碳分压(PaCO2)差异均无统计学意义(P均>0.05);仰卧位组背侧肺组织的肺损伤总评分明显高于俯卧位组[(12.00±1.69)分比(6.03±1.56)分,P<0.05].结论 俯卧位通气联合合适的PEEP可改善ARDS家猪氧合,并且不影响血流动力学和呼吸力学,肺组织损伤的重新分布可能是其机制之一.     

Comparison of the effect of aminophylline and low PEEP vs. high PEEP on EGF concentration in critically ill patients with ALI/ARDS

BACKGROUND: Acute respiratory distress syndrome (ARDS) remains a serious, often fatal, condition, despite progress in modern critical care treatment. Cytokines play important roles in the pathogenesis of the syndrome, although their roles in the evaluation and outcome have not been clearly elucidated yet. OBJECTIVES: We tested whether serum concentration of epidermal growth factor (EGF), as one of the important inflammatory mediators, changes with time and administration of mechanical ventilation and aminophylline. PATIENTS AND METHODS: Thirty patients [mean (SD): age = 56.6 (17.4) years] with ARDS were enrolled. After diagnosis based on inclusion and exclusion criteria, the patients were intubated and mechanically ventilated. Two hours after ventilation with definite positive end-expiratory pressure (PEEP), aminophylline with a specific dose was started. Serum samples were obtained at five time points of 0, 2, 2.5, 4 and 8 h post-starting PEEP. RESULTS: Serum EGF concentration decreased after mechanical ventilation with PEEP (P < 0.05). The serum EGF concentrations 8 h after intervention was statistically lower in the low PEEP group than in the high PEEP group. The Acute Physiology and Chronic Health Evaluation (APACHE) Pi score and PaO2/FiO2 improved significantly after 8 h (P < 0.05). CONCLUSION: Beneficial effects of mechanical ventilation and aminophylline on APACHE Pi score and PaO2/FiO2 influence serum EGF levels. These findings may have relevance to the development of multisystem organ failure.     

肺保护性通气策略在急性百草枯中毒致肺损伤中的临床应用

目的探讨肺保护性通气策略（LPVS）在急性百草枯中毒（APP）致肺损伤中的临床应用价值。方法将31例急性百草枯中毒致肺损伤且符合上呼吸机指征的患者随机分为LPVS组16例和传统机械通气组（对照组）15例。分别观察3～5d内（通气期间）两组的潮气量（VT）、呼气末正压（PEEP）、气道峰压（PIP）、平均气道压（MAP）等呼吸机参数;动脉血氧分压（PaO2）、动脉血二氧化碳分压（PaCO2）、氧合指数（PaO2／FiO2）等动脉血气指标;以及呼吸机相关性肺损伤（VALI）、X线胸片与患者的病死率。结果LPVS组MAP水平低于对照组,差异有统计学意义（P〈0．01）,LPVS组患者的PIP、PEEP较对照组（P均〈0．05）;LPVS组患者的PaCO2、PaO2／FiO2高于对照组,差异均有统计学意义（P均〈0．01）,两组患者的PaO2比较差异无统计学意义（P〉0．05）;LPVS组VALI的发生率低于对照组,X线胸片显示进展延缓病例数高于对照组（P均〈0．05）：两组患者的病死率无统计学差异（P〉0．05）。结论采取LPVS可以一定程度改善APP肺损伤患者的呼吸功能、降低VALI的发生率,对APP导致的肺损伤有积极的治疗作用。     

肺复张对肺内/外源性急性呼吸窘迫综合征模型犬呼吸生理和肺形态学影响的比较

目的 探讨以压力-容积(P-V)曲线为导向的肺复张(RM)策略对肺内/外源性急性呼吸窘迫综合征(ARDSexp/ARDSp)模型犬呼吸生理和肺形态学的影响.方法 将24只健康杂种犬按随机数字表法均分为两组,分别以静脉注射油酸0.1 ml/kg复制ARDSexp模型,以气管内注入盐酸2 ml/kg复制ARDSp模型.每种模型再随机均分为肺保护通气策略(LPVS)组和LPVS+RM组.LPVS组采用LPVS进行机械通气(MV);LPVS+RM组先进行以P-V曲线为导向的RM,RM采用压力控制通气(PCV),压力上限为高位转折点(UIP),呼气末正压(PEEP)为低位转折点(LLP)+2 cm H2O(1 cm H2O=0.098 kPa),维持60 s后再按LPVS进行MV.两组MV时间均为4 h.观察动物基础状态(成模前)及RM前后的氧合指数(PaO2/FiO2)、呼吸力学指标变化;采用低流速法记录准静态P-V曲线并计算UIP、LIP ;根据肺CT比较不同肺充气区容积占全肺容积的百分比.结果 成模前和RM前两组PaO2/FiO2及UIP、LIP比较差异均无统计学意义.RM后4 h,两种模型LPVS+RM组PaO2/FiO2和肺顺应性(Crs)均较同模型LPVS组显著升高[ARDSexp模型PaO,/FiO2(mm Hg,1 mm Hg=0.133 kPa):263.9±69.2比182.8±42.8,Crs(ml/cm H2O):11.3±4.2比9.7±3.7;ARDSp模型PaO2/FiO2(mm Hg):193.4±33.5比176.4±40.2,Crs(ml/cm H2O):10.1±3.9比9.0±3.9,P＜0.05或P＜0.01],气道压力明显低于同模型LPVS组[ARDSexp模型吸气峰压(PIP,cm H2O):24.1±7.4比30.2±8.5,气道平台压(Pplat,cm H2O):19.1±7.3比25.6±7.7;ARDSp模型PIP(cm H2O):26.6±8.4比29.6±10.3,Pplat(cm H2O):21.9±7.3比25.1±8.4,P＜0.05或P＜0.01];且ARDSexp模型改善程度较ARDSp模型更为显著(P＜0.05或P＜0.01).两种模型LPVS+RM组肺组织闭合区和充气不足区所占比例均较同模型LPVS组明显减少,正常充气区所占比例明显增加[ARDSexp模型闭合区:(9.9±3.1)%比(16.3±5.2)%,充气不足区:(10.2±4.2)%比(23.4±6.7)%,正常充气区:(76.2±12.3)%比(57.5±10.1)%;ARDSp模型闭合区:(14.3±4.8)%比(1 8.2±5.1)%,充气不足区:(17.4±6.3)%比(24.1±5.9)%,正常充气区:(63.2±10.7)%比(54.6±11.3)%,P＜0.05或P＜0.01];且ARDSexp模型各充气区所占比例改善程度均明显优于ARDSp模型(均P＜0.05).结论 对于不同原因ARDS,以P-V曲线为导向的RM均具有增加肺氧合、改善肺顺应性和肺组织通气的作用,且对ARDSexp的治疗效果明显优于ARDSp.

Abstract：

Objective To determine effects of recruitment maneuver (RM) guided by pressure-volume (P-V) curve on respiratory physiology and lung morphology in canine models of acute respiratory distress syndrome of pulmonary or extrapulmonary origin (ARDSp and ARDSexp). Methods Twenty-four healthy dogs were randomly divided into two groups with 12 dogs each: ARDSexp and ARDSp. Each dog in ARDSexp group was injected with oleic acid 0. 1 ml/kg through femoral vein, and each dog in ARDSp group received hydrochloric acid 2 ml/kg via trachea. Subsequently, dogs with both models were randomly subdivided into lung protective ventilation strategy (LPVS) group and LPVS+RM group, respectively. Dogs in LPVS group were given LPVS only without RM. RM guided by P-V curve was performed in LPVS+RM group followed by LPVS and pressure controlled ventilation (PCV) mode was selected. Phigh was set at upper inflection point (UIP) of the P-V curve, positive end-expiratory pressure (PEEP) was set at lower inflection point (LIP)+2 cm H2O (1 cm H2O=0. 098 kPa), and the duration of RM was 60 seconds. The duration of mechanical ventilation (MV) in both subgroups was 4 hours. The oxygenation index (PaO2/FiO2), relative lung mechanical indexes were measured in two ARDS models before establishment of ARDS model, and before and after RM. The UIP and LIP were calculated with P-V curve. The percentage of different volume in ventilation of lung accounting for total lung volume was compared by CT scan.Results The PaO2/FiO2, UIP and LIP did not showed significant differences among all groups before ARDSand before RM. PaO2/FiO2 and respiratory system compliance (Crs) were significantly elevated in LPVS+RM group of both models 4 hours after RM compared with corresponding LPVS group [PaO2/FiO2(mm Hg,1 mm Hg=0. 133 kPa) of ARDSexp model: 263. 9±69. 2 vs. 182.8±42. 8, Crs (ml/cm H2O) of ARDSexp model: 11.3±4. 2 vs. 9. 7±3. 7; PaO2/FiO2(mm Hg) of ARDSp model: 193. 4±33.5 vs. 176. 4±40. 2, Crs (ml/cm H2O) of ARDSp model: 10.1±3.9 vs. 9.0±3.9, P＜0. 05 or P＜0.01], and the airway pressure was significantly declined compared with corresponding LPVS group [peak inspiratory pressure (PIP),cm H2O) of ARDSexp model: 24. 1±7. 4 vs. 30. 2±8. 5, plateau pressure (Pplat, cm H2O) of ARDSexp model: 19.1±7.3 vs. 25.6±7.7; PIP (cm H2O) of ARDSp model: 26.6±8.4 vs. 29.6±10.3, Pplat (cm H2O) of ARDSp model: 21.9±7. 3 vs. 25.1±8.4, P＜0. 05 or P＜0. 01]. Moreover, PaO2/FiO2, Crs,PIP and Pplat were improved better in ARDSexp model than ARDSp model (P＜ 0. 05 or P＜ 0. 01).Compared with LPVS maneuver, RM plus LPVS maneuver could significantly decrease the proportion of closure and hypoventilation region, and increase the proportion of normal ventilation region in both models [closure region of ARDSexp model : (9.9±3.1) % vs. (16. 3± 5. 2) %, hypoventilation region of ARDSexp model: (10. 2±4.2)% vs. (23. 4±6. 7)%, normal ventilation region of ARDSexp model: (76. 2±12. 3)%vs. (57.5±10. 1)%; closure region of ARDSp model: (14.3±4. 8)% vs. (18. 2±5.1)%, hypoventilation region of ARDSp model : (17.4±6. 3) % vs. ( 24. 1 ± 5. 9) 0%, normal ventilation region of ARDSp model :(63. 2 ± 10. 7 ) % vs. ( 54. 6±11.3 ) %, P ＜ 0. 05 or P ＜ 0. 01]. All of the ventilation regions were better improved with ARDSexp model than ARDSp model (all P＜0. 05). Conclusion RM guided by P-V curve could help obtain better oxygenation, improve pulmonary compliance and lung ventilation in ARDSexp and ARDSp, and better treatment effects are seen in ARDSexp dogs than ARDSp dogs.