压力控制法肺复张对ARDS患者氧代谢和血流动力学的影响

目的探讨压力控制法肺复张对急性呼吸窘迫综合征(ARDS)患者氧代谢和血流动力学的影响。方法选择苏州市立医院重症医学科(ICU)收治的行机械通气及脉搏轮廓法持续血流动力学监测(PiCCO)的ARDS患者30例,采用肺保护通气策略(LPVS),给予压力控制法(PCV)肺复张(RM)。压力上限为高位转折点(UIP),呼气末正压(PEEP)为低位转折点(LIP)+2 cmH2O,维持时间60 s,RM后维持原方案通气。观察不同时间段氧代谢指标和血流动力学的变化。结果患者在RM后动脉血氧分压(PaO2)、静脉血氧分压(PvO2)、中心静脉血氧饱和度(ScvO2)和氧输送量(DO2)均明显升高(P0.05),氧摄取率(ERO2)明显降低(P0.05)。患者心率(HR)无明显变化;RM时中心静脉压(CVP)显著增加(P0.05),但RM结束后很快恢复至基础水平。RM时平均动脉压(MAP)和心脏指数(CI)均有下降(P0.05),但很快恢复至基础水平。两组均未发生气胸、纵隔及皮下气肿等并发症。结论压力控制法肺复张可提高ARDS患者氧输送,改善组织缺氧;ARDS患者在进行压力控制法肺复张时血液动力学会有短暂变化;压力控制法肺复张安全易行。     

压力控制法肺复张策略对非体外循环冠状动脉旁路移植术后早期低氧血症患者呼吸和血流动力学的影响

目的评价不同压力的压力控法肺复张策略(LRM)对非体外循环冠状动脉旁路移植术(OPCABG)后早期低氧患者的呼吸和血流动力学的影响。方法选取我院2013~2014择期行OPCABG患者40例,年龄40~70岁,NYHA心功能分级Ⅱ~Ⅲ级,术后转入ICU早期出现低氧血症(100≤Pa O2/Fi O2≤200),采用随机数字表法将其分为高压力组和低压力组,各20例。两组均在常规机械通气的基础上,采用压力控制法进行LRM,低压力组支持压力15 cm H2O,呼气末正压为20 cm H2O,气道峰压上限35 cm H2O,维持30 s后调回原通气模式,可反复进行。高压力组支持压力15 cm H2O和呼气末正压为25 cm H2O,气道峰压上限40 cm H2O,可反复进行。分别于入ICU后30 min(T1)、分组后(T2)及复张后30 min(T2+)停止机械通气前即刻(T3)采集桡动脉血样,进行血气分析,计算氧合指数和肺动态顺应性。分别记录复张后30 min最低CO和MAP。结果与低压力组比较,高压力LRM组停止机械通气前即刻氧合指数升高、动态肺顺应性改善,差异有统计学意义(P0.05),一氧化碳(CO)和平均动脉压(MAP)降低明显,差异有统计学意义(P0.05)。结论术后高压力组较低压力组LRM明显改善OPCABG后早期低氧血症患者肺氧合和肺顺应性,但低压力组血流动力学变化不明显。     

PEEP肺复张术治疗心脏手术后早期ALI—ARDS（附20例报告）

目的观察应用呼气末正压（PEEP）递减方式进行肺复张治疗心脏术后早期急性肺损伤—急性呼吸窘迫综合征（ALI-ARDS）的疗效。方法20例符合ALI-ARDS诊断标准并接受机械通气的心脏术后患者,将PEEP逐渐增加至20cmH2O,吸气压35cmH2O,呼吸频率为12次／min并保持2min,以后以2cmH2O／5min递减,直至恢复到肺复张术前PEEP水平,观察患者生命体征、肺静态顺应性、氧合指数以及血流动力学变化。结果所有患者均能够较好耐受肺复张术,在肺复张后氧合指数明显高于术前（P〉0．05）,且能够保持2h。患者血流动力学以及肺静态顺应性治疗前后均无显著差异（P〉0．05）。结论心脏术后早期发生ALI—ARDS患者,采用PEEP递减进行肺复张可以有效地改善肺氧合功能,同时对血流动力学影响较小。     

短暂高水平PEEP对压力控制通气ARDS患者氧合和血液动力学的影响

目的观察短暂高水平呼气末正压通气(PEEP)对急性呼吸窘迫综合征(ARDS)患者氧合情况及血流动力学的影响。方法 40例ARDS患者,随机分为实验组22例和对照组18例。实验组给予压力控制通气+短暂高水平PEEP促进肺复张,对照组仅给予压力控制通气。观察并比较两组患者的氧合及血流动力学变化。结果通气13、7、d后实验组患者PaO2/FiO2明显优于对照组(P均<0.05);通气17、d时实验组患者动脉血pH、PaCO2明显低于对照组(P均<0.05);通气1 d时实验组患者PaO2明显低于对照组(P<0.05)。两组患者通气1、2、3 d时HR、MAP、CVP相比,P均>0.05。结论短暂高水平PEEP可改善ARDS患者的氧合,对血流动力学无明显影响。     

分侧肺通气时不同呼气末正压和潮气量对单侧肺损伤犬循环的影响

目的 观察不同步分侧肺通气和同步分侧肺通气对单侧急性肺损伤(ALI)犬循环的影响.方法 取健康杂种犬12只,建立盐酸所致单侧肺损伤动物模型,行容积控制通气,将犬按随机数字表法分为不同步分侧肺通气组(NS组)和同步分侧肺通气组(S组).参数:患侧潮气量3.5 ml/kg保持不变,呼气末正压(PEEP)选择15、20、25 cm H2O(1 cm H2O=0.098 kPa);患侧PEEP 10 cm H2O不变,潮气量用随机数字表法选择5、7.5、10 ml/kg.健侧通气参数始终不变,检测不同通气条件下两组犬血流动力学和氧动力学指标.结果 (1)患侧潮气量3.5 ml/kg不变,PEEP为15、20 cm H2O时,两组血流动力学和氧动力学参数差异无统计学意义.当患侧PEEP为25 cm H2O时,NS组心率、体循环平均压(mABP)、心输出量、氧合指数和混合静脉血氧饱和度(SvO2)分别为(98±8)次/min、(84±6)mm Hg(1 mm Hg=0.133 kPa)、(1.10±0.13)L/min、(199±14)mm Hg和(55±6)%,明显低于S组[分别为(124±9)次/min、(103±7)mm Hg、(1.52±0.28)L/min、(221±15)mm Hg和(62±4)%,t值分别为-7.852、-16.561、-15.043、-13.314和-5.653,均P＜0.01].(2)患侧PEEP 10 cm H2O不变,潮气量分别为5、7.5 ml/kg时,两组的血流动力学和氧动力学参数比较差异无统计学意义.当患侧潮气量为10 ml/kg时,NS组HR、mABP、心输出量、氧合指数和SvO2均低于S组(均P＜0.01).结论 在本实验动物模型中,患侧与健侧所用PEEP水平相差≤20 cm H2O或患侧潮气量≤7.5 ml/kg时,同步和非同步分侧肺通气均能保持循环稳定.若需要更高水平PEEP时,建议选用同步分侧肺通气.     

死腔分数导向急性呼吸窘迫综合征呼气末正压选择的临床研究

目的 探讨早期急性呼吸窘迫综合征( ARDS)患者采用死腔分数法选择呼气末正压(PEEP)的可行性.方法 选23例机械通气的早期ARDS患者行持续肺膨胀手法充分肺复张,PEEP递减过程中分别采用最小死腔分数法、最大顺应性法、最佳氧合法选择最佳PEEP,观察不同方法选择的PEEP对患者氧合、解剖死腔容积(VD)/潮气容积(VT)、静态肺顺应性(CLst)和功能残气量(FRC)等的影响.结果 最小死腔分数法[(10.1±2.8)cm H2O(1 cm H2O =0.098 kPa)]和最大顺应性法[(11.3±2.5) cmH2O]选择的最佳PEEP间差异无统计学意义(P＞0.05),均明显低于最佳氧合法[(15.0±3.4) cm H2O,P＜0.05].最小死腔分数法选择PEEP机械通气时患者VD/VT(0.53±0.09)较基础状态(0.59±0.09)明显下降,但最大顺应性法和最佳氧合法选择的PEEP机械通气时VD/VT较基础状态未见明显变化.最小死腔分数法选择的PEEP,其氧合指数明显低于最佳氧合法[(288±123) mm Hg(1 mm Hg=0.133 kPa)比(356±119)mm Hg,P＜0.05],与最大顺应性法相比差异无统计学意义(P＞0.05),均高于基础状态.最小死腔分数法选择PEEP机械通气时气道平台压[(24±4) cm H2O]明显低于最大氧合法[(31±9) cm H2O].最佳氧合法选择的PEEP机械通气时的FRC明显高于最小死腔分数法和最大顺应性法.结论 采用最小死腔分数法选择的最佳PEEP,可改善ARDS患者氧合和CLst,减少死腔通气、降低气道平台压,是床边选择最佳PEEP的可行方法.     

床旁超声指导下肺保护通气对ARDS患者氧合指数的影响研究

目的探讨床旁超声指导下肺保护通气对急性呼吸窘迫综合征(acute respiratory distress syndrome, ARDS)患者氧合指数的影响。方法将125例ARDS患者分为床旁超声指导组(n=63)和最大氧合法组(n=62)。床旁超声指导组通过连续两次超声再气化评分增加幅度30%则将肺复张后PEEP值增加2cmH_2O,以此值作为肺复张后最佳PEEP值;最大氧合法组在氧合指数原基础上降低幅度10%,则重新将PEEEP增加22cmH_2O,以此值作为肺复张后最佳PEEP值。结果床旁超声指导组最佳PEEP值明显高于最大氧合法组,APACHEⅡ评分明显低于最大氧合法组,ICU留院时间明显短于最大氧合法组,P0.05。肺复张0.5、1h后,床旁超声指导组氧合指数明显低于最大氧合法组,但肺复张2h后,床旁超声指导组氧合指数明显高于最大氧合法组,P0.05,随着肺复张时间的延长,氧合指数呈逐渐增高的倾向P0.05。床旁超声指导组PVPI、ELWI明显低于最大氧合法组,P0.05。结论床旁超声指导下肺保护通气,有助于明显改善ARDS患者肺复苏后氧合指数,且不影响血流动力学参数。     

打开肺通气策略治疗重症ARDS的可行性研究

目的 探讨打开肺通气策略治疗重症急性呼吸窘迫综合征(ARDS)的临床价值.方法 对14例重症ARDS患者采用肺复张手法联合双水平正压通气,动态观察肺开放策略实施对动脉血气指标、中心静脉压(CVP)和平均动脉压(MAP)和肺顺应性的变化,并与传统呼吸方式就带机时间、ICU住院时间和病死率、并发症等对比.结果 患者肺顺应性明显提高,氧合功能障碍明显改善,待机时间缩短、存活率提高.结论 肺开放策略治疗重症ARDS明显改善了患者的氧合功能,对血流动力学影响小,安全有效地提高了抢救成功率.     

不同模式通气治疗对颅脑损伤合并ARDS患者的影响

目的探讨不同通气模式在颅脑损伤合并急性呼吸窘迫综合征(ARDS)患者治疗中的应用效果。方法将62例颅脑损伤合并ARDS患者纳入研究对象,在统一初始通气治疗6~8h后,随机分为Ⅰ、Ⅱ两组,每组31例,分别再给予不同机械通气模式实验,Ⅰ组采用同步间歇指令通气(SIMV)+压力支持通气(PSV)模式,而Ⅱ组采用适应性支持通气(ASV)+肺复张策略(LRM)模式;实验期分别对两组血气分析指标、呼吸力学参数及相关血流动力学指标进行观察记录。结果实验过程中,在相同PEEP水平下,两组间在MAP、Pa CO2及PH值方面比较差异无显著性(P0.05);而采用ASV+LRM模式的Ⅱ组患者在RR、CVP、PIP、Pplat及Qs/Qt水平较Ⅰ组患者降低(P0.05),在Pa O2/Fi O2、Pa O2则较Ⅰ组患者增高(P0.05)。结论在颅脑损伤合并ARDS患者通气治疗中,ASV+LRM模式与SIMV模式对患者的血流动力学影响相同,但ASV+LRM模式下人机协调性好,在预防肺气压伤及改善氧合方面具有优势。     

急性呼吸窘迫综合征肺复张时机探讨

目的:在急性呼吸窘迫综合征(ARDS)治疗过程中,探索肺复张的时机。方法:选取3例并发ARDS的甲型H1N1流感患者,设置呼吸机基本参数:通气模式压力调节-容量控制(PRVC),潮气量(Vt)6～8mL/kg,较高呼气末正压(PEEP),根据氧合目标是否达到,平台压是否急速增加和>40cmH2O,是否出现CO2潴留,决定是否使用肺复张。结果:患者均存活,均未出现气胸,行肺复张1例,颈部出现皮下气肿,在肺复张过程中需要用血管活性药物保证血压稳定。结论:ARDS时,如果在增加PEEP后,PaO2有改善,平台压<30cmH2O(肥胖者<40cmH2O),应保持在这个水平直至持续30h。肺复张动作的适应症是:ARDS时,PEEP已经达到较高水平仍然存在的顽固性低氧血症。肺复张动作的时机是:如果PEEP已经达到较高水平,氧合仍不稳定,平台压越来越高,降低潮气量不能阻止平台压增加,特别是PaCO2突然增加,血流动力学尚稳定。去复张后,调整PEEP可以达到氧合目标的患者,不再作肺复张操作。     

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.     

Oxygenation response to a recruitment maneuver during supine and prone positions in an oleic acid-induced lung injury model

Prone position and recruitment maneuvers (RM) are proposed as adjuncts to mechanical ventilation to open up the lung and keep it open. We studied the oxygenation response to a RM (composed of a 30-s sustained inflation at 60 cm H(2)O airway pressure) performed in prone and supine positions in dogs after oleic acid- induced lung injury using an inspired O(2) fraction of 0.60. In one group (n = 6) first supine then prone positions were examined after a RM at 8 cm H(2)O and 15 cm H(2)O of positive end-expiratory pressure (PEEP). In the second group (n = 6) the sequence of positions was reversed. Prone positioning after supine position always improved oxygenation, whereas the decrement in Pa(O(2)) was relatively small when dogs were returned to the supine position. Oxygenation improved in both groups after a RM, and the improvement was sustained (after 15 min) in the prone position at 8 cm H(2)O of PEEP, but 15 cm H(2)O of PEEP was required in supine position. Our results suggest that a RM improves oxygenation more effectively with a decreased PEEP requirement for the preservation of the oxygenation response in prone compared with supine position.     

Recruitment maneuvers during lung protective ventilation in acute respiratory distress syndrome.

The objective was to analyze the physiologic effects of recruitment maneuvers (RM) in 17 patients with acute respiratory distress syndrome (ARDS) ventilated with a lung protective strategy. RM consisted of 2 min of pressure-controlled ventilation at a peak pressure of 50 cm H(2)O and a positive end-expiratory pressure (PEEP) above the upper inflection point of the respiratory pressure-volume curve obtained at zero PEEP. In eight patients, RM were repeated in the late phase of ARDS. Oxygenation did not change 15 min after RM in the early and late phase of ARDS. When Pa(O(2))/fraction of inspired oxygen (FI(O(2))) increased during RM, venous admixture (Q VA/Q T) decreased. The opposite occurred in patients in whom Pa(O(2))/FI(O(2)) decreased during RM. RM-induced changes in cardiac output were not observed. A significant correlation was found between RM-induced changes in Pa(O(2))/FI(O(2)) during the RM and changes in respiratory system compliance at 15 min (r = 0.66, p < 0.01) and RM-induced changes in Q VA/Q T (r = -0.85; p < 0.01). The correlation between RM-induced changes in Pa(O(2))/FI(O(2)) in responders (improvement in Pa(O(2))/FI(O(2)) of greater than 20% during the RM) and the inspired oxygen fraction was also significant. In ARDS patients ventilated with a lung protective strategy we conclude that RM have no short-term benefit on oxygenation, and regional alveolar overdistension capable of redistributing blood flow can occur during RM.     

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。     

应用肺动态压力-容积曲线低位转折点选择最佳呼气末正压的研究

目的探讨根据动态肺压力-容积曲线低位转折点压力(Pinf)选择急性呼吸窘迫综合征(ARDS)患者最佳呼气末正压(PEEP)的可行性.方法以8例早期ARDS患者为研究对象,测定动态肺压力-容积曲线及Pinfd.采用低流速法测定准静态肺压力-容积曲线,并确定静态肺压力-容积曲线低位转折点压力(Pinfs).调整PEEP水平,观察患者血流动力学、肺机械力学和氧代谢的变化.结果当PEEP从Pinfd-6cmH2O水平增加到Pinfd+6cmH2O时,动脉血氧分压、动脉血氧饱和度、气道平均压和气道峰压均显著增加.与Pinfd+6cmH2O比较,Pinfd-4cmH2O时的动态肺顺应性显著增高.Pinfd+6cmH2O时的心脏指数有降低趋势,Pinfd-4cmH2O时的氧输送有升高趋势.当Pinfd为(12.8±3.2)cmH2O,Pinfs为(11.0±3.2)cmH2O,两者具有正相关性(r=0.99,P《0.05).回归方程为Pinfd=1.66+1.01×Pinfs.结论当ARDS患者行机械通气治疗时,Pinfd-4cmH2O或Pinfs-2cmH2O为最佳PEEP,可获得最大氧输送.     

呼气末压力为零时的静态压力容积曲线在急性呼吸窘迫综合征患者控制性肺膨胀中的应用

目的　评价呼气末压力为零 (ZEEP)时静态压力 容积 (P V)曲线在预测急性呼吸窘迫综合征 (ARDS)患者对控制性肺膨胀 (SI)反应性的作用。方法　 2 0例ARDS患者进行机械通气并测量ZEEP时的静态P V曲线 ,在使用呼气末正压通气 (PEEP) 2h后进行SI。根据 2 0例患者使用SI后改良氧合指数 (PaO2 /FiO2 )进行分组 ,增加≥ 2 0 %为SI反应组 (A组 ) ,<2 0 %为SI无反应组 (B组 )。结果　(1)A组ZEEP时静态P V曲线参数c - 2d≥ 0cmH2 O(1cmH2 O =0 0 98kPa) ,且c≥ 18cmH2 O ,呈向上凹的形态 ;而B组c - 2d <0cmH2 O或c <18cmH2 O ,呈向上凸的形态或一直线。 (2 )使用SI后 ,A组患者可减少肺内分流 (P =0 0 0 6 ) ,而B组不减少肺内分流 (P =0 339)。相同吸气压下的肺容积增加 ,A、B组间比较差异有显著性 [(2 4 1± 111)ml,(2 9± 4 6 )ml,P =0 0 36 ]。结论ARDS患者在ZEEP时静态P V曲线具有不同的形态 ,使用曲线参数的c - 2d及c值可迅速判断静态P V曲线形态 ,对指导预测ARDS患者中SI治疗具有一定的意义。     

外源性肺泡表面活性物质联合肺泡复张手法对急性呼吸窘迫综合征的疗效

目的 观察肺泡表面活性物质(PS)、肺泡复张手法(RM)及两者联合治疗ARDS的疗效.方法 健康新西兰长耳白兔28只,反复温盐水肺泡灌洗建立ARDS动物模型,行容积控制通气,通气稳定后按随机数字表法分为对照组、PS组、RM组及PS+RM组,每组7只,分别气管内注入安慰剂、外源性PS、实施RM或PS联合RM治疗,观察动脉血气及呼吸力学指标的变化.处理后4 h处死动物,行病理组织学检查评价肺损伤程度.结果 (1)对照组、PS组、RM组和PS+RM组的PaO2分别为(74 ±15)、(234±42)、(231±17)和(253±52)mm Hg(1 mm Hg=0.133 kPa),PS、RM和PS+RIM3组均高于对照组(F=84.201,P<0.01),PS、PS+RM组氧合改善稳定,RM组PaO2随观测时间延长呈下降趋势;(2)4组的PaCO2分别为(56±11)、(46±10)、(51±8)和(46±10)mm Hg,对照组明显高于PS、PS+RM组(F=4.234,P<0.05).RM组PaCO2随时间延长呈增高趋势;(3)4组动物气道峰压分别为(33±2)、(23±1)、(24±2)和(22±1)cm H2O(1 cm H2O=0.098 kPa),静态肺顺应性(Cst)分别为(1.1±0.3)、(1.7±0.3)、(1.5±0.1)、(1.9±0.4)ml/cm H2O,PS、RM、PS+RM 3组气道峰压、Cst均较对照组显著改善(F值分别为74.911、15.863,均P<0.01).RM组Cst改善较PS+RM组差(q=2.58,P<0.05);(4)PS、RM、PS+RM 3组动物肺损伤评分分别为3.9 ±0.8、6.1±0.7和4.2±0.6,均低于对照组的13.5±0.7(F=369.6,P<0.01),RM组高于PS及PS+RM组(q值分别为6.35、5.70,均P<0.01).结论 ARDS早期补充外源性PS或实施RM均能有效改善氧合及肺脏顺应性,但RM后易出现肺泡再萎陷及呼吸机相关性肺损伤;PS联合RM治疗能防止肺泡再萎陷,并可减轻呼吸机相关性肺损伤.     

Optoelectronic plethysmography in intensive care patients

We used optoelectronic plethysmography to study 11 normal subjects during quiet and deep breathing, six sedated and paralyzed patients with acute lung injury and acute respiratory distress syndrome (ALI/ARDS) receiving continuous positive pressure ventilation (CPPV) (positive end-expiratory pressure [PEEP] = 10 cm H(2)O, tidal volume [VT] = 300, 600, 900 ml), and seven ALI/ARDS patients receiving pressure support ventilation (PSV) (PEEP 10 cm H(2)O, pressure support = 5, 10, 15, 25 cm H(2)O). The volumes measured using optoelectronic plethysmography were compared with measurements taken using spirometry and pneumotachography. The three methods were highly correlated. The discrepancies found were 1.7 +/- 5.9%, -1.6 +/- 5.4%, and 4.9 +/- 6.4% when comparing optoelectronic plethysmography with spirometry, optoelectronic plethysmography with pneumotachography, and spirometry with pneumotachography, respectively. Accuracy of the compartmentalization procedure (upper thorax, lower thorax, and abdomen) was assessed by calculating compartmental volume changes during isovolume maneuvers. The discrepancy from the ideal zero line was -2.1 +/- 48.3 ml. Abdominal contribution to inspired volume was greater for normal subjects than for PSV patients (63 +/- 11% versus 43 +/- 14%, p < 0.001). It decreased with VT for normal subjects (48.5 +/- 15%, p < 0.05), whereas it increased for CPPV patients (61 +/- 10%, p < 0.05). No significant distribution differences were found between 5 and 25 cm H(2)O PSV. We conclude that optoelectronic plethysmography is a feasible technique able to provide unique data on the distribution of chest wall volume changes in intensive care patients.     

急性呼吸窘迫综合征犬肺牵张指数与肺复张及氧合的关系

目的探讨以不同肺牵张指数(lung stress index)选择的呼气末正压(PEEP)与急性呼吸窘迫综合征(ARDS)肺复张容积与氧合的关系。方法油酸静脉注射复制犬ARDS模型,容量控制通气,流速恒定的压力-时间(P-t)曲线吸气支,回归法计算得方程P=a×timeb+c,b为肺牵张指数。调整PEEP水平使b=1。采用控制性肺膨胀实施肺复张手法,复张后再次调整PEEP水平分别达到b=1、0．60．05)。在呼吸力学方面,与复张后b=1相比, 1．1相似文献   

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.