控制性肺膨胀治疗急性呼吸窘迫综合征后最佳PEEP选择

目的探讨控制性肺膨胀（SI）治疗急性呼吸窘迫综合征（ARDS）后最佳呼气末正压（PEEP）。方法利用肺泡灌洗法建立家兔ARDS模型,测定静态肺顺应性（P—V）曲线,确定曲线低位转折点（Pinf）,实施SI后,分别以Pinf-6 cmH2O、Pinf-4 cmH2O、Pinf-2 cmH2O、Pinf、Pinf＋2 cmH2O、Pinf＋4 cmH2O、Pinf＋6 cmH2O的PEEP进行机械通气,监测家兔血流动力学、肺力学、肺气体交换。结果随着PEEP增加,PaO2和SaO2逐渐增加,气道峰值压、平台压、Pm逐渐升高。与Pinf、Pinf＋6 cmH2O相比,Pinf-4 cmH2O时动态肺顺应性（Cdyn）最高。结论ARDS进行机械通气时,在实施SI后以静态P—V曲线Pinf-4 cmH2O为ARDS早期最佳PEEP。     

允许性高碳酸血症治疗ARDS对肺力学的影响

目的探讨允许性高碳酸血症(PHC)对重度急性呼吸窘迫综合征(ARDS)肺力学及血流动力学的影响。方法观察不同潮气量(VT)时,30例重度ARDS患者肺气体交换、肺力学的改变。结果当VT从15ml/kg降至6ml/kg时,病人均出现PHC,动脉血氧分压、氧饱和度和混合静脉血氧饱和度显著降低(P<0.05)。PHC时,气道压力显著降低,气道阻力明显增高(P<0.05)。静态肺压力-容积曲线高位转折点对应的压力为(22.2±1.9)cmH2O,容积为10ml/kg。结论在实施PHC时,只有当气道平台压<20~25cmH2O时才有可能避免肺泡过度膨胀,减少呼吸机相关性肺损伤。     

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。     

低流速法测定急性呼吸窘迫综合征静态肺压力-容积曲线的比较性实验研究

目的 探讨低流速法代替气道闭合法测定急性呼吸窘迫综合征(ARDS)静态肺压力-容积曲线的可行性.方法 采用内毒素(LPS)诱导的绵羊ARDS模型,利用低流速法和气道闭合法测定肺压力-容积曲线,并用双向直线回归法确定相应曲线低位转折点压力(Pinf), 低流速法和气道闭合法测定的Pinf分别表示为Pinfd和Pinfb.结果 Pinfd与Pinfb分别为(8.91±0.82) cm H2O与(8.59±0.78) cm H2O ,两者比较差异无显著性,具有显著相关性(r=0.93, P<0.05).相同潮气量情况下,两种方法 测定的相应气道压力呈正相关(r=0.99, P<0.005).低流速法和气道闭合法测定的肺顺应性分别为(19±7) L/cm H2O和(20±7) L/cm H2O,差异无显著性(P>0.05).低流速法测定肺压力-容积曲线的时间需3～4 min,气道闭合法需30～35 min.结论 低流速法测定肺压力-容积曲线准确安全,简便省时,可代替气道闭合法.     

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-容积曲线与急性呼吸窘迫综合征

急性呼吸窘迫综合征(ARDS)的充气相压力-容积曲线(P-V曲线)可概括为三段两点:低位平坦段,下曲点(LIP),中间陡直段,上曲点(UIP),高位平坦段。可根据P-V曲线个体化地选择PEEP(呼气末压力)和Vt(潮气量)。一般选择PEEP和PLIP,另有观点认为应根据呼气相的P-V曲线选择PEEP。UIP代表肺过度扩张的开始,应使 Vt相似文献   

吸痰联合肺复张后不同PEEP水平对ARDS机械通气患者呼吸力学的影响

目的探讨吸痰联合肺复张后调整不同的呼气末正压(PEEP)水平对急性呼吸窘迫综合征(ARDS)机械通气患者呼吸力学的影响。方法选择22例ARDS机械通气患者,吸痰后给予肺复张,在原有PEEP水平(P0)基础上调整。于调整PEEP后10、30、60 min,监测患者各压力水平气道峰压(Ppeak)、平台压(Pplat)、肺实时顺应性(Cd)变化。结果与实验前比较,Cd在不同PEEP水平均显著升高(P均<0.05)。随着PEEP水平的不断增加,Cd也随之升高,与调整后其他PEEP水平相比,P0+4 cmH2O和P0+6 cmH2O测得Cd显著高于其他水平(P<0.05)。30 min Cd监测值显著高于10、60 min(P均<0.05)。与其他四组比较,P0+4 cmH2O和P0+6 cmH2O在30～60 min时段Cd下降趋势较小(P<0.05)。随着PEEP水平不断增加,Ppeak、Pplat也随之升高,但不同PEEP水平对Ppeak、Pplat的影响无统计学差异(P>0.05)。结论 ARDS机械通气患者在吸痰联合肺复张后选择在P0基础上增加4～6 cmH2O,有利于维持患者复张后肺顺应性,延缓肺泡去复张时间。     

急性呼吸窘迫综合征绵羊肺复张与静态肺压力-容积曲线低位转折点的关系

呼气末正压（PEEP）可复张急性呼吸窘迫综合征（ARDS）时塌陷的肺泡，增加肺容积。一般认为，静态肺压力-容积（P-V)曲线吸气支上的低位转折点（LIP）代表大量肺泡复张，临床上常根据LIP来选择PEEP，但LIP与肺泡复张之间的关系如何？本实验通过探讨LIP与肺复张容积的关系，为临床合理选择PEEP提供实验依据。     

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。     

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.     

Effect of PEEP on the arterial minus end-tidal carbon dioxide gradient

The effect of PEEP on the arterial minus end-tidal carbon dioxide gradient (PaCO2-PetCO2) was evaluated in 13 adult patients with acute respiratory failure. The morphologic study of the pressure-volume (P-V) curves allowed separation of the patients into two groups: group 1 (n = 7) with initial inflection point in the (P-V) curve, and group 2 without inflection point. We hypothesized that the profile of the PaCO2-PetCO2 gradient would indicate an appropriate PEEP level only in patients with recruitable air spaces. We ventilated group 1 patients with zero end expiratory pressure (ZEEP), PEEP corresponding to inflection point pressure (PEEPPi) and PEEP5 cm H2O above PEEPPi, and group 2 patients with ZEEP, 6 cm H2O PEEP and 12 cm H2O PEEP. The PaCO2-PetCO2 gradient changed significantly in group 1 (ZEEP: 13.59 mm Hg; PEEPPi: 8.33 mm Hg; PEEPPi + 5 cm H2O: 10.54 mm Hg), but not in group 2 (ZEEP: 14.15 mm Hg; PEEP 6 cm H2O: 14.20 mm Hg; PEEP 12 cm H2O: 16.53 mm Hg). Our results show that the PaCO2-PetCO2 gradient may be useful in selecting a PEEP level which produces alveolar recruitment, but only in those patients with initial inflection point in the P-V curve.     

静态压力-容积曲线在急性呼吸窘迫综合征肺复张和肺塌陷中的应用

目的在新西兰兔肺泡灌洗的急性呼吸窘迫综合征(ARDS)机械通气过程中,使用静态压力-容积(P-V)曲线描述肺复张及肺塌陷的特征,寻找复张肺泡并减少呼吸机相关性肺损伤的方法。方法在10例新西兰兔肺泡灌洗ARDS模型中,动态CT扫描肺泡逐步复张及逐步塌陷时肺内气体压力、容积及分布,同时测量静态P-V曲线,评估肺复张和肺塌陷的特征。结果吸气时各充气区域容积比例随气道压力的变化而变化(t=2．477-9．794,P均<0．05)。肺复张不仅包括闭合区域开放过程即肺开放,还包括充气不良区域肺泡张大的过程;肺塌陷也不只是闭合区域的产生即肺闭合,还包括充气不良区域的产生。肺开放与肺吸气频数分布不一致(r=0．219,P=0．220);肺闭合与肺呼气频数分布也不一致(r=0．094,P=0．593);静态P-V曲线顺应性仅与充气不良区域容积相关(吸气相r=0．827,P=0．006;呼气相r=0．792,P=0．011);吸气相曲线最大顺应性点压力[(16．2±3．5)cm H2O,1 cm H2O=0．098 kPa]与肺开放压[(16．4±3．4)em H2O]接近(r=0．900,P=0．002),而呼气相曲线最大顺应性点压力[(11．9±2．4)cm H2O]与肺闭合压[(11．3±2．5)cm H2O]接近(r= 0．887,P=0．003)。结论吸气时肺复张和肺泡过度膨胀同时发生。静态P-V曲线顺应性可反映肺增大潜能,并可预测肺开放压和闭合压。     

Recruitment and derecruitment during acute respiratory failure: a clinical study.

In a model of acute lung injury, we showed that positive end-expiratory pressure (PEEP) and tidal volume (VT) are interactive variables that determine the extent of lung recruitment, that recruitment occurs across the entire range of total lung capacity, and that superimposed pressure is a key determinant of lung collapse. Aiming to verify if the same rules apply in a clinical setting, we randomly ventilated five ALI/ARDS patients with 10, 15, 20, 30, 35, and 45 cm H2O plateau pressure and 5, 10, 15, and 20 cm H2O of PEEP. For each PEEP-VT condition, we obtained computed tomography at end inspiration and end expiration. We found that recruitment occurred along the entire volume-pressure curve, independent of lower and upper inflection points, and that estimated threshold opening pressures were normally distributed (mode = 20 cm H2O). Recruitment occurred progressively from nondependent to dependent lung regions. Overstretching was not associated with hyperinflation. Derecruitment did not parallel deflation, and estimated threshold closing pressures were normally distributed (mode = 5 cm H2O). End-inspiratory and end-expiratory collapse were correlated, suggesting a plateau-PEEP interaction. When superimposed gravitational pressure exceeded PEEP, end-expiratory collapse increased. We concluded that the rules governing recruitment and derecruitment equally apply in an oleic acid model and in human ALI/ARDS.     

肺保护性通气对急性呼吸窘迫综合征兔肺部炎症反应的影响

目的　观察肺保护性通气对急性呼吸窘迫综合征 (ARDS)家兔肺部炎症反应的影响。方法　生理盐水肺泡灌洗法复制ARDS家兔模型 ,将 36只家兔随机分为 6组 :(1)正常对照组 (N组 ) ,(2 )ARDS模型组 (M组 ) ,(3)小潮气量 (VT) 最佳呼气末正压 (PEEP)组 (A组 ) ,(4)常规VT 最佳PEEP组 (B组 ) ,(5 )小VT 高PEEP组 (C组 ) ,(6 )高VT 零PEEP组 (D组 )。机械通气 4h后测定肺组织湿/干重比 (W/D) ,迁移率改变电泳法 (EMSA)测定肺组织核因子κB(NF κB)活性 ,逆转录 聚合酶链反应(RT PCR)检测肺组织中肿瘤坏死因子α(TNF α)和白细胞介素 10 (IL 10 )mRNA表达 ,酶联免疫吸附测定 (ELISA)检测肺组织TNF α及IL 10浓度。结果　A组肺组织W/D为 5 6± 1 1,不但显著低于B组(6 6± 0 8)和D组 (6 9± 1 0 ) ,而且也显著低于C组 (6 6± 1 0 ,P均 <0 0 5 ) ,但与M组 (5 8± 0 5 )比较差异无显著性 (P >0 0 5 )。A组肺组织NF κB活性 (331± 113)显著低于B组 (45 5± 6 3)、C组 (478±74 )和D组 (6 4 5± 16 2 ,P均 <0 0 5 ) ,其中D组NF κB活性最高。与A组比较 ,B、C和D组肺组织TNF α及IL 10mRNA表达及浓度显著增高 ,其中D组TNF α和IL 10mRNA表达及其浓度在各组中最高。肺组织髓过氧化物酶 (MPO)及丙二醛 (MDA)含     

压力—容量曲线对急性肺损伤家兔实行个体化保护性通气？…

OBJECTIVE: To explore the lung-protective effect of ventilation with tidal volume and PEEP determined on pressure-volume curve in oleic acid rabbit models of acute lung injury. METHODS: 24 New Zealand rabbits were randomly divided into 4 groups (V1P1, V1P2, V2P1, V2P2). After inducing lung injury, the P-V curves were measured and drawn. The low and upper inflection point pressure (Pinf and Pdef respectively) were manually determined. Two levels of tidal volume (V1 = 15 ml/kg, V2 reduced for Pplat < Pdef) and two levels of PEEP (P1 = Pinf, P2 = Pinf - 3 cm H2O) were selected. The peak airway pressure (PIP), plateau pressure (Pplat), mean pressure (PAW), static compliance (Cst), heart rate, arterial blood pressure and blood-gas analysis were measured. The lung tissues were pathologically analyzed with light microscope. RESULTS: The oxygenation was not significantly different among 4 groups. The reduced VT significantly raised PaCO2 and lowered pH. Larger VT reduced arterial blood pressure. VT and PEEP synergetically raised airway pressure. Larger PEEP improved Cst, which was counteracted by larger VT. Reduced VT significantly lessened alveolar barotrauma. Larger PEEP lightened alveolar hyaline membrane formation and hemorrhage. CONCLUSION: The ventilation with VT and PEEP determined on P-V curve has significant protective effect on the acutely injured lung.     

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.     

Influence of tidal volume on alveolar recruitment. Respective role of PEEP and a recruitment maneuver

Both reduction in tidal volume (VT) and alveolar recruitment may be important to limit ventilator-associated lung injury during mechanical ventilation of patients with the acute respiratory distress syndrome (ARDS). The aim of this study was to assess the risk of alveolar derecruitment associated with VT reduction from 10 to 6 ml/kg. Whether this VT-related derecruitment could be reversed, either by a recruitment maneuver or by an increase in positive end-expiratory pressure (PEEP) level, was also investigated. Fifteen patients with ARDS were successively ventilated using conventional VT (CVT = 10 +/- 1 ml/kg) and low VT (LVT = 6 +/- 1 ml/ kg); total PEEP (PEEPtot) was individually set at the lower inflection point (Plip) of the pressure-volume curve (PEEPtot = 11 +/- 4 cm H(2)O). Pressure-volume curves were recorded from zero PEEP (ZEEP) and from PEEP, and recruited volume (Vrec) was calculated as the volume difference between the two curves for a given pressure. Despite a similar PEEPtot, Vrec was significantly lower with LVT than with CVT, indicating low VT-induced alveolar derecruitment. Reduction in VT was associated with a reduced Sa(O(2)). In 10 patients, Vrec was also measured before and after a recruitment maneuver (two sustained inflations at 45 cm H(2)O), and after an increase in PEEP (by 4 cm H(2)O). Low VT-induced derecruitment was reversed by a recruitment maneuver and by increasing PEEP. We conclude that a reduction in VT could be responsible for alveolar derecruitment, which may be transiently reversed by a reexpansion maneuver or prevented by a PEEP increase above Plip.     

压力-容量曲线对急性肺损伤家兔实行个体化保护性通气的应用

目的研究以压力容量（P-V）曲线确定通气参数对急性肺损伤家兔肺的保护作用。方法新西兰家兔24只,随机分为4组（V1P1、V1P2、V2P1、V2P2）,每组4只。用油酸复制急性肺损伤模型,测定P-V曲线,以下曲点压力（Pinf）和上曲点压力（Pdef）分别选择呼气末正压（PEEP）的两水平：P1＝PinfP2＝Pinf－3cmH2O,潮气量（VT）两水平：V1＝15ml／kg,V2下调使平台压小于上曲点压力（Pplat＜Pdef）。观察肺力学、血气、血循环及肺病理改变。结果4组氧合效果基本相同,动脉血二氧化碳分压（PaCO2）和pH主要受VT影响。平均动脉压在大PEEP和（或）大VT时有所下降。呼吸系统静态顺应性（Cst）则以PEEP为Pinf时改善最明显,但大VT抵消了其作用且对肺泡有明显的损伤。小PEEP组肺泡透明膜变加重。结论以呼吸系统P-V曲线选择PEEP和VT进行个体化通气,对肺的力学特性和肺的病理性损伤有明显的保护作用,可能有利于改善急性肺损伤的预后。