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   

腹腔镜结直肠癌手术中不同通气策略对患者机械功及炎症因子水平的影响

［摘要］　目的　观察腹腔镜结直肠癌手术中不同通气策略对患者机械功（mechanical power，MP）及炎症因子水平的影响。方法　选择2021年5月至2021年11月在广州市红十字会医院接受腹腔镜下结直肠癌手术的患者60例，采用随机数字表法将其分为常规通气组（V组）和肺保护通气组（P组），每组30例。V组：潮气量（VT）=9 ml/kg，呼吸末正压（PEEP）=0 cmH₂O。P组：VT=7 ml/kg，PEEP=5 cmH₂O。于气管插管后5 min（T₁）、建立气腹后10 min（T₂）、60 min（T₃）和气腹消失后10 min（T₄）时间点，记录气道峰压（P_peak）、气道平台压（P_plat）、肺动态顺应性（Cdyn）并计算MP。于T₁、T₂、T₃、进入麻醉后监测治疗室（PACU）时采集动脉血行血气分析，记录血气酸碱度（pH值）、二氧化碳分压（PaCO₂）、氧分压（PaO₂）并计算氧合指数（OI）和肺泡-动脉氧分压差（P_A-aO₂）。于T₁、T₃和术毕测定血清中肺Clara细胞分泌蛋白（CC-16）、白细胞介素-6（IL-6）和中性粒细胞弹性蛋白酶（NE）水平。结果　两组MP在T₂～T₄时间点呈升高趋势，血清CC-16、IL-6和NE水平在T₃和术毕均较T₁时间点显著升高（P<0.05）。在T₂、T₃时间点，P组MP水平低于V组，差异有统计学意义（P<0.05）。在术毕即刻，P组血清CC-16、IL-6水平均显著低于V组（P<0.05）。气腹期间总MP大小与血清CC-16、IL-6和NE变化水平呈正相关（P<0.05）。结论　肺保护性通气策略的保护机制可能与较低的MP有关。     

慢性心力衰竭患者体重指数与运动耐量的相关性研究

  目的 探讨慢性收缩性心力衰竭（心衰）患者BMI与运动耐量的关系。方法 收集慢性收缩性心衰患者,计算BMI,心肺运动试验测定运动峰耗氧量（PVO₂）,公斤体重耗氧量（PKVO₂）,每搏耗氧量（VO₂/HR）和每分通气量/每分CO₂产生量（VE/VCO₂）。结果 273例慢性收缩性心衰患者中,消瘦者（BMI＜18.5 kg/m²）6例,体重正常者（BMI 18.5~<24.0 kg/m²）113例,超重者（BMI 24.0~<28.0 kg/m²）116例,肥胖者（BMI≥28 kg/m²）38例。肥胖组和超重组患者PVO₂显著高于消瘦组和正常体重组患者［（1077.2±30.9）、（1095.3±54.3）ml/min比（550.2±192.1）、（886.0±31.2）ml/min］,而PKVO₂和VE/VCO₂显著低于消瘦组和正常体重组［（14.6±2.2）、（16.5±0.5）ml·min^-1 ·kg^-1比（14.4±0.5）、（11.6±0.9）ml·min^-1·kg^-1 ,43.4±6.1、42.3±1.5比42.3±1.5、38.6±1.6,P<0.05］。在不同心功能状态下,单相关分析显示,BMI和PVO₂呈正相关（r=0.40, P<0.01）,与PKVO₂和VE/VCO₂分别呈负相关（r=-0.15、-0.25,P值均<0.01）。多元逐步回归分析显示,年龄、性别、BMI和LVEF是PKVO₂的独立影响因素,而年龄和BMI是VE/VCO₂的独立影响因素（P<0.05）。结论 慢性收缩性心衰患者BMI与运动耐量显著相关,且是运动耐量的独立危险因素。     

水杨酸钠增强氧化应激介导耳蜗螺旋神经节神经元损伤作用的实验观察

［摘要］　目的　观察水杨酸钠（SS）作用大鼠耳蜗螺旋神经节神经元（SGN）后,SGN中氧化应激水平的变化。方法　将6只SD大鼠随机分为对照组和SS组,每组3只。通过耳蜗器官培养48 h后,用5 mM SS处理48 h,对照组不予处理,采用免疫荧光染色技术定位耳蜗器官中活性氧自由基（ROS）的主要生成位置。将15只SD大鼠随机分成5组,即对照组、SS组、SS+N-乙酰-L-半胱氨酸(NAC)组、阳性对照过氧化氢（H₂O₂）组、H₂O₂+NAC组,每组3只。通过急性分离SGN,原代培养48 h后分别用5 mM SS、5 mM SS联合100 μM NAC、300 μM H₂O₂、300 μM H₂O₂联合100 μM NAC处理48 h,对照组不予处理。采用荧光染色法检测并量化各组大鼠SGN中ROS荧光探针DCFH-DA的平均荧光强度;采用CCK8法检测SGN细胞存活率。结果　在耳蜗器官培养中,SS作用后,免疫荧光染色显示ROS荧光增强,并且主要在SGN中表达,而在其他细胞中荧光强度无明显变化。为进一步量化荧光强度,在原代培养SGN中加入5 mM SS处理后,荧光染色法显示ROS平均荧光强度较对照组升高（P<0.001）,与H₂O₂组结果一致（P<0.000 1）。在加入ROS抑制剂NAC之后,ROS平均荧光强度较SS组下降（P<0.01）。CCK8法结果显示,SS作用之后细胞存活率较对照组下降41.34%（P<0.01）;在加入NAC之后,细胞存活率较SS组上升36.05%（P<0.01）,与对照组比较差异无统计学意义（P>0.05）。H₂O₂组细胞存活率较对照组下降52.31%（P<0.001）,在加入NAC之后,细胞存活率较H₂O₂组上升34.73%（P<0.01）。结论　SS增强SGN的氧化应激,并且导致了SGN损伤。氧化应激抑制剂NAC可以降低SGN的氧化应激,并且对SS致SGN损伤具有保护作用。     

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.     

H2S拮抗HUVEC衰老与促进SIRT1巯基化和减少FOXO1乙酰化有关

目的]探讨沉默信息调节因子1(SIRT1)/叉头转录因子O1(FOXO1)在H₂S拮抗H₂O₂诱导内皮细胞衰老过程中的作用。 [方法]建立内皮细胞衰老模型,通过衰老相关β-半乳糖苷酶(SA-β-gal)染色在光学显微镜下观察到的蓝染细胞数(即衰老细胞)计算阳性细胞率。采用Western blot检测细胞P21、P53、纤溶酶原激活物抑制剂1(PAI-1)、叉头转录因子O1(FOXO1)、乙酰化FOXO1(ac-FOXO1)、锰超氧化物歧化酶(MnSOD)及过氧化氢酶的蛋白表达水平,采用生物素转换法测定S-巯基化SIRT1的表达,采用活性氧(ROS)检测定量评估细胞内ROS水平。 [结果]经100 μmol/L H₂O₂处理可显著提高SA-β-gal染色阳性细胞率和P21、P53、PAI-1的蛋白表达,提示衰老细胞模型成功建立,而100 μmol/L NaHS可明显拮抗这一作用,SA-β-gal染色阳性细胞数明显下降(P＜0.01),P21、P53、PAI-1的蛋白表达显著降低(P＜0.01)。与对照组相比,H₂O₂组SIRT1、FOXO1、ac-FOXO1、MnSOD及过氧化氢酶的蛋白表达显著降低(P＜0.05或P＜0.01),ac-FOXO1/FOXO1比值显著增加(P＜0.01),ROS水平明显升高(P＜0.01)。与H₂O₂组相比,NaHS＋H₂O₂组SIRT1、S-巯基化SIRT1、FOXO1、ac-FOXO1、MnSOD及过氧化氢酶的蛋白表达显著升高((P＜0.05或P＜0.01),ac-FOXO1/FOXO1比值显著下降(P＜0.01),ROS水平明显降低(P＜0.05)。 [结论]H₂S可拮抗H₂O₂诱导的HUVEC衰老,其机制与促进SIRT1巯基化和减少FOXO1乙酰化有关。     

耐索拉非尼肝癌细胞株的构建及耐药机制研究

［摘要］　目的　构建耐索拉非尼肝癌细胞株并探讨其耐药机制。方法　应用HepG2、Huh7细胞通过浓度递增法建立耐索拉非尼细胞模型。通过CCK8法检测细胞对不同浓度索拉非尼的敏感性。通过划痕实验检测细胞的迁移能力。通过流式细胞术分析细胞凋亡情况。通过荧光实时定量RT-PCR和Western blot实验检测凋亡相关因子caspase-3和自噬标志因子P62、LC3的表达水平。结果　获得耐索拉非尼肝癌细胞株HepG2-SR、Huh7-SR。随着索拉非尼药物干预浓度的升高，耐药细胞株及野生型细胞株的存活率均逐渐降低。HepG2-SR细胞的半数抑制浓度（IC₅₀）显著高于HepG2细胞［（15.74±0.38）μM vs （7.27±0.44）μM ；t=5.450，P<0.001］；Huh7-SR细胞的IC₅₀显著高于Huh7细胞［（11.73±0.27）μM vs （4.92±0.31）μM；t=4.807，P<0.001］。相较于野生型细胞株，耐药细胞株具有更高的抗凋亡和迁徙能力。耐药细胞株的caspase-3、P62表达水平显著低于野生型细胞株（P<0.05），而LC3表达水平显著高于野生型细胞株（P<0.05）。结论　耐索拉非尼肝癌细胞株HepG2-SR、Huh7-SR具有更强的抗凋亡、抗生殖抑制和迁移能力，且自噬水平更高，为研究肝细胞癌对索拉非尼的耐药机制提供了基础。     

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。     

加温加氧超声雾化对急性加重期慢性阻塞性肺疾病的疗效观察

［摘要］　目的　观察加温加氧超声雾化对急性加重期慢性阻塞性肺疾病（AECOPD）的疗效。方法　选取2018年4月至2019年8月广西壮族自治区江滨医院收治的AECOPD患者60例,采用随机数字表法将其分为对照组和观察组,每组30例。对照组予传统氧气雾化吸入治疗,观察组予加温加氧超声雾化吸入治疗。两组疗程均为1周。比较两组治疗前后慢性阻塞性肺疾病评估测试（CAT）评分、动脉血氧分压（PaO₂）、动脉血二氧化碳分压（PaCO₂）、第1秒用力呼气容积占预计值百分比（FEV₁%pred）。结果　治疗前,两组CAT评分、PaO₂、PaCO₂、FEV₁%pred比较差异无统计学意义（P>0.05）。治疗后,观察组CAT评分、PaCO₂低于对照组,PaO₂、FEV₁%pred高于对照组,差异有统计学意义（P<0.05）。结论　与传统氧气雾化相比,加温加氧超声雾化对AECOPD的疗效更佳。     

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。     

Role of positive end-expiratory pressure changes on functional residual capacity in surfactant treated preterm infants

Both surfactant replacement and positive end-expiratory pressure (PEEP) increase lung volume in infants with respiratory distress syndrome (RDS). We measured pulmonary mechanics and functional residual capacity (FRC) in 21 preterm infants with RDS, > 48 hr post-surfactant therapy (BW, 1,168 ± 441 g; GA, 28.3 ± 2.8 weeks; postnatal age, 3–7 days). A non-linear but significant increase in mean FRC was noted as PEEP increased from 2 to 5 cmH₂O: 18.4 ± 4.7mL/kg at 2 cmH₂O; 19.7 ± 4.3 mL at 3 cm H₂O; 22.6 ± 5.5ml/kg at 4 cmH₂O; and 26.2 ± 6.2 mL/kg at 5 cmH₂O (P < 0.01). Because of the synergistic combined effect on lung volume, surfactant treated neonates should be weaned cautiously from PEEP during ventilatory management. Our study also suggests that the occurrence of inadvertent end-distending pressure during FRC measurement in the ventilated neonate lead to erroneous results. Pediatr Pulmonal. 1994;18:89–92. © 1994 Wiley-Liss, Inc.     

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.     

Preservation of pulmonary function in the ventilated neonatal piglet with normal lungs

Little attention has been focused on the progressive pulmonary deterioration which occurs in mechanically ventilated infants with normal or mildly abnormal lungs. We hypothesized that lung function would deteriorate over a 24-hr period in anesthetized neonatal piglets with normal lungs mechanically ventilated at 2 cm H₂O PEEP (2PEEP group). We further hypothesized that an intermittent lung inflation procedure consisting of 15 out of 60 min of increasing lung distention (4,8,12 cm H₂O PEEP), with the remaining 45 min at 2 cm H₂O PEEP (Inflation group) would prevent this deterioration in lung function, similar to piglets mechanically ventilated continuously at 6 cm H₂O PEEP (6PEEP). Results indicate that 2PEEP piglets experienced progressive deterioration in lung function, including dynamic lung compliance (-42%) and lung resistance (+55%). In contrast, Inflation piglets and GPEEP piglets had no deterioration in lung function. Hemodynamics were similar between groups, although they were the most stable in the 6PEEP group. Histopathological changes were not significantly different. We conclude that (1) prolonged mechanical ventilation at 2 cm H₂O PEEP in neonatal piglets resulted in progressive deterioration in pulmonary function, (2) intermittent lung inflation or continuous 6 cm H₂O PEEP prevented deterioration, and (3) functional changes occurred without changes in histopathology. Lung inflation strategies other than PEEP can be used to prevent deterioration in lung function which accompanies prolonged mechanical ventilation in anesthetized nonspontaneously breathing piglets with normal lungs. © 1995 Wiley-Liss, Inc.     

Alveolar Recruitment Strategy During Cardiopulmonary Bypass Does Not Improve Postoperative Gas Exchange and Lung Function

Pulmonary dysfunction with impairment of lung function and oxygenation is one of the most serious problems in the early postoperative period after cardiac surgery. In this study we investigated the effect of alveolar recruitment strategy during cardiopulmonary bypass on postoperative gas exchange and lung function. This prospective randomized study included 32 patients undergoing elective myocardial revascularization with cardiopulmonary bypass. In 16 patients 5 cm H₂O of positive end-expiratory pressure was applied after intubation and maintained until extubation (Group I). In the other 16 patients (group II) a positive end expiratory pressure (PEEP) of 5 cm H₂O was maintained as well but was increased to 14 cm H₂O every 20 min for 2 min during cross clamp. Measurements were taken preoperatively, before skin incision, before and after (3, 24, 48 h) cardiopulmonary bypass and before discharge (6th postoperative day). Postoperative gas exchange, extravascular lung water and lung function showed no significant difference between the groups. Postoperative pulmonary function variables were lower in both groups compared to baseline values. In patients with normal preoperative pulmonary function, application of an alveolar recruitment strategy during cardiopulmonary bypass does not improve postoperative gas exchange and lung function after cardiac surgery.     

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.     

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.     

A decremental PEEP trial for determining open-lung PEEP in a rabbit model of acute lung injury

A positive end-expiratory pressure (PEEP) above the lower inflection point (LIP) of the pressure-volume curve has been thought necessary to maintain recruited lung volume in acute lung injury (ALI). We used a strategy to identify the level of open-lung PEEP (OLP) by detecting the maximum tidal compliance during a decremental PEEP trial (DPT). We performed a randomized controlled study to compare the effect of the OLP to PEEP above LIP and zero PEEP on pulmonary mechanics, gas exchange, hemodynamic change, and lung injury in 26 rabbits with ALI. After recruitment maneuver, the lavage-injured rabbits received DPTs to identify the OLP. Animals were randomized to receive volume controlled ventilation with either: (a) PEEP = 0 cm H2O (ZEEP); (b) PEEP = 2 cm H2O above OLP (OLP + 2); or (c) PEEP = 2 cm H2O above LIP (LIP + 2). Peak inspiratory pressure and mean airway pressure were recorded and arterial blood gases were analyzed every 30 min. Mean blood pressure and heart rate were monitored continuously. Lung injury severity was assessed by lung wet/dry weight ratio. Animals in OLP + 2 group had less lung injury as well as relatively better compliance, more stable pH, and less hypercapnia compared to the LIP + 2 and ZEEP groups. We concluded that setting PEEP according to the OLP identified by DPTs is an effective method to attenuate lung injury. This strategy could be used as an indicator for optimal PEEP. The approach is simple and noninvasive and may be of clinical interest.     

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。     

Montelukast versus inhaled corticosteroids in the management of pediatric mild persistent asthma

Background

Lung tissue of patients with acute respiratory distress syndrome (ARDS) is heterogeneously damaged and prone to develop atelectasis. During inflation, atelectatic regions may exhibit alveolar recruitment accompanied by prolonged filling with air in contrast to regions with already open alveoli with a fast increase in regional aeration. During deflation, derecruitment of injured regions is possible with ongoing loss in regional aeration. The aim of our study was to assess the dynamics of regional lung aeration in mechanically ventilated patients with ARDS and its dependency on positive end-expiratory pressure (PEEP) using electrical impedance tomography (EIT).

Methods

Twelve lung healthy and twenty ARDS patients were examined by EIT during sustained step increases in airway pressure from 0, 8 and 15 cm H₂O to 35 cm H₂O and during subsequent step decrease to the corresponding PEEP. Regional EIT waveforms in the ventral and dorsal lung regions were fitted to bi-exponential equations. Regional fast and slow respiratory time constants and the sizes of the fast and slow compartments were subsequently calculated.

Results

ARDS patients exhibited significantly lower fast and slow time constants than the lung healthy patients in ventral and dorsal regions. The time constants were significantly affected by PEEP and differed between the regions. The size of the fast compartment was significantly lower in ARDS patients than in patients with healthy lung under all studied conditions.

Conclusion

These results show that regional lung mechanics can be assessed by EIT. They reflect the lower respiratory system compliance of injured lungs and imply more pronounced regional recruitment and derecruitment in ARDS patients.     

Bi-level Positive Airway Pressure (BiPAP) with Standard Exhalation Valve Does Not Improve Maximum Exercise Capacity in Patients with COPD

Background: Although BiPAP has been used as an adjunct to exercise, little is know about its effect on exercise in COPD. We aimed to evaluate the acute effect of BiPAP delivered with a standard valve (Vision, Respironics), compared to no assist, on exercise capacity in individuals with COPD. Methods: Peak exercise workload (WL_peak), dyspnea (Borg), end-expiratory lung volume (EELV), tidal volume (V_T), minute ventilation (V_E), O₂ uptake (VO₂), and CO₂ production (VCO₂) were assessed in 10 COPD patients (FEV₁ 53 ± 22% pred) during three symptom-limited bicycle exercise tests while breathing i) without a ventilator (noPS), ii) with a pressure support (PS) of 0 cm H₂O (PS0; IPAP & EPAP 4 cm H₂O) and iii) PS of 10 cm H₂O (PS10; IPAP 14 & EPAP 4 cm H₂O) on separate days using a randomized crossover design. Results: WL_peak was significantly lower with PS10 (33 ± 16) and PS0 (30.5 ± 13) than noPS (43 ± 19) (p < 0.001). Dyspnea at peak exercise was similar with noPS, PS0 and PS10; at isoload it was lower with noPS compared to PS10 and PS0 (p < 0.01). V_T and V_E were highest with PS10 and lowest with noPS both at peak exercise and isoload (p < 0.001). EELV was similar at peak exercise with all three conditions. VO₂ and VCO₂ were greater with PS10 and PS0 than noPS (p < 0.001), both at peak exercise and isoload. Conclusion: Use of BiPAP with a standard exhalation valve during exercise increases V_T and V_E at the expense of augmenting VCO₂ and dyspnea, which in turns reduces WL_peak in COPD patients.