Different positive end expiratory pressure and tidal volume controls on lung protection and inflammatory factors during surgical anesthesia

BACKGROUND Mechanical ventilation can lead to the severe impairment of the metabolic pathway of alveolar surfactants,inactivating alveolar surfactants and significantly reducing lung-chest compliance.The cardiopulmonary function of elderly patients usually reduced to a certain extent,and there are lung complications after surgical anesthesia,just like lung barotrauma caused by mechanical ventilation,atelectasis and postoperative hypoxemia.AIM To investigate the effects of different positive end expiratory pressures(PEEPs)and tidal volumes(VTs)on respiratory function,the degree of the inflammatory response and hemodynamic indexes in patients undergoing surgery under general anesthesia.METHODS A total of 120 patients undergoing surgery for gastric or colon cancer under general anesthesia in Xinghua People's Hospital from January 2017 to January 2021 were randomly divided into Group A and Group B,with 60 cases in each group.The ventilation mode in Group A was VT(6.0 mL/kg)+PEEP(5.0 cmH_(2)O),while that in Group B was VT(6.0 mL/kg)+PEEP(8.0 cmH_(2)O).Blood gas parameters,respiratory mechanical parameters,inflammatory response indicators,hemodynamic indicators and related complications were compared between the two groups.RESULTS There were no significant differences in PaCO_(2),PaO_(2),oxygen or the examined indexes at T0 between group A and group B(P>0.05).The measured PaO_(2) value of patients in group A at T3 was higher than that in group B,and the difference was significant(P<0.05).There were no significant differences in peak airway pressure(P_(peak)),mean airway pressure or dynamic pulmonary compliance(Cdyn)at T0 between group A and group B(P>0.05).The measured P_(peak) value of patients in group A at T1 was higher than that in group B,and the difference was significant(P<0.05).The measured Cdyn value at T1 and T2 was greater than that in group B(P<0.05).Before surgery,there were no significant differences in tumor necrosis factor-α(TNF-α),interleukin(IL)-6 or IL-10 between group A and group B(P>0.05).After 4 h,the measured values of TNF-αand IL-6 in group A were lower than those in group B,and the differences were significant(P<0.05).The IL-10 Level in group A was higher than that in group B(P<0.05).At T0,there were no significant differences in cardiac output,cardiac index(CI),stroke volume index(SVI)or mean arterial pressure between group A and group B(P>0.05).The measured values of CI and SVI at T2 in patients in group A were higher than those in group B,and the differences were significant(P<0.05).CONCLUSION For patients undergoing surgery for gastric or colon cancer under general anesthesia,the VT(6.0 mL/kg)+PEEP(5.0 cmH_(2)O)regimen was more effective than the VT(6.0 mL/kg)+PEEP(8.0 cmH_(2)O)regimen in protecting the lung function and ventilatory function of patients,and it had better effects on maintaining hemodynamic stability and reducing inflammatory reactions.

Expiratory flow-limitation in mechanically ventilated patients: A risk for ventilator-induced lung injury?

Expiratory flow limitation(EFL), that is the inability of expiratory flow to increase in spite of an increase of the driving pressure, is a common and unrecognized occurrence during mechanical ventilation in a variety of intensive care unit conditions. Recent evidence suggests that the presence of EFL is associated with an increase in mortality, at least in acute respiratory distress syndrome(ARDS) patients, and in pulmonary complications in patients undergoing surgery. EFL is a major cause of intrinsic positive end-expiratory pressure(PEEPi), which in ARDS patients is heterogeneously distributed, with a consequent increase of ventilation/perfusion mismatch and reduction of arterial oxygenation. Airway collapse is frequently concomitant to the presence of EFL.When airways close and reopen during tidal ventilation, abnormally high stresses are generated that can damage the bronchiolar epithelium and uncouple small airways from the alveolar septa, possibly generating the small airways abnormalities detected at autopsy in ARDS. Finally, the high stresses and airway distortion generated downstream the choke points may contribute to parenchymal injury, but this possibility is still unproven. PEEP application can abolish EFL, decrease PEEPi heterogeneity, and limit recruitment/derecruitment.Whether increasing PEEP up to EFL disappearance is a useful criterion for PEEP titration can only be determined by future studies.

不同PEEP水平联合PCV-VG通气模式对腹腔镜大肠癌根治术老年患者呼吸力学的影响

目的探讨不同呼气末正压(PEEP)水平联合压力控制容量保证通气模式(PCV-VG)对腹腔镜大肠癌根治术老年患者呼吸力学的影响。方法选择2019年11月至2020年11月于内蒙古自治区人民医院行腹腔镜大肠癌根治术的老年患者90例,根据随机数表法将患者分为三组,每组各30例,A组PEEP为0cmH2O,B组PEEP为5cmH2O,C组为个体化PEEP。比较三组患者于插管时(T_(1))、Trendelenburg体位后30min(T_(2))、Trendelenburg体位后60 min(T_(3))及手术结束时(T_(4))的气道平台压(Pplat)和肺动态顺应性(Cdyn);于麻醉诱导前(T_(0))、T_(3)及拔管后10 min(T_(5))采集动脉血标本,记录并比较动脉氧分压(PaO_(2))、动脉二氧化碳分压(PaCO_(2))值。结果三组患者T_(2)、T_(3)、T_(4)时Cdyn低于T_(1)时,T_(4)时Cdyn高于T_(2)、T_(3)时;T_(2)、T_(3)时Pplat高于T_(1)时,T_(4)时Pplat低于T_(2)、T_(3)时,且C组T_(4)时Pplat高于T_(1);T_(3)、T_(5)时PaO_(2)显著高于T_(0)时,A组T_(5)时PaO_(2)显著低于T_(3)时;T_(3)时PaCO_(2)高于T_(0)时,差异均有统计学意义(P<0.05)。T_(2)、T_(3)和T_(4)时,C组Cdyn高于A组和B组,且T_(4)时B组Cdyn显著高于A组;T_(3)时,C组PaO_(2)显著高于A组;T_(5)时,三组患者PaO_(2)分别比较后,由高到低为C组、B组、A组,差异均有统计学意义(P<0.05)。除PaCO_(2)外,其余各指标组间比较,差异均有统计学意义(P<0.05)。结论个体化滴定的PEEP联合PCV-VG通气模式可增加腹腔镜大肠癌根治术老年患者术中Cdyn及PaO_(2),改善术中氧合,减少肺损伤。

Positive End-expiratory Pressure Titration after Alveolar Flecruitment Directed by Electrical Impedance Tomography

Background： Electrical impedance tomography （EIT） is a real-time bedside monitoring tool, which can reflect dynamic regional lung ventilation. The aim of the present study was to monitor regional gas distribution in patients with acute respiratory distress syndrome （ARDS） during positive-end-expiratory pressure （PEEP） titration using EIT. Methods： Eighteen ARDS patients under mechanical ventilation in Department of Critical Care Medicine of Peking Union Medical College Hospital from January to April in 2014 were included in this prospective observational study. After recruitment maneuvers （RMs）, decremental PEEP titration was performed from 20 cmH20 to 5 cmH20 in steps of 3 cmH20 every 5-10 min. Regional over-distension and recruitment were monitored with EIT. Results： After RMs, patient with arterial blood oxygen partial pressure （PaO2） ＋ carbon dioxide partial pressure （PaCO2） 〉400 mmHg with 100% of fractional inspired oxygen concentration were defined as RM responders. Thirteen ARDS patients was diagnosed as responders whose PaO2 ＋ PaCO2, were higher than nonresponders （419 ± 44 mmHg vs. 170 ±73 mmHg, P 〈 0.0001）. In responders, PEEP mainly increased-recruited pixels in dependent regions and over-distended pixels in nondependent regions. PEEP alleviated global inhomogeneity of tidal volume and end-expiratory lung volume. PEEP levels without significant alveolar derecruitment and over-distension were identified individually. Conclusions： After RMs, PEEP titration significantly affected regional gas distribution in lung, which could be monitored with EIT. EIT has the potential to optimize PEEP titration.

Effects of different levels of end-expiratory positive pressure on lung recruitment and protection in patients with acute respiratory distress syndrome

Background It is still controversial as to the implementation of higher positive end-expiratory pressure （PEEP） in patients with acute respiratory distress syndrome （ARDS）. This study was conducted to compare the lower and higher PEEP in patients with ARDS ventilated with low tidal volume, to investigate the relationship between the recruited lung volume by higher PEEP and relevant independent variables and to provide a bedside estimate of the percentage of potentially recruitable lung by higher PEEP. Methods Twenty-four patients with ARDS were studied. A lung recruiting maneuver was performed, then each patient was ventilated with PEEP of 8 cmH20 for 4 hours and subsequently with PEEP of 16 cmH20 for 4 hours. At the end of each PEEP level period, gas exchange, hemodynamic data, lung mechanics, stress index ＂b＂ of the dynamic pressure-time curve, intrinsic PEEP and recruited volume by PEEP were measured. Results Fourteen patients were recruiters whose alveolar recruited volumes induced by PEEP 16 cmH20 were （425_＋65） ml and 10 patients were non-recruiters. Compared with the PEEP 8 cmH20 period, after the application of the PEEP 16 cmH20, the PaO2/FiO2 ratio and static lung compliance both remained unchanged in non-recruiters, whereas they increased significantly in recruiters. Changes in PaO2/FiO2 and static lung compliance after PEEP increase were independently associated with the alveolar recruitment. Analyzing the relationship between recruiting maneuver （RM）-induced change in end-expiratory lung volume and the alveolar recruitment induced by PEEP, we found a notable correlation. Conclusions The results of this study indicated that the potential for alveolar recruitment might vary among the ARDS population and the higher PEEP levels should be limited to recruiters. Improving in PaO2/FiO2, static lung compliance after PEEP increase and the shape of the pressure-time curve could be helpful for PEEP application.

Alveolar stability under different combinations of positive end-expiratory pressure and tidal volume： alveolar microscopy in isolated injured rat lungs

Background High positive end-expiratory pressure （PEEP） and low tidal volume （VT） ventilation is thought to be a protective ventilation strategy. It is hypothesized that the stabilization of collapsible alveoli during expiration contributes to lung protection. However, this hypothesis came from analysis of indirect indices like the analysis of the pressure-volume curve of the lung. The purpose of this study was to investigate isolated healthy and injured rat lungs by means of alveolar microscopy, in which combination of PEEP and VT is beneficial with respect to alveolar stability （I-E%）. Methods Alveolar stability was investigated in isolated, non-perfused mechanically ventilated rat lungs. Injured lungs were compared with normal lungs. For both groups three PEEP settings （5, 10, 20 cmH20） were combined with three VT settings （6, 10, 15 ml/kg） resulting in nine PEEP-VT combinations per group. Analysis was performed by alveolar microscopy. Results In normal lungs alveolar stability persisted in all PEEP-VT combinations （I-E% （3.2±11.0）%）. There was no significant difference using different settings （P 〉0.01）. In contrast, alveoli in injured lungs were extremely instable at PEEP levels of 5 cmH20 （mean I-E% 100%） and 10 cmH2O （mean I-E% （30.7±16.8）%）; only at a PEEP of 20 cmH20 were alveoli stabilized （mean I-E% of （0.2±9.3）%）. Conclusions In isolated healthy lungs alveolar stability is almost unaffected by different settings of PEEP and VT. In isolated injured lungs only a high PEEP level of 20 cmH2O resulted in stabilized alveoli whereas lower PEEP levels are associated with alveolar instability.

Effect of protective lung ventilation strategy combined with lung recruitment maneuver in patients with acute respiratory distress syndrome (ARDS)

Objective:To evaluate the efficacy and safety of protective lung ventilation strategy combined with lung recruitment maneuver (RM) in the treatment patients with acute respiratory distress syndrome (ARDS).Methods:Totally 74 patients with ARDS admitted to the Department of Intensive Care Unit, Changshu Second People's Hospital in Jiangsu Province between September 2010 and June 2013 were selected and randomly divided into lung recruitment group and non-lung recruitment group, and the initial ventilation solution for both groups was synchronized intermittent mandatory ventilation (SIMV). For RM, SIMV mode (pressure control and pressure support) was adopted. Positive end expiratory pressure (PEEP) was increased by 5 cm H2O every time and maintained for 40-50 s before entering the next increasing period, and the peak airway pressure was kept below 45 cm H2O. After PEEP reached the maximum value, it was gradually reduced by 5 cm H2O every time and finally maintained at 15 cm H2O for 10 min.Results:A total of 74 patients with mean age of (49.0±18.6) years old were enrolled, 36 patients were enrolled in lung recruitment maneuver (RM) group and 38 patients were enrolled into non-lung recruitment maneuver (non-RM) group. 44 were male and accounted for 59.5% of all the patients. For the indicators such as PEEP, pressure support (PS), plateau airway pressure (Pplat), peak airway pressure (Ppeak), vital capacity (VC) and fraction of inspired oxygen (FiO2), no statistical differences in the indicators were found between the RM group and non-RM group on D1, D3 and D7 (P>0.05), except that only FiO2 of RM group on D7 was significantly lower than that of non-RM group (47.2±10.0) vs. (52.2±10.5),P<0.05]. For the indicators of blood gas analysis, including pH, arterial oxygen pressure (PaO2), arterial carbon dioxide pressure (PaCO2) and oxygenation index (PaO2/FiO2), PaO2 and PaO2/FiO2 of RM group were significantly higher than those of non-RM group on D7, and the values were [(90.2±16.1) mmHg vs. (76.4±11.3) mmHg,P<0.05] and [(196.5±40.7) mmHg vs. (151.7±37.3) mmHg,P<0.05] respectively. There was no statistical difference in heart rate (HR), cardiac index (CI), central venous pressure (CVP) or mean arterial pressure (MAP) between RM group and non-RM group on D1, D3 and D7 (P>0.05). 28-day mortality, ICU mortality and in-hospital mortality were 25% vs. 28.9%, 25% vs. 26.3% and 36.1% vs. 39.5% respectively between RM group and non-RM group (allP>0.05).Conclusion:Protective lung ventilation strategy combined with lung recruitment maneuver can improve the indicators such as PaO2, FiO2 and PaO2/FiO2 on D7, but failed to improve the final outcomes such as 28-day mortality, ICU mortality and in-hospital mortality.

Anesthetic management of the SRS^(TM) endoscopic stapling system for gastro-esophageal reflux disease

The SRS TM Endoscopic Stapling System(Medigus,Tel Aviv,Israel) is a new tool capable of creating a totally endoscopic fundoplication,combined with an endoscope,endoscopic ultrasound and a surgical stapler.SRS TM endoscopic stapling for gastro-esophageal reflux disease is a minimally invasive,outpatient procedure,which requires general anesthesia with positive-pressure ventilation.Keeping the patient on positive endexpiratory pressure(PEEP) may minimize the pressure gradient between the esophagus and the mediastinum,as well as help to prevent air from leaking around the screws and causing pneumomediastinum.In addition,in patients with hiatal hernia,higher PEEP levels may be required to increase intra-thoracic pressure and to force the stomach to slide into the abdomen for ease of endoscopy.We advise smoother emergence from anesthesia,taking precautions for retching,postoperative nausea and vomiting(PONV),while coughing and gagging during extubation and PONV may affect the success of the procedure.Total intravenous anesthesia with propofol and remifentanil seems to be a good choice for these reasons.

基于驱动压的肺保护性通气策略在婴儿单肺通气中的应用效果

目的探讨基于驱动压(Pd)个体化调节呼气末正压(PEEP)的保护性通气策略在婴儿单肺通气(OLV)中的临床效果。方法60例择期胸腔镜手术婴儿随机分成对照组(C组)和驱动压力组(DP组),每组30例。于OLV期间,比较两组婴儿人工气胸前(T0)、人工气胸后10 min(T_(1))、人工气胸后30 min(T_(2))、人工气胸后60 min(T_(3))和人工气胸结束(T4)时的MAP、HR、潮气量(Vt)、PEEP、Pd、气道峰压(Ppeak),肺静态顺应性(Cs),以及人工气胸前后的动脉血气分析结果。结果两组患儿在各时间点上的MAP、HR和Vt均差异无统计学意义(P>0.05)。与T0相比,两组患儿在T_(1)、T_(2)和T_(3)时的Pd和Ppeak均升高,Cs降低(P<0.05),在T_(2)时的Pa O_(2)和OI降低,Pa CO_(2)升高(P<0.05)。与C组相比,DP组在T_(1)、T_(2)和T_(3)时的Pd和Ppeak更低,PEEP和Cs更高(P<0.05),在T_(2)时Pa O_(2)和OI更高(P<0.05),Pa CO_(2)和FiO_(2)无明显差异(P>0.05)。OLV期间,DP组需要通气补救2例(6.9%)低于C组9例(32.4%)(P<0.05)。两组患儿术后并发症差异无统计学意义(P>0.05)。结论基于驱动压的肺保护性通气策略可个体优化婴儿OLV中PEEP设置,改善通气侧肺部顺应性和氧合。

肺复张在急性A型主动脉夹层术后低氧血症中的应用

目的 探讨肺复张治疗急性A型主动脉夹层(acute type A aortic dissection,ATAAD)术后低氧血症的疗效及安全性。方法 选取2019年11月至2022年5月广西医科大学第一附属医院ATAAD术后低氧血症患者56例,将其随机分为肺复张组(n=36)及常规治疗组(n=20)。常规治疗组患者在肺保护性通气基础上行常规机械通气,肺复张组患者采用呼气末正压通气(positive end expiratory pressure,PEEP)递增法进行肺复张。比较两组患者治疗前后的动脉血气分析、呼吸力学指标、血流动力学指标和血清白细胞介素(interleukin,IL)-6及IL-10水平。结果 治疗后12h、24h,两组患者的动脉血氧分压(arterial partial pressure of oxygen,PaO_(2))、氧合指数(oxygenation index,OI)、肺静态顺应性(C_(stat))及肺动态顺应性(C_(dyn))均显著高于本组治疗前,肺泡动脉氧分压差[PO_(2)(A-a)]、呼吸指数(respiratory index,RI)、气道峰压(P_(peak))及气道平台压(P_(plat))均显著低于本组治疗前(P<0.05);肺复张组患者的PaO_(2)、OI、C_(stat)及C_(dyn)均显著高于常规治疗组,PO_(2)(A-a)、RI、P_(peak)及P_(plat)均显著低于常规治疗组(P<0.05)。肺复张组患者肺复张过程中收缩压及平均动脉压有所下降(P<0.05),中心静脉压有所升高(P<0.05),肺复张结束后均恢复至基线水平。治疗后12h,两组患者的血清IL-6和IL-10水平均显著低于本组治疗前(P<0.05)。结论 PEEP递增法肺复张可改善ATAAD术后低氧血症患者的氧合及肺顺应性,但对血流动力学存在一过性影响,治疗时应进行严密监测。

不同潮气量和PEEP对脉搏轮廓法与经肺热稀释法测量巴马猪心排血量的影响

【目的】探究机械通气时不同潮气量和呼气末正压(PEEP)对脉搏轮廓法与经肺热稀释法测量巴马猪心排血量的影响。【方法】选取实验用巴马猪12只,随机分为对照组(肺动脉导管热稀释法)、研究组A(经肺热稀释法)和研究组B(脉搏轮廓法),各4只。建立模型,采用不同方法测量心排出量,分析其一致性,比较不同潮气量和PEEP对心排出量的影响。【结果】脉搏轮廓法与热稀释法测定猪心排血量的相关系数为r=0.754,两者具有正相关性。经肺热稀释法与热稀释法测定猪心排血量的相关系数为r=0.771,两者具有正相关性。脉搏轮廓法、与热稀释法测定猪心排血量相对误差为13.5%,两者具有一致性。经肺热稀释法与热稀释法测定猪心排血量相对误差为12.9%,两者具有一致性。随着潮气量增加,心排出量值明显降低,差异具有统计学意义(P<0.05)。随着PEEP增加,猪心排出量明显降低,差异具有统计学意义(P<0.05)。【结论】脉搏轮廓法、经肺热稀释法与热稀释法测定猪心排血量的一致性良好;当机械通气潮气量或PEEP增加时猪心排血量逐渐下降。

个体化PEEP通气策略对围手术期肺保护、肺不张及血流动力学的影响:系统性评价及荟萃分析

目的 在全麻患者术中使用不同的方法(电阻抗断层成像、肺部超声、动/静态肺顺应性、驱动压、跨肺压)确定个体化呼吸末正压(PEEP),与传统的固定PEEP相比是否引起肺损伤、肺不张及血流动力学不稳定。方法 计算机检索PubMed、clinicaltrials.gov、Web of Science、Cochrane Library及中国知网,并筛选所有选定文章的参考列表和类似文献,搜索截至2023年1月的所有中英文出版物,使用Revman 5.3软件进行Meta分析。结果 研究了45篇文献,共3 767患者。Meta分析显示个体化PEEP组CC-16浓度、肺部超声评分及肺部并发症发生率与传统PEEP组相比明显降低(P<0.05)。个体化PEEP与术中更高的动态肺顺应性和更低的驱动压有关(P<0.000 01)。同时,个体化PEEP组相较于传统PEEP组对MAP(P=0.13)和HR(P=0.94)差异无统计学意义。结论 与传统PEEP相比,术中使用个体化PEEP增加了患者围手术期肺保护效应,降低了围手术期肺不张的发生率和严重程度。同时,并不引起围手术期血流动力学紊乱。

肺动态顺应性指导个体化PEEP滴定对颅面重建术患儿术后肺不张的影响

目的探讨肺动态顺应性(Cdyn)指导个体化PEEP滴定对颅面重建术患儿术后肺不张的影响。方法选择全麻下行颅面重建术患儿80例,男52例,女28例,年龄≤1岁,ASAⅠ或Ⅱ级,麻醉时间≥2 h。采用随机数字表法将患儿分为两组:Cdyn导向个体化PEEP组(I组)和固定PEEP组(P组),每组40例。I组在插管后5 min肺部超声评分(LUS)后进行PEEP滴定,Cdyn最高值对应的PEEP为个体化PEEP;P组PEEP固定为6 cmH_(2)O。记录插管后5 min和手术结束时胸膜旁实变评分、B线评分、LUS总评分和肺不张发生情况。记录插管后5 min和PEEP建立后Cdyn、气道峰压(Ppeak)、HR、MAP。记录插管后5 min和手术结束时氧合指数(OI)和术后72 h肺部并发症的发生情况。结果I组滴定过程中Cdyn最高值时对应个体化PEEP滴定值中位数为9 cmH_(2)O。与插管后5 min比较,两组手术结束时胸膜旁实变总评分、后胸部胸膜旁实变评分、B线总评分和前、侧、后胸部B线评分、LUS总评分均明显降低(P<0.05)。与P组比较,I组手术结束时胸膜旁实变评分、后胸部胸膜旁实变总评分、B线总评分、后胸部B线评分、LUS总评分、肺不张发生率明显降低(P<0.05),I组PEEP建立后Cdyn和Ppeak明显升高(P<0.05),手术结束时OI明显升高(P<0.05),术后72 h肺部并发症总发生率明显降低(P<0.05)。结论术中应用Cdyn指导个体化PEEP滴定能有效降低颅面重建术患儿手术结束时LUS评分和肺不张发生率,改善氧合功能,降低术后肺部并发症发生率。

肺动态顺应性指导个体化呼气末正压通气对老年患者腹腔镜结直肠癌术中肺功能的影响

目的观察肺动态顺应性(Cdyn)指导个体化呼气末正压通气(PEEP)对老年患者腹腔镜结直肠癌术中肺功能的影响。方法选择择期行腹腔镜结直肠癌根治术的老年患者68例,男37例,女31例,年龄65~79岁,BMI<30 kg/m^(2),ASAⅡ或Ⅲ级。采用随机数字表法将患者分为两组:个体化PEEP组(P组)和对照组(C组),每组34例。P组在插管完成即刻、气腹-屈氏体位建立即刻、气腹结束即刻行肺复张及PEEP滴定试验,C组设置固定PEEP 5 cmH_(2)O。记录P组3次滴定时最佳PEEP和实际VT。记录气管插管完成后10 min(T_(1))、气腹-屈氏体位建立后10 min(T_(2))、60 min(T_(3))、手术结束拔管前(T_(4))PaO_(2)、PaCO_(2)、PETCO_(2),计算氧合指数(OI)、死腔/潮气量比值(Vd/VT)、肺泡-动脉血氧分压差(A-aDO_(2))、驱动压和Cdyn。采用ELISA法测定麻醉诱导前(T0)、拔管后10 min(T5)的白细胞介素-8(IL-8)、肿瘤坏死因子-α(TNF-α)、肺Clara细胞分泌蛋白(CC16)及肺泡表面活性物质-D(SP-D)的浓度。记录术后肺部并发症(PPCs)的发生情况。结果P组滴定最佳PEEP的中位数为4 cmH_(2)O。与C组比较,P组T_(4)时PaO_(2)、OI明显升高,T_(1)、T_(3)、T_(4)时Cdyn明显升高,T_(1)—T_(4)时驱动压明显降低,T5时CC16血清浓度明显降低(P<0.05)。两组T_(1)—T_(4)时PaCO_(2)、PETCO_(2)、A-aDO_(2)、Vd/VT差异无统计学意义。两组术后3 d均未发生严重PPCs。结论在老年患者腹腔镜结直肠癌根治术中,采用压力控制通气下肺动态顺应性指导个体化PEEP的肺保护通气策略,可提高患者术中肺动态顺应性,降低驱动压,改善手术结束时氧合,降低术后CC16血清浓度,改善术中肺功能。

不同通气模式对Trendelenburg体位腹腔镜手术患者PaO_2和PaCO_2的影响

目的探讨压力控制通气（PCV）联合呼气末正压（PEEP）在Trendelenburg体位腹腔镜手术中对PaO_2和PaCO_2的影响。方法腹腔镜直肠癌根治术患者40例,年龄35~55岁,随机分为两组,每组20例。A组采用容量控制通气模式（VCV）通气[VT=体重（kg）×10ml]20min后,改用PCV模式通气20min,返回VCV模式继续通气20min后,采用PCV＋低PEEP（5cm H_2O）模式通气20min。B组则将PCV与PCV＋PEEP的顺序调换。在切换通气模式时行动脉血气分析。结果两组VCV模式时PaO_2均明显低于PCV模式及PCV＋PEEP模式（P〈0.05）。PCV模式时PaO_2明显低于PCV＋PEEP模式（P〈0.05）;VCV模式时PaCO_2明显高于PCV模式和PCV＋PEEP模式（P〈0.05）,而PCV模式和PCV＋PEEP模式时PaCO_2差异无统计学意义。VCV模式时动脉血pH值明显低于PCV和PCV＋PEEP模式（P〈0.05）,PCV和PCV＋PEEP模式时动脉血pH值差异无统计学意义。结论 Trendelenburg体位腹腔镜手术时采用PCV＋PEEP通气模式,与单纯VCV或单纯PCV模式比较,在提高PaO_2以及降低PaCO_2方面更具优势。

肺复张在体外循环心脏术后早期急性肺损伤-急性呼吸窘迫综合征患者的疗效观察

目的观察肺复张对体外循环心脏术后早期急性肺损伤-急性呼吸窘迫综合症(ALI-ARDS)患者的疗效与可能出现的不良反应。方法对符合ALI-ARDS诊断标准并接受机械通气的心脏术后患者34例进行肺复张,在原有的呼气末正压(PEEP)水平基础上以5 cmH2O/2 min逐渐增加PEEP至20 cmH2O,维持2min,以5 cmH2O/2 min递减至肺复张前的PEEP水平。观察患者生命体征、氧合指数以及血流动力学变化。结果 34例患者在肺复张术后氧合均有明显改善(PaO2/FiO2从(108.6±36.6)升高至(173.3±64.8),P<0.05),血流动力学在治疗前后均无显著差异(P>0.05)。所有病例在PEEP升高至一定水平时均会出现一过性动脉压下降,降低PEEP水平后很快恢复;全部病例未发生气压伤或其他并发症。结论对心脏术后早期发生AL-I-ARDS患者,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。

压力-容积曲线在急性呼吸窘迫综合征患者机械通气中的应用

目的探讨静态与动态压力-容积(P-V)曲线低位拐点(LIP)的相关性,为临床选择最佳呼气末正压(PEEP)提供简捷的方法。方法记录14例急性呼吸窘迫综合征(ARDS)患者的准静态及动态肺P-V曲线,确定P-V曲线上的LIP及高位拐点(UIP),将PEEP设定在动态P-V曲线的0、LIP/2、LIP+2 cm H2O、(LIP+UIP)/2和UIP,各水平PEEP分别维持30 min后测血气分析及静态顺应性(Cst)、气道峰压(PIP)、中心静脉压(CVP)及平均动脉压(MAP)。结果14例ARDS患者准静态LIP和动态LIP分别为(6.5±1.7)cm H2O和(4.5±1.7)cmH2O,两者经相关性检验呈正相关(r=0.76,P<0.05)。当PEEP为LIP+2 cm H2O时,PaO2/FiO2及Cst均显著提高(P均<0.01),动态肺顺应性达最高,且对CVP及MAP无明显影响。继续增加PEEP,虽PaO2/FiO2有增高,但Cst及MAP下降,CVP、MAP及平均气道压明显升高。结论动态P-V曲线的LIP+2 cm H2O作为最佳PEEP水平时可获较佳治疗效果。

利用压力-容积曲线呼气支最大曲率拐点选择PEEP对ARDS患者氧合及血流动力学的影响

目的探讨利用压力一容积（P—V）曲线呼气支最大曲率拐点选择呼气末正压（PEEP）对急性呼吸窘迫综合征（ARDS）患者氧合及血流动力学影响。方法选取25例ARDS患者，采用肺保护性通气，肺复张（RM）后随机分为两组：利用P—V曲线呼气支最大曲率拐点设置PEEP组（PPMc）和以P—V曲线低位拐点设置PEEP组（PLIP），观察并比较RM前后两组患者PaO2／FiO2、呼吸系统动态顺应性（Cdyn）、心率（HR）、平均动脉压（MAP）、中心静脉压（CVP）等指标的变化。结果RM后两组患者短时间内PaO：／FiO：和Cdyn均明显增加，PPMc组PaO2／FiO2在RM后1、2、4h较Pup组升高（P〈0．05）。PLIP组Cdyn在RM后很快降至RM前水平，PPMC组Cdyn在RM后1、2h高于PLIP组（P〈0．05）。两组RM时均有MAP、CVP下降，HR升高（P〈0．01）；HR、MAP在RM后很快恢复，PPMC组CVP持续升高至RM后2h（P〈0．05）。结论RM后利用P—V曲线呼气支最大曲率拐点选择PEEP可以使氧合及呼吸系统顺应性改善更为明显，对血流动力学无严重的不良影响。

压力-容积曲线指导个体化保护性单肺通气在开胸术中的应用

目的:应用动态压力-容积曲线设定全身麻醉单肺通气时个体化的潮气量和呼气末正压(PEEP)。方法:42例ASAⅠ～Ⅱ级择期行肺叶切除术患者,常规双肺通气30min后(T0)行单肺通气,按照患者单肺通气即刻动态压力-容积曲线低位拐点对应的压力(PLIP)+0.196kPa设定PEEP值,依次按照100%、80%、60%高位拐点对应的容量(VUIP)设定潮气量,分别通气30min(T1、T2、T3)。记录各时点血流动力学和呼吸力学参数,并采集动脉和混合静脉血行血气分析,根据公式计算肺内分流率。结果:T1、T2、T3的PEEP值均为(0.64±0.13)kPa,潮气量分别为(10.1±1.2)mL/kg、(7.2±1.1)mL/kg、(5.6±0.7)mL/kg,与T1相比,T2的气道峰压、气道阻力、分流率降低;动脉氧分压、胸肺顺应性增加;T3的平均动脉压、动脉二氧化碳分压增高,差异有统计学意义(P<0.05)。结论:根据动态压力-容积曲线,80%VUIP联合PLIP+0.196kPa水平的PEEP有助于改善单肺通气氧合,降低分流,对血流动力学影响轻微。

高水平呼气末正压通气联合肺复张在肥胖患者全麻俯卧位手术中的应用研究

目的评价高水平呼末正压通气(PEEP)联合肺复张(RM)在肥胖患者全麻俯卧位手术中的应用效果。方法选择60例BMI≥28 kg/m^(2)择期拟行全麻下腰骶椎手术的肥胖患者,采用随机数字表法分为两组:对照组(A组)和实验组(B组),每组30例。A组设置PEEP=5 cmH_(2)O,B组设置PEEP=10 cmH_(2)O联合肺复张手法。观察并记录两组患者麻醉前(T0)、气管插管后仰卧位机械通气10 min(T1)、气管插管后俯卧位机械通气10 min(T2)、俯卧位机械通气1 h(T3)和气管拔管后脱氧30 min(T4)的血流动力学指标、呼吸力学指标、动脉血气分析指标、T0、T4和术后1 d(T5)时肺部超声评分(LUS)总分以及术后5 d内呼吸系统并发症的发生情况。结果两组患者心率(HR)、平均动脉压(MAP)比较差异无统计学意义;B组在T2、T3、T4时刻的氧合指数(OI)均显著高于A组,肺泡动脉氧分压差(A-aDO_(2))均低于A组(P<0.05);与T1时刻相比,T2、T3时刻两组患者的气道峰压(Ppeak)和驱动压(ΔP)呈上升趋势,肺动态顺应性(Cdyn)呈下降趋势(P<0.05)。B组术中的Ppeak、Cdyn相比于A组明显升高,而ΔP均低于A组(P<0.05);B组LUS评分在T4和T5时刻低于A组(P<0.05);两组术后5 d内呼吸系统并发症发生率比较差异无统计学意义。结论对于需行全麻俯卧位手术的肥胖患者,高水平PEEP联合肺复张有助于改善肺顺应性和氧合状态,提高患者氧储备和肺功能的恢复能力,但并未发现能够降低患者术后呼吸系统并发症的发生率。