单肺通气期间麻醉期用药对肺内分流的影响

背景 低氧血症是单肺通气(one lung ventilation,OLV)期间最常见的并发症.缺氧性肺血管收缩(hypoxic pulmonary vasoconstriction,HPV)是肺血管对局部低氧分压的反射性收缩,可以减少肺内分流(pulmonary shunt fraction,Qs/Qt)、维持动脉血氧分压(partial pressure of arterial oxygen,PaO2)、防止低氧血症的发生.目的 探讨OLV期间麻醉期用药对Qs/Qt的影响,指导临床应用.内容 综述OLV期间麻醉期用药对机体HPV、Qs/Qt和PaO2的影响.趋向 OLV期间麻醉期用药可以对HPV产生抑制或增强作用,从而影响Qs/Qt和PaO2.临床上要避免使用抑制HPV作用、增加Qs/Qt的药物,防止患者出现低氧血症.     

开胸手术时双肺两种不同通气方式可行性应用

开胸手术行健侧单肺通气,所出现的肺内分流和低氧血症,倍受人们关注.我院在开胸手术中采用健侧肺间歇正压通气(intermittent positive pressure ventilation,IPPV),患侧肺采用持续正压通气(continuous positive airway pressure,CPAP),收到满意疗效.     

肥胖患者单肺通气期间的通气策略

背景 肥胖人群比例不断升高,肥胖影响正常生理功能,给麻醉带来不少问题,尤其在单肺通气(one-lung ventilation,OLV)过程中. 目的 减少肥胖患者OLV过程对预后转归的影响,降低肥胖患者围手术期呼吸系统并发症的发生率. 内容 探讨肥胖患者围手术期OLV期间的通气策略,包括通气模式的选择、保护性通气策略、高碳酸血症、肺泡复张策略和吸氧浓度的选择. 趋向 肥胖患者OLV期间采用小潮气量联合呼气末正压通气(positive end-expiratory pressure, PEEP)、间断肺泡复张和低到中度Fi02等通气策略有助于改善氧合、降低肺不张发生率,高碳酸血症在无肺部疾病患者中是否具有肺保护作用尚待研究.     

胸科手术的单肺通气策略

背景 在胸科手术的麻醉中进行单肺通气(one-lung ventilation,OLV),不但可以为手术提供良好的术野,而且可以隔离并保护肺脏.但是,这是一种非生理状态下的通气方式,OLV期间的气压伤和氧毒性等因素常导致机械通气相关性肺损伤(ventilator-induced lung injury,VILI). 目的 探讨适合胸科手术的OLV策略. 内容 在OLV期间,采用肺泡复苏策略(alveolar recruitment strategy,ARS)和“小潮气量+呼气末正压通气(positive end-expiratory pressure,PEEP)”的保护性通气策略,使吸气平台压(plateau pressure,Pplat)＜25 cmH2O(1 cmH2O=0.098 kPa)和气道峰压(peak inspiratory pressure,Ppeak)＜35 cmH2O;限制FiO2;依据动脉血气分析的结果,酌情调整呼吸频率. 趋向 在OLV期间,应避免肺泡的过度膨胀和循环性的萎陷-复张,避免高浓度氧导致氧化应激加重,可以接受短时间内的高碳酸血症.对患者进行个体化管理,降低ICU的入住率及住院时间,提高患者的生存率及生存质量.     

肺保护通气策略在全身麻醉手术中的应用进展

背景 全身麻醉可以通过多种方式影响呼吸系统,其中,机械通气是最主要的因素,能够导致容积伤、气压伤、肺不张及生物伤等肺损伤.对此,人们提出了很多肺保护通气策略,已被证明这些策略对于急性肺损伤(acute lung injury,ALI)和急性呼吸窘迫综合征(acute respiratory distress syndrome,ARDS)患者是有益的.目的 详细阐述保护性通气策略的原理及其在全身麻醉手术中的应用进展.内容 阐明小潮气量、呼气末正压通气(positive end expiratory pressure,PEEP)、肺复张策略(recruitment maneuver,RM)、open-lung策略、反比呼吸、降低FiO2、持续气道正压通气(continuous positive airway pressure,CPAP)、高频振荡通气、压力控制通气(pressure-controlled ventilation,PCV)的肺保护作用机制、临床使用现状及其相关风险.趋向 如何在手术麻醉中合理地、个性化地联合使用这些方法达到肺保护的作用还需要进一步的研究.     

单肺通气时炎性反应机制及预防的研究进展

背景 开胸手术需要长时间维持单肺通气(one-lung ventilation,OLV),这一过程可激活炎性细胞并释放大量炎性因子,导致肺部炎症反应及并发症. 目的 着重探讨OLV所致炎性因子释放的机制,保护性通气策略,促炎症消退等相关进展.内容 OLV时,过度机械牵张刺激作用于肺细胞膜表面机械感受器,激活细胞内各种传导通路,导致各种致炎因子及炎症介质的上调表达.术中小潮气量、低气道压、低呼气末正压通气(end-expiratory positive pressure,PEEP)为策略的保护性通气模式的应用及吸入麻醉药、局部麻醉药、糖皮质激素等药物的使用可显著减少炎性因子的释放,减少胸科患者术后肺损伤的发病率.趋向 内源性炎症消退机制及基因和生物靶向治疗已成为近年来研究炎症的新的热点.     

不同通气模式对单肺通气影响的Meta分析

目的 采用Meta分析的方法评价压力控制通气(pressure controlled ventilation,PCV)与容量控制通气(volume controlled ventilation,VCV)对术中单肺通气(one lung ventilation,OLV)患者呼吸力学及循环的影响. 方法 检索PubMed、Embase、Cochrane图书馆,检索时间从建库至2016年2月.收集术中OLV使用PCV与VCV的临床随机对照试验(randomizedcontrolled trim,RCT).采用Cochrane协作网系统评价法评价纳入文献的质量,采用RevMan 5.0软件对收集的患者资料进行Meta分析评价. 结果 共纳入14项研究,包括964例患者,其中PCV组480例,VCV组484例.与VCV组比较:在开胸前双肺通气时(T1),PCV组气道平均压(mean airway pressure,Pmean)比值比(odds ratio,OR)[0R=-0.22,95％CI(-0.42,-0.01),P＜0.05]较低;OLV时(T2),PCV组气道峰压(peak airway pressure,Ppeak)[加权均数差(weighted mean difference,WMD)=-1.37,95％CI(-1.69,-1.05)]及气道平台压(pause pressure,Plateau)较低[WMD=-0.29,95％CI(-0.51,-0.07)],而PaO2高[WMD=0.52,95％CI(0.08,0.95)];关胸后双肺通气时(T3),PCV组Ppeak较低[WMD=-0.63,95％CI(-1.09,0.17)]. 结论 与VCV比较,OLV期间PCV可提供较低的气道压,可能是一种较好的通气模式.     

术侧肺部分通气法与单肺通气的比较研究

目的 与单肺通气(one-lung ventilation,OLV)比较术侧肺部分通气(partial ventilation of independent lung,PLV)情况下的氧合与气道压力.方法 16例接受食道手术的患者随机分为两组,进行自身对照交叉研究.在双肺通气后按不同顺序接受OLV和术侧肺PLV,比较3种通气时氧合指数(oxygen index,OI)及气道压力的变化.结果 两种通气方式下OI均显著低于双肺通气(two-lung ventilation,TLV),但PLV时显著高于OLV(PLV391±112,OLV134±53,TLV530±92,P<0.05);气道压力值在PLV时也显著低于OLV[Ppeak:(19±3)cm H2O vs(27±5)cm H2O,Pplat:(17±2)cm H2O vs(23±3)cm H2O,P<0.05](1 cm H2O=0.098 kPa). 结论PLV显著改善了氧合和呼吸力学指标.     

肥胖患者围手术期通气策略Meta分析

目的 系统评价围手术期不同通气策略对肥胖患者通气和肺功能的影响,选择最佳通气策略. 方法 网上检索EBSCO、PubMed、Spring、Ovid、Wiley、中国知网、维普网、万方数据等数据库,选择全身麻醉诱导期和拔管后的给氧模式以及术中不同潮气量对肥胖患者通气和肺功能影响的随机对照试验(randomized controlled trial,RCT),应用RevMan 5.3软件对纳入文献进行Meta分析. 结果 共纳入24篇RCT,946例患者.①麻醉诱导期头高位吸氧较平卧位吸氧无通气安全时限更长(P＜0.001),而自主呼吸时加用持续正压通气(continues positive airway pressure,CPAP)PaO2水平更高(P=0.005),转为机械通气后间歇正压通气(intermittent positive pressure ventilation,IPPV)+呼气末正压通气(positive end expiratory pressure,PEEP)较单用IPPV无通气安全时限更长(P＜0.001),PaO2更高(P＜0.001).②术中大潮气量比小潮气量通气联合PEEP获得更高的氧合指数(oxygenation index,OI)(P=0.02),但同时大潮气量通气可引起更高的气道压(P＜0.001).③拔管后采用无创正压通气(non-invasive positive pressure ventilation,NIPPV)较鼻导管吸氧PaO2更高(P=0.004). 结论 肥胖患者诱导期宜采用头高位CPAP以及IPPV+PEEP通气,术中采用大潮气量+高PEEP,术后拔管后采用NIPPV.     

电视胸腔镜手术治疗胸腺瘤合并重症肌无力的麻醉处理

目的 探讨电视胸腔镜手术（video-assisted thoracoscopic surgery,VATS）治疗胸腺瘤合并重症肌无力（myasthenia gravis,MG）单肺通气 （one-lung ventilation,OLV） 期间应用呼气末正压（positive end-expiratory pressure,PEEP）对脉搏氧饱和度（SPO2）的影响. 方法 1999年1月～2005年12月,23例 MG按手术时间顺序分为A、B 2组,A组为单肺通气,B组为单肺通气联合呼气末正压5 cm H2O,观察不同时点SPO2变化. 结果 术前双肺通气5 min SPO2 A组与B组间比较差异无显著性差异（t=0.318,P=0.754）;OLV 30、60 min时SPO2 A组明显低于B组（t=-4.787,-7.028;P=0.000）,须双肺通气5 min才能达到B组水平.A组此后每1 h间断双肺通气5 min维持SPO2在正常范围至手术结束. 结论 胸腔镜下胸腺瘤切除术治疗MG, OLV时应用 PEEP 5 cm H2O能维持满意的SPO2,是一种安全有效的防治低氧血症措施.     

Non-invasive ventilation in surgical patients in a district general hospital

We have retrospectively audited the use of non-invasive ventilation (NIV) in surgical patients. We analysed the case notes of 38 surgical patients who received NIV over a 9-month period. Twenty-three patients received NIV following emergency surgery, eight after elective surgery, and seven did not have an operation. Co-morbidity was common. The commonest reasons for starting NIV were chest infection, acute respiratory distress syndrome and pulmonary oedema. NIV was often only one aspect of treatment in surgical patients with complex medical problems. With intensive support from the critical care outreach team, NIV can be safely delivered on a surgical ward, and may sometimes prevent intensive care unit admission. Use of NIV on the intensive care unit may obviate the need for tracheal intubation in some patients. In very ill surgical patients with a poor prognosis, NIV was frequently used as the ceiling of respiratory support.     

Principles of artificial ventilation

The application of intermittent positive pressure ventilation (IPPV) during the 1952 Copenhagen polio epidemic led to the development of the world's first intensive care unit. The requirement for ventilatory support is the most common indication for intensive therapy unit (ITU) admission and is a defining feature of the specialty. Ventilator technology continues to develop and there are many ways to deliver IPPV. The variety of modes of ventilation is increasingly complex and expanding, without evidence that any one mode is associated with improved outcome. Ventilatory support is part of the treatment for a range of conditions including acute respiratory failure, raised intracranial pressure (ICP) and circulatory shock. Ventilator-associated lung injury is reduced by using low tidal volumes and limiting plateau airway pressure to less than 30 cmH₂O. Prolonged artificial ventilation has an associated morbidity and mortality and thus should be reviewed by an expert clinician on a daily basis. Weaning aims to identify those patients who will be able to breathe spontaneously. Protocols exist to facilitate timely extubation without the need for re-intubation.     

Principles of artificial ventilation

The application of intermittent positive pressure ventilation (IPPV) during the 1952 Copenhagen polio epidemic led to the development of the world’s first intensive care unit. The requirement for ventilatory support is the most common indication for intensive therapy unit (ITU) admission and is a defining feature of the specialty. Ventilator technology continues to develop and there are many ways to deliver IPPV. The variety of modes of ventilation is increasingly complex and expanding, without evidence that any one mode is associated with improved outcome. Ventilatory support is part of the treatment for a range of conditions including acute respiratory failure, raised intracranial pressure (ICP) and circulatory shock. Ventilator-associated lung injury is reduced by using low tidal volumes and limiting plateau airway pressure to less than 30 cmH₂O. Prolonged artificial ventilation has an associated morbidity and mortality and thus should be reviewed by an expert clinician on a daily basis. Weaning aims to identify those patients who will be able to breathe spontaneously. Protocols exist to facilitate timely extubation without the need for re-intubation.     

A clinical trial of volume- versus pressure-controlled intraoperative ventilation during laparoscopic bariatric surgeries

BackgroundIntra-operative ventilation is often challenging in patients with morbid obesity undergoing bariatric surgery.ObjectivesTo test the noninferiority of pressure-controlled ventilation (PCV) to volume-controlled ventilation (VCV) in respiratory mechanics.SettingBariatric Surgery Center, Iran.MethodsIn a randomized open-labeled clinical trial, 66 individuals with morbid obesity undergoing laparoscopic bariatric surgeries underwent intraoperative ventilation with either PCV or VCV. The measurements taken were peak and mean airway pressures (H₂O), partial pressure of arterial oxygen (PaO₂), partial pressure of arterial carbon dioxide (PaCO₂) and end-tidal carbon dioxide (CO₂). We additionally collected pulse-oximetric oxygen saturation, inspiratory concentration of oxygen (FiO₂), and hemodynamic variables. Data were analyzed with repeated measures over the time of intubation, after peritoneal insufflation, and every 15 minutes, thereafter up to one hour.ResultsPCV mode was successful to sustain adequate ventilation in 97% of the patients, which was similar to the 94% success rate of the VCV mode. Peak airway pressure increased 6 cmH₂O and end-tidal CO₂ rose by 5 mm Hg after abdominal insufflation in both groups (P = .850 and .376). Alveolar-arterial oxygen gradient similarly increased within 30 minutes after tracheal intubation both in PCV and VCV groups, with small trend of being higher in the VCV group. The ratio of dead space to tidal volumes (VD/VT) did not have a meaningful change (P = .724).ConclusionPCV was noninferior to VCV during laparoscopic bariatric surgery. Either mode of ventilation could be alternatively used during the anesthesia care of these patients.     

Respiration: ventilation

Anaesthetists and intensivists directly manipulate pulmonary function, in particular ventilation. A sound and thorough working knowledge of applied pulmonary physiology of ventilation is essential to the safe conduct of anaesthesia and intensive care medicine. This article discusses pulmonary anatomy, gas exchange in the lung, the mechanics of ventilation, airway resistance, elastance and compliance, the work of breathing and ventilation/perfusion relationships including hypoxic pulmonary vasoconstriction. General anaesthesia has profound effects on the respiratory system including the ventilatory response to hypercapnia and hypoxia, upper airway muscle function, lung volumes and ventilation/perfusion matching. Many surgical procedures are facilitated by one-lung ventilation. When utilizing one-lung ventilation a key aim for the anaesthetist is to maintain adequate alveolar ventilation while minimizing the amount of shunt through the non-ventilated lung. A detailed understanding of one-lung ventilation is therefore vital if a logical approach to management is to be adopted.     

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目的　探讨适应性支持通气(ASV)对术后恢复期急性肺损伤(ALI)呼吸力学的影响。方法　采用自身对照方法,对广东省人民医院2 0 0 3年1～9月2 3例术后ALI病人序贯应用同步间歇指令 压力支持通气模式(SIMV PS)和ASV模式进行机械通气(MV) ,记录两种模式下的各项呼吸力学参数。结果　全部病人均成功脱机,总呼吸频率明显降低(P <0 . 0 5 ) ,自主呼吸频率增加(P >0 . 0 5 ) ,潮气量(VT)明显升高(P <0 . 0 5 ) ,平台压(Pplat)和平均气道压(Pawm)有所升高(P <0 .0 5 ) ,顺应性(Cst)有所下降,P0. 1(0. 1s的口腔闭合压)稍有下降(P >0 .0 5 ) ,生命体征、血气分析和血流动力学指标无明显变化。结论　ASV对术后ALI病人,可根据病人的呼吸力学状况自动调整吸气压力支持水平,提高潮气量、降低呼吸频率,而对血流动力学和生命体征没有影响。     

Pressure-controlled ventilation is superior to volume-controlled ventilation with a laryngeal mask airway in children

Background:  This prospective, randomized, crossover study had two purposes: first, to determine whether pressure-controlled ventilation (PCV) is safer than volume-controlled ventilation (VCV) by preventing gastric insufflation in children ventilated through an laryngeal mask airway (LMA); second, to assess whether the measurement of LMA leak pressure (P_leak) is useful for preventing leakage during positive pressure ventilation (PPV).
Methods:  Forty-one, 2 to 15-year-old children underwent general anesthesia with an LMA. The expiratory valve was set at 30 cmH₂O and P_leak was measured using constant gas flow. Children were randomly ventilated using PCV or VCV for 5 min in order to reach a P_ETCO₂ not exceeding 45 mm Hg, and then they were ventilated with the alternative mode. If the target P_ETCO₂ could not be obtained in one mode, we switched to the other. If both modes failed, children were intubated. Tidal volumes, P_ETCO₂ and airway pressures were noted and compared between modes. Gastric insufflation was checked by epigastric auscultation.
Results:  PCV provided more efficient ventilation than VCV, as targeted P_ETCO₂ was obtained without gastric insufflation using PCV in all cases except one, whereas VCV failed in three cases. No gastric insufflation occurred when ventilating below peak.
Conclusions:  These findings suggest that in the age group studied, PCV is more efficient than VCV for controlled ventilation with a laryngeal mask. Gastric insufflation did not occur with this mode.