机械通气ppt课件

1,机械通气的临床应用,北京医科大学第一医院呼吸内科 王广发,2,机械通气的目的,维持通气 改善气体交换 减少呼吸功，缓解膈肌疲劳,3,Steps to Establish Mechanical Ventilation,Establish an indication What is reversible? Patients wishes Establish an airway Premedication: sedative and muscle relaxant selection of route of intubation (oral vs. nasal) Select initial ventilator settings,4,机械通气的适应症,呼吸心跳骤停 膈肌疲劳（矛盾呼吸、咳嗽无力） 预防性应用（重症、外伤、心肺腹颅脑手术后短期内可能出现呼吸功能不全） 难以纠正的低氧血症 呼衰PaCO2升高同时出现严重酸中毒、呼吸抑制及神志障碍 神经肌肉病（最大吸气压30-40次/分）,5,成人机械通气的呼吸力学指标,6,成人机械通气的气体交换和循环指标,7,机械通气的相对禁忌症,大咯血 多发肋骨骨折 气胸和纵隔气肿 肺大泡和肺囊肿 气管食管瘘,8,人工气道气管插管,适应症：严重低氧或高碳酸血症 气道分泌物或血液过多 上气道存在病变 需反复插入支气管镜者 注意事项：高容低张气囊： 2周，MOV，每12小时放气 低容高张气囊：3天，现少用 根据患者选择管径,9,10,气管插管的方法,经鼻：优点耐受好、易固定、便于口腔护理 缺点管径小、鼻部损伤、鼻窦炎、技术难 经口：优点技术易、快速、管径大 缺点耐受差、固定难、口腔护理难 引导方法： 直接喉镜：快速 纤支镜：准确、清醒、经鼻易、须准备 盲插：技术要求高、有自主呼吸,11,人工气道气管切开,适应症：需长时间机械通气 插管后气道分泌物吸出困难 上气道病变无法施行气管插管 优点： 口腔护理方便 容易耐受 减少死腔 可长期保留 可以进食,12,人工气道其它方法,喉罩 优点：简便、易行 急救 头面部手术 不能插管者 缺点：未完全堵塞食道 不能引流痰液,面罩和鼻罩 优点：无创 容易为患者接受 缺点：容易漏气 人机协调要求高 适用轻中度患者 不能引流痰液,13,人工气道建立后的初步评价,通过人工通气“感受”肺脏情况 吸毯确定分泌物的特性 调节呼吸机以适应患者的需求 望、触、听 气囊充气 生命体征及ECG 观察人机系统是否协调 血气分析决定进一步的通气治疗 胸片肺脏情况及插管位置,14,人工气道建立后的初步评价,通过人工通气“感受”肺脏情况 确定肺脏的顺应性和阻力,15,人工气道建立后的初步评价,吸痰观察痰液的特点 确定是否需要增强湿化、纤维支气管镜、吸痰的频率 使用密闭吸痰系统,16,人工气道建立后的初步评价,根据病人需要调节呼吸机参数 评估 呼吸机波形显示 压力变化 患者的反应 调节 吸气流速 触发敏感度 通气模式,17,人工气道建立后的初步评价,视、触、听 人工气道的安全性 双侧胸廓运动 呼吸音 哮鸣音：抗炎药物或支气管扩张剂 确定双侧对称 湿罗音：进行吸痰,18,人工气道建立后的初步评价,人工气道及气囊充气 检测气囊压力：25mmHg 气管粘膜闭合压： 动脉30-35mmHg 静脉18-20mmHg 淋巴管4.5-8mmHg， 听诊气囊漏气声音 最小闭合容量(MOV),19,人工气道建立后的初步评价,生命征及ECG 生命征是否稳定 SpO2 ECG有无心律失常,20,人工气道建立后的初步评价,检查人机系统情况 管路是否密封 报警限设定 病人是否舒适 管路对插管有无牵引 升起护栏,21,人工气道建立后的初步评价,血气分析 保证恰当的通气和酸碱平衡 保证适当的氧合 根据血气分析进行适当调整,22,人工气道建立后的初步评价,胸片 确定插管位置恰当 有无肺实质异常 有无气胸的发生,23,人工气道管理,吸痰：吸痰管直径插管内径的1/2 吸引负压100mmHg 持续时间15sec, 频度每0.5-1小时一次 气道湿化： 湿化器、雾化器、滴水(NS、NaHCO3) 放气囊：先吸口腔、呼吸机吸气时放 翻身拍背：定时,24,气囊的管理,气囊积存物,气囊放气,25,呼吸机参数的调节和设定,26,呼吸机的切换方式,吸气向呼气的切换 压力切换： 恒压、容量可变 容量切换：容量有保证、压力和吸气时间不恒定 时间切换：时间准确、压力或容量可变 流量切换：低于预设压、受肺脏顺应性和压力影响,呼气向吸气的切换 自主切换：同步 压力触发 流量触发 人工切换：人工控制 时间切换： 不受病人吸气影响 保障安全,27,自主切换的同步性能,触发敏感度 敏感度百分比=触发吸气量/自主潮气量100% 反应时间 反应时间百分比=呼吸机的反应时间/自主吸气时间100%,28,人机的协调,The onset of inspiratory effort, The onset of flow delivered by the ventilator The switch between inspiration and expiration,29,机械通气的参数设定,潮气量： 6-10ml/kg体重 通气频率：12-20次/分 吸呼比： 无气道阻塞1:1.5-2 有气道阻塞伴CO2升高可达1:3 吸氧浓度：维持PaO2在60-90mmHg 纯氧不超过15-30分钟 高于60%不超过24-48小时 吸气流速：40-100L/min,初始60L/min,30,机械通气中的监测,呼吸：RR、胸廓运动、人机对抗、紫绀 循环：BP、HR、皮肤温度、尿量 神志 血气分析、经皮血氧饱和度、呼出气CO2 气道峰压、平台压、潮气量、分钟通气量 血液动力学监测,31,Monitoring Techniques Used During Mechanical Ventilation,Mechanical monitoring Pressures and volumes Each associated with an alarm Resistance and compliance Physiologic monitoring Oxygenation, ventilation, acid-base balance, shunt, hemodynamics, spontaneous ventilatory parameters,32,Airway Pressures,Peak Pressure Amount of force to overcome opposition to airflow Circuit and ETT resistance Airway resistance and elastic recoil Increased in: Bronchospasm Edema Retained secretions Foreign body Obesity Kinked tube Chest wraps ARDS Pneumonia Fibrosis Atelectasis Active expiration,33,Pressure-time diagram,Cstat=,Vt Pplat-PEEP,Cdyn=,Vt Ppeak-PEEP,34,Airway Pressures,Static or Plateau Pressure Separates resistance from elastic recoil Determined during an end-inspiratory hold Should be kept 35 cm H2O to avoid volutrauma Allows computation of static compliance, which decreases as the lungs become stiff Static compliance = _VT_ Pplat - PEEP,35,Airway Resistance,Opposition to airflow by nonelastic forces Normally 2-5 cmH2O/L/sec Increases with bronchospasm and secretions Useful for evaluating tracheobronchial hygiene and bronchodilator therapy Raw = PIP Pplat flow,36,Measured Volumes,Tidal Volume 5-7 mL/kg IBW VT = VA + VD VD = 1 mL/lb IBW Mechanical tidal volume varies with disease process Discrepancy between set and expired VT is a leak: ETT cuff leak Pneumothorax Tubing disconnection VT will decrease in PCV as compliance decreases,37,Measured Volumes,Minute Ventilation (VE) VT x f 4-8 L/minute VE of 6 L/min associated with a PaCO2 of 40 mm Hg High PaCO2 with a high VE indicates increased dead space or increased metabolism Spontaneous VE 10 L/min may indicate failure to wean during an SBT,38,Physiologic Monitoring,Oxygenation Ventilation Acid-base balance Shunt Hemodynamics Spontaneous ventilatory parameters,39,Monitoring Arterial Oxygenation,Arterial PaO2 80-100 mm Hg SaO2 90% SpO2 90% Pulse oximetry ? Reliability during motion and poor perfusion Assure correlation with ECG,40,Monitoring Arterial Oxygenation,Adequacy of oxygenation PaO2, SaO2, SpO2 P(A-a) O2 (5-10 mm Hg) Efficiency of oxygenation P/F ratio = PaO2/FiO2 200 in ARDS a-A Tension ratio Intrapulmonary shunt,41,Monitoring Venous Oxygenation,SvO2 = 75% Fiberoptic PA catheter Mixed venous sample PvO2 = 40 mm Hg Mixed venous sample Decreased CO, severe hypoxemia Increased Oxygen consumption,42,Monitoring Ventilation,PaCO2 35-45 mm Hg PETCO2 3-5 mm Hg PaCO2 Capnometry Mainstream or sidestream Useful during weaning, ventilation after closed head injury May detect leaks, hypoventilation, hypoperfusion,43,Capnography,Illustrates exhalation of dead space gas, alveolar gas, and end-tidal carbon dioxide Keep secretions out of the sample chamber or tubing Requires high and low CO2 calibration,44,Monitoring Acid-Base Balance,pH 7.35-7.45 Acidemia (pH 7.45) Metabolic: hypokalemia, steroids, diuretics Respiratory: hyperventilation, ARDS, acute respiratory distress,45,Shunt Fraction (QS/QT),% of the cardiac output not participating in gas exchange（正常5%） QS/QT = CCO2 CaO2 CCO2 CVO2 Increased in significant atelectasis, ARDS, pneumonia Requires mixed venous sample (PA catheter),46,Hemodynamics,Arterial blood pressure Mean arterial pressure Central venous pressure Right atrial pressure Right ventricular pressure Right ventricular end diastolic pressure,Pulmonary artery pressure Mean pulmonary artery pressure Pulmonary capillary wedge pressure Left atrial pressure Left ventricular pressure Left ventricular end diastolic pressure,47,Useful Data from PA Catheters,CVP Measures right heart function and vascular volume PAP Measures right heart function, pulmonary artery resistance PCWP Assesses left ventricular function Cardiac output Heart function, effect of PEEP,48,Monitoring Techniques Used During Mechanical Ventilation,Ventilator waveforms pressure, volume and flow vs time flow-volume and pressure volume loops Allows analysis of auto-PEEP, bronchodilator response, work of breathing, hyperexpansion, adequacy of flow, ventilator sensitivity, compliance, and leaks,49,Spontaneous Ventilatory Parameters,Useful when considering weaning, but not ultimately predictive of success VT: 5-8 mL/kg f: -20-30 cm H2O RSBI(f/Vt): 105,50,Ventilator Waveforms,Scalars Volume versus time Pressure versus time Flow versus time Loops Flow-Volume Pressure -Volume,51,Flow versus Time,ACCELERATING,DECELERATING,SINE,SQUARE,52,Volume vs Time,Inspiration,Expiration,Time (sec),Volume (ml),TI,53,Pressure versus Time,Inspiration,Expiration,Paw (cm H2O),Time (sec),TI,TE,54,Pressure-Volume Loop,Controlled,Assisted,Spontaneous,Vol (ml),Paw (cm H2O),I: Inspiration E: Expiration,I,E,E,E,I,I,55,Flow-Volume Loop,Volume (ml),PEFR,FRC,Inspiration,Expiration,Flow (L/min),PIFR,VT,56,Measurement of occlusive pressure(P0.1),57,Work of Breathing,A: Resistive Work B: Elastic Work,Pressure (cm H2O),Volume (ml),B,A,58,机械通气常见问题的识别与排除,通气管道的阻塞： 原因：痰、异物、管道折叠 表现：气道压升高、每分通气量降低 通气环路漏气： 原因： 接口松脱、气囊破或充气不足、位置过高、气胸 表现：气道压降低、每分通气量降低、吸气潮气量呼气潮气量,气源故障：压缩机、氧气源及管路 人机对抗： 原因：自主呼吸过快过强、频繁咳嗽、内源性PEEP、烦躁、抽搐、气道阻塞、漏气、触发灵敏度设置不当、响应时间过长、气胸、肺不张、肺栓塞 处理：排除原因、调整触发敏感度、镇静肌松剂、PEEP、改用压力切换,59,机械通气中镇静剂和肌松剂的应用,应用指征： 躁动、不配合者、呼吸过强过快、人机对抗 药物： 镇静剂：安定、咪唑安定 肌松剂：司可林、卡肌宁、潘可罗宁、万 可罗宁,60,常用的镇静剂和肌松剂,镇静剂： 安定 IM or IV, 60ys 延长3倍 负荷给药0.03-0.3mg/kg, 1.5mg 维持0.03-0.2mg/kg,60ys 或衰弱、低血容量、低体温、血管收缩减量,61,常用的镇静剂和肌松剂,肌松剂： 潘可罗宁：0.08-0.1mg/kg,45-60min追加首剂的1/3，肾肝代谢，交感兴奋BPHR 万可罗宁：0.08-0.1mg/kg,维持0.01-0.015mg/kg, 20-30min,不增快心率、不增高血压，肝脏代谢 卡肌宁： 0.5-0.6mg/kg，维持0.2-0.3mg/kg,组织胺释放 司可林：1-2mg，IV，40S起作用，持续4-6min,与多粘菌素、新霉素、氨基糖苷类合用协同，可能导致永久性肌松,62,Nutritional Complications,Malnutrition, Fatty Liver, High CO2 Muscle weakness Delayed wound healing Bacterial translocation Monitor prealbumin Feed the gut first TPN,63,机械通气患者的营养,每日总热量(kcal)： Harris-Benedict公式：男性=66.5+13.8W+5.0H-6.8A 女性=65.5+9.6W+1.8H-4.7A 蛋白质12g/kg/d，占总热量20%，氮平衡指数+2 氮平衡(g/d)=氮摄入量-尿尿素氮(g/d)+4 1g蛋白质补充 2535kcal(104.75kJ146.65kJ)非蛋白热量 脂肪占总热量的2030% 葡萄糖最低需补150g/d,占总热量的5060%,64,Recognize and Control Complications Related To,Artificial Airways Ventilators Pulmonary System Cardiovascular System,Gastrointestinal and Nutritional Systems Renal System Neurologic-Psychologic Effects Acid-Base Balance,65,Complications of Artificial Airways,Laryngeal edema Tracheal mucosal trauma Presence and irritation of ETT Stabilize the ETT Perform a cuff leak test Steroids and racemic epinephrine,66,Complications of Artificial Airways,Loss of humidifying function of the upper airway Humidify the airway with a water-filled humidifier or heat and moisture exchanger Monitor mucus characteristics,67,机械通气引起的病理生理生理改变,增高胸内压 减少静脉血回流 增加肺血管阻力 减少心搏出量 减少肝肾等内脏的灌注 增高颅内压,68,Difference between spontaneous respiration and artificial respiration,69,机械通气对呼吸生理的影响,吸气相气道内压、肺泡内压、胸膜腔内压增高 人工气道、反射性小气道收缩、呼吸回路气道阻力增高 正压的气道扩张作用降低气道阻力 顺应性随压力而增加，超过40cmH2O降低 气道和肺泡容积增大：机械扩张、压迫血管、萎陷的肺泡复张 解剖死腔减少、肺泡死腔变化不大 改善肺泡通气和气体的分布 通气血流比值增高对机体具有双重影响 改善弥散功能减轻水肿、肺泡复张 减少呼吸功、抑制自主呼吸,70,机械通气的并发症呼吸系统损害,通气不足： 漏气、人机对抗、气道阻力过大、 顺应性过低、参数调节不当 通气过度： 自主呼吸过强过快、潮气量过高,71,The potentially harmful effects of Mechanical Ventilation,high airway pressures (barotrauma), excessive distending alveolar volumes (volutrauma), shear forces acting upon lung units during opening and closing (atelectrauma) release of harmful cytokines (biotrauma) Oxygen toxicity,72,Pulmonary Complications,Barotrauma Pneumothorax, pneumomediastinum, subcutaneous emphysema High mean/peak pressures Keep PIP 40 cm H2O,73,Pulmonary Complications,Oxygen Toxicity Exposure to a high FiO2 for a long period 50% oxygen Maintain adequate arterial oxygenation Use PEEP to decrease FiO2,74,Pulmonary Complications,Ventilator-induced lung injury Alveolar distention caused by high peak inflation volumes Keep Pplat 35 cm H2O Use “lung protective strategies”,Hess D. Respiratory Care, Saunders, 2001, p.784.,75,Cytokines and VILI “biotrauma“ theory,MV can increase the production of cytokines in the lung, which may pass into the circulation and have effects on distal organs. High volume/low PEEP ventilation are associated with increased cytokine levels in the BALF and circulation Injurious ventilatory strategies increase apoptosis in the kidney（a rabbit acid-aspiration model） Serum cytokine levels were significantly lower in patients with ARDS received a “lung protective“ model rather than a more conventional strategy. Low tidal volume was associated with a lower mortality rate than conventional tidal volume ventilation, as well as a more rapid decline in plasma IL-6 Pretreatment of saline-lavaged rabbits with anti-TNF antibodies attenuated the hypoxia and inflammation caused by injurious ventilation.,76,Effect of Ventilation on Surfactant,Surfactant ： LAs and SAs ARDS patients contains an increased concentration of SA Ventilation at high tidal volume, but not high frequency, increased degradation of LAs to SAs. Low tidal volume ventilation of 5 mL/kg was associated with higher lavage LA levels than ventilation at 10 mL/kg. Ventilation with high-frequency oscillation (HFO) results in even lower LA to SA conversion than low-volume conventional mechanical ventilation.,77,Alveolar overdistention,changes in epithelial and endothelial permeability alveolar hemorrhage hyaline-membrane formation in laboratory animals,78,低潮气量的策略,低潮气量可减少ARDS的死亡率 60% Hickling 1990 46% Amato 1995,1998(6 vs 12ml/kg) 22% The ARDS network 2000(6 vs 12ml/kg) 气道平台压超过32cmH2O时应用可以改善预后（Tobin 2000),79,80,Hazards of Lowering Vt,Hypercapnia The volume of aerated lung is decreased Increase in shunting Worsening oxygenation,81,Pulmonary Complications,VAP 翻身改善气管支气管引流 保持半卧位减少反流 采用封闭性吸痰装置 吸引气囊上方分泌物 洗手！ 减少抑酸剂和制酸药物的使用,82,Cardiovascular Complications,Decreased venous return, cardiac output, and blood pressure Due to increased intrathoracic pressure Hypovolemia Keep PIP and PEEP as low as possible Physiologic compensation,83,Relationship between CO and end-diastolic volume,84,Gastrointestinal Complications,急性胃粘膜病变 出血 腹胀：影响呼吸功能 使用胃粘膜保护剂 尽量使用胃肠道营养,85,肝脏的副作用,内脏血流减少导致门脉血流减少 胸内压增高导致肝静脉回流减少 过度通气导致内脏血管的收缩 胆道粘膜下静脉充血,86,Renal side-effectssodium and water retension,降低动脉灌注压 降低心搏出量 增加肾静脉压 胸内压增高导致心钠素释放减少 激活肾素血管紧张素醛固酮系统 增加血浆ADH的水平 增加交感神经的张力 改变肾内灌注,87,脑血管的影响,胸内压增高导致颅内压增加 脑灌注压降低（CPP=MAP-ICP） 预防： 头抬高15-30 维持血压 保持在PaCO2正常范围 升压药物,88,Acid-Base Complications,Acidosis Sepsis and hypoventilation Stimulates breathing Arrhythmias Increases demand, prolongs CMV Increase VE, decrease I/E, treat underlying cause,Alkalosis Steroids, diuretics or hyperventilation Inhibits breathing Arrhythmias Anoxia of tissue Potential cause of failed weaning Treat underlying cause, decrease VT，increase I/E,89,撤机注意事项,患者状态的调整： 心理准备、营养准备、水电解质酸碱失衡的纠正、其它脏器功能的维持 撤机过程的监测： 呼吸频率、心率、血压、一般状况、矛盾呼吸有无、潮气量、分钟通气量、动脉血气 撤机过程的护理： 心理护理、人工气道的管理,90,机械通气的撤离,撤机指征 原发病得到改善 呼吸功能显著改善 神志清楚 血液动力学稳定 胃肠道功能稳定 无高分解代谢,生理指标 MIP1015ml/kg ,IC10ml/kg VT5ml/kg, VD/ VT10ml/kg MV2*MV Qs/Qt200,91,Criteria for tolerating weaning trials,Oxygenation (PaO2 /= 60 mm Hg or SaO2 /= 90% on FIO2 /= 90 or /= 50 or /= 140 beats/min; increase or decrease /= 20%) Respiratory rate (f /= 35 breaths/min) No sign of excessive respiratory work (absence of thoracoabdominal paradox, respiratory alternans, or accessory respiratory muscle action) No diaphoresis, agitation, depressed mental status, or distress f/VT of 80, 95% successful weaning(Yang N Engl J Med 1991;324:1445-50),Epstein SK. Respir Care Clin North Am. 2000;6:1-20.,92,Strategy of ventilator weaning,直接停机 间断停机 过渡撤机,VC PC IMV IPPV PRVC,AV SIMV SIMV+PSV,PS、VS MMV PAV,CPAP,Noninvasive Mask Ventilation as an Adjunct in the Weaning Process,93,气管插管的拔除,指征： 停机24小时、无明显呼吸困难、血气稳定、 膈肌功能恢复 拔管方法： 准备抢救器具、吸净口咽及气管内分泌物、 放气囊 拔管后可能的并发症 喉痉挛、胃内容物误吸、喉或声门下水肿、 气道狭窄、气管软骨受压坏死、声带麻痹,94,机械通气的并发症呼吸机依赖,原发病控制不满意或诱发因素未去除 呼吸中枢驱动降低或呼吸肌疲劳 继发感染加重或存在水电解质酸碱紊乱 全身营养不足造成呼吸肌无力 应用呼吸机时间过长造成呼吸肌废用性萎缩 合并其它重要脏器功能障碍：心、肝、肾,95,Intrinsic (Auto-) PEEP,产生机制： 呼气时间相对不足 气道阻力增加 动态气道受压 呼气肌的作用 等压点理论 PEEPi增加： 分钟通气量增加 RR加快 气道痉挛、水肿等造成的阻塞 分泌物增加,病理生理意义： 增加吸气阈负荷(P=PEEPi-Ptriger) 增加呼吸功 膈肌低平 人机不同步 增加循环阻力PCWP增加 增加气压伤的可能,96,Measurement of Intrinsic PEEP,阻塞法 对阻塞的时间非常敏感 控制呼吸的病人容易测定 有自主呼吸者测定困难 呼气保持法 简便 需具有“expiratory hold”,食道气囊法 要求同时检测食道压和吸气气流 呼气肌必须松弛 比阻塞法测定偏低 压力、流速记录估测法,97,Measuring manoeuvre intrinsic PEEP,98,Minimizing auto-PEEP,Decrease obstruction Bronchodilation Suctioning Larger ETT Decrease Ti/T tot Decrease rate, Vt,Increase flow Low compressed volume circuit Low rate IMV Permissive hypercapnia Apply PEEP,99,auto-PEEP的对策-外源性PEEP,临 界 压,PEEPi,PEEP,100,Indications for PEEP,PaO2 0.5* P(A-a)O2 300 on FiO2 1.0 Refractory hypoxemia* Shunt 30% Recurrent atelectasis with low FRC Reduced CL* Disease specific: ARDS, IRDS, bilateral atelectasis, auto-PEEP,101,PEEP Ranges,Optimum PEEP PEEP to maintain a PaO2 of 60 mm Hg with an FiO2 0.4 Without cardiac output depression Adequate oxygenation, compliance and FRC are increased Shunt (Qs/QT) is decreased,102,Contraindications for PEEP,Relative Hypovolemia Recent lung surgery Elevated intracranial pressure Preexisting hyperinflation Unilateral lung disease,Absolute Untreated significant pneumothorax Tension pneumothorax,103,Pulmonary Effects of PEEP,Alveolar recruitment Alveoli that were small are made larger by PEEP and some alveoli that have been closed are opened,104,PEEP improves compliance,As optimum PEEP is approached Monitor static compliance (Cs) Beyond optimal PEEP, compliance decreases Point at which compliance increases suddenly is the lower inflexion point difficult to determine,105,PEEP Decreases Work of Breathing,As compliance improves PEEP shifts the compliance curve,Decreased FRC/ARDS,Normal,Volume,Pressure,PEEP,106,PEEP Opens Small Airways,Mechanical bronchodilation Decreases auto-PEEP by facilitating alveolar emptying,107,PEEP的血液动力学效应,静脉回流减少、右室充盈减少 右室后负荷增加 左室前负荷减少 机械性压迫心脏 心肌血流减少 通过神经体液因素抑制心脏功能,108,Effects of PEEP on differentially ventilated alveolar compartments,Without PEEP,With PEEP,109,Ventilatory pressure changes with inspiratory flow,110,Inverse-ratio ventilation,reduce inspiratory flow reduce Ppeak increase Pmean improve ventilation of “slow” lung compartment build-up of a regionally different “intrinsic PEEP”,111,Pendelluft（摆动呼吸）, =RC,：呼出63%的潮气量所需的时间,112,Effects of IRV on differentially ventilated alveolar compartments,Without IRV,With IRV,PEEPi,113,Assisted ventilation vs Controled ventilation,114,Pressure controlled ventilation,115,Pressure support ventilation,同步良好 减少人机对抗 诱导自主呼吸 通气量不能确保,116,Pressure-limitted ventilation,削减气道峰压 减少气压伤 Pmax须大于Pplat以确保容量 Pmax应超过Pplat3cmH2O,117,Ventilatory pressure changes with inspiratory flow,118,Ventilation with low inspiratory flow,保持肺脏通气均匀 保证气道压尽可能低 使吸气暂停尽可能短,119,Pressure Regulated Volume Control,自动根据胸廓/肺顺应性和压力/容积曲线调节吸气压力 压力在压力上限与 PEEP之间自动调节 最大吸气压低于压力上限5cmH2O，减少气压伤 吸气为减速波 结合VC和PC的优点,120,Volume support(VS),自动根据胸廓/肺顺应性和自主呼吸能力调节支持水平 自主呼吸控制吸呼比 自主呼吸触发 可自动转换为自主呼吸 吸气切换为呼气 流量、容量、时间 减少气压伤 吸气为减速波,121,Pressure release ventilation（PRV）,降低气道峰压和气压伤 增加潮气量和分钟通气量 可能导致肺过度膨胀,Phigh,Plow,122,Proportional assist ventilation(PAV),不控制自主呼吸 提供与自主呼吸呈一定比例的辅助压力 舒适 降低气道峰压 减少过度通气 难以确保分钟通气量,Paw = elastance (Vt) + resistance (flow),123,Mandatory minute ventilation(MMV),按需给予通气支持 利于呼吸机的锻炼 便于平稳撤机 存在潜在危险 自主呼吸浅快肺泡通气不足 呼吸节律不匀窒息,124,Biphasic Positive Airway Pressure(BIPAP),125,Sigh ventilation,126,Synchronized Intermittent Mandatory V