吸入麻醉

null第七章 吸入麻醉 Inhalational Anesthesia第七章 吸入麻醉 Inhalational Anesthesia 一、概述 （introduction） 1.概念(concept) 2.特点(characteristic) 一、概述 （introduction） 1.概念(concept) 2.特点(characteristic)可控性好 不留任何后遗症二、吸入麻醉药的吸收、分布与消除 Uptake, distribution and elimination of inhalational anesthetics二、吸入麻醉药的吸收、分布与消除 Uptake, distribution and elimination of inhalational anesthetics 1、吸收与分布Uptake and distribution 作用部位:大脑 central nerve system PA PB PBr 动态平衡 dynamic equilibrium吸收与分布影响因素： 吸收与分布影响因素： 吸入浓度 inspired concentration 分钟通气量 minute volume 血/气分配系数 blood/gas partition coefficient 每分钟肺灌流量 perfusion of pulmonary 2.消除 Elimination ●大部分以原形经肺排出 Eliminated mostly in an unchanged form via the lungs ●少部分经肝、肾排出 a small proportion is metabolized in liver and eliminated via kidney2.消除 Elimination ●大部分以原形经肺排出 Eliminated mostly in an unchanged form via the lungs ●少部分经肝、肾排出 a small proportion is metabolized in liver and eliminated via kidney 三、吸入麻醉药的临床评价 Clinical evaluation of inhalational anesthetics三、吸入麻醉药的临床评价 Clinical evaluation of inhalational anesthetics1.可控性 controllable ● 与血/气分配系数有关 associated with blood/gas partition coefficient 2. 麻醉强度 anesthetic potency ● 与油/气分配系数有关 associated with oil/gas partition coefficient ● MAC(minimal alveolar concentration) MAC is minimal alveolar concentration of an inhalational anesthetic at 1 atmosphere absolute that prevents movements of 50% of the population to a standard stimulus. MAC is minimal alveolar concentration of an inhalational anesthetic at 1 atmosphere absolute that prevents movements of 50% of the population to a standard stimulus. 3. 对心血管的影响 Effects on Cardiovascular system ● 心肌抑制 depression of myocardial contractility ●增加心肌对儿茶酚胺的敏感性：氟烷 ●增加心肌对儿茶酚胺的敏感性：氟烷 Increased myocardial excitability Arrhythmias are common during halothane Increased circulating catecholamines ●呼吸抑制 Respiratory depression dose-dependent depression of ventilation ●呼吸道刺激 irritant to respiratory depression ●支气管平滑肌舒张 relaxation of bronchial smooth muscle 4.对呼吸的影响 Effects on respiratory ●呼吸抑制 Respiratory depression dose-dependent depression of ventilation ●呼吸道刺激 irritant to respiratory depression ●支气管平滑肌舒张 relaxation of bronchial smooth muscle 5.对运动终板的影响 Effects on neuromuscular junction5.对运动终板的影响 Effects on neuromuscular junction ●肌松作用，增强肌松剂的肌松作用 Skeletal muscle relaxation and potentiates non-depolarizing relaxants. ●安氟醚肌松作用最强 Skeletal muscle relaxation of enflurane is the greatest in all inhalational anesthetic . ●氟烷对子宫平滑肌松弛作用最强,增加产后出血可能 Hatholane relaxes uterine muscle and may cause postpartum hemorrhage. ●增加颅内压，异氟醚影响最小 increase ICP, and this action of isoflurane is the lowest in all volatiles. ●抑制EEG，安氟醚可引起痉挛性EEG改变 Dose-dependent depression of EEG activity, at moderate to high concentration (more than 3%), enflurane produces epileptiform paroxysmal spike activity. 6.对颅内压及EEG的影响 Effects on ICP and EEG7.理想吸入麻醉药的特点 Properties of the ideal inhalational anesthetic7.理想吸入麻醉药的特点 Properties of the ideal inhalational anestheticPleasant odour, non-irritant to respiratory depression low blood/solubility—rapid induction and recover from anesthesia Neither flammable nor explosive Producing unconsciousness with analgesia and some degree of muscle relaxation Not be metabolized in the body, non-toxic, not provoke allergic reactions Minimal depression of cardiovascular and respiratory system and not interact with the other drugs used commonly during anesthesia, e.g. catecholamines. null 优 点： ●毒性小，对循环系统抑制轻 low-toxicity, light depression of cardiovascular system ●呼吸道无刺激 non-irritant to respiratory depression ●适用于危重病人 suitable for seriously ill patient ● 诱导和苏醒快 rapid induction and recover from anesthesia 8.气体麻醉药-氧化亚氮 anesthetic gas—nitrous oxide注意事项 announcements 注意事项 announcements ●长时间高浓度吸入时，对红细胞生成有一定的影响,补充vitB12 Affects vitamine B12 synthesis when the duration of nitrous oxide exceeds 8 hours. ●不能单独吸入，最低吸氧浓度为30%，否则，易导致缺氧 Diffusion hypoxia: essential to administer a minimum FiO2 of 30% ●麻醉作用弱，常与安氟醚、异氟醚氧气同时吸入 Good analgesia, poor anesthesia, is used combination with enflurane or isoflurane四、常用吸入麻醉装置 Inhalational anesthesia outfit四、常用吸入麻醉装置 Inhalational anesthesia outfit气源 Gases 流量计 Flow meters 蒸发器 Vaporizers 呼吸囊 Breathing bag 呼吸螺纹管 Anesthetic breathing system 呼吸活瓣 Breathing value 二氧化碳吸收装置 Canister or carbon dioxide absorber null五、常用吸入麻醉方法 Methods of Inhalational anesthesia ㈠ 开放式(open circuits))：开放点滴法、充 气法、无重复吸入法五、常用吸入麻醉方法 Methods of Inhalational anesthesia ㈠ 开放式(open circuits))：开放点滴法、充 气法、无重复吸入法 特点： ●无重复吸入，无CO2吸收装置 优点： ●简单，机械无效腔及呼吸阻力小 ●通过无重复吸入装置可辅助或控制呼吸 缺点： ●气道干燥，污染空气 ●呼呼吸不易管理：舌后坠、呼吸道梗阻， 通气困难 ●麻醉深度不易掌握 ㈡ 半开放式(semi-open circuits) suitable for spontaneous ㈡ 半开放式(semi-open circuits) suitable for spontaneous 特点： ●呼出气部分被重复吸入，无CO2吸收装置 及无重复吸入活瓣，重复吸收CO2<1% 缺点： ●吸入气流量大（分钟通气量的2-3倍), 吸入气流量小时→CO2蓄积 Fresh gas flow rate must be very high (at least 2-3 times Alveolar minute volume to prevent rebreathing) 临床常用“T”管装置： 特点： ●呼出气部分被重复吸入，无CO2吸收装置 及无重复吸入活瓣，重复吸收CO2<1% 缺点： ●吸入气流量大（分钟通气量的2-3倍), 吸入气流量小时→CO2蓄积 Fresh gas flow rate must be very high (at least 2-3 times Alveolar minute volume to prevent rebreathing) 临床常用“T”管装置： ●优点：呼吸阻力及无效腔小 ●适用于20Kg以下儿童，尤其是新生儿、婴幼儿 ●可保留自主呼吸，亦可辅助或控制呼吸㈢半紧闭式 semi-closed circuits㈢半紧闭式 semi-closed circuits特点： ●循环式麻醉机，呼出气部分重复吸入，部 分通过CO2吸收装置 优点： ●麻醉深度可控，不易产生CO2蓄积 缺点： ●麻醉药浪费大，空气污染重 ●呼低流量和吸入氧浓度低时→缺氧 ㈣紧闭式 closed circuit or circle system is the only true circuit as anesthetic gases are recycled.㈣紧闭式 closed circuit or circle system is the only true circuit as anesthetic gases are recycled.特点： ●循环回路，呼出气全部重复吸入，有CO2吸收装置，低流量 exhaled alveolar gas is rebreathed entirely 优点： ●CO2排出完全 ●麻醉深度易控制，低流量吸入节约麻醉药和氧气 ●便于呼吸管理，可监测气道压机潮气量 ●保持气道湿润及维持体温，减少空气污染 缺点： ●结构复杂 ●活瓣失灵→CO2蓄积，呼吸道完全梗阻 ●婴幼儿不宜使用 ㈤低流量吸入麻醉 Inhalational anesthesia with Low flow rate ㈤低流量吸入麻醉 Inhalational anesthesia with Low flow rate 概念： 新鲜气流>4L/min------高流量吸入麻醉 新鲜气流<2L/min------低流量吸入麻醉 特点：半紧闭式或紧闭式 优点： 缺点： ●N2O麻醉时，监测氧浓度<30%时易缺氧 ●吸入气浓度不易控制 ●回路内有麻醉气体以外的气体蓄积 ●麻醉机 ㈥吸入麻醉诱导、维持、苏醒 Induction, maintenance and recovery of inhalational anesthesia ㈥吸入麻醉诱导、维持、苏醒 Induction, maintenance and recovery of inhalational anesthesia 诱导： 慢诱导法 高浓度诱导法 适用范围：不宜用静脉麻醉或不易保持静脉开放的小儿 注意事项：保持呼吸道通畅 维持： 根据手术刺激大小，随时调整吸入浓度 苏醒： 逐渐减少吸入浓度，以减浅麻醉 加强通气，促进吸入麻醉药的排出 六、吸入麻醉期间的管理 Management during inhalational anesthesia 六、吸入麻醉期间的管理 Management during inhalational anesthesia ㈠麻醉前准备preanesthetic preparation ● Preanesthetic visit to assess the risks of anesthesia and surgery and to plan the anesthetic management. ● Anesthetics, equipment for monitoring anesthetic machine and intravenous fluids should be prepared. ㈡麻醉深度监测 monitoring depth of anesthesia ㈢麻醉期间的管理 1.呼吸系统 respiratory system 首要任务-----保持呼吸道通畅 maintaining the airway 1.呼吸系统 respiratory system 首要任务-----保持呼吸道通畅 maintaining the airway 内容： 频率、节律、通畅度、幅度 措施： 望：呼吸方式、胸廓运动幅度、是否有梗阻 听：呼吸音、附加音，双侧是否对称 量：TV、MV、SPO2、血气分析----是否有缺氧和 CO2蓄积 异常呼吸Abnormal breathing ●通气量↓--呼吸浅快,低氧（原因：麻醉过深、肌松剂） MV↓, brachypnea, hypoxia ●呼吸道梗阻(airway obstruction)：呼吸困难 (Dyspnoea)，三凹征(three depressions sign) ●CO2蓄积早期表现：HR↑、BP↑ 上呼吸道梗阻 (Upper respiratory tract obstruction )： 舌后坠、喉痉挛 下呼吸道梗阻( Lower respiratory tract obstruction )： 返流(regurgitation)、分泌物 (secretion)、支气管痉挛(Bronchospasm) ●医源性呼吸道梗阻：导管扭曲(distortion of tracheal tube)、气管异物(foreign body in trachea)、麻醉机失灵(malfunction of anesthesia apparatus ) 异常呼吸Abnormal breathing ●通气量↓--呼吸浅快,低氧（原因：麻醉过深、肌松剂） MV↓, brachypnea, hypoxia ●呼吸道梗阻(airway obstruction)：呼吸困难 (Dyspnoea)，三凹征(three depressions sign) ●CO2蓄积早期表现：HR↑、BP↑ 上呼吸道梗阻 (Upper respiratory tract obstruction )： 舌后坠、喉痉挛 下呼吸道梗阻( Lower respiratory tract obstruction )： 返流(regurgitation)、分泌物 (secretion)、支气管痉挛(Bronchospasm) ●医源性呼吸道梗阻：导管扭曲(distortion of tracheal tube)、气管异物(foreign body in trachea)、麻醉机失灵(malfunction of anesthesia apparatus ) 2.循环系统 听诊： 心音强弱，心脏节律 Cardiac sound and rhythm 量： Blood pressure, peripheral pulse, urine volume MAP、CVP、PAWP、CO ECG：观察心律失常及心肌缺血 arrhythmia and myocardial ischemia Hypovolemia：BP↓、P↑↑、脉压↓、尿量↓、CVP↓ Cardiac failure：BP↓、P↑↑、CVP↑、 颈静脉怒张、肺部湿罗音、肝大 Deep Anesthesia： BP↓、P↓ 2.循环系统 3.全身情况—神志、体温、瞳孔3.全身情况—神志、体温、瞳孔神志：●休克---神志淡漠 ●缺氧---昏迷或苏醒延迟 体温：小儿易高热 瞳孔：●眼球固定、瞳孔缩小---麻醉适宜 ●眼球固定、瞳孔散大、光反应迟钝--- 深度脑抑制、缺氧 其他：体位的影响 坐位开颅： 体位性低血压 上肢外展：臂丛神经损伤、肢体麻痹 术中知晓 Intraoperative awareness 缺氧与CO2蓄积的观察缺氧与CO2蓄积的观察缺氧早期表现Initial signs of hypoxia BP↑、HR↑↑、不一定有紫绀（cyanosis） CO2蓄积早期表现Initial signs of carbon dioxide retention： BP↑、HR↑、呼吸深快、面部潮红 严重缺氧及CO2蓄积表现 呼吸不规则（respiration is irregular）、BP↓、HR↓伴心律失常→呼吸、心跳停止