电解质和酸碱平衡紊乱的生物化学检验(酸碱)(课堂PPT)课件(PPT 102页)

1、第七章 体液平衡与酸碱平衡紊乱（II)孙艳虹中山大学附属第一医院检验医学部Tel: 87755766 ext 8468Email: 1.第1页，共102页。第四节 血气分析血气分析（analysis of blood gas）与酸碱指标测定是临床急救和监护病人的一组重要生化指标，尤其对呼吸衰竭和酸碱平衡紊乱病人的诊断治疗起着关键的作用。 2.第2页，共102页。血气分析仪的发展历史 20世纪五十年代末，丹麦的PoulAstrup研制出第一台血气分析仪大致可将其分为三个发展阶段 50年代末-60年代 手动、笨重、样品用量大、项目少70年代-80年代 自动定标、自动进样、自动清洗、自动检测仪器故障

2、和电极状态，并自动报警，电极的使用寿命和稳定性不断提高，仪器的预热和测量时间也逐步缩短。几百几十微升 ，测量+计算90年代-90年代以来 血气电解质分析仪 便携式、免维护、易操作 3.第3页，共102页。血气分析仪指标血液氧分压（PO2）pH值二氧化碳分压（PCO2）HCO3-三个主要项目并由这三个指标计算出其它酸碱平衡相关的诊断指标，从而对病人体内酸碱平衡、气体交换及氧合作用作出比较全面的判断和认识。 4.第4页，共102页。一 血液中的气体及运输5.第5页，共102页。（一）血液中的气体及运输血液中的气体分压：根据Dalton定律，混合气体的总压强等于各气体分压之和(P=Pi)。气体分压强

3、可由下式计算： 气体分压强=混合气体总压强该气体容积百分比6.第6页，共102页。溶解度系数根据Henry定律，在一定温度下某种气体在血液中的溶解量与其分压呈正比，而且随温度升高其数值减少。气体的溶解量用溶解度系数(Bunsen coefficient)表示。 溶解度系数：指压力为760mmHg(101kPa)和特定温度时1ml液体中溶解气体的毫升数。 7.第7页，共102页。（二）血中的氧血液氧含量(ct o2)ct o2 = cd o2 + o2 Hb 1.5% 98.5%血红蛋白(hemoglobin Hb) 对氧的运输：血浆中PO2的改变会直接影响O2与Hb结合 8.第8页，共102页

4、。血氧饱和度：血液中HbO2的量与Hb总量（包括HHb和HbO2）之比 血氧饱和度=HbO2/（HHb+HbO2）氧的运输与氧解离曲线9.第9页，共102页。以血氧饱和度对PO2作图，所得的曲线称为氧解离曲线。 氧解离曲线呈S型具有重要的生理意义 氧解离曲线（Oxygen dissociation curve） 10.第10页，共102页。由组织扩散入血浆，其中少量溶于水 8.8%向红细胞内扩散，在红细胞内碳酸酐酶（carbonic anhydrase， CA）作用下与水结合成H2CO3 77.8%与Hb结合成氨基甲酸血红蛋白（HbNHCOOH) 13.4%（三）CO2的运输11.第11页，共

5、102页。12.第12页，共102页。（一）血气分析标本的采集与处理1. 动脉血2. 动脉化毛细血管血3. 静脉血4. 取血前病人的准备5. 抗凝剂及采血器6. 标本的贮存 二、血气分析标本的采集和质量控制13.第13页，共102页。仪器分析性能的保证 控制物 采集合格的血液标本制定统一的操作规程 温度的控制 对精密度和准确度的要求二、血气分析标本的采集和质量控制14.第14页，共102页。采集标本的标准化 注射器和针头的标准化2ml注射器比5ml注射器为佳死腔量小肝素与血之比约为1202ml注射器针蕊较轻，当针刺入动脉后，血液进入针筒较快，这时无需抽拉注射器的针蕊造成负压，气泡不易混入 15

6、.第15页，共102页。采集标本的标准化 抗凝剂的标准化肝素是血气分析的最佳抗凝剂 使用液体肝素，要最大限度地减小标本的稀释。 把吸入针筒的抗凝剂尽量排出，肝素的浓度必须足够低，标本的最终浓度要在50100ul/ml之间。 残留肝素愈多，使标本中PH值偏低，PO2偏高，PCO2偏低，实验证明对PCO2影响最大。 16.第16页，共102页。采集标本的标准化 血液和肝素混合的标准化取样后要认真混匀，将注射器放在手心中慢慢滚动1分钟，并上下翻转5次，充分混合，动作要慢不能太剧烈，避免溶血。 17.第17页，共102页。采集标本的标准化 确保密闭必须防止外界空气进入。抽血时必须做到：抽血针筒不漏气；

7、抽气时应让血液自动进入注射器，切勿用力拉针蕊，以免空气沿针筒壁进入；针头拔出时应立刻将针头刺入橡皮塞内，注意针头不要穿通橡皮塞。隔绝空气空气中氧分压高于动脉血，二氧化碳分压低于动脉血18.第18页，共102页。采集标本的标准化 抽血后及时送检细胞离体后还在不断地进行新陈代谢，使PH下降、PCO2上升、PO2下降，标本存放时间愈长，室温愈高，变化愈大 ； 如不能及时测定，将标本放置于4，2小时内检测 19.第19页，共102页。采集标本的标准化 测定前标本要充分混合除血液与抗凝剂充分混合外，在测定前血浆和血球要充分混合，特别是对血红蛋白、红细胞压积影响最大。把注射器针头部位不能混合的血弃去，然后

8、慢慢进行注入。 20.第20页，共102页。仪器的标准化 仪器调试新购仪器必须进行性能鉴定（电极线性、稳定性、气压计精密度、重复性试验），是观察电子元件及电极的重要方法，并要有详细的记录。 21.第21页，共102页。仪器的标准化 仪器的标定在进行标本测定之前必须用三个标准物分别定标，使其各参数值均在标准物参数范围内，才能进行标本测定。 22.第22页，共102页。仪器安装标准化 放置仪器的实验台要稳固(最好水泥台)，工作环境要清洁(最好操作间单独隔开)，要防潮、防止阳光直射，室内温度应在1525之间，相对湿度应80%。仪器应有稳压器，并有良好的接地。 23.第23页，共102页。制订严格的操

9、作规程 严格的操作规程是质量的保证，将操作规程张贴在操作台前，随时检查及时对照，同时要建立仪器使用工作记录，每天记录仪器的使用情况及故障的发生与排除。 24.第24页，共102页。其他质控物：要定期对仪器进行质量监控。查找失控之可能原因进行逐项排除直至在控，方可用于病人标本分析。电极的线性：用不同浓度的气体进行校正，制作曲线。用于验证电极的质量温度控制：仪器内温度必须设定在370.1。25.第25页，共102页。三、血气分析常用指标与参数及 临床意义26.第26页，共102页。【参考范围】动脉血pH 7.357.45(一)酸碱度（pH） NaHCO3 pH=6.1+log 0.03Pco2 p

10、H 电极判断酸或碱紊乱不能确定紊乱的性质27.第27页，共102页。二氧化碳分压（partial pressure of carbon dioxide， pCO2）是指物理溶解在血液中的CO2所产生的张力。在HH方程中H2CO3代表了呼吸成分，并直接影响pH值，即：【参考范围】动脉血PCO2：3545mmHg（4.67-6.0kPa）(二)二氧化碳分压 pCO2 NaHCO3 pH=6.1+log 0.03Pco2 是否为呼吸性酸碱紊乱， 代偿后的代谢性酸碱紊乱。28.第28页，共102页。氧分压（partial pressure of oxygen，PO2）是指血浆中物理溶解的O2所产生的张

11、力。 PO2是缺氧的敏感指标，肺通气和换气功能障碍动脉血氧分压（PaO2）的正常参考范围为75-100mmHg55mmHg 呼吸衰竭 代偿变化原发失衡的变化决定pH偏向 例1：血气 pH 7.32，PaCO230 mmHg，HCO3- 15 mmol/L。判断原发失衡因素 例2：血气 pH 7.42， PaCO2 29 mmHg，HCO3- 19 mmol/L。判断原发失衡因素 pH 7.357.45PCO235-45 mmHg 40 mmHgHCO3-2227 mmol/L 24 mmol/L酸碱平衡的判断概念257.第57页，共102页。代偿公式代谢 HCO3-改变为原发时：代酸时：代偿后

12、PaCO2 极限10mmHg 代碱时：代偿后的PaCO2升高55mmHg58.第58页，共102页。代偿公式呼吸( PaCO2）改变为原发时，所继发HCO3-变化分急性和慢性（35天），其代偿程度不同:急性呼吸（PaCO2）改变时，所继发HCO3-变化为34 mmol 慢性呼吸性酸中毒时：代偿后的HCO3-升高水平(HCO3-）=0.35PaCO25.58 慢性呼吸性碱中毒时：代偿后的HCO3-降低水平(HCO3-）=0.49 PaCO21.7259.第59页，共102页。酸碱平衡判断的四步骤据pH、PaCO2、HCO3-变化判断原发因素据所判断的原发因素选用相关的代偿公式据实测HCO3-/P

13、aCO2与相关公式所计算出的代偿区间相比，确定是单纯或混合酸碱失衡高度怀疑三重酸碱失衡（TABD）的，同时测电解质，计算AG和潜在HCO3-60.第60页，共102页。pH碱中毒?正常?呼吸性碱中毒酸中毒?代谢碱中毒呼吸性酸中毒*代谢性碱中毒#代谢性酸中毒呼吸性碱中毒*代谢性酸中毒#呼吸性酸中毒呼吸性酸中毒代谢性碱中毒正常呼吸性碱中毒代谢性酸中毒呼吸性碱中毒代谢性碱中毒(HCO3-）=0.35PaCO25.58(HCO3-）=0.49 PaCO21.72呼吸性酸中毒呼吸性碱中毒代谢性酸中毒*实测预计上限实测预计上限实测7.45PCO2PCO2PCO245 mmHg45 mmHg45 mmHg

14、7.35路线图黑体表示起主要作用*可能是代偿/病理#临床观察61.第61页，共102页。病例分析一男性患者,62岁,因“肺气肿合并感染”于1996.8.1日入院.入院后经常规治疗,病情没有好转,反而加重,8.14日出现轻度昏迷,痰多并不能排出,肺部感染难以控制.表:病人入院时和病情严重时的血气分析、电解质变化日期 pH Pco2 HCO3- BE AG K+ Cl- 2/8 7.31 12.36 44.8 17.7 9.1 4.3 89.914/8 7.20 12.28 34.2 6.4 22.6 5.9 92.3请分析该病人酸碱平衡失调的类型(含诊断依据) 62.第62页，共102页。检查酸

15、碱平衡的生化指标1.CO2结合力(CO2CP):主要反映代谢性因素的变化2.血液pH值:反映代偿性或失偿性酸碱平衡失常的指标3.CO2分压(Pco2):反映呼吸性酸碱平衡失调4.缓冲碱(BB):反映代谢性酸碱平衡失调5.碱剩余(BE):反映代谢性酸碱平衡失调6.实际HCO3-(AB):主要反映代谢性因素的变化7.标准HCO3-(SB):反映代谢性酸碱平衡失调8.阴离子隙(AG):有助于诊断代谢性酸中毒63.第63页，共102页。小 结1.血液pH值正常,不能排除混合型酸碱平衡失调2.BE:标态下,用标准酸滴定至Ph7.4所用的量正值 BD:标态下,用标准碱滴定至Ph7.4所用的量负值3.不受呼

16、吸代谢性酸碱平衡的主要指标:BB、BE、SB4.临床反映代谢性酸碱平衡的主要指标:BE、AB或SB5.临床反映呼吸性酸碱平衡的主要指标:Pco26.临床反映代偿或失偿酸碱平衡失调的指标:血液pH值64.第64页，共102页。65.第65页，共102页。小节不拘小节胆大心细融会贯通66.第66页，共102页。A step by step guideArterial Blood GasesA step by step guideHCO3- + H+ H2CO3 CO2 + H2067.第67页，共102页。ObjectivesTo be able to interpret simple arter

17、ial blood gasTo know the meaning of common terms used in arterial blood gas interpretationTo know the normal ranges for arterial blood gas values68.第68页，共102页。How to Analyze an ABGPO2NL = 80 100 mmHg2. pHNL = 7.35 7.45Acidotic7.45PCO2NL = 35 45 mmHgAcidotic45Alkalotic35HCO3NL = 22 26 mmol/LAcidotic

18、2669.第69页，共102页。Normal ABG Values?PaO2 pHPaCO2HCO3Base Excess10.0 kPa（75mmHg)7.35 - 7.454.5 - 6.0 kPa(35-45mmHg)22 - 26-2 - +2Many modern gas machines also measureK+ Na+ Cl- SaO2 Hb COHb MetHb LactateTo convert kPa to mmHg multiply by 7.570.第70页，共102页。5 steps to analysing an ABGIs the patient hypoxi

19、c? Is there a significant degree of lung injury? A a GradientThe gradient between alveolar PAO2 and arterial PaO2 in a person with healthy lungs is 15 20 mmHgThe higher the gradient, the worst the lung injury71.第71页，共102页。5 steps to analysing an ABGDoes the patient have an acidaemia or an alkalaemia

20、? Is the cause respiratory or metabolic?Is there any attempt at compensation? 72.第72页，共102页。CompensationRespiratory compensation is quickMetabolic compensation is slowCompensation is not usually completePatients never over compensate73.第73页，共102页。Acid-Base disorderpHPaCO2HCO3Respiratory acidosisMeta

21、bolic acidosisRespiratory alkalosisMetabolic alkalosisRespiratory acidosis with partial renal compensationMetabolic acidosis with partial respiratory compensationRespiratory alkalosis with partial renal compensationMetabolic alkalosis with partial respiratory compensationMixed metabolic & respirator

22、y acidosisMixed metabolic & respiratory alkalosisNNNNFill in the gaps74.第74页，共102页。Scenario 1 Arterial blood gas analysis reveals:FiO20.4 (40%)PaO27.0 kPapH7.25PaCO28.9 kPa HCO33565 year old male with known COPD presents in A&E complaining of increased breathlessness. The paramedics have put him on

23、a venturi mask to give an FiO2 of 40% due to his breathlessness and initial low saturations.Significant findings on your examination is a drowsy patient with a resp rate of 8, SpO2 of 85% and wide-spread coarse cracklesHypoxiaRespiratory acidosis with chronic renal compensationInfective exacerbation

24、 of COPD?Hypoxic drive ?tired75.第75页，共102页。Scenario 2 Arterial blood gas analysis reveals:FiO20.3 (30%)PaO222.0 kPapH7.15PaCO22.5 kPa HCO310Na135K5.4Cl106Anion Gap = ?18 year old male with diabetes has been suffering from D&V for 48 hours and because he has been unable to eat he has not taken his in

25、sulinSignificant findings on your examination are a resp rate of 40, heart rate of 120, BP 95/50, Blood glucose 30mmol/lMetabolic acidosis with respiratory compensationDKA2476.第76页，共102页。Scenario 3 Arterial blood gas analysis reveals:FiO20.21 (21%)PaO215.1 kPapH7.53PaCO23.1 kPa HCO325.017 year old m

26、ale has taken his fathers BMW (without asking) to impress his girlfriend and had a altercation with a large bus where the BMW came off much the worse.There is little abnormal to find on examination apart from bruising, a resp rate of 24, a pulse of 110 and a BP of 120/85Respiratory alkalosisAnxiety7

27、7.第77页，共102页。Scenario 4 Arterial blood gas analysis reveals:FiO20.4 (40%)PaO28.2 kPapH7.17PaCO23.7 kPaHCO3-12 mmol/LA 75 year old female is on the surgical ward 2 days after a laparotomy for a perforated sigmoid colon secondary to diverticular disease. She has become hypotensive over the last 6 hour

28、s. A nurse has started 40% O2On examination vital signs are: RR 35 min-1, SpO2 92%, HR 120 min-1, warm peripheries, BP 70/40 mmHg, Urine output 50 ml in the last 6 hoursHypoxiaMetabolic acidosis with respiratory compensationShock secondary to Sepsis78.第78页，共102页。Scenario 5 A 75 year old man presents

29、 to the emergency department after a witnessed out-of-hospital VF cardiac arrest. The paramedics arrived after 5 minutes, during which CPR had not been attempted. The paramedics had successfully restored spontaneous circulation after 3 shocks but have been unable to intubate him. He is breathing spo

30、ntaneously with a re breathing mask in situ. On arrival: comatose (GCS 3) Resp rate 8 HR 120 min-1BP 150/95 mmHg.Arterial blood gas analysis reveals:FiO20.85 (85%)PaO210.5 kPapH7.10PaCO27.0 kPa HCO314BE- 10Mixed respiratory and metabolic acidosisHypoperfusion and respiratory failure79.第79页，共102页。Any

31、 Questions?80.第80页，共102页。SummaryIdentify the hypoxic patientIdentify an acidosis or alkalosisRecognise when compensation is taking placeFormulate an initial treatment plan for some common scenariosUnderstand the role Arterial Blood Gases play in patient management You should now be able to:81.第81页，共

32、102页。Mixed Acid-Base AbnormalitiesCase Study No. 3:56 yo neurologic dz required ventilator support for severalweeks. She seemed most comfortable when hyperventilatedto PaCO2 28-30 mmHg. She required daily doses of lasix toassure adequate urine output and received 40 mmol/L IV K+each day. On 10th day

33、 of ICU her ABG on 24% oxygen & VS:82.第82页，共102页。ABG ResultspH7.62BP115/80 mmHgPCO230 mmHgPulse88/minPO285 mmHgRR10/minHCO330 mmol/LVT1000mlBE10 mmol/LMV10LK+2.5 mmol/L Interpretation:Acute alveolar hyperventilation (resp. alkalosis) and metabolic alkalosis with corrected hypoxemia.83.第83页，共102页。Cas

34、e study No. 427 yo retarded with insulin-dependent DM arrived at ERfrom the institution where he lived. On room air ABG & VS:pH7.15BP180/110 mmHgPCO222 mmHgPulse130/minPO292 mmHgRR40/minHCO3 9 mmol/LVT800mlBE-30 mmol/LMV32LInterpretation:Partly compensated metabolic acidosis.84.第84页，共102页。Case study

35、 No. 574 yo with hx chronic renal failure and chronic diuretic therapywas admitted to ICU comatose and severely dehydrated. On40% oxygen her ABG & VS:pH7.52BP130/90 mmHgPCO255 mmHgPulse120/minPO292 mmHgRR25/minHCO342 mmol/LVT150mlBE17 mmol/LMV 3.75LInterpretation:Partly compensated metabolic alkalos

36、is with corrected hypoxemia.85.第85页，共102页。Case study No. 643 yo arrives in ER 20 minutes after a MVA in which heinjured his face on the dashboard. He is agitated, has mottled,cold and clammy skin and has obvious partial airway obstruction.An oxygen mask at 10 L is placed on his face. ABG & VS:pH7.10

37、BP150/110 mmHgPCO260 mmHgPulse150/minPO2125 mmHgRR45/minHCO318 mmol/LVT? mlBE-15 mmol/LMV? L.Interpretation:Acute ventilatory failure (resp. acidosis) andacute metabolic acidosis with corrected hypoxemia86.第86页，共102页。Case study No. 717 yo, 48 kg with known insulin-dependent DM came to ERwith Kussmau

38、l breathing and irregular pulse. Room airABG & VS:pH7.05BP140/90 mmHgPCO212 mmHgPulse118/minPO2108 mmHgRR40/minHCO35 mmol/LVT1200mlBE-30 mmol/LMV48LInterpretation:Severe partly compensated metabolicacidosis without hypoxemia. 87.第87页，共102页。Case No. 7 contdThis patient is in diabetic ketoacidosis.IV

39、glucose and insulin were immediately administered. Ajudgement was made that severe acidemia was adverselyaffecting CV function and bicarb was elected to restore pH to 7.20.Bicarb administration calculation:Base deficit X weight (kg) 430 X 48 = 360 mmol/LAdmin 1/2 over 15 min & 4 repeat ABG88.第88页，共1

40、02页。Case No. 7 contdABG result after bicarb:pH7.27BP130/80 mmHgPCO225 mmHgPulse100/minPO292 mmHgRR22/minHCO311 mmol/LVT600mlBE-14 mmol/LMV13.2L89.第89页，共102页。Case study No. 847 yo was in PACU for 3 hours s/p cholecystectomy. Shehad been on 40% oxygen and ABG & VS:pH7.44BP130/90 mmHgPCO232 mmHgPulse95

41、/min, regularPO2121 mmHgRR20/minHCO322 mmol/LVT350mlBE-2 mmol/LMV7LSaO298%Hb13 g/dL90.第90页，共102页。Case No. 8 contdOxygen was changed to 2L N/C. 1/2 hour pt. ready to be D/Cto floor and ABG & VS:pH7.41BP130/90 mmHgPCO210 mmHgPulse95/min, regularPO2148 mmHgRR20/minHCO36 mmol/LVT350mlBE-17 mmol/LMV7LSaO

42、299%Hb7 g/dL91.第91页，共102页。Case No. 8 contd What is going on?92.第92页，共102页。Case No. 8 contdIf the picture doesnt fit, repeat ABG!pH7. 45BP130/90 mmHgPCO231 mmHgPulse95/minPO287 mmHgRR20/minHCO322 mmol/LVT350mlBE-2 mmol/LMV7LSaO2 96% Hb13 g/dLTechnical error was presumed.93.第93页，共102页。Case study No. 9

43、67 yo who had closed reduction of leg fx without incident.Four days later she experienced a sudden onset of severe chestpain and SOB. Room air ABG & VS:pH7.36BP130/90 mmHgPCO233 mmHgPulse100/minPO255 mmHgRR25/minHCO318 mmol/LBE-5 mmol/LMV18LSaO288% Interpretation:Compensated metabolic acidosis withm

44、oderate hypoxemia. Dx: PE94.第94页，共102页。Case study No. 1076 yo with documented chronic hypercapnia secondary tosevere COPD has been in ICU for 3 days while being tx forpneumonia. She had been stable for past 24 hours and wastransferred to general floor. Pt was on 2L oxygen & ABG &VS:pH7.44BP135/95 mm

45、HgPCO263 mmHgPulse110/minPO252 mmHgRR22/minHCO342 mmol/LBE+16 mmol/LMV10LSaO286%. Interpretation:Chronic ventilatory failure (resp. acidosis)with uncorrected hypoxemia95.第95页，共102页。Case No. 10 contdShe was placed on 3L and monitored for next hour. She remained alert, oriented and comfortable. ABG wasrepeated:pH7.36BP140/100 mmHgPCO275 mmHgPulse105/minPO265 mmHgRR24/minHCO342 mmol/LBE+16 m