医学血气分析课件

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,2019/12/25,#,血气分析,的常用指标及其意义,陈钢,血气分析的常用指标及其意义陈钢,2024/8/23,2,反映机体酸碱状态的主要指标,1,、,酸碱度,（,pH,）,2,、,PaCO,2,3,、,碳酸氢根,（,HCO,3,-,）,4,、,剩余碱,（,BE,）,5,、,缓冲碱,（,BB,）,6,、,CO,2,结合力,（,CO,2,-CP,）,2023/8/302反映机体酸碱状态的主要指标1、酸碱度（p,2024/8/23,3,酸碱度,（,pH,）,反映,H,+,浓度的指标，以,H,+,浓度的负对数表示。,正常值：,7.35 7.45,。,pH7.45,碱,中毒（失代偿）,2023/8/303酸碱度（pH） 反映H+浓,2024/8/23,4,PaCO,2,PaCO,2,是判断呼吸性酸碱失衡的重要指标，代表溶解于血浆中的,CO,2,量，反映肺泡通气效果。,正常值：,35 45mmHg,。,PaCO,2,45mmhg,，,原发性呼酸,或继发性,代偿性代碱,。,2023/8/304PaCO2 PaCO2,2024/8/23,5,碳酸氢根,（,HCO,3,-,）,HCO,3,-,是,反映代谢方面情况的指标。,实际碳酸氢根（,AB,）,：直接从血浆测得数据，受代谢和呼吸双重影响（当,PaCO,2,升高时，,HCO,3,-,升高）。正常值：,21 27mmol/L,。,标准碳酸氢根（,SB,）,：在隔绝空气、,38,度、,PaCO,2,为,40mmHg,、,SaO,2,为,100%,时测得的,HCO,3,-,含量。不受呼吸因素的影响， 基本反映体内,HCO,3,-,储量的多少，比,AB,更为准确，但不能测出红细胞内缓冲作用，也不能反映全部非呼吸酸碱失衡的程度。正常值：,22 27mmol/L,。,2023/8/305碳酸氢根（HCO3-） H,2024/8/23,6,碳酸氢根,（,HCO,3,-,）,健康人,AB = SB,，撒播碱失衡时两值不一致：,AB SB,：存在,呼酸,AB SB,：存在,呼碱,2023/8/306碳酸氢根（HCO3-）,2024/8/23,7,剩余碱,（,BE,）,在标准条件下，,Hb,充分氧合、,38,度、,PaCO,2,40mmHg,时将,1L,全血用酸或碱滴定至,pH=7.40,时所需的酸或碱量。反映总的缓冲碱的变化，较,SB,更全面，只反映代谢变化，不受呼吸因素影响。正常值：,-3 +3mmol/L,（全血）。,BE +3mmol/L,：,代碱,2023/8/307剩余碱（BE）,2024/8/23,8,缓冲碱,（,BB,）,是,1,升全血（,BBb,）或,1,升血浆（,BBp,）中所具有缓冲作用的阴离子总和，主要是和血浆蛋白，反映机体在酸碱紊乱时总的缓冲能力。正常范围：,45,55mmol/L,，与,HCO,3,-,有所不同，由于其受,Hb,、血浆蛋白的影响，当出现,BB,降低，而,HCO,3,-,正常时，说明存在,HCO,3,-,以外碱储备不足，如低蛋白血症、贫血等，纠正这种碱储不足，补充,HCO,3,-,是不适宜的。,2023/8/308缓冲碱（BB）是1升全血（BBb）或1升,2024/8/23,9,CO,2,结合力,（,CO,2,-CP,）,将静脉血在室温下与含,5.5% CO,2,的空气平衡，然后测定血浆之,CO,2,含量，减去物理溶解的,CO,2,，即得出,CO,2,结合力。受呼吸和代谢因素的影响，目前已不受重视。,CO,2,-CP,：,呼酸,或,代碱,CO,2,-CP,：,呼碱,或,代酸,2023/8/309CO2结合力（CO2-CP）,2024/8/23,10,反映血氧合状态的指标,1,、,PaO,2,2,、,SaO,2,3,、,CaO,2,4,、,氧解离曲线和,P,50,5,、,肺泡,-,动脉血氧分压差,（,P,(A-a),O,2,）,2023/8/3010反映血氧合状态的指标1、PaO2,2024/8/23,11,PaO,2,动脉血浆中物理溶解的氧分子所产生的分压，是确定,SaO,2,的重要因素。,正常值：,80 100mmHg,。随年龄增大而降低。,PaO,2,= (100,0.33,年龄,)mmHg,。,2023/8/3011PaO2 动脉血浆中,2024/8/23,12,SaO,2,动脉血中,Hb,实际结合的氧量与所能结合的最大氧量之比。与,PaO,2,和,Hb,氧解离曲线直接相关。,正常值：,93% 99%,。,2023/8/3012SaO2,2024/8/23,13,CaO,2,血液实际结合的氧总量（,Hb,氧含量和物理溶解量）。,血红蛋白氧含量,= 1.34Hb SaO,2,%,物理溶解氧含量,= PaO,2,0.003ml%,正常人：,20.3ml%,2023/8/3013CaO2,2024/8/23,14,氧解离曲线和,P,50,氧解离曲线：,PaO,2,与,SaO,2,间的关系曲线，呈,S,型。,P,50,：,pH=7.40,、,PaCO,2,=40mmHg,条件下，,SaO,2,为,50%,时的,PaO,2,。,正常值：,2428mmHg,。,P,50,：曲线右移，,Hb,与,O,2,亲和力降低，有利于释氧。,P,50,：曲线左移，,Hb,与,O,2,亲和力增加，不有利于释氧。,影响因素：,pH,、温度、,2,3-DPG,2023/8/3014氧解离曲线和P50 氧,2024/8/23,15,肺泡,-,动脉血氧分压差,（,P,(A-a),O,2,）,正常值：,5 15mmHg,。,P,(A-a),O,2,增大：肺泡弥散障碍；生理性分流或病理性左,-,右分流；,通气,/,血流比例失调。,2023/8/3015肺泡-动脉血氧分压差（P(A-a)O2,2024/8/23,16,酸碱失衡的诊断,1,、分清原发和继发（代偿）？酸中毒或碱中毒？,2,、,分清单纯性或混合性酸碱失衡？,3,、阴子间隙,（,anion gap,，,AG,）,2023/8/3016酸碱失衡的诊断1、分清原发和继发（代偿,2024/8/23,17,分清酸中毒或碱中毒？,PH ,7.40,提示原发失衡可能为,碱中毒,2023/8/3017分清酸中毒或碱中毒？ PH 7.,2024/8/23,18,分清单纯性或混合性酸碱失衡？,PaCO,2,同时伴,HCO,3,-,，必为,呼酸合并代酸,PaCO,2,同时伴,HCO,3,-,，必为,呼碱合并代碱,2023/8/3018分清单纯性或混合性酸碱失衡？,2024/8/23,19,不同酸碱失衡类型的血气改变,酸碱失衡类型,pH PaCO,2,HCO,3,-,BE,呼吸性酸中毒, （稍）,=,呼吸性酸中毒代偿,= ,呼吸性碱中毒, （稍）,=,呼吸性碱中毒代偿,= ,代谢性酸中毒,= ,代谢性酸中毒代偿,= ,代谢性碱中毒,= ,代谢性碱中毒代偿,= ,呼酸并代酸, ,呼碱并代碱, ,呼酸并代碱,= ,呼碱并代酸,= ,2023/8/3019不同酸碱失衡类型的血气改变,2024/8/23,20,阴子间隙,（,AG,）,血清中所测得的阳离子总数和阴离子总数之差。,AG =,（,Na,+,+ K,+,）（,Cl,+ HCO,3,-,）,可简化为,AG = Na,+,（,Cl,+ HCO,3,-,） 正常值：,8 16mmol/L,AG,：代酸、脱水、低,K,+,，,Ca,2+,、,Mg,2+,AG,：未测定阴离子浓度（细胞外液稀释、低蛋白血症）,未测定阳离子浓度（高,K,+,，,Ca,2+,、,Mg,2+,、多发性骨髓瘤,2023/8/3020阴子间隙（AG）,2024/8/23,21,Example 4.,A patient with COPD has a ABG taken in out-patient clinic to assess his need for home oxygen. He is breathing room air.,pH,7.34,P,a,CO,2,60,P,a,O,2,56,HCO,3,-,32.1,Base excess,+8,Saturation,86%,Click to continue,Click to continue,2023/8/3021Example 4.A patien,2024/8/23,22,Example 4.,pH,7.34,P,a,CO,2,8.0,P,a,O,2,7.5,HCO,3,-,32.1,Base excess,+8,Saturation,86%,1.,Is he hypoxic?,YES.,The,(A-a) PO,2,= 2.4 kPa,The (A-a) gradient is increased, and home oxygen might be appropriate,Click to continue,2023/8/3022Example 4.pH7.34PaC,2024/8/23,23,Example 4.,pH,7.34,P,a,CO,2,8.0,P,a,O,2,7.5,HCO,3,-,32.1,Base excess,+8,Saturation,86%,2,.,Is there an acid base or ventilation problem?,YES.,Click to continue,2023/8/3023Example 4.pH7.34PaC,2024/8/23,24,Example 4.,There is:,Mild acidosis,P,a,CO,2,is elevated,RESPIRATORY ACIDOSIS,pH,7.34,P,a,CO,2,8.0,P,a,O,2,7.5,HCO,3,-,32.1,Base excess,+8,Saturation,86%,Diagnose disturbance,Click to continue,2023/8/3024Example 4.There is:,2024/8/23,25,Example 4.,There is:,HCO,3,-,= 32.1,Expected HCO,3,-,= 24 + (8.0,5.3) x 3.0 = 32.1,This is the expected HCO,3,-, if there has been significant renal compensation over a long period; in addition the base excess has increased.,CHRONIC RESPIRATORY ACIDOSIS,pH,7.34,P,a,CO,2,8.0,P,a,O,2,7.5,HCO,3,-,32.1,Base excess,+8,Saturation,86%,Click to continue,2023/8/3025Example 4.There is:,2024/8/23,26,Example 4.,There is:,pH change:,8.0,5.3 x 0.02 = 0.054,pH = 7.4,0.054 = 7.346,CONSISTENT WITH SIMPLE CHRONIC RESPIRATORY ACIDOSIS; NO ADDITIONAL DISTURBANCE,pH,7.34,P,a,CO,2,8.0,P,a,O,2,7.5,HCO,3,-,32.1,Base excess,+8,Saturation,86%,Return to examples,2023/8/3026Example 4.There is:,2024/8/23,27,Example 5.,A 35 year old woman with a history of anxiety attacks presents to ER .,1.,Is she hypoxic?,pH,7.54,P,a,CO,2,22.5,P,a,O,2,91,HCO,3,-,22,Base excess,+2,Saturation,100%,Click to continue,2023/8/3027Example 5.A 35 yea,2024/8/23,28,Example 5.,NO.,This is a normal P,a,O,2,for room air,2. Is there an acid base or ventilation problem?,pH,7.54,P,a,CO,2,2.9,P,a,O,2,12.1,HCO,3,-,22,Base excess,+2,Saturation,100%,Click to continue,2023/8/3028Example 5.pH7.54PaC,2024/8/23,29,Example 5.,2. Is there an acid base or ventilation problem?,YES.,pH,7.54,P,a,CO,2,2.9,P,a,O,2,12.1,HCO,3,-,22,Base excess,+2,Saturation,100%,Click to continue,2023/8/3029Example 5.2. Is the,2024/8/23,30,Example 5.,There is:,Alkalosis,P,a,CO,2,is decreased,RESPIRATORY ALKALOSIS,pH,7.54,P,a,CO,2,2.9,P,a,O,2,12.1,HCO,3,-,22,Base excess,+2,Saturation,100%,Diagnose disturbance,Click to continue,2023/8/3030Example 5.There is,2024/8/23,31,Example 5.,pH,7.54,P,a,CO,2,2.9,P,a,O,2,12.1,HCO,3,-,20,Base excess,+2,Saturation,100%,There is:,HCO,3,-,= 20,Expected HCO,3,-,= 24 - (5.3,2.9) x 1.5 = 20.4,This is the expected HCO,3,-, if there has only been a small amount of renal compensation,ACUTE RESPIRATORY ALKALOSIS,Click to continue,2023/8/3031Example 5.pH7.54PaC,2024/8/23,32,Example 5.,pH,7.54,P,a,CO,2,2.9,P,a,O,2,12.1,HCO,3,-,22,Base excess,+2,Saturation,100%,There is:,pH change:,5.3-2.9 x 0.06 = 0.144,pH = 7.4 + 0.144 = 7.54,CONSISTENT WITH SIMPLE ACUTE RESPIRATORY ALKALOSIS; NO ADDITIONAL DISTURBANCE,Return to examples,2023/8/3032Example 5.pH7.54PaC,2024/8/23,33,Example 6.,pH,7.23,P,a,CO,2,25,P,a,O,2,225,HCO,3,-,12,Base excess,-10,Saturation,100%,A 42 year old diabetic woman present with UTI symptoms; she has deep sighing respiration. This is the ABG on FiO,2,0.4,1.,Is she hypoxic?,Click to continue,2023/8/3033Example 6.pH7.23PaC,2024/8/23,34,Example 6.,pH,7.23,P,a,CO,2,3.3,P,a,O,2,29.9,HCO,3,-,12,Base excess,-10,Saturation,100%,NO.,This P,a,O,2,is adequate for an FiO,2,of 0.4,2. Is there an acid base or ventilation problem?,Click to continue,2023/8/3034Example 6.pH7.23PaC,2024/8/23,35,Example 6.,pH,7.23,P,a,CO,2,3.3,P,a,O,2,29.9,HCO,3,-,12,Base excess,-10,Saturation,100%,2. Is there an acid base or ventilation problem?,YES.,Click to continue,2023/8/3035Example 6.pH7.23PaC,2024/8/23,36,Example 6.,pH,7.23,P,a,CO,2,3.3,P,a,O,2,29.9,HCO,3,-,12,Base excess,-10,Saturation,100%,There is:,Acidosis,P,a,CO,2,is decreased, NOT respiratory acidosis,Look at HCO,3,-,HCO,3,-, is reduced,Base excess is negative,METABOLIC ACIDOSIS,Click to continue,2023/8/3036Example 6.pH7.23PaC,2024/8/23,37,Example 6.,pH,7.23,P,a,CO,2,3.3,P,a,O,2,29.9,HCO,3,-,12,Base excess,-10,Saturation,100%,Using Winters formula:,Expected P,a,CO,2,= (1.5 x 12) + (8 2) x 0.133,= 3.2 3.7 kPa,The P,a,CO,2,falls within this range,SIMPLE METABOLIC ACIDOSIS,What is the anion gap?,Click to continue,2023/8/3037Example 6.pH7.23PaC,2024/8/23,38,Example 6.,pH,7.23,P,a,CO,2,3.3,P,a,O,2,29.9,HCO,3,-,12,Base excess,-10,Na,+,135,Cl,-,99,What is the anion gap?,= Na+ ( Cl,-, + HCO,3,-, ),= 135 ( 99 + 12 ),Na,= 24 mmol/l,There is an anion gap acidosis due to accumulation of organic acids caused by diabetic ketoacidosis,Click to continue,2023/8/3038Example 6.pH7.23PaC,2024/8/23,39,Example 6.,pH,7.23,P,a,CO,2,3.3,P,a,O,2,29.9,HCO,3,-,12,Base excess,-10,Na,+,135,Cl,-,99,Corrected bicarbonate,= 24 mmol/l,The P,a,CO,2,falls within the expected range,SIMPLE METABOLIC ACIDOSIS; NO OTHER DISTURBANCE,Return to examples,2023/8/3039Example 6.pH7.23PaC,2024/8/23,40,Example 7.,A 70 year old man presents with a 3 day history of severe vomiting.,Here is his ABG on room air.,1.Is he hypoxic?,pH,7.5,P,a,CO,2,6.2,P,a,O,2,10.6,HCO,3,-,38,Base excess,+8,Saturation,96%,Click to continue,2023/8/3040Example 7.A 70 yea,2024/8/23,41,Example 7.,NO.,This is a normal P,a,O,2,for a patient this age breathing room air,2. Is there an acid base or ventilation problem?,pH,7.5,P,a,CO,2,46.5,P,a,O,2,80,HCO,3,-,38,Base excess,+8,Saturation,96%,Click to continue,2023/8/3041Example 7.pH7.5PaCO,2024/8/23,42,Example 7.,YES.,pH,7.5,P,a,CO,2,6.2,P,a,O,2,10.6,HCO,3,-,38,Base excess,+8,Saturation,96%,Click to continue,2023/8/3042Example 7.pH7.5PaCO,2024/8/23,43,Example 7.,There is:,Alkalosis,P,a,CO,2,is elevated, NOT respiratory alkalosis,Look at HCO,3,-,HCO,3,-, is increased,Base excess is positive,METABOLIC ALKALOSIS,pH,7.5,P,a,CO,2,6.2,P,a,O,2,10.6,HCO,3,-,38,Base excess,+8,Saturation,96%,Click to continue,2023/8/3043Example 7.There is:,2024/8/23,44,Example 7.,3.Is there respiratory compensation?,Expected P,a,CO,2,=, 0.8 kPa per 10 mmol/l in,HCO,3,-,= 5.3 + (0.8 x ( 38,24 /10),= 6.4, CONSISTENT WITH SIMPLE METABOLIC ALKALOSIS,pH,7.5,P,a,CO,2,6.3,P,a,O,2,10.6,HCO,3,-,38,Base excess,+8,Saturation,96%,Return to examples,2023/8/3044Example 7.3.Is the,2024/8/23,45,谢谢！,2023/8/3045谢谢！,