血气分析的常用指标和其意义PPT培训课件

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,*,*,*,血气分析的常用指标和其意义,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）,10/6/2024,2,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）,10/6/2024,3,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,。,10/6/2024,4,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。,10/6/2024,5,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,10/6/2024,6,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,10/6/2024,7,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：4555mmol/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。,10/6/2024,8,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,10/6/2024,9,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,）,10/6/2024,10,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,=(1000.33年龄)mmHg。,10/6/2024,11,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%。,10/6/2024,12,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%,10/6/2024,13,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,10/6/2024,14,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。,10/6/2024,15,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）,10/6/2024,16,分清酸中毒或碱中毒？,PH,7.40,提示原发失衡可能为,碱中毒,10/6/2024,17,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,10/6/2024,18,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,=,10/6/2024,19,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,10/6/2024,20,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,10/6/2024,21,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,10/6/2024,22,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%,2,.,Is there an acid base or ventilation problem?,YES.,Click to continue,10/6/2024,23,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,10/6/2024,24,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,10/6/2024,25,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,10/6/2024,26,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,10/6/2024,27,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,10/6/2024,28,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,10/6/2024,29,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,10/6/2024,30,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 compen