ABG 简明血气分析

,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,*,ABG INTERPRETATION,血气分析解读,SIMC ICU Liu,Objectives,What,s an ABG?,Understanding Acid/Base Relationship,General approach to ABG Interpretation,Clinical causes Abnormal ABG,s,Case studies,What is an ABG,Arterial Blood Gas,动脉血气,Drawn from artery- radial, brachial, femoral,由动脉取样,一般取桡动脉、肱动脉、股动脉,It is an,invasive,procedure.,这是,侵入性,检查,Caution must be taken with patient on anticoagulants.,有凝血功能障碍的患者慎用,Helps differentiate oxygen deficiencies from primary ventilatory deficiencies from primary metabolic acid-base abnormalities,协助区分缺氧,/,通气不足和酸碱代谢异常,What Is An ABG?,pH H,+,PCO,2,Partial pressure CO,2,PO,2,Partial pressure O,2,HCO,3,Bicarbonate,BE Base excess,SaO,2,Oxygen Saturation,Acid/Base Relationship,This relationship is critical for homeostasis,酸碱平衡对内环境是非常重要的,Significant deviations from normal pH ranges are poorly tolerated and may be life threatening,酸碱严重失衡后果严重，甚至可能致命,Achieved by Respiratory and Renal systems,一般由呼吸系统和肾脏决定,Case Study No. 1,60 y/o male comes ER c/o SOB.Tachypneic, tachycardic, diaphoretic and Cyanotic. Dx acute resp. failure and ABG,sShow PaCO2 well below nl, pH above nl, PaO2 is very low. The blood gas documentResp. failure due to primary O2 problem.,60,岁男性进入急诊室。查体见呼吸过速、心动过速、大汗、发绀，诊断急性呼衰。动脉血气分析结果,PaCO,轻度降低，,PH,升高，,PaO2,非常低。结果显示其主要问题为缺氧,Case Study No. 2,60 y/o male comes ER c/o SOB.Tachypneic, tachycardic, diaphoretic and,Cyanotic. Dx acute resp. failure and ABG,sShow PaCO2 very high, low pH and PaO2 is moderately low. The blood gas document Resp. failure due to primarily ventilator insufficiency.,60,岁男性进入急诊室。查体，呼吸过塑，心动过速，大汗，发绀，诊断急性呼衰。动脉血气分析结果显示,PaCO2,非常高，,PH,降低，,PaO2,中,度降低。结果显示其主要问题为通气不足。,Buffers,There are two buffers that work in pairs,H2CO3NaHCO3Carbonic acidbase bicarbonate,These buffers are linked to the respiratory and renal compensatory system,两者和呼吸、肾脏代偿密切相关,Respiratory Component,function of the lungs,Carbonic acid H2CO3,Approximately 98% normal metabolites are in the form of CO2,CO2 + H2O,H2CO3,excess CO2 exhaled by the lungs,Metabolic Component,Function of the kidneys,base bicarbonate NaHCO3,Process of kidneys excreting H+ into the urine and reabsorbing,HCO3- into the blood from the renal tubules,肾脏将,H+,排泄至尿液，并从肾小管重吸收,HCO3-1)active exchange Na+ for H+ between the tubular cells and glomerular filtrate,在肾小管和肾小球主动用,Na+,交换,H+2)carbonic anhydrase is an enzyme that accelerates hydration/dehydration CO2 in renal epithelial cells,可以加速,CO2,在肾上皮细胞的水化和脱水反应,Acid/Base Relationship,H2O+CO2,H2CO3,HCO3+H+,Normal ABG values,pH 7.35,7.45,PCO2 35,45 mmHg,PO280,100 mmHg,HCO3 22,26 mmol/L,BE -2 - +2,SaO2 95%,Acidosis,酸中毒,Alkalosis,碱中毒,pH 45,HCO,3, 7.45,PCO,2, 26,Respiratory Acidosis,Think of CO2 as an acid,把二氧化碳想象成酸,failure of the lungs to exhale adequate CO2,肺无法排出足够的二氧化碳,pH 45,CO2+ H2CO3,pH,Causes of Respiratory Acidosis,Emphysema,肺气肿,drug overdose,药物过量,narcosis,麻醉,respiratory arrest,呼吸暂停,airway obstruction,气道阻塞,Metabolic Acidosis,failure of kidney function,blood HCO3 which results in,availability of renal tubular HCO3 for H+ excretion,pH 7.35,HCO3 7.45,PCO2 7.45,HCO3 26,Causes of Metabolic Alkalosis,loss acid from stomach or kidney,由胃或肾脏过量丢失酸性物质,hypokalemia,低血钾,excessive alkali intake,过量碱性物质摄入,How to Analyze an ABG,PO2NL = 80 100 mmHg,pHNL = 7.35 7.45,Acidotic7.45,PCO2NL = 35 45 mmHg,Acidotic45,Alkalotic35,HCO3NL = 22 26 mmol/L,Acidotic 26,Four-step ABG Interpretation,Step 1:,Examine PaO2 & SaO2,Determine oxygen status,Low PaO2 (80 mmHg) & SaO2 means hypoxia,PaO2,和,SaO2,降低提示缺氧,NL/elevated oxygen means adequate oxygenation,正常或更高的数值表明氧合充分,Four-step ABG Interpretation,Step 2:,pHacidosis 7.45,Four-step ABG Interpretation,Step 3:,study PaCO2 & HCO 3,respiratory irregularity if PaCO2 abnl & HCO3 NL,呼吸系统异常会显示,PaCO2,异常，,HCO3,正常,metabolic irregularity if HCO3 abnl & PaCO2 NL,代谢系统异常会显示,HCO3,异常，,PaCO2,正常,Four-step ABG Interpretation,Step 4:,Determine if there is a compensatory mechanism working,to try to correct the pH.,判断机体是否在进行代偿,ie: if have primary respiratory acidosis will have increased PaCO2 and decreased pH.Compensation occurs when the kidneys retain HCO3.,例如：如果主要是呼吸性酸中毒的话会导致,PaCO2,升高，,PH,降低。当肾脏仍有足够的,HCO3,时会进行代偿, PaCO,2, pH Relationship,807.20607.30407.40307.50207.60,ABG Interpretation,Compensated,Respiratory,Acidosis,CO2,More Abnormal,Respiratory,Acidosis,CO2,Expected,Mixed,Respiratory,Metabolic,Acidosis,CO2,Less Abnormal,CO2 Change,c/w,Abnormality,Metabolic,Metabolic,Acidosis,CO2,Normal,Compensated,Metabolic,Acidosis,CO2 Change,opposes,Abnormality,Acidosis,酸中毒,ABG Interpretation,Compensated,Respiratory,Alkalosis,CO2,More Abnormal,Respiratory,Alkalosis,CO2,Expected,Mixed,Respiratory,Metabolic,Alkalosis,CO2,Less Abnormal,CO2 Change,c/w,Abnormality,Metabolic,Alkalosis,CO2,Normal,Compensated,Metabolic,Alkalosis,CO2 Change,opposes,Abnormality,Alkalosis,Respiratory Acidosis,pH 7.30,PaCO,2,60,HCO,3,26,Respiratory Alkalosis,pH 7.50,PaCO,2,30,HCO,3,22,Metabolic Acidosis,pH 7.30,PaCO,2,40,HCO,3,15,Metabolic Alkalosis,pH 7.50,PCO,2,40,HCO,3,30,What are the compensations?,Respiratory acidosis,metabolic alkalosis,Respiratory alkalosis,metabolic acidosis,In respiratory conditions, therefore, the kidneys will attempt to compensate and visa versa.,In chronic respiratory acidosis (COPD) the kidneys increase the elimination of H+ and absorb more HCO3. The ABG will Show NL pH, CO2 and HCO3.,Buffers kick in within minutes.Respiratory compensation is rapid and starts within minutes and complete within 24 hours.Kidney compensation takes hours and up to 5 days.,Mixed Acid-Base Abnormalities,Case Study No. 3:,56 yo neurologic dz required ventilator support for several weeks.She seemed most comfortable when hyperventilated to PaCO2 28-30 mmHg.She required daily doses of lasix,（速尿）,to assure adequate urine output and received 40 mmol/L IV K+ each day.On 10th day of ICU her ABG on 24% oxygen & VS:,ABG Results,pH7.62BP115/80 mmHg,PCO,2,30 mmHgPulse88/min,PO,2,85 mmHgRR10/min,HCO,3,30 mmol/LVT1000ml,BE10 mmol/LMV10L,K,+,2.5 mmol/L,Interpretation,:Acute alveolar hyperventilation,(resp. alkalosis) and metabolic alkalosis with corrected,hypoxemia.,Case study No. 4,27 yo retarded,with insulin-dependent DM arrived at ER,from the institution where he lived. On room air ABG & VS:,pH7.15BP180/110 mmHg,PCO,2,22 mmHgPulse130/min,PO,2,92 mmHgRR40/min,HCO,3,9 mmol/LVT800ml,BE-30 mmol/LMV32L,Interpretation,:Partly compensated metabolic acidosis.,Case study No. 5,74 yo,with hx chronic renal failure and chronic diuretic therapy,was admitted to ICU comatose and severely dehydrated. On,40% oxygen her ABG & VS:,pH7.52BP130/90 mmHg,PCO,2,55 mmHgPulse120/min,PO,2,92 mmHgRR25/min,HCO,3,42 mmol/LVT150ml,BE17 mmol/LMV 3.75L,Interpretation,:Partly compensated metabolic alkalosis with,corrected hypoxemia.,Case study No. 6,43 yo,arrives in ER 20 minutes after a MVA in which he,injured 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:,pH7.10BP150/110 mmHg,PCO,2,60 mmHgPulse150/min,PO,2,125 mmHgRR45/min,HCO,3,18 mmol/LVT? ml,BE-15 mmol/LMV? L,.,Interpretation,:Acute ventilatory failure (resp. acidosis) and,acute metabolic acidosis with corrected hypoxemia,Case study No. 7,17 yo, 48 kg,with known insulin-dependent DM came to ER,with Kussmaul breathing and irregular pulse. Room air,ABG & VS:,pH7.05BP140/90 mmHg,PCO,2,12 mmHgPulse118/min,PO,2,108 mmHgRR40/min,HCO,3,5 mmol/LVT1200ml,BE-30 mmol/LMV48L,Interpretation:,Severe partly compensated metabolic,acidosis without hypoxemia.,Case No. 7 contd,This patient is in diabetic ketoacidosis.,IV glucose and insulin were immediately administered. A,judgement was made that severe acidemia was adversely,affecting CV function and bicarb was elected to restore pH to, 7.20.,Bicarb administration calculation:,Base deficit X weight (kg),4,30 X 48,= 360 mmol/LAdmin 1/2 over 15 min &,4 repeat ABG,Case No. 7 contd,ABG result after bicarb:,pH7.27BP130/80 mmHg,PCO,2,25 mmHgPulse100/min,PO,2,92 mmHgRR22/min,HCO,3,11 mmol/LVT600ml,BE-14 mmol/LMV13.2L,Case study No. 8,47 yo,was in PACU for 3 hours s/p cholecystectomy. She,had been on 40% oxygen and ABG & VS:,pH7.44BP130/90 mmHg,PCO,2,32 mmHgPulse95/min, regular,PO,2,121 mmHgRR20/min,HCO,3,22 mmol/LVT350ml,BE-2 mmol/LMV7L,SaO,2,98%,Hb13 g/dL,Case No. 8 contd,Oxygen was changed to 2L N/C. 1/2 hour pt. ready to be D/C,to floor and ABG & VS:,pH7.41BP130/90 mmHg,PCO,2,10 mmHgPulse95/min, regular,PO,2,148 mmHgRR20/min,HCO,3,6 mmol/LVT350ml,BE-17 mmol/LMV7L,SaO,2,99%,Hb7 g/dL,Case No. 8 contd,What is going on?,Case No. 8 contd,If the picture doesnt fit, repeat ABG!,pH7. 45BP130/90 mmHg,PCO,2,31 mmHgPulse95/min,PO,2,87 mmHgRR20/min,HCO,3,22 mmol/LVT350ml,BE-2 mmol/LMV7L,SaO,2,96%,Hb13 g/dL,Technical error was presumed.,Case study No. 9,67 yo,who had closed reduction of leg fx without incident.,Four days later she experienced a sudden onset of severe chest,pain and SOB. Room air ABG & VS:,pH7.36BP130/90 mmHg,PCO,2,33 mmHgPulse100/min,PO,2,55 mmHgRR25/min,HCO,3,18 mmol/L,BE-5 mmol/LMV18L,SaO,2,88%,Interpretation:,Compensated metabolic acidosis with,moderate hypoxemia. Dx: PE,Case study No. 10,76 yo,with documented chronic hypercapnia secondary to,severe COPD has been in ICU for 3 days while being tx for,pneumonia. She had been stable for past 24 hours and was,transferred to general floor. Pt was on 2L oxygen & ABG &VS:,pH7.44BP135/95 mmHg,PCO,2,63 mmHgPulse110/min,PO,2,52 mmHgRR22/min,HCO,3,42 mmol/L,BE+16 mmol/LMV10L,SaO,2,86%,.,Interpretation:,Chronic ventilatory failure (resp. acidosis),with uncorrected hypoxemia,Case No. 10 contd,She was placed on 3L and monitored for next hour. She remained alert, oriented and comfortable. ABG was,repeated:,pH7.36BP140/100 mmHg,PCO,2,75 mmHgPulse105/min,PO,2,65 mmHgRR24/min,HCO,3,42 mmol/L,BE+16 mmol/LMV,4.8L,SaO,2,92%,.,Pts ventilatory pattern has changed to more rapid and,shallow breathing. Although still acceptable the pH and,CO,2,are trending in the wrong direction. High-flow,oxygen may be better for this pt to prevent intubation,Practice ABGs,PaO,2,90SaO,2,95 pH 7.48 PaCO,2,32 HCO,3,24,PaO,2,60SaO,2,90 pH 7.32 PaCO,2,48 HCO,3,25,PaO,2,95SaO,2,100 pH 7.30 PaCO,2,40 HCO,3,18,PaO,2,87SaO,2,94 pH 7.38 PaCO,2,48 HCO,3,28,PaO,2,94SaO,2,99 pH 7.49 PaCO,2,40 HCO,3,30,6. PaO,2,62SaO,2,91 pH 7.35 PaCO,2,48 HCO,3,27,PaO,2,93SaO,2,97 pH 7.45 PaCO,2,47 HCO,3,29,PaO,2,95SaO,2,99 pH 7.31 PaCO,2,38 HCO,3,15,PaO,2,65SaO,2,89 pH 7.30 PaCO,2,50 HCO,3,24,10. PaO,2,110SaO,2,100 pH 7.48 PaCO,2,40 HCO,3,30,Answers to Practice ABGs,Respiratory alkalosis,Respiratory acidosis,Metabolic acidosis,Compensated Respiratory acidosis,Metabolic alkalosis,Compensated Respiratory acidosis,Compensated Metabolic alkalosis,Metabolic acidosis,Respiratory acidosis,Metabolic alkalosis,