血气分析——英文版优秀PPT.ppt

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1、A Practical Approach to Acid-Base DisordersBin DU,MDMedical Intensive Care UnitPeking Union Medical College HospitalPrimary Acid-Base DisordersVariablePrimary DisorderNormal Range,Arterial GasPrimary DisorderpHAcidemia7.35 7.45AlkalemiaPCO2,mmHgRespiratory alkalosis35 45Respiratory acidosisHCO3,mmol

2、/LMetabolic acidosis22 26Metabolic alkalosisRules of Thumb for Recognizing Primary Acid-Base Disorders Without Using a NomogramRule 1Look at the pH.Whichever side of 7.40 the pH is on,the process that caused it to shift to that side is the primary abnormality.Principle:The body does not fully compen

3、sate for primary acid-base disordersSimple Acid-Base DisordersAcute Respiratory AlkalosisArterial Gas ValueInterpretationpHPCO2*HCO37.5029 mmHg22 mmol/LAlkalemiaRespiratory alkalosisNormal HCO3CausesAnxietyHypoxiaLung disease with or without hypoxiaCentral nervous system diseaseDrug use salicylates,

4、catecholamins,progesteronePregnancySepsisHepatic encephalopathyMechanical ventilation*This is the primary abnormalityAcute Respiratory AcidosisArterial Gas ValueInterpretationpHPCO2*HCO37.2560 mmHg26 mmol/LAcidemiaRespiratory acidosisNormal HCO3CausesCentral nervous system(CNS)depression drugs,CNS e

5、ventNeuromuscular disorders myopathies,neuropathiesAcute airway obstruction upper airway,laryngospasm,bronchospasmSevere pneumonia or pulmonary edemaImpaired lung motion hemothorax,pneumothoraxThoracic cage injury flail chestVentilator dysfunction*This is the primary abnormalityChronic Respiratory A

6、cidosis With Metabolic CompensationArterial Gas ValueInterpretationpHPCO2*HCO37.3460 mmHg31 mmol/LRespiratory acidosisMetabolic compensationCausesChronic lung disease obstructive or restrictiveChronic neuromuscular disordersChronic respiratory center depression central hypoventilation*This is the pr

7、imary abnormalityThe Importance of Differentiating Acute From Chronic Respiratory AcidosisAcute respiratory acidosisMedical emergency requiring emergent intubation and mechanical ventilationChronic respiratory acidosisOften a clinically stable conditionMetabolic Acidosis With Respiratory Compensatio

8、nArterial Gas ValueInterpretationpHPCO2HCO3*7.5048 mmHg36 mmol/LAlkalemiaRespiratory compensationMetabolic alkalosisCausesUrinary Chloride Level LowUrinary Chloride Level Normal or HighVomiting,nasogastric suctionDiuretic use in pastPosthypercapniaExcess mineralocorticoid activity Cushings syndrome,

9、Conns syndrome,exogenous steroids,licorice ingestion,increased renin states,Bartters syndromeCurrent or recent diuretic useExcess alkali administrationRefeeding alkalosis*This is the primary abnormalityMetabolic Acidosis With Respiratory CompensationArterial Gas ValueInterpretationpHPCO2HCO3*7.2021

10、mmHg8 mmol/LAcidemiaRespiratory compensationMetabolic acidosisAnion gap=sodium chloride bicarbonateNormal=12 2(SD)mmol/LCausesNonanion GapAnion GapGI bicarbonate loss Diarrhea Ureteral diversionsHydrochloric administrationPosthypocapniaGI=gastrointestinalRenal bicarbonate loss Renal tubular acidosis

11、 Early renal failure Carbonic anhydrase inhibitors Aldosterone inhibitorsKetoacidosis Diabetic AlcoholicRenal failureLactic acidosisRhabdomyolysisToxins Methanol Ethylene glycol Paraldehyde Salicylates*This is the primary abnormalityMixed Acid-Base DisordersABG InterpretationABGpH 7.49,PCO2 47 mmHg,

12、HCO3 35 mmol/L,Na 139 mmol/L,K 3 mmol/L,Cl 89 mmol/LInterpretationSimple metabolic alkalosis with compensatory respiratory acidosis?orMixed metabolic alkalosis and respiratory acidosis?Summary of Expected Compensation for Simple Acid-Base DisordersPrimary disorderInitial chemical changeCompensatory

13、responseExpected range of compensationMetabolic acidosisHCO3 decreasePCO2 decreasePCO2=1.5(HCO3)+8 2PCO2=last two digits of pHPCO2=1 1.3(HCO3)Metabolic alkalosisHCO3 increasePCO2 increasePCO2:variable increasePCO2=0.9(HCO3)+9PCO2=0.6(HCO3)Summary of Expected Compensation for Simple Acid-Base Disorde

14、rsPrimary disorderInitial chemical changeCompensatory responseExpected range of compensationRespiratory acidosisPCO2 increaseHCO3 increaseAcute(H+)=0.8(PCO2)HCO3=PCO2/10Chronic(H+)=0.3(PCO2)HCO3=3.5 x PCO2/10Respiratory alkalosisPCO2 decreaseHCO3 decreaseAcute(H+)=0.8(PCO2)HCO3=2 x PCO2/10Chronic(H+

15、)=0.17(PCO2)HCO3=5 x PCO2/10ABG InterpretationABGpH 7.40,PCO2 40 mmHg,HCO3 24 mmol/L,Na 139 mmol/L,K 4 mmol/L,Cl 105 mmol/LCalculationAG=139 105 24=10InterpretationnormalABG InterpretationABGpH 7.49,PCO2 47 mmHg,HCO3 35 mmol/L,Na 139 mmol/L,K 3 mmol/L,Cl 89 mmol/LCalculationAG=139 89 35=15PCO2=0.6(H

16、CO3)=0.6 x 11=6.6 mmHgInterpretationSimple metabolic alkalosisABG InterpretationABGpH 7.65,PCO2 30 mmHg,HCO3 32 mmol/L,Na 139 mmol/L,K 2.8 mmol/L,Cl 92 mmol/LCalculationAG=139 92 32=15HCO3=2(PCO2/10)=2 x 10/10=2 mmHgInterpretationMixed metabolic and respiratory alkalosisABG InterpretationABGpH 7.61,

17、PCO2 30 mmHg,HCO3 29 mmol/L,Na 140 mmol/L,K 3 mmol/L,Cl 94 mmol/LCalculationAG=140 94 29=17HCO3=2(PCO2/10)=2 x 10/10=2 mmHgInterpretationMixed metabolic and respiratory alkalosis and lactic acidosisIs There A Simple Way?Mixed Acid-Base DisordersABGpH 7.32,PCO2 28 mmHg,HCO3 14 mmol/L,BUN 100 mmol/LIn

18、terpretationAcidemic with low PCO2 and low bicarbonate concentrationLow bicarbonate as a primary disorder metabolic acidosis(secondary to renal failure)PaCO2 30 in the presence of low HCO3 primary respiratory alkalosisPaCO2 30 in the presence of acutely elevated PCO2 primary metabolic alkalosisHCO3

19、45 in the presence of chronically elevated PCO2 primary metabolic alkalosisHCO3 30 in the presence of acutely elevated PCO2orHCO3 45 in the presence of chronically elevated PCO2 primary metabolic alkalosisMixed Acid-Base Disorders?ABGpH 7.50,PCO2 38 mmHg,HCO3 31 mmol/L,K 3.5 mmol/LInterpretationAlka

20、lemic with low PCO2 and high bicarbonate concentrationHigh HCO3 as a primary disorder metabolic alkalosis PCO2 55 in the presence of elevated HCO3 primary respiratory alkalosisPCO2 55 in the presence of elevated HCO3 primary respiratory acidosisMixed Acid-Base Disorders?ABGpH 7.48,PCO2 29 mmHg,HCO3

21、23 mmol/LInterpretationAlkalemic with low PCO2 and normal bicarbonate concentrationLow PCO2 as a primary disorder respiratory alkalosis(secondary to asthma)HCO3 20 in the presence of acutely decreased PCO2 primary metabolic acidosisHCO3 15 in the presence of chronically decreased PCO2 primary metabo

22、lic acidosisHCO3 20 in the presence of acutely decreased PCO2orHCO3 30 mmol/L),there is an underlying metabolic alkalosis;if the sum is less than a normal serum bicarbonate(20 anion gap metabolic acidosisExcess AG=22 12=10 mmol/LExcess AG+HCO3=25 mmol/L no further primary abnormalitiesRespiratory Al

23、kalosis And Metabolic AcidosisDiagnosisRespiratory Alkalosis And Metabolic AcidosisReasonIngestion of a large quantity of aspirinCentrally mediated respiratory alkalosisAnion gap metabolic acidosis associated with salicylate overdoseMetabolic Alkalosis And Metabolic AcidosisABGpH 7.40,PCO2 40 mmHg,H

24、CO3 24 mmol/L,Na 145 mmol/L,Cl 100 mmol/LInterpretationNormal ABGAG=145 (100+24)=21 20 anion gap metabolic acidosisExcess AG=21 12=9 mmol/LExcess AG+HCO3=33 mmol/L metabolic alkalosisMetabolic Alkalosis And Metabolic AcidosisDiagnosisMetabolic Alkalosis And Metabolic AcidosisReasonChronic renal fail

25、ure(metabolic acidosis)Vomiting(metabolic alkalosis)Respiratory Alkalosis,Metabolic Acidosis and Metabolic AlkalosisABGpH 7.50,PCO2 20 mmHg,HCO3 15 mmol/L,Na 145 mmol/L,Cl 100 mmol/LInterpretationAlkalemic with low PCO2 and low bicarbonate concentrationLow PCO2 as a primary disorder respiratory alka

26、losisAG=145 (100+15)=30 20 anion gap metabolic acidosisExcess AG=30 12=18 mmol/LExcess AG+HCO3=33 mmol/L metabolic alkalosisRespiratory Alkalosis,Metabolic Acidosis and Metabolic AlkalosisDiagnosisRespiratory Alkalosis,Metabolic Acidosis and Metabolic AlkalosisReasonHistory of vomiting(metabolic alk

27、alosis)Evidence of alcoholic ketoacidosis(metabolic acidosis)Bacterial pneumonia(respiratory alkalosis)Respiratory Acidosis,Metabolic Acidosis and Metabolic AlkalosisABGpH 7.10,PCO2 50 mmHg,HCO3 15 mmol/L,Na 145 mmol/L,Cl 100 mmol/LInterpretationAcidemic with elevated PCO2 and low bicarbonate concen

28、trationIncreased PCO2 and decreased bicarbonate both as primary disorders respiratory acidosis and metabolic acidosisAG=145 (100+15)=30 20 anion gap metabolic acidosisExcess AG=30 12=18 mmol/LExcess AG+HCO3=33 mmol/L metabolic alkalosisRespiratory Acidosis,Metabolic Acidosis and Metabolic AlkalosisD

29、iagnosisRespiratory Acidosis,Metabolic Acidosis and Metabolic AlkalosisReasonObtunded state(respiratory acidosis)History of vomiting(metabolic alkalosis)Diabetic ketoacidosis(metabolic acidosis)Anion Gap and Nonanion Gap Metabolic AcidosisABGpH 7.15,PCO2 15 mmHg,HCO3 5 mmol/L,Na 140 mmol/L,Cl 110 mm

30、ol/LInterpretationAcidemic with low PCO2 and low bicarbonate concentrationLow bicarbonate as a primary disorder metabolic acidosis with respiratory compensation?AG=140 (110+5)=25 20 anion gap metabolic acidosisExcess AG=25 12=13 mmol/LExcess AG+HCO3=18 mmol/L nonanion gap metabolic acidosisAnion Gap and Nonanion Gap Metabolic AcidosisDiagnosisAnion Gap and Nonanion Gap Metabolic AcidosisReasonDiabetic ketoacidosis(anion gap acidosis)Failure to regenerate bicarbonate from ketoacids lost in the urine during recovery phase of diabetic ketoacidosis(nonanion gap metabolic acidosis)