血气分析(英文版)-PPT课件.ppt

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,

2、mmol/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

3、 compensate 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 salic

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

5、drugs, CNS eventNeuromuscular 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 abnormalityChron

6、ic Respiratory Acidosis With Metabolic CompensationArterial Gas ValueInterpretationpHPCO2*HCO37.3460 mmHg31 mmol/LRespiratory acidosisMetabolic compensationCausesChronic lung disease obstructive or restrictiveChronic neuromuscular disordersChronic respiratory center depression central hypoventilatio

7、n*This is the primary abnormalityThe Importance of Differentiating Acute From Chronic Respiratory Acidosis Acute respiratory acidosis Medical emergency requiring emergent intubation and mechanical ventilation Chronic respiratory acidosis Often a clinically stable conditionMetabolic Acidosis With Res

8、piratory CompensationArterial Gas ValueInterpretationpHPCO2HCO3*7.5048 mmHg36 mmol/LAlkalemiaRespiratory compensationMetabolic alkalosisCausesUrinary Chloride Level LowUrinary Chloride Level Normal or HighVomiting, nasogastric suctionDiuretic use in pastPosthypercapniaExcess mineralocorticoid activi

9、ty Cushings syndrome, Conns syndrome, exogenous steroids, licorice ingestion, increased renin states, Bartters syndromeCurrent or recent diuretic useExcess alkali administrationRefeeding alkalosis*This is the primary abnormalityImportance of Urinary Chloride Level in Metabolic Alkalosis Low urinary

10、chloride level Decreased ECF Or posthypercapnic state Normal or high urinary chloride level Normal or increased ECF Or recent diuretic useUrinary chloride level = preferred method for assessing the renal response to circulating volume in patients with metabolic alkalosisUrinary sodium level = less r

11、eliable as a guideMetabolic Acidosis With Respiratory CompensationArterial Gas ValueInterpretationpHPCO2HCO3*7.2021 mmHg8 mmol/LAcidemiaRespiratory compensationMetabolic acidosisAnion gap = sodium chloride bicarbonateNormal = 12 2 (SD) mmol/LCausesNonanion GapAnion GapGI bicarbonate loss Diarrhea Ur

12、eteral diversionsHydrochloric administrationPosthypocapniaGI = gastrointestinalRenal bicarbonate loss Renal tubular acidosis Early renal failure Carbonic anhydrase inhibitors Aldosterone inhibitorsKetoacidosis Diabetic AlcoholicRenal failureLactic acidosisRhabdomyolysisToxins Methanol Ethylene glyco

13、l Paraldehyde Salicylates*This is the primary abnormalityMixed Acid-Base DisordersABG Interpretation ABG pH 7.49, PCO2 47 mmHg, HCO3 35 mmol/L, Na 139 mmol/L, K 3 mmol/L, Cl 89 mmol/L Interpretation Simple metabolic alkalosis with compensatory respiratory acidosis ?or Mixed metabolic alkalosis and r

14、espiratory acidosis ?Summary of Expected Compensation for Simple Acid-Base DisordersPrimary disorderInitial chemical changeCompensatory responseExpected range of compensationMetabolic acidosisHCO3 decreasePCO2 decreasePCO2 = 1.5 (HCO3) + 8 2PCO2 = last two digits of pHPCO2 = 1 1.3 (HCO3)Metabolic al

15、kalosisHCO3 increasePCO2 increasePCO2: variable increasePCO2 = 0.9 (HCO3) + 9PCO2 = 0.6 (HCO3)Summary of Expected Compensation for Simple Acid-Base DisordersPrimary disorderInitial chemical changeCompensatory responseExpected range of compensationRespiratory acidosisPCO2 increaseHCO3 increaseAcute(H

16、+) = 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+) = 0.17 (PCO2)HCO3 = 5 x PCO2 /10ABG Interpretation ABG pH 7.40, PCO2 40 mmHg, HCO3 24 mmol/L, Na 139 mmol/L, K 4 mmol/L, Cl 1

17、05 mmol/L Calculation AG = 139 105 24 = 10 Interpretation normalABG Interpretation ABG pH 7.49, PCO2 47 mmHg, HCO3 35 mmol/L, Na 139 mmol/L, K 3 mmol/L, Cl 89 mmol/L Calculation AG = 139 89 35 = 15 PCO2 = 0.6 (HCO3) = 0.6 x 11 = 6.6 mmHg Interpretation Simple metabolic alkalosisABG Interpretation AB

18、G pH 7.45, PCO2 25 mmHg, HCO3 17 mmol/L, Na 139 mmol/L, K 3.5 mmol/L, Cl 107 mmol/L Calculation AG = 139 107 17 = 15 HCO3 = 2 (PCO2 / 10) = 2 x 15 / 10 = 3 mmHg Interpretation Simple respiratory alkalosis ?ABG Interpretation ABG pH 7.65, PCO2 30 mmHg, HCO3 32 mmol/L, Na 139 mmol/L, K 2.8 mmol/L, Cl

19、92 mmol/L Calculation AG = 139 92 32 = 15 HCO3 = 2 (PCO2 / 10) = 2 x 10 / 10 = 2 mmHg Interpretation Mixed metabolic and respiratory alkalosisABG Interpretation ABG pH 7.67, PCO2 30 mmHg, HCO3 34 mmol/L, Na 140 mmol/L, K 3 mmol/L, Cl 94 mmol/L Calculation AG = 140 94 34 = 12 HCO3 = 2 (PCO2 / 10) = 2

20、 x 10 / 10 = 2 mmHg Interpretation Mixed metabolic and respiratory alkalosisABG Interpretation ABG pH 7.61, PCO2 30 mmHg, HCO3 29 mmol/L, Na 140 mmol/L, K 3 mmol/L, Cl 94 mmol/L Calculation AG = 140 94 29 = 17 HCO3 = 2 (PCO2 / 10) = 2 x 10 / 10 = 2 mmHg Interpretation Mixed metabolic and respiratory

21、 alkalosis and lactic acidosisABG Interpretation ABG pH 7.33, PCO2 70 mmHg, HCO3 36 mmol/L, Na 140 mmol/L, K 4.0 mmol/L, Cl 94 mmol/L Calculation AG = 140 94 36 = 10 HCO3 = 3.5 (PCO2 / 10) = 3.5 x 30 / 10 = 10.5 mmHg Interpretation Simple chronic respiratory acidosisABG Interpretation ABG pH 7.40, P

22、CO2 67 mmHg, HCO3 40 mmol/L, Na 140 mmol/L, K 3.5 mmol/L, Cl 90 mmol/L Calculation AG = 140 90 40 = 10 HCO3 = 3.5 (PCO2 / 10) = 3.5 x 27 / 10 = 9.5 mmHg Interpretation Mixed respiratory acidosis and metabolic alkalosisABG Interpretation ABG pH 7.11, PCO2 16 mmHg, HCO3 5 mmol/L, Na 140 mmol/L, K 4.5

23、mmol/L, Cl 125 mmol/L Calculation AG = 140 125 5 = 10 PCO2 = 11 mmHg Interpretation Simple hyperchloremic metabolic acidosisABG Interpretation ABG pH 7.11, PCO2 16 mmHg, HCO3 5 mmol/L, Na 140 mmol/L, K 4.0 mmol/L, Cl 105 mmol/L Calculation AG = 140 105 5 = 30 PCO2 = 11 mmHg Interpretation Simple hig

24、h AG metabolic acidosisABG Interpretation ABG pH 7.11, PCO2 16 mmHg, HCO3 5 mmol/L, Na 140 mmol/L, K 4.0 mmol/L, Cl 115 mmol/L Calculation AG = 140 115 5 = 20 PCO2 = 11 mmHg Interpretation Mixed hyperchloremic and high AG metabolic acidosisIs There A Simple Way ?Mixed Acid-Base Disorders ABG pH 7.32

25、, PCO2 28 mmHg, HCO3 14 mmol/L, BUN 100 mmol/L Interpretation Acidemic with low PCO2 and low bicarbonate concentration Low 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 a

26、cutely elevated PCO2 primary metabolic alkalosis HCO3 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 ? ABG pH 7.50,

27、PCO2 38 mmHg, HCO3 31 mmol/L, K 3.5 mmol/L Interpretation Alkalemic with low PCO2 and high bicarbonate concentration High 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

28、acidosisMixed Acid-Base Disorders ? ABG pH 7.48, PCO2 29 mmHg, HCO3 23 mmol/L Interpretation Alkalemic with low PCO2 and normal bicarbonate concentration Low PCO2 as a primary disorder respiratory alkalosis (secondary to asthma) HCO3 20 in the presence of acutely decreased PCO2 primary metabolic aci

29、dosis HCO3 15 in the presence of chronically decreased PCO2 primary metabolic 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 acidosis Excess AG = 22 12

30、 = 10 mmol/L Excess AG + HCO3 = 25 mmol/L no further primary abnormalitiesRespiratory Alkalosis And Metabolic Acidosis Diagnosis Respiratory Alkalosis And Metabolic Acidosis Reason Ingestion of a large quantity of aspirin Centrally mediated respiratory alkalosis Anion gap metabolic acidosis associat

31、ed with salicylate overdoseMetabolic Alkalosis And Metabolic Acidosis ABG pH 7.40, PCO2 40 mmHg, HCO3 24 mmol/L, Na 145 mmol/L, Cl 100 mmol/L Interpretation Normal ABG AG = 145 (100 + 24) = 21 20 anion gap metabolic acidosis Excess AG = 21 12 = 9 mmol/L Excess AG + HCO3 = 33 mmol/L metabolic alkalos

32、isMetabolic Alkalosis And Metabolic Acidosis Diagnosis Metabolic Alkalosis And Metabolic Acidosis Reason Chronic renal failure (metabolic acidosis) Vomiting (metabolic alkalosis)Respiratory Alkalosis, Metabolic Acidosis and Metabolic Alkalosis ABG pH 7.50, PCO2 20 mmHg, HCO3 15 mmol/L, Na 145 mmol/L

33、, Cl 100 mmol/L Interpretation Alkalemic with low PCO2 and low bicarbonate concentration Low PCO2 as a primary disorder respiratory alkalosis AG = 145 (100 + 15) = 30 20 anion gap metabolic acidosis Excess AG = 30 12 = 18 mmol/L Excess AG + HCO3 = 33 mmol/L metabolic alkalosisRespiratory Alkalosis,

34、Metabolic Acidosis and Metabolic Alkalosis Diagnosis Respiratory Alkalosis, Metabolic Acidosis and Metabolic Alkalosis Reason History of vomiting (metabolic alkalosis) Evidence of alcoholic ketoacidosis (metabolic acidosis) Bacterial pneumonia (respiratory alkalosis)Respiratory Acidosis, Metabolic A

35、cidosis and Metabolic Alkalosis ABG pH 7.10, PCO2 50 mmHg, HCO3 15 mmol/L, Na 145 mmol/L, Cl 100 mmol/L Interpretation Acidemic with elevated PCO2 and low bicarbonate concentration Increased PCO2 and decreased bicarbonate both as primary disorders respiratory acidosis and metabolic acidosis AG = 145

36、 (100 + 15) = 30 20 anion gap metabolic acidosis Excess AG = 30 12 = 18 mmol/L Excess AG + HCO3 = 33 mmol/L metabolic alkalosisRespiratory Acidosis, Metabolic Acidosis and Metabolic Alkalosis Diagnosis Respiratory Acidosis, Metabolic Acidosis and Metabolic Alkalosis Reason Obtunded state (respirator

37、y acidosis) History of vomiting (metabolic alkalosis) Diabetic ketoacidosis (metabolic acidosis)Anion Gap and Nonanion Gap Metabolic Acidosis ABG pH 7.15, PCO2 15 mmHg, HCO3 5 mmol/L, Na 140 mmol/L, Cl 110 mmol/L Interpretation Acidemic with low PCO2 and low bicarbonate concentration Low bicarbonate

38、 as a primary disorder metabolic acidosis with respiratory compensation? AG = 140 (110 + 5) = 25 20 anion gap metabolic acidosis Excess AG = 25 12 = 13 mmol/L Excess AG + HCO3 = 18 mmol/L nonanion gap metabolic acidosisAnion Gap and Nonanion Gap Metabolic Acidosis Diagnosis Anion Gap and Nonanion Gap Metabolic Acidosis Reason Diabetic ketoacidosis (anion gap acidosis) Failure to regenerate bicarbonate from ketoacids lost in the urine during recovery phase of diabetic ketoacidosis (nonanion gap metabolic acidosis)