Abg

arterial blood gas analysis - anion gap - diabetic ketoacidosis

1. Dr. Ashutosh kumar
singh
(ABG )
ARTERIAL BLOOD GAS

2. What is ABG ?
Bloodgasanalysis,alsocalledArterialBloodGas(ABG)
analysis,isaninvasivetestwhichmeasurestheamountof
oxygen(O2)andcarbondioxide(CO2)intheblood,aswell
astheacidity(pH)oftheblood.

3. Contents & normal values

4. Purpose of doing ABG !!!
•EvaluateshoweffectivelythelungsaredeliveringO2to
thebloodandhowefficientlytheyareeliminatingCO2
fromit.
•Indicateshowwellthelungsandkidneysareinteractingto
maintainnormalbloodpH(acid-basebalance).
•Assessrespiratorydiseaseandotherconditionsthatmay
affectthelungs,andtomanagepatientsreceivingoxygen
therapy(respiratorytherapy).

5. Cont..
•DeterminethepHofthebloodandthepartialpressures
ofcarbondioxide(PaCO2)andoxygen(PaO2)withinit.
•Assesstheeffectivenessofgaseousexchangeand
ventilation,beitspontaneousormechanical.
•Assessmetabolicstatusofthepatient,givingan
indicationofhowtheyarecopingwiththeirillness

6. Complication of arterial puncture

7. Contraindications

8. Allen’s test

9. ABG Interpretation
ABGBasicinterpretationcanbedoneby6easysteps.

10. Basic terminology

11. Step1 -Analyze pH
Normal blood pH is 7.4 (range 7.35 to 7.45).
• pH < 7.35 acidic.
• pH > 7.45 alkaline.
• If it falls into the normal range, label what side of
7.4 it falls on. Lower than 7.4 is normal/acidic,
higher than 7.4 is normal / alkalotic.

12. Step 2 -Analyze pCO2
Normal pCO2 levels = 35-45mmHg
• Below 35 is alkaline,
• Above 45 is acidic.

13. Step 3 –Analyze HCO3
Normal HCO3 level is 22-26 mEq/L.
• If the HCO3 is below 22, the patient is acidotic.
• If the HCO3 is above 26, the patient is alkalotic

14. Step 4 –Match Co2 or HCO3 with pH
IfthepHisacidotic,andtheCO2isacidotic,thenthe
acid-basedisturbanceisbeingcausedbythe
respiratorysystem.
Therefore,wecallitarespiratoryacidosis.
•However,ifthepHisalkaloticandtheHCO3is
alkalotic,theacid-basedisturbanceisbeingcausedby
themetabolic(orrenal)system.
Therefore,itwillbeametabolicalkalosis.

15. Step-5 Does Co2& HCO3 going in
opposite direction of pH???
Ifso,thereiscompensationbythatsystem.
•Forexample,thepHisacidotic,theCO2isacidotic,
andtheHCO3isalkalotic:TheCO2matchesthepH
makingtheprimaryacid-basedisorderi.e.respiratory
acidosis.
TheHCO3isoppositeofthepHandwouldbe
evidenceofcompensationfromthemetabolicsystem.

16. Compensation

17. Cont…

18. Step-6 -Analyze PO2& O2 saturation
If they are below normal there is evidence of
hypoxemia.

19. Interpretation of Values

20. Arterial Vs Venous sample

21. Anion Gap
Theaniongapisthedifferencebetweenprimary
measuredcations(sodiumNa
+
andpotassiumK
+
)and
theprimarymeasuredanions(chlorideCl
-
and
bicarbonateHCO3
-
)inserum.
NormalAnionGapis12+/-2

22. Anion Gap Metabolic acidosis

23. Non anion gap metabolic acidosis

24. Respiratory Failure
TypeIRespiratoryFailure:
(Diffusiondefect;CO2diffusionisbetter;Eg:Pneumonia,Pulmonary
edema)
•pO2,butnormalpCO2
•TypeIIRespiratoryFailure:
(Respiratorygasesnotreachingalveoliforpropergaseousexchange;
Eg:HMD,RespiratoryparalysisinPolio)
•pO2andpCO2

25. DIABETIC KETOACIDOSIS

26. What is DKA??
Diabeticketoacidosis(DKA)isanacute,life-
threateningcomplicationofdiabetesmellitus.
DKAoccurspredominantlyinpatientswithtype1
(insulin-dependent)diabetesmellitus.

27. Pathophysiology

28. Pathophysiology

29. Causes of DKA

30. Types
Types pH Hco3 Anion Gap
Mild
7.25-7.3 15-18 mEq/L >10 mEq/L
Moderate
7.0-7.24 10-15 mEq/L >12mEq/L
Alert / Drowsy
Severe
< 7.0 <10 mEq/L >12 mEq/L
Stuporous
Comatose

32. Symptoms

33. Physical examination findings

34. Classic triad of DKA

35. Diagnosis
•bloodglucoselevel>250milligrams/dL(13.9mmol/L)
•aniongap>10to12mEq/L(>10mmol/L)
•abicarbonatelevel<15mEq/L(<15mmol/L)
•pH<7.3withmoderateketonuriaorketonemia

36. Differential diagnosis

37. Treatment

38. Fluids & electrolytes

39. Initial fluid resuscitation

40. Cont..

41. Insulin therapy

42. Once DKA resolved

43. Complications of DKA