1. Arterial Blood Gases
Made Easy
Prepared by:
Rafiq Suleman
BScN

2. Purpose of ABG
 Assess degree to which
 Lungs are able to provide adequate O2 & remove
CO2 and
 Kidneys are able to reabsorb or excrete HCO3 .
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Rafiq Suleman BScN
Feb 1st, 2014.

3. You Must Know What is Normal to
be Able to Know What is Abnormal
pH
= 7.35 to 7.45
PaC02 = 35 to 45 mm Hg
PaO2 = 80 to 100 mm Hg
HCO3 = 22 – 26 mEq/l
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Rafiq Suleman BScN
Feb 1st, 2014.

4. What You Must Look At To Interpret
ABGs
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Rafiq Suleman BScN
Feb 1st, 2014.

5. Look at Your pH
Is it normal?
Is it high ?
Is it low?
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Rafiq Suleman BScN
Feb 1st, 2014.

6. Examples
pH = 7.36
pH = 7.23
pH = 7.47
A high pH indicates alkalosis.
A low pH indicates acidosis.
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Rafiq Suleman BScN
Feb 1st, 2014.

7. Look at Your PaCO2
Is it normal ?
Is it high ?
Is it low ?
This is the respiratory component.
An
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abnormality in the PaCO2 will
indicate
Rafiq Suleman BScN
a respiratory problem.
Feb 1st, 2014.

8. Examples
PaCO2 = 40 mm Hg
PaCO2 = 23 mm Hg
PaCO2 = 48 mm Hg
A high PaCO2 indicates acidity.
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A low PaCO2 indicates alkalosis.eb 1st, 2014.
F
Rafiq Suleman BScN

9. PaCO2
Lungs will increase or decrease
ventilation to remove the appropriate
amount of CO2 .
Lung compensation begins quickly.
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Rafiq Suleman BScN
Feb 1st, 2014.

10. Now Look at Your HCO3
Is it normal ?
Is it high ?
Is it low ?
This is the metabolic component.
An abnormality in the HCO3 indicates a
metabolic problem.
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Rafiq Suleman BScN
Feb 1st, 2014.

11. Examples
HCO3 = 25 mEq/l
HCO3 = 19 mEq/l
HCO3 = 32 mEq/l
A low HCO3 indicates acidity.
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A high HCO3 indicates alkalosis.
Rafiq Suleman BScN
Feb 1st, 2014.

12. HCO3
The kidneys excrete Hydrogen
(acid) & retain bicarbonate (base) to
help maintain pH.
Renal compensation is slow.
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Rafiq Suleman BScN
Feb 1st, 2014.

13. Let’s Look at the 4 Situations that
Can Occur
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Feb 1st, 2014.

14. Acidosis
Develops when:
Excess accumulation of acid
Decreased amount of alkali.
Can be respiratory or metabolic.
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Rafiq Suleman BScN
Feb 1st, 2014.

15. Metabolic Acidosis
ABGs:
Low pH (below 7.35).
Decreased HCO3 (below 22)
PaCO2 will be normal.
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Remember both the pH & HCO3 will be low.
Rafiq Suleman BScN
Feb 1st, 2014.

16. Metabolic Acidosis
Caused by too much acid in the body or loss
of bicarbonate.
Diarrhea (loss of HCO3).
Diabetic ketoacidosis.
Renal failure.
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Rafiq Suleman BScN
Feb 1st, 2014.

17. Respiratory Acidosis
ABGs:
Low pH (below 7.35)
Increased PaCO2 (above 45)
HCO3 will be normal.
Remember the pH will be low & PaCO2 will be
elevated (opposite).
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Rafiq Suleman BScN
Feb 1st, 2014.

18. Respiratory Acidosis
Caused by acid buildup due to lungs not
eliminating CO2 .
Anything that decreased. respirations can cause
respiratory acidosis.
Chronic respiratory disease.
CNS depression.
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Rafiq Suleman BScN
Feb 1st, 2014.

19. Alkalosis
Develops when:
Excess accumulation of bicarbonate.
Loss of acid.
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Rafiq Suleman BScN
Feb 1st, 2014.

20. Metabolic Alkalosis
ABGs:
Increase in pH (greater than 7.45)
 Increased HCO3 (greater than 26)
PaCO2 will be normal.
Remember both the pH & the HCO3 will be elevated.
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Rafiq Suleman BScN
Feb 1st, 2014.

21. Metabolic Alkalosis
Loss of acid or increase in HCO3
Vomiting or NG drainage
(loss of Hydrogen).
Excessive use of antacids.
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Rafiq Suleman BScN
Feb 1st, 2014.

22. Respiratory Alkalosis
ABGs:
Increase in pH
(greater than 7.45)
Decrease in PaCO2 (less than 35)
HCO3 will be normal.
Remember the pH will be high & PaCO2 will be low
(opposite).
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Rafiq Suleman BScN
Feb 1st, 2014.

23. Respiratory Alkalosis
Caused by too much CO2 being
excreted
by the lungs.
Hyperventilation.
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Rafiq Suleman BScN
Feb 1st, 2014.

24. Interpreting ABGs
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Rafiq Suleman BScN
Feb 1st, 2014.

25. 1st Step Look at pH
Is it normal (7.35 to 7.45)
Does it reflect acidosis ( less than 7.35).
Does it reflect alkalosis (greater than 7.45).
Label accordingly.
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Rafiq Suleman BScN
Feb 1st, 2014.

26. 2nd Step Look at PaCO2
This is the respiratory component.
Is it normal.
Does it reflect alkalosis (less than 35).
Does it reflect acidosis (greater than 45).
Label accordingly.
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Rafiq Suleman BScN
Feb 1st, 2014.

27. 3rd Step Look at the HCO3
This is the metabolic component
Is it normal.
Does it reflect acidosis (less than 22).
Does it reflect alkalosis (greater than 26).
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Label accordingly.
Rafiq Suleman BScN
Feb 1st, 2014.

28. Let’s Put It
All
Together
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Rafiq Suleman BScN
Feb 1st, 2014.

29. Problems
pH of 7.33
PaCO2 of 40 mmHg
HCO3 of 20 mEq/L
What does this indicate
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Break it down
Rafiq Suleman BScN
Feb 1st, 2014.

30. pH
= Acidosis
PaCO2 = Normal
HCO3 = Acidosis
An abnormal HCO3 indicates a metabolic
problem.
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Rafiq Suleman BScN
Feb 1st, 2014.

31. Metabolic Acidosis
Way to
go!!
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Rafiq Suleman BScN
Feb 1st, 2014.

32. Problem
pH of 7.59
PaCO2 of 29 mm Hg
HCO3 of 24mEq/L
What does this indicate
Break it down
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Rafiq Suleman BScN
Feb 1st, 2014.

33. pH
= Alkalosis
PaCO2 = Alkalosis
HCO3 = Normal
An abnormal PaCO2 indicates a respiratory
problem.
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Rafiq Suleman BScN
Feb 1st, 2014.

34. Respiratory Alkalosis
Great
Job!!
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Rafiq Suleman BScN
Feb 1st, 2014.

35. Problem
pH of 7.25
PaCO2 of 61 mmHg
HCO3 of 26 mEq/L
What does this indicate
Break it down
35
Rafiq Suleman BScN
Feb 1st, 2014.

36. pH
= Acidosis
PaCO2 = Acidosis
HCO3 = Normal
An abnormal PaCO2 indicates a respiratory
problem.
36
Rafiq Suleman BScN
Feb 1st, 2014.

37. Respiratory Acidosis
You are
doing a
great job !!
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Rafiq Suleman BScN
Feb 1st, 2014.

38. Problem
pH of 7.51
PaCO2 of 44mmHg
HCO3 of 56
What does this indicate
Break it down
38
Rafiq Suleman BScN
Feb 1st, 2014.

39. pH
= Alkalosis
PaCO2 = Normal
HCO3 = Alkalosis
An abnormal HCO3 indicates a metabolic
problem.
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Rafiq Suleman BScN
Feb 1st, 2014.

40. Metabolic Alkalosis
You have
become an
ABG pro!!
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Rafiq Suleman BScN
Feb 1st, 2014.

41. You Are Doing Great
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Rafiq Suleman BScN
Feb 1st, 2014.

42. Compensation
Occurs as the body begins to correct the acid
base imbalance
pH will be normal or near normal if total
compensation
pH will be abnormal if partial compensation
42
Rafiq Suleman BScN
Feb 1st, 2014.

43. Compensation
Both the PaCo2 & HCO3 will be abnormal
Respiratory imbalances are compensated
for by the renal system
Metabolic imbalances are compensated for
by the respiratory system
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Rafiq Suleman BScN
Feb 1st, 2014.

44. Example
pH of 7.27
PaCO2 of 27 mm Hg
HCO3 of 10 mEq/l
Note that both the PaCO2 & the HCO3 are low.
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Rafiq Suleman BScN
Feb 1st, 2014.

45. Let’s Break it Down
Low pH
= Acidosis
Low PaCO2 = Alkalosis
Low HCO3 = Acidosis
HCO3 corresponds with the pH
This is a metabolic problem
Metabolic acidosis with partial compensation.
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Rafiq Suleman BScN
Feb 1st, 2014.

46. Problems
pH of 7.52
PaCO2 of 47 mmHg
HCO3 of 36 mEq/L
What does this indicate
Break it down
46
Rafiq Suleman BScN
Feb 1st, 2014.

47. pH
= Alkalosis
PaCO2 = Acidosis
HCO3 = Alkalosis
Which two go together?
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Rafiq Suleman BScN
Feb 1st, 2014.

48. Metabolic Alkalosis with Partial
Compensation
You are
doing great!!
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Rafiq Suleman BScN
Feb 1st, 2014.

49. Problems
pH of 7.45
PaCO2 of 50 mmHg
HCO3 of 33 mEq/L
What does this indicate
Break it down
49
Rafiq Suleman BScN
Feb 1st, 2014.

50. pH
= Normal
PaCO2 = Acidosis
HCO3 = Alkalosis
Your pH leans toward the alkalosis side.
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Rafiq Suleman BScN
Feb 1st, 2014.

51. Fully Compensated Metabolic
Alkalosis
You have
done great!!
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Rafiq Suleman BScN
Feb 1st, 2014.

52. 52
Rafiq Suleman BScN
Feb 1st, 2014.