Easy and simple explanation of ABG arterial blood gas analysis ..U will be able to solve most of the questions related to ABG

1. ABG Analysis

2. •Arterial blood gas
•Colour- bright Red
•Pressure- High
•VBG- Venous Blood Gas
•Colour-Dark Red
•Pressure-Low
BasicDifference between arterial blood and venous blood

3. •SITE-
Most Common Site- RADIAL ARTERY
Why??
• Easily accessible because of its anatomical
location
• Because of collateral circulation
OTHERS- Brachial artery
Femoral artery

4. Modified Allen’s Test-
• Close the fist
• Press both the radial and
ulnar artery
• It will turn pale because of
blocked supply
• Release the ulnar artery
• Circulation must be restored
within 3-15 secs
• NORMAL CAPILLARY REFILL TIME-
<3 secs

5. • Positive Allen’s test- Normal
Circulation restored within seconds
Signifies patency of the radial and ulnar artery
Can Cannulate the radial artery
• Negative Allen’s test- Abnormal
Ulnar artery is blocked
No collateral circulation
**Not adequate to puncture the radial artery as if by some
reason the radial artery gets damaged or thrombus formation
occurs then whole circulation of the hand will be blocked.

6. Normal values*most important
• pH – 7.35- 7.45 (less than 7.35 is acidosis & more than 7.45 is Alkalosis)
• PaCO2 – 35-45 mm Hg
• HCO3- 22-26 mEq/L
• PaO2- 80-100 mm/Hg
Rules-
1. pH and PaCO2 moves in same direction
Then it’s METABOLIC (both increases /both decreases)
2. pH and PaCO2 moves in opposite direction
Then it’s RESPIRATORY (one increases other one decreases)
**ROME
Respiratory Opposite
Metabolic Equal

7. Eg.
• pH- 7.2
• PaCO2- 32
• HCO3- 13
• PaO2- 92
• pH- 7.1
• PaCO2- 75
• HCO3- 44
• PaO2- 88
Metabolic
Acidosis
Respiratory
Acidosis
**HINT
pH – 7.35- 7.45
(less than 7.35
is acidosis &
more than 7.45
is Alkalosis)
PaCO2 – 35-45
mm Hg

8. Eg.
• pH- 7.5
• PaCo2-49
• HCO3-24
• PaO2-76
• pH-7.6
• PaCo2- 31
• HCO3- 26
• PaO2-86
Metabolic
Alkalosis
Respiratory
Alkalosis
**HINT
pH – 7.35- 7.45
(less than 7.35
is acidosis &
more than 7.45
is Alkalosis)
PaCO2 – 35-45
mm Hg

9. Respiratory Acidosis
(PaCO2:HCO3)
ACUTE- 10:1
CHRONIC-10:4
Respiratory Alkalosis
• ACUTE- 10:2
• CHRONIC-10:4
**Every 10 mm Hg increase in PaCO2 leads
to 1 mEq/L increase in HCO3
CO2+ H2O H+ + HCO3-

10. RESPIRATORY ACIDOSIS
• RULES
1. HCO3- Normal – Uncompensated
2. pH – Normal- Fully Compensated
3. pH- not Normal- Partially Compensated
Eg.
pH- 7.25
PaCO2- 60
HCO3- 23
Eg.
• pH- 7.42
• PaCo2-31
• HCO3-28
Respiratory acidosis
Uncompensated
Respiratory Alkalosis fully
compensated
**HINT
pH – 7.35- 7.45
(less than 7.35 is
acidosis & more
than 7.45 is
Alkalosis)
PaCO2 – 35-45 mm
Hg
HCO3- 22-26
mEq/L

11. • pH-7.47
• PaCo2-34
• HCO3-21
1. pH-7.32
2. PaCo2-47
3. HCO3-29
**HINT
pH – 7.35- 7.45 (less than
7.35 is acidosis & more
than 7.45 is Alkalosis)
PaCO2 – 35-45 mm Hg
HCO3- 22-26 mEq/L
pH- not Normal-
Partially
Compensated
Respiratory
alkalosis
Partially
compensated
Respiratory
acidosis
partially
compensated

12. METABOLIC
• PaCO2-Normal- Uncompensated
• pH- Normal- fully compensated
• pH-7.37
• PaCo2-33
• HCO3-17
**HINT
pH – 7.35- 7.45
(less than 7.35 is
acidosis & more
than 7.45 is
Alkalosis)
PaCO2 – 35-45
mm Hg
Metabolic acidosis
Fully compensated

13. • pH- 7.52
• PaCO2- 37
• HCO3- 26
Metabolic alkalosis
uncompensated
**HINT
pH – 7.35- 7.45 (less
than 7.35 is acidosis &
more than 7.45 is
Alkalosis)
PaCO2 – 35-45 mm Hg
HCO3- 22-26 mEq/L
(Uncompensated)

14. Thank You