An arterial blood gas (ABG) analysis measures pH, oxygen, and carbon dioxide levels in arterial blood to assess lung and acid-base balance functions of the body. It helps identify respiratory or metabolic acidosis or alkalosis. The ABG measures pH, partial pressures of oxygen and carbon dioxide, bicarbonate, and oxygen saturation. Conditions that can cause respiratory acidosis include COPD, asthma, and pneumonia which result in carbon dioxide retention. Respiratory alkalosis may occur due to hyperventilation during pregnancy, panic attacks, or sepsis. Metabolic acidosis can be caused by diabetic ketoacidosis, lactate excess, or renal disease. Metabolic alkalosis may be due to potassium loss

1. ABG- Arterial
Blood Gas Analysis

2. INTRODUCTION
 ABG tells the activity of two systems in
the body. If one system is disturbed, the
other tries to restore balance. Both
systems are concerned about keeping
blood pH in the normal range.
 ABG measures pH, levels of oxygen and
carbon dioxide from an artery.
 It is used to measure the lung function.

3. COMPONENTS AND NORMAL
RANGE :
COMPONENTS NORMAL
RANGE
pH 7.35 – 7.45
Partial pressure of
oxygen(PaO2)
75 – 100 mm Hg
Partial pressure of carbon
dioxide(PaCO2)
35- 45 mmHg
Bicarbonate (HCO3) 22 – 26 mEq/L
Oxygen Saturation 95 – 100%

4. STEPS FOR EASY
INTERPRETATION OF ABG
ROME Method
 Respiratory Opposite – pH and CO2 goes
in opposite direction
 Metabolic Equal – pH and CO2 goes in
same direction

5. STEPS
 STEP 1 : IDENTIFY THE PLACE OF
pH
 Normal 7.35 – 7.45
 Acidosis < 7.35
 Alkalosis >7.45
 STEP 2 : IDENTIFY IF PaCO2 IS
 Normal 35 -45
 Acidosis < 35
 Alkalosis >45

6.  STEP 3 : IDENTIFY IF HCO3 IS
 Normal 22- 26
 Acidosis < 22
 Alkalosis >26

7. CAUSES
RESPIRATORY ACIDOSIS
- CO2 Retention
a) COPD
b) Asthma
c) Pneumonia
d) Hypoventilation
e) CNS Disease
f) Opioid Toxicity
g) Pulmonary edema
h) Pulmonary embolism

8. RESPIRATORY ALKALOSIS – Excess
Co2 Clearance
a) Hyperventilation
b) Pregnancy
c) Panic attack
d) Aspirin
e) Sepsis
f) Hypothyroidism

9. METABOLIC ACIDOSIS - Bicarb Loss
Or Acid Excess
a) Diabetic Ketoacidosis
b) Lactate
c) Aspirin
d) Drugs / alcohol
e) Diarrhea
f) Renal disease
g) Adrenal Insufficiency

10. METABOLIC ALKALOSIS – Bicarb
Excess
a) Potassium loss
b) Aldosterone excess(potassium loss)
c) Dehydration
d) Vomiting
e) Diuretics
f) Chronic diarrhea
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