ABG - Arterial blood gases

Test Sample Type

• Arterial blood

Normal Values

-pH: 7.35-7.45
-pCO2: 35-45 mm Hg
-HCO3: 21-28 mEq/L
-pO2:

• Adult: 80-100 mm Hg
• Newborn: 60-70 mm Hg

-SaO2:

• Adult: > 95%
• Newborn: 40-90%

-Base excess: 2 mEq/L
 

Purpose of the Test

• The diagnosis of chronic and restrictive pulmonary disease, adult respiratory failure, acid-base disturbances, Pulmonary Emboli, sleep disorders, central nerve system dysfunctions, cardiovascular disorders
• In management of patients on mechanical ventilators and during the weaning process from the ventilators

Findings
1. Hypoxia

2. Respiratory acidosis (low pH, high pCO2 )

• Respiratory center dysfunction; opiates, anesthetics, sedatives, oxygen-induced hypoventilation
• Disorders of the respiratory muscles or chest wall; Myasthenia Gravis, kyphoscoliosis, amyotrophic lateral sclerosis
• Disorders of gas exchange; chronic pulmonary disorders, asphyxia, acute Pulmonary Edema

3. Respiratory alkalosis

• Hyperventilation; Atelectasis, severe anemia, Anxiety, Pulmonary Emboli
• Central nerve system disorders; brain stem dysfunction, Subarachnoid Hemorrhage, Salicylate poisoning
• Hypermetabolic states; fever, Thyrotoxicosis, Sepsis
• Hyperventilation while on mechanical ventilation

4. Metabolic acidosis (low pH, low HCO3 )

• Diabetic Ketoacidosis
• Lactic acidosis
• Excessive ingestion of acid; salicylates, ethylene, methanol, paraldehyde
• Loss of bicarbonate (diarrhea, fistulas)
• Renal failure

5. Metabolic alkalosis (high pH, high HCO3 )

Loss of body acid; vomiting, excess gastric suction, excessive diuretics, hypokalemia, excessive ingestion of licorce, nonparathyroid hypercalcemia, HCO3 overload

Interfering Factor

• Air bubbles in syringe
• Low hemoglobin level
• Hemolysis of sample