Normal Values

• Normal ABG values in adults are:
  
  pH- 7.35-7.45
  CO2- 35-45 mm Hg
  PO2- 80-100 mm Hg
  HCO3- 22-26 mEq/liter
  SaO2- 95-100 percent
  
  The renal (kidney) and respiratory systems balance each other to maintain balance in the body.
  
  

pH

• The pH component meaures the acidity or alkalinity by measuring hydrogen ions. The lower the pH the more acidic it is. A higher pH indicates that the blood is alkaline. Normal pH has a narrow range; pH less than 6.8 or above 7.8 is not compatible with life.
  
  

CO2

• The CO2 is a respiratory parameter which measures partial pressure of dissolved carbon dioxide produced by the body's cells. A patient with a slow breathing rate retains more carbon dioxide, while fast breathing blows off more carbon dioxide. Aspirin overdose is one cause of low CO2.
  
  

HCO3

• The HCO3 (bicarbonate ion) measures the acid-base balance controlled by the kidneys. It tells if the pH imbalance is caused by respiratory or kidney imbalance. While the respiratory system can quickly compensate for an abnormal bicarbonate, the kidneys are much slower to react. Patients with normal kidney function typically take several hours to adjust bicarbonate levels, while those with decreased kidney function may take days. Changes in HCO3 may be caused by oversedation, anemia, diabetic ketoacidosis and prolonged nasal suctioning of ventilator patients.
  
  

PO2

• PO2 measures the oxygen level in the blood. A level of less than 80 indicates hypoxemia and requires immediate supplemental oxygen. Severe hypoxemia, with levels below 40 alters the acid-base balance and causes anaerobic metabolism. If hypoxemia is not corrected, cellular death follows.