Arterial Blood Gas

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Contents 1 More Specific Terms 2 Indications 3 Reference-interval 4 Clinical-significance 5 Procedure 6 More General Terms 7 Additional Terms 8 References

More Specific Terms

• arterial oxygen pressure (PaO2)
• partial pressure of carbon dioxide (pCO2)
• pH in blood

Indications

• evaluation of acid-base status
• ventilation- perfusion abnormalities

• hypoxemia
• hypercarbia

Reference-interval

• room air

• pO2: 70-100 mm Hg
• pCO2: 35-45 mm Hg
• pH:* 7.38-7.44 (H+ 40 nmol/L)
  

• * pH measurements may be obtained from venous blood, collected & analyzed as arterial blood. pH values are a mean of -0.04 pH units lower with venous blood (2 SDs -0.11 to + 0.04) [2].
  
• In the elderly, pO2 ( PaO2) is generally less than that in younger patients. (see PaO2)

Clinical-significance

• arterial blood is used to measure

• oxygen (O2)
• carbon dioxide (CO2)
• pH

• these measurements are important for establishing

• acid-base status
• ventilation- perfusion abnormalities

• consider use of pulse oximetry plus transcutaneous CO2 if pH not needed

Procedure

• arteries of choice for obtaining specimen:

• radial artery
• brachial artery
• femoral artery

More General Terms

• general chemistry test

Additional Terms

• base excess
• transcutaneous blood gas monitoring

References

1. Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996
2. Journal Watch 21(24):196, 2001 Kelly et al Emerg Med J 18:340, 2001

arterial blood gas (ABG)