Blood Gas Analysis | Specialty Gas Mixtures | Coregas NZ

Blood gas analysis

Blood gas analysers are used in clinical labs and hospitals to measure the pH, oxygen and carbon dioxide levels in blood. They require periodic calibration with specialty gases mixtures.

Clinical applications

A blood gas analyser is an analytical instrument which is widely used in clinical diagnostics. It measures pH and blood gas, meaning the concentration of hydrogen ions (pH), partial pressure of carbon dioxide (pCO2) and partial pressure of oxygen (pO2), in whole blood.

The technique is particularly useful because the pH value of blood, serum or plasma is an indicator of the balance between the blood, renal, and respiratory systems, and it is one of the most tightly controlled parameters in the body. So, any imbalance in the pH will be an indication of some potential pathology in the patient.

The pCO2 value of arterial blood is used to assess how well the body eliminates carbon dioxide, a by-product of metabolism. The pO2 value of arterial blood is a measure of how well the body is able to absorb oxygen in the lungs. Both measurements are useful for diagnosis of respiratory disorders.

The technique may also be used to measure the following example electrolytes and metabolites which give further information about body chemistry:

  • Electrolytes: cK+, cNa+, cCa2, cCl
  • Metabolites: cGlu (glucose), cLac (lactate), ctBil (total bilirubin)

Product selection notes

The instrument must be tested and calibrated using a specialty gas mixture. A number of typical blood gas analyser calibration gas mixtures are available in small portable cylinders for bench top use and large cylinders for longer periods of supply. The larger cylinders will rest on the floor and may be securely strapped to the side of the work bench for convenience and safety.

To withdraw the gas from the cylinder a single stage chrome plated brass specialty gases regulator will be appropriate. A larger two stage regulator may also be used, but this more sophisticated equipment is not essential for this application and will incur additional cost in comparison to a single stage regulator. A stainless steel specialty gases regulator may be used or specified instead of chrome plated brass, but this higher specification material is generally not called for in this application. The regulator to be used should not have been previously used for any chemical gases applications as small amounts of residual gases may contaminate the blood gas analyser.