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Learning About the System
Sample Information
This section describes sample requirements, collection procedures, and handling
techniques for pH, blood gas, and electrolyte analysis. For a detailed review of
sample requirements, refer to NCCLS Document C27–A, Blood Gas Preanalytical
Considerations: Specimen Collection, Calibration, and Controls.
1
Since blood gases are typically the most sensitive of the parameters measured by
the 800 system, the requirements and procedures described in this section are
based on techniques appropriate to pH and blood gas analysis. The sample
collection and handling guidelines described in this section are also suitable for
electrolyte analysis.
BIOHAZARD: Refer to Appendix A, Protecting Yourself from Biohazards, for
recommended precautions when working with biohazardous materials.
Perform blood sample collection under proper medical supervision when selecting
a site and performing the procedure. Ensure that the appropriate sample handling
documents are in place.
Use sterile technique at all times to avoid infecting the sample site.
Limitations
The following indicate some of the procedural limitations encountered with blood
gas analysis:
S Some auto-venting syringes contain sodium carboxymethylcellulose (CMC), a
substance within the porous venting mechanism. CMC can dissolve into the
sample, causing optical errors during CO-ox measurement. Optical errors may
lower reported tHb and O
2
Hb levels and elevate reported COHb. The
recommended syringe is Bayer Diagnostics arterial sampling device because it
uses a patented, non-exposed auto-venting design that does not affect the
integrity of the sample.
S Interpret results from patients anesthetized with halothane or nitrous oxide
cautiously. Patients anesthetized with these substances may have unreliable pO
2
values due to the reduction of halothane or nitrous oxide by the pO
2
electrode.
2
S Avoid using sample collection devices containing EDTA, citrate, oxalate, and
fluoride anticoagulants. These anticoagulants have a significant effect on blood
pH and ionized calcium.