The Post-Analytic Phase

Report the results as per your local protocol i.e. attach hardcopy to the patient notes, check the electronic copy is available, or inform the requesting doctor or nurse, for example.

Results should always be checked against any previous results as a sample dilution or contamination during the pre-analytical stage may be identified. Ask the following questions:

  • Do the values look significantly lower or higher than that of previous gases, with no clinical explanation?
  • Are the values accurate given the status of the patient at the time of sampling?
  • Is the oxygen value (SaO2) from the blood gas result consistent with the SpO2 measurement measured by a pulse oximeter?

The common errors that we see includes air bubbles in the sample, which will affect the O2 and CO2 values. Poor perfusion will mean the sample is less likely to be arterialised so the oxygen saturation will be much lower than that measured by a pulse oximeter. Temperature disparities between the blood gas machine and the patient can also affect the readings.

Any uncertainties discuss with a colleague or senior clinician and consider taking another blood gas measurement. Alternatively, you may wish to send the patient to the laboratory for confirmation.

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