4.46: Blood Gases

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A technologist is working in the blood-gas area of a laboratory in an acute-care hospital. While the technologist is at the instrument, a physician brings a blood-gas sample in a syringe at room temperature (not in ice-water). The laboratory test ordering slip indicates that the sample was drawn about 30 minutes previously. When the physician hands the syringe to the technologist, the technologist notices that the syringe is half-filled with air.

QUESTIONS

What should you, the technologist, do with the blood-gas sample?
The physician demands that the results of the blood-gas analysis be placed in the LIS. What do you tell the physician?

Questions to Consider

How might the 30 minutes delay in bringing the sample, not-iced, to the laboratory change the blood-gas results?
How might the large amount of air in the syringe affect the accuracy of the blood-gas results?
What is the technologist’s responsibility for rejecting a sample that does not appear to have been collected properly?
Is there a way of providing the physician with information without compromising the laboratory’s policy?
Many blood-gas analyzers enable the measurement of electrolytes in addition to traditional blood-gas parameters. If the physician wants only the data on electrolytes placed in the LIS, should you agree to this request? Why?

Answer

Further delays in analyzing the sample will only cause further deterioration of the sample; perform the blood-gas analysis immediately, do not immediately report the results, and discuss the value of the results later. See chapter 3 and 25.
Tell the physician after analysis that because of an unsatisfactory sample that does not comply with the laboratory’s sample policy, the blood-gas results will not be placed in the patient’s records. However, the technologist could report Na and Cl results comfortably.

Answers to Questions to Consider

Because of the effect of the delay in bringing the non-iced sample to the laboratory the results of a blood-gas analysis will not be reported to the physician because the results will be inaccurate. The blood cells will be able to continue metabolism, producing CO₂ and consuming O₂ and glucose. The result will be falsely decreased PO₂ and glucose levels and falsely increased PCO₂. See chapter 3, 25, and Blood-gas methods on CD-ROM.
Air in the syringe will affect the accuracy of blood-gas results by providing oxygen to blood and decreasing the PCO₂ levels and thereby increasing the pH. Overall, the most likely effects on the blood-gas sample will be those listed in Answer #1, with unreliable PCO₂, pH, PO₂, and glucose levels. See chapter 3, 25, and Blood-gas methods (Specimen) on CD-ROM.
The laboratory’s policy for sample rejection must always be followed. This is a medical-legal responsibility that cannot be ignored. See chapter 2 and 3. If the physician is upset enough, he can speak with the laboratory’s supervisor or medical director.
It is best that the physician obtain a new sample. However, the technologist can show the results to the physician, but still not place the questionable results in the LIS or patient’s chart. The physician will most likely not act on this information because it will not be part of the official records and the physician could be held responsible if any problem occurred with the patient.
I would agree to provide the electrolyte data because the effect of changes in PCO₂ and PO levels will most likely not affect the concentration of SODIUM or CHLORIDE. However, potassium levels may increase if the blood pH decreases too much. So the safest response would be to only report Na and Cl, or inform the physician of the possible problems with the remaining results.