Blood is one of the most important fluids in the human body. It helps carry nutrients such as oxygen to the cells in the body and transports out wastes like carbon dioxide and other metabolites from these cells. Since blood is the medium through which the different organs and tissues in our body communicates, keeping a close eye on the constituents of a blood sample would provide a good indication of the functioning of the human body.
Blood gas tests are ordered for patients who might have symptoms of pH imbalance, extreme levels of oxygen/ carbon dioxide, or in order to evaluate the functioning of organs such as the kidneys and the presence of disorders such as diabetes. The latter tests are measured through the analysis of electrolytes and metabolites in the blood. Patients who are on a “ventilator” in a hospital may have their treatment procedures also monitored using a blood gas analysis test.
In the Core Laboratory of University Hospital in London, Ontario, the Gem Premiere 3000 Blood Gas Analyzer is used in order to perform tests on patients. There are two analyzers present in this laboratory. Both machines can run tests for levels of pH, partial pressure of carbon dioxide, partial pressure of oxygen, Na+, K+, Ca++, and hematocrit (Hct). One of the machines however, is also capable of running glucose and lactate tests as well. One other final blood constituent that is also analyzed in this analyzer is for carboxyhemoglobin.
If a sample is to be tested for carboxyhemoglobin, the sample must be injected from the syringe into the GEM cuvette. The cuvette is then inserted into another analyzer in order to test carboxyhemoglobin levels. The samples collected for blood gas analysis tests can be arterial, venous, or capillary blood. Reference ranges for the electrolytes and metabolites measured using this instrument are as follows: | Range| pH| 7. 35 – 7. 45| pCO2 (mm/Hg)| Arterial: (32-48) Venous: (41-51)| pO2 (mm/Hg)| Arterial: (80-100) Venous: (35-40)|.
Na+ (mmol/L)| 136-146| K+| 3. 4 – 4. 5| Ca++| 1. 15 – 1. 29| Glucose| 70 – 199| Lactate| 0 – 2. 0| Hct| Varying values depending on age between 28 – 67| Table 1. Reference Range values of measurements in the “normal range” using the Gem Premiere 3000 (UCSF Medical Center, 2011). All samples are delivered to the laboratory in syringes or capillaries from the bedside of the patient in the hospital. A sample that arrives from the Operation Room can only be stored for and has to be analyzed within 15-20 minutes.
Samples that are delivered to the laboratory on ice can be stored for one hour while all other samples must be analyzed within half an hour. Unlike other samples that are analyzed in the lab, these samples are not archived after analysis. All samples must also be warmed between the hands before being analyzed in order to mix the contents thoroughly. All syringes with samples contain a coating of heparin sulfate in order to avoid the clotting of blood samples. Once the source of blood sample (arterial, venous, capillary) has been selected on the display screen of the analyzer, the sample is checked for clots.
This is done by testing a drop or two onto a gauze pad. The barcode on the sample syringe is then scanned in order to read the patient ID and store the results. A message then appears on the screen of the analyzer that reads “Present sample now”. The tip of the syringe can then be inserted at an angle, into the needle that protrudes from the Analyzer. The results will then appear on the screen and be saved on the patient’s profile according to their ID that was scanned. The maintenance conducted on the Gem Premiere 3000 is very minimal.
The Gem Premiere 3000 contains a cartridge that has electrodes with all the calibration measurements for the machine. The analyzer is checked daily for printer paper. Every week, quality control tests are run in order to ensure the accurate working of the Gem Premiere 3000. The two control tests administered are the ‘Critical Care QC ContrIL9’ and the ‘GEM critCheck’. The first control tests for the proper analysis of of pH, partial pressure of carbon dioxide, partial pressure of oxygen, Na+, K+ and Ca++, while the second control tests for hematocrit low and normal levels (UCSF Medical Center, 2011).
The cartilage with electrodes for calibration measurements expires every three weeks. However, if there is a power cut or an issue with the analyzer, the cartridge must be changed immediately before any other tests are conducted. Once the cartridge has been replaced, it takes half an hour for the cartridge to warm up after the CVP control has been run and before tests can be run again. Once all the tests are run, they are saved on the patient’s profile and are available for access by all physicians and hospital staff throughout the hospital.