Introduction:Blood gas analysis is an important test for making quick and important clinical decisions, and it is recommended that a dedicated syringe that contains heparin be used to measure blood gas. We hypothesized that a plastic syringe could be used as a less-expensive substitute for a dedicated syringe, given that the test is performed immediately after collection.Methods:This single-center, prospective, observational study involved patients admitted to the Kanoya Medical Center (Kagoshima, Japan) between July 2020 and March 2021, who were requiring blood gas analysis using a dedicated syringe under arterial line (A-line) monitoring. There were no exclusion criteria. Two samples were collected from each patient using a dedicated syringe, and one sample was collected using a plastic syringe. To determine clinical substitutability, Bland-Altman analysis was performed.Results:A total of 60 samples from 20 consecutive patients were collected and assayed. The mean patient age was 72 years, and 75% patients were men. The 95% limit of agreement for pH, PCO2, PO2, Na, K, Ca, and SO2were similar for both dedicated and plastic syringes. HCO3and BE were significantly higher in the samples taken with plastic syringes, whereas Hb and Ht could not be measured accurately with any syringe.Conclusions:The use of plastic syringes in place of dedicated syringes is generally considered acceptable for most items considering that measurement is performed within 3 min of collection, and the cost of medical materials may be reduced. Regardless of the type of syringe, caution should be exercised in interpreting the results of measuring Hb and Ht using a blood gas analyzer.