Heparinised whole blood collected into arterial sampling syringe or capillary tube. Samples must be assayed ASAP. Any delay in analysis requires the samples to be stored on ice. These samples must be delivered to the lab by porter NOT the pneumatic pod system
8hrs
Blood gas analysis is performed when assessing acid-base balance and monitoring the response to treatment. A blood gas assay produces PO2, PCO2, pH and bilirubin while calculated results consist of bicarbonate, base excess, haematocrit, MCHC, and anion gap (if sufficient parameters are assayed). Blood gas analysis may also be used to aid in identifying the cause of the pH anomaly (i.e. metabolic or respiratory). The blood gas analysers used within the Trust may also provide other biochemical parameters to users such as: electrolytes, lactate and glucose.
Air bubbles with in samples may substantially alter the results as the dissolved gases equilibrate with the atmospheric gas concentrations: an air bubble of 1% of the syringe volume can increase the pO2 measurement by as much as 15%. Samples not assayed immediately post venepuncture require storage on ice to inhibit metabolic activity within the sample. The age of the sample is critical to the accuracy of blood gas measurements; samples greater than 1 hour old must not be analysed.
