Blood gas samples are highly susceptible to preanalytic error due to improper methods of obtaining or handling the sample prior to delivery to the laboratory. The errors in the measurement of blood gas analysis are currently derived from the exposure of sample to atmosphere, effects of anticoagulant itself, temperature difference between the measuring electrode and drawn blood and the delay in running the sample. To study the effects of the delay in measuring the sample and the temperature difference between the measuring electrode and drawn blood on values of blood gases and pH, we analyzed the arterial sampling from the 24 patients who were taking elective surgery or on his/her recovery period with indwelling arterial catheter. The plastic sampling syringes were kept at 4 degrees C (refrigerator) or 22-24 degrees C (room temperature) and analyzed at regular intervals (1, 10, 30, 60,120 min) for 120 minutes. The following results were obtained: 1) When the arterial blood drawn from the anesthetized patients were stored at 4 degrees C, partial pressure of oxygen (PaO2) decreased significantly after 20 min, whereas those stored at room temperature decreased significantly after 10 min. 2) When the arterial blood drawn from the recovery patients were stored at 4 degrees C, PaO2 did not decrease significantly through the experimental period of 120 min. Although those stored at room temperature did not decrease significantly through the period of 120 min. 3) Partial pressure of carbon dioxide in the arterial blood (PaCO2,) drawn from the anesthetized patients increased significantly by 120 min. at 4 degrees C, whereas those at room temperature increased significantly after 20 min. 4) PaCO2, of the recovery patients increased signigicantly by 120 min. at 4 degrees C, whereas those at room temperature increased significantly after 30 min. 5) pH of the arterial blood drawn from either anesthetized or recovery patients decreased significantly by 120 min. at 4 degrees C, whereas those at room temperature decreased significantly after 60 min. 6) No significant changes of arterial oxygen saturation (SaO2) and content (CaO2) were noted in either anesthetized or recovery. patients in accordance with time elapsed at 4 degrees C or room temperature. In summary, as the changes of PO2 in particular higher than physiologic PO2 and PCO2 in the arterial blood stored at room temperature are significant in accordance with the delay in measuring, it would be advisable to analyze the sample in a short period of time or to store it in a cool place when the measuring will be delayed.
Atmosphere ; Blood Gas Analysis ; Carbon Dioxide ; Catheters ; Electrodes ; Gases* ; Humans ; Hydrogen-Ion Concentration* ; Oxygen ; Partial Pressure ; Plastics ; Running ; Syringes