Effects of post-sampling analysis time, type of blood samples and collection tubes on values of blood gas testing.

AIM To investigate effects of post-sampling analysis time, a type of blood samples and collection tubes on blood gas testing. METHODS This study included 100 patients at the Clinic for Pulmonary Diseases, Clinical Centre Sarajevo. The partial pressure of oxygen (pO2) and carbon dioxide (pCO2), and the oxygen saturation level of hemoglobin (sO2) were analyzed in the arterial blood samples (ABS) and capillary blood samples (CBS) by a potentiometric method using a blood gas analyzer ABL 555 (Radiometer, Copenhagen, Denmark). Paired measurements of ABS were performed within 15 minutes and after 60 minutes from sampling and compared. The results of CBS obtained within 15 minutes were compared with matching ABS results, as well as the results obtained from CBS within 15 minutes taken into glass and plastic tubes. RESULTS pO2 and sO2 values were significantly lower after 60 minutes compared to those within 15 minutes in ABS (9.20±1.89 vs. 9.51±1.95 and 91.25±5.03 vs. 92.40±4.5; p<0.01, respectively). Values of pO2 and sO2 in CBS were significantly lower than values obtained in ABS (8.92±2.07 vs. 9.51±1.95 and 91.25±4.86 vs. 92.40±4.50; p<0.01, respectively). Obtained pO2 and sO2 values in CBS in the plastic tubes were higher than those in the glass tubes (8.50±1.98 vs. 7.89±2.0 and 89.66±11.04 vs. 88.23±11.22, p<0.01 respectively). pCO2 blood values were not influenced significantly (p>0.05). CONCLUSION The length of post-sampling analysis time, a type of blood samples and collection tubes have significant impact on blood oxygen parameters. Analysis within 15 minutes after blood sampling is considered as appropriate.