Sandler P, Goldstein L N
Division of Emergency Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
S Afr Med J. 2018 Feb 27;108(3):224-229. doi: 10.7196/SAMJ.2018.v108i3.12626.
Point-of-care blood gas analysis plays an integral role in the management of critically ill and injured patients presenting to the emergency department (ED). While the use of specially manufactured syringes containing electrolyte-balanced dried heparin is recommended when processing these specimens, alternatives including manually self-prepared syringes washed with liquid heparin or heparin vacutainers are still often used.
To assess the effect of two concentrations of liquid heparin and the use of heparin vacutainers on the reliability of blood gas analysis results compared with the recommended standard of dried heparin syringes in the ED setting.
Blood samples were drawn from 54 patients attending a tertiary-level hospital ED. Individual samples were distributed equally among each of four different collection devices: a dried heparin syringe, self-prepared syringes washed separately with 1 000 IU/mL and 5 000 IU/mL liquid heparin, and a heparin vacutainer. Results obtained from the standard dried heparin syringes were compared with those from the other three methods.
For both the liquid heparin cohorts, partial pressure of carbon dioxide (pCO2), potassium (K+), sodium (Na+), ionised calcium (iCa2+) and haemoglobin had >20% of results falling beyond the total allowable error. iCa2+ and K+ results were most affected in the 5 000 IU/mL cohort and iCa2+ and Na+ in the 1 000 IU/ml cohort. pCO2, pH and iCa2+ were the most significantly affected in the heparin vacutainer cohort.
Use of liquid heparin can result in significant negative bias in the majority of blood gas analytes, especially electrolytes. Heparin vacutainer use can result in unacceptable variations in the respiratory analytes. While standard dried heparin syringes may not always be available, it is of vital importance that practitioners be aware of these biases and limitations when using substitutes.
即时检验血气分析在急诊科对危重症和受伤患者的管理中发挥着不可或缺的作用。虽然在处理这些标本时推荐使用装有电解质平衡干燥肝素的特制注射器，但包括用液体肝素手工自行准备的注射器或肝素真空采血管在内的替代方法仍经常被使用。
在急诊科环境中，与推荐的干燥肝素注射器标准相比，评估两种浓度的液体肝素以及肝素真空采血管对血气分析结果可靠性的影响。
从一家三级医院急诊科的54名患者中采集血样。将个体样本平均分配到四种不同的采集装置中：干燥肝素注射器、分别用1000 IU/mL和5000 IU/mL液体肝素冲洗的自行准备的注射器，以及肝素真空采血管。将标准干燥肝素注射器获得的结果与其他三种方法的结果进行比较。
对于两个液体肝素组，二氧化碳分压（pCO2）、钾（K+）、钠（Na+）、离子钙（iCa2+）和血红蛋白超过总允许误差的结果均超过20%。在5000 IU/mL组中，iCa2+和K+结果受影响最大，在1000 IU/mL组中，iCa2+和Na+结果受影响最大。在肝素真空采血管组中，pCO2、pH和iCa2+受影响最为显著。
使用液体肝素会导致大多数血气分析物出现显著的负偏差，尤其是电解质。使用肝素真空采血管会导致呼吸分析物出现不可接受的变化。虽然标准干燥肝素注射器可能并非总是可用，但从业者在使用替代品时意识到这些偏差和局限性至关重要。
