1Department of Clinical Chemistry, Microbiology and Immunology, Ghent University, Ghent, Belgium. 2Department of Laboratory Medicine, Ghent University Hospital, Ghent, Belgium. 3Department of Critical Care Medicine, Ghent University Hospital, Ghent, Belgium. 4Department of Emergency Medicine, Ghent University Hospital, Ghent, Belgium.
Crit Care Med. 2016 Feb;44(2):e83-8. doi: 10.1097/CCM.0000000000001304.
The availability of a fast and reliable sodium result is a prerequisite for the appropriate correction of a patient's fluid balance. Blood gas analyzers and core laboratory chemistry analyzers measure electrolytes via different ion-selective electrode methodology, that is, direct and indirect ion-selective electrodes, respectively. Sodium concentrations obtained via both methods are not always concordant. A comparison of results between both methods was performed, and the impact of the total protein concentration on the sodium concentration was investigated. Furthermore, we sought to develop an adjustment equation to correct between both ion-selective electrode methods.
A model was developed using a pilot study cohort (n = 290) and a retrospective patient cohort (n = 690), which was validated using a prospective patient cohort (4,006 samples).
ICU and emergency department at Ghent University Hospital.
Patient selection was based on the concurrent availability of routine blood gas Na⁺(direct) as well as core laboratory Na⁺(indirect) results.
In the pilot study, left-over blood gas syringes were collected for further laboratory analysis.
There was a significant negative linear correlation between Na⁺(indirect) and Na⁺(direct) relative to changes in total protein concentration (Pearson r = -0.69; p < 0.0001). In our setting, for each change of 10 g/L in total protein concentration, a deviation of ~1.3 mmol/L is observed with the Na⁺(indirect) result. Validity of our adjustment equation protein-corrected Na⁺(indirect) = Na⁺(indirect) - 10.53 + (0.1316 × total protein) was demonstrated on a prospective patient cohort.
As Na⁺(direct) measurements on a blood gas analyzer are not influenced by the total protein concentration in the sample, they should be preferentially used in patients with abnormal protein concentrations. However, as blood gas analyzers are not available at all clinical wards, the implementation of a protein-corrected sodium result might provide an acceptable alternative.
快速可靠的钠离子结果是正确纠正患者液体平衡的前提。血气分析仪和核心实验室化学分析仪通过不同的离子选择性电极方法测量电解质，即直接和间接离子选择性电极。通过这两种方法获得的钠离子浓度并不总是一致的。对这两种方法的结果进行了比较，并研究了总蛋白浓度对钠离子浓度的影响。此外，我们试图开发一个调整方程来校正两种离子选择性电极方法之间的差异。
使用试点研究队列（n = 290）和回顾性患者队列（n = 690）开发了一个模型，并使用前瞻性患者队列（4006 个样本）进行了验证。
根特大学医院的 ICU 和急诊室。
根据同时获得常规血气 Na⁺（直接）和核心实验室 Na⁺（间接）结果选择患者。
在试点研究中，收集了剩余的血气注射器进行进一步的实验室分析。
Na⁺（间接）与 Na⁺（直接）之间存在显著的负线性相关，与总蛋白浓度的变化有关（Pearson r = -0.69；p < 0.0001）。在我们的环境中，总蛋白浓度每变化 10 g/L，Na⁺（间接）结果就会出现约 1.3 mmol/L 的偏差。前瞻性患者队列验证了我们的调整方程蛋白校正的 Na⁺（间接）= Na⁺（间接）-10.53 +（0.1316×总蛋白）的有效性。
由于血气分析仪上的 Na⁺（直接）测量不受样品中总蛋白浓度的影响，因此应优先用于蛋白浓度异常的患者。然而，由于并非所有临床病房都配备血气分析仪，因此实施蛋白校正的钠结果可能是一个可接受的替代方案。
