Davies D G
J Appl Physiol. 1976 Jan;40(1):123-5. doi: 10.1152/jappl.1976.40.1.123.
The pH and PCO2 values measured by the Astrup technique were compared in cerebrospinal fluid (CSF) obtained using two different sampling techniques: 1) a direct or in vivo technique and 2) the widely accepted syringe sampling technique. In 65 pairs of measurements in 9 dogs it was found that the pH was always overestimated and the PCO2 always underestimated in the syringe sample when compared to the in vivo sample. The equations describing the relationships are as follows: 1) pH (syringe = 0.995 pH (in vivo) + 0.084 and 2) PCO2 (syringe) = 0.873 PCO2 (in vivo) + 0.2. The amount by which the syringe sample underestimated the true PCO2 value increased with the absolute PCO2 value, consistent with the possibility of there being a diffusional loss of CO2 during the transfer of CSF from the syringe to the pH electrode (PCO2 (in vivo)- PCO2 (syringe) = 2.4, 4.9, 7.5, and 10.0 mmHg at in vivo PCO2's of 20, 40, 60, and 80 mmHg). This study indicates that the technique used for sampling CSF is crucial to the expected accuracy of the results and that the number of transfers of CSF during the sampling and measurement procedures should be minimized in order to obtain reliable results.
使用两种不同采样技术获取的脑脊液（CSF），对通过阿斯特鲁普技术测量的pH值和PCO₂值进行了比较：1）直接或体内技术；2）广泛接受的注射器采样技术。在9只狗的65对测量中发现，与体内样本相比，注射器样本中的pH值总是被高估，而PCO₂值总是被低估。描述这种关系的方程如下：1）pH（注射器）= 0.995×pH（体内）+ 0.084；2）PCO₂（注射器）= 0.873×PCO₂（体内）+ 0.2。注射器样本低估真实PCO₂值的程度随绝对PCO₂值增加，这与脑脊液从注射器转移到pH电极过程中存在CO₂扩散损失的可能性一致（体内PCO₂为20、40、60和80 mmHg时，PCO₂（体内）- PCO₂（注射器）分别为2.4、4.9、7.5和10.0 mmHg）。这项研究表明，用于采集脑脊液的技术对于结果的预期准确性至关重要，并且在采样和测量过程中脑脊液的转移次数应减至最少以获得可靠结果。
