Department of Emergency Medicine, University of California, Irvine, CA 92868, USA.
Am J Emerg Med. 2012 Oct;30(8):1371-7. doi: 10.1016/j.ajem.2011.09.027. Epub 2011 Dec 12.
The objective of this study is to assess if venous blood gas (VBG) results (pH and base excess [BE]) are numerically similar to arterial blood gas (ABG) in acutely ill trauma patients.
We prospectively correlated paired ABG and VBG results (pH and BE) in adult trauma patients when ABG was clinically indicated. A priori consensus threshold of clinical equivalence was set at ± less than 0.05 pH units and ± less than 2 BE units. We hypothesized that ABG results could be predicted by VBG results using a regression equation, derived from 173 patients, and validated on 173 separate patients.
We analyzed 346 patients and found mean arterial pH of 7.39 and mean venous pH of 7.35 in the derivation set. Seventy-two percent of the paired sample pH values fell within the predefined consensus equivalence threshold of ± less than 0.05 pH units, whereas the 95% limits of agreement (LOAs) were twice as wide, at -0.10 to 0.11 pH units. Mean arterial BE was -2.2 and venous BE was -1.9. Eighty percent of the paired BE values fell within the predefined ± less than 2 BE units, whereas the 95% LOA were again more than twice as wide, at -4.4 to 3.9 BE units. Correlations between ABG and VBG were strong, at r(2) = 0.70 for pH and 0.75 for BE.
Although VBG results do correlate well with ABG results, only 72% to 80% of paired samples are clinically equivalent, and the 95% LOAs are unacceptably wide. Therefore, ABG samples should be obtained in acutely ill trauma patients if accurate acid-base status is required.
本研究旨在评估在急性疾病创伤患者中，静脉血气（VBG）结果（pH 值和碱剩余[BE]）是否与动脉血气（ABG）在数值上相似。
我们前瞻性地比较了在临床需要 ABG 时成人创伤患者的 ABG 和 VBG 配对结果（pH 值和 BE）。临床等效性的预设共识阈值设定为 pH 值相差小于 0.05，BE 值相差小于 2。我们假设 ABG 结果可以通过来自 173 名患者的回归方程预测，并在 173 名独立患者中进行验证。
我们分析了 346 名患者，发现推导组的平均动脉 pH 值为 7.39，平均静脉 pH 值为 7.35。72%的配对样本 pH 值落在预设的共识等效性阈值±0.05 pH 单位内，而 95%的一致性界限（LOA）则宽了两倍，在-0.10 到 0.11 pH 单位之间。平均动脉 BE 值为-2.2，静脉 BE 值为-1.9。80%的配对 BE 值落在预设的±2 BE 单位内，而 95%的 LOA 再次宽了两倍，在-4.4 到 3.9 BE 单位之间。ABG 和 VBG 之间的相关性很强，pH 值的 r(2)为 0.70，BE 值的 r(2)为 0.75。
尽管 VBG 结果与 ABG 结果相关性良好，但只有 72%到 80%的配对样本在临床上等效，95%的 LOA 过大。因此，如果需要准确的酸碱状态，应在急性疾病创伤患者中获得 ABG 样本。
