Medical and Research Services VHAGLA Healthcare System, UCLA Membrane Biology Laboratory, and Division of Nephrology VHAGLA Healthcare System and David Geffen School of Medicine, Los Angeles, California, USA.
Department of Statistics, University of California at Los Angeles, Los Angeles, California, USA.
Am J Nephrol. 2018;48(1):15-20. doi: 10.1159/000489965. Epub 2018 Jul 10.
The initial assessment of acid-base status is usually based on the measurement of total CO2 concentration ([TCO2]) in venous blood, a surrogate for [HCO3-]. Previously, we posited that the reference limits of serum [TCO2] in current use are too wide. Based on studies on the acid-base composition of normal subjects, we suggested that the reference limits of serum [TCO2] at sea level be set at 23-30 mEq/L. To validate this proposal, we queried the University of California at Los Angeles (UCLA's) Integrated Clinical and Research Data Repository, a database containing information on 4.5 million patients seen at UCLA from 2006 to the present. Criteria for inclusion included adults (18-40 years of age), who were free of disorders that could affect acid-base balance, were not taking medications that could affect acid-base balance, and were seen for a routine medical examination or immunization in the outpatient setting. The number of individuals who met the inclusion criteria (52% female and 48% male) was 28,480, with a mean age of 28.9 ± 5.1 years. The mean serum [TCO2] level was slightly higher in males than females, 26.6 ± 2.16 mEq/L vs. 25.0 ± 2.11 mEq/L (p < 0.05). Ninety-one percent of patient values were within the proposed 23-30 mEq/L range and 61.7% were within the 24-27 mEq/L range. These findings validate our proposal that the reference range of serum [TCO2] in venous blood at sea level be narrowed to 23-30 mEq/L. Subjects with serum [TCO2] outside this range might require assessment with a venous blood gas to exclude the presence of clinically important acid-base disorders.
酸碱平衡状态的初始评估通常基于静脉血中总二氧化碳浓度（[TCO2]）的测量，该值可替代[HCO3-]。此前，我们假设当前使用的血清[TCO2]参考范围太宽。基于对正常受试者酸碱组成的研究，我们建议海平面地区血清[TCO2]的参考范围设定为 23-30 mEq/L。为了验证这一建议，我们查询了加利福尼亚大学洛杉矶分校（UCLA）的综合临床和研究数据存储库，该数据库包含了自 2006 年以来在 UCLA 就诊的 450 万名患者的信息。纳入标准包括成年人（18-40 岁），无影响酸碱平衡的疾病，未服用可能影响酸碱平衡的药物，且因常规体检或门诊免疫接种就诊。符合纳入标准的个体数量（女性占 52%，男性占 48%）为 28480 人，平均年龄为 28.9 ± 5.1 岁。男性的血清[TCO2]水平略高于女性，分别为 26.6 ± 2.16 mEq/L 和 25.0 ± 2.11 mEq/L（p < 0.05）。91%的患者值在建议的 23-30 mEq/L 范围内，61.7%在 24-27 mEq/L 范围内。这些发现验证了我们的建议，即海平面静脉血血清[TCO2]的参考范围应缩小至 23-30 mEq/L。血清[TCO2]超出此范围的患者可能需要进行静脉血气评估，以排除存在临床上重要的酸碱平衡紊乱。
