Department of Emergency Medicine, Upstate New York Poison Center at Upstate Medical University, Syracuse, NY 13202, USA.
Clin Toxicol (Phila). 2012 Aug;50(7):562-6. doi: 10.3109/15563650.2012.704039. Epub 2012 Jul 6.
The aim of this study was to validate the formula derived by Purssell et al. that relates blood ethanol concentration to the osmolar gap and determine the best coefficient for use in the formula. The osmolar gap is often used to help diagnose toxic alcohol poisoning when direct measurements are not available.
Part I of the study consisted of a retrospective review of 603 emergency department patients who had a concurrent ethanol, basic metabolic panel and a serum osmolality results available. Estimated osmolarity (excluding ethanol) was calculated using a standard formula. The osmolar gap was determined by subtracting estimated osmolarity from the actual osmolality measured by freezing point depression. The relationship between the osmolar gap and the measured ethanol concentration was assessed by linear regression analysis. In Part II of this study, predetermined amounts of ethanol were added to aliquots of plasma and the estimated and calculated osmolarities were subjected to linear regression analysis.
In the cases of 603 patients included in Part I of the study, the median ethanol concentration in these patients was 166 mg/dL (Q1: 90, Q3: 254) and the range ethanol concentrations was 10-644 mg/dL. The mean serum osmolality was 338 mOsm/kg (SD: 30) and a range of 244-450 mOsm/kg. The mean osmolar gap was 47 (SD: 29) and a range of - 15 to 55. There was a significant proportional relationship between ethanol concentration and osmolar gap (r(2) = 0.9882). The slope of the linear regression line was 0.2498 (95% CI: 0.2472-0.2524). The slope of the linear regression line derived from the data in Part II of the study was 0.2445 (95% CI: 0.2410-0.2480).
The results of our study are in fairly close agreement with previous studies that used smaller samples and suggest that an accurate conversion factor for estimating the contribution of ethanol to the osmolar gap is [Ethanol (mg/dL)]/4.0.
本研究旨在验证 Purssell 等人提出的血乙醇浓度与渗透间隙关系的公式，并确定该公式中最佳的系数。当无法直接测量时，渗透间隙通常用于帮助诊断有毒性的酒精中毒。
研究的第一部分是对 603 名同时有乙醇、基本代谢组和血清渗透压结果的急诊科患者进行回顾性分析。采用标准公式计算估计渗透压（不包括乙醇）。渗透间隙通过从冰点降低法测量的实际渗透压中减去估计渗透压来确定。通过线性回归分析评估渗透间隙与实测乙醇浓度之间的关系。在本研究的第二部分中，向血浆等分试样中添加预定量的乙醇，对估计和计算的渗透压进行线性回归分析。
在研究的第一部分纳入的 603 例患者中，这些患者的中位乙醇浓度为 166mg/dL（Q1：90，Q3：254），乙醇浓度范围为 10-644mg/dL。血清渗透压的平均值为 338mOsm/kg（SD：30），范围为 244-450mOsm/kg。平均渗透间隙为 47（SD：29），范围为-15 至 55。乙醇浓度与渗透间隙之间存在显著的比例关系（r²=0.9882）。线性回归直线的斜率为 0.2498（95%CI：0.2472-0.2524）。从研究第二部分的数据中得出的线性回归直线的斜率为 0.2445（95%CI：0.2410-0.2480）。
本研究的结果与之前使用较小样本量的研究结果相当吻合，表明准确的转换因子用于估计乙醇对渗透间隙的贡献是[乙醇（mg/dL）]/4.0。
