DOI QR코드

DOI QR Code

Discrepancies and Validation of Ethanol Level Determination with Osmolar Gap Formula in Patients with Suspected Acute Poisoning

급성 중독환자에서 삼투압 계산식으로 추정된 에탄올 농도의 유효성 검증

  • Jung, Haewon (Department of Emergency Medicine, School of Medicine, Kyungpook National University) ;
  • Lee, Mi Jin (Department of Emergency Medicine, School of Medicine, Kyungpook National University) ;
  • Cho, Jae Wan (Department of Emergency Medicine, School of Medicine, Kyungpook National University) ;
  • Ahn, Jae Yun (Department of Emergency Medicine, School of Medicine, Kyungpook National University) ;
  • Kim, Changho (Department of Emergency Medicine, School of Medicine, Kyungpook National University)
  • 정해원 (경북대학교 의과대학 응급의학교실) ;
  • 이미진 (경북대학교 의과대학 응급의학교실) ;
  • 조재완 (경북대학교 의과대학 응급의학교실) ;
  • 안재윤 (경북대학교 의과대학 응급의학교실) ;
  • 김창호 (경북대학교 의과대학 응급의학교실)
  • Received : 2019.06.06
  • Accepted : 2019.11.15
  • Published : 2019.12.31

Abstract

Purpose: Osmolar gap (OG) has been used for decades to screen for toxic alcohol levels. However, its reliability may vary due to several reasons. We validated the estimated ethanol concentration formula for patients with suspected poisoning and who visited the emergency department. We examined discrepancies in the ethanol level and patient characteristics by applying this formula when it was used to screen for intoxication due to toxic levels of alcohol. Methods: We retrospectively reviewed 153 emergency department cases to determine the measured levels of toxic ethanol ingestion and we calculated alcohol ingestion using a formula based on serum osmolality. Those patients who were subjected to simultaneous measurements of osmolality, sodium, urea, glucose, and ethanol were included in this study. Patients with exposure to other toxic alcohols (methanol, ethylene glycol, or isopropanol) or poisons that affect osmolality were excluded. OG (the measured-calculated serum osmolality) was used to determine the calculated ethanol concentration. Results: Among the 153 included cases, 114 had normal OGs (OG≤14 mOsm/kg), and 39 cases had elevated OGs (OG>14). The mean difference between the measured and estimated (calculated ethanol using OG) ethanol concentration was -9.8 mg/dL. The 95% limits of agreement were -121.1 and 101.5 mg/dL, and the correlation coefficient R was 0.7037. For the four subgroups stratified by comorbidities and poisoning, the correlation coefficients R were 0.692, 0.588, 0.835, and 0.412, respectively, and the mean differences in measurement between the measured and calculated ethanol levels were -2.4 mg/dL, -48.8 mg/dL, 9.4 mg/dL, and -4.7 mg/dL, respectively. The equation plots had wide limits of agreement. Conclusion: We found that there were some discrepancies between OGs and the calculated ethanol concentrations. Addition of a correction factor for unmeasured osmoles to the equation of the calculated serum osmolality would help mitigate these discrepancies.

Keywords

References

  1. Garrard A, Sollee DR, Butterfield RC, et al. Validation of a pre-existing formula to calculate the contribution of ethanol to the osmolar gap. Clin Toxicol (Phila) 2012;50:562-6. https://doi.org/10.3109/15563650.2012.704039
  2. Hovda KE, Hunderi OH, Rudberg N, et al. Anion and osmolal gaps in the diagnosis of methanol poisoning: clinical study in 28 patients. Intensive Care Med 2004;30:1842-6. https://doi.org/10.1007/s00134-004-2373-7
  3. Choy KW, Wijeratne N, Lu ZX, et al. Harmonisation of Osmolal Gap - Can We Use a Common Formula? Clin Biochem Rev 2016;37:113-9.
  4. Osterloh JD, Kelly TJ, Khayam-Bashi H, et al. Discrepancies in osmolal gaps and calculated alcohol concentrations. Arch Pathol Lab Med 1996;120:637-41.
  5. Purssell RA, Pudek M, Brubacher J, et al. Derivation and validation of a formula to calculate the contribution of ethanol to the osmolal gap. Ann Emerg Med 2001;38:653-9. https://doi.org/10.1067/mem.2001.119455
  6. Khajuria A, Krahn J. Osmolality revisited--deriving and validating the best formula for calculated osmolality. Clin Biochem 2005;38:514-9. https://doi.org/10.1016/j.clinbiochem.2005.03.001
  7. Lepeytre F, Ghannoum M, Ammann H, et al. Formulas for calculated osmolarity and osmolal gap: a study of diagnostic accuracy. Am J Kidney Dis 2017;70:347-56. https://doi.org/10.1053/j.ajkd.2017.03.023
  8. Krasowski MD, Wilcoxon RM, Miron J. A retrospective analysis of glycol and toxic alcohol ingestion: utility of anion and osmolal gaps. BMC Clin Pathol 2012;12:1. https://doi.org/10.1186/1472-6890-12-1
  9. Lynd LD, Richardson KJ, Purssell RA, et al. An evaluation of the osmole gap as a screening test for toxic alcohol poisoning. BMC Emerg Med 2008;8:5. https://doi.org/10.1186/1471-227X-8-5
  10. Siervo M, Bunn D, Prado CM, et al. Accuracy of prediction equations for serum osmolarity in frail older people with and without diabetes. Am J Clin Nutr 2014;100:867-76. https://doi.org/10.3945/ajcn.114.086769
  11. Lee DW, Cho YS, Lim H, et al. A study of the Tono-Pen for assessing ocular pressure in patients with headache combined with ocular pain in the emergency department. J Korean Soc Emerg Med 2009;20:210-4.
  12. Heavens KR, Kenefick RW, Caruso EM, et al. Validation of equations used to predict plasma osmolality in a healthy adult cohort. Am J Clin Nutr 2014;100:1252-6. https://doi.org/10.3945/ajcn.114.091009
  13. Geller RJ, Spyker DA, Herold DA, et al. Serum osmolal gap and ethanol concentration: a simple and accurate formula. J Toxicol Clin Toxicol 1986;24:77-84. https://doi.org/10.3109/15563658608990448
  14. Carstairs SD, Suchard JR, Smith T, et al. Contribution of serum ethanol concentration to the osmol gap: a prospective volunteer study. Clin Toxicol (Phila) 2013;51:398-401. https://doi.org/10.3109/15563650.2013.791695
  15. Purssell RA, Lynd LD, Koga Y. The use of the osmole gap as a screening test for the presence of exogenous substances. Toxicol Rev 2004;23:189-202. https://doi.org/10.2165/00139709-200423030-00005
  16. Glaser DS. Utility of the serum osmol gap in the diagnosis of methanol or ethylene glycol ingestion. Ann Emerg Med 1996;27:343-6. https://doi.org/10.1016/S0196-0644(96)70271-8
  17. Snyder H, Williams D, Zink B, et al. Accuracy of blood ethanol determination using serum osmolality. J Emerg Med 1992;10:129-33. https://doi.org/10.1016/0736-4679(92)90205-8
  18. Davidson DF. Excess osmolal gap in diabetic ketoacidosis explained. Clin Chem 1992;38:755-7. https://doi.org/10.1093/clinchem/38.5.755
  19. Chang HW, Sim MS, Han SK, et al. Correlation between the osmolar gap and serum ethanol level and the accuracy of estimated ethanol level in trauma patients and non-trauma patients. J Korean Soc Traumatol 2009;22:148-53.