Utility of Stewart's Approach to Diagnose Missed Complex Acid–Base Disorders as Compared to Bicarbonate-anion Gap-based Methodology in Critically Ill Patients: An Observational Study
Rohit Paliwal, Adrian Pakavakis
Citation Information :
Paliwal R, Pakavakis A. Utility of Stewart's Approach to Diagnose Missed Complex Acid–Base Disorders as Compared to Bicarbonate-anion Gap-based Methodology in Critically Ill Patients: An Observational Study. Indian J Crit Care Med 2022; 26 (1):23-32.
Background: Traditional arterial blood gas (ABG) analysis may miss out on some metabolic acid–base disorders. We prospectively compared Stewart's approach in critically ill patients to traditional bicarbonate-anion gap-based methods (with and without correction for albumin) to diagnose acid–base disorders. Patients and methods: Five hundred ABG samples from medical or surgical patients in the ICU were analyzed with traditional bicarbonate-anion gap-based methodology with and without correction for albumin and Stewart's biochemical approach. The primary outcome identification of additional metabolic disorders diagnosed with Stewart's approach in comparison to bicarbonate system-based approaches. We also looked at the correlation between the strong ion gap (SIG) and the albumin-corrected anion gap (acAnion Gap). Results: Stewart's approach detected missed metabolic disorders in 58 (11.6%) blood gas results reported as “within normal limits” with the bicarbonate-uncorrected anion gap approach. In 50 (10%) of these ABGs, the acAnion Gap approach was able to diagnose the missed metabolic disorders. Thus, the albumin-corrected anion gap method had a similar diagnostic performance to Stewart's approach, as it missed additional disorders in only eight (1.6%) blood gases. Conclusion: In this study, we found that the acAnion Gap approach was similar in diagnostic performance to Stewart's approach. We feel that the corrected anion gap approach can be safely used if a ready calculator for Stewart's approach is not available.
Narins RG, Emmett M. Simple and mixed acid–base disorders: a practical approach. Medicine (Baltimore) 1980;59(3):161–187. DOI: 10.1097/00005792-198005000-00001.
Emmet M, Narins RG. Clinical use of anion gap. Medicine (Baltimore) 1977;56(1):38–54. PMID: 401925.
Figge J, Jabor A, Kazda A, Fencl V. Anion gap and hypoproteinemia. Crit Care Med 1998;26(11):1807–1810. DOI: 10.1097/00003246-199811000-00019.
Durward A, Mayer A, Skellett S, Taylor D, Hanna S, Tibby SM, et al. Hypoalbuminaemia in critically ill children: Incidence, prognosis, and influence on the anion gap. Arch Dis Child 2003;88(5):419–422. DOI: 10.1136/adc.88.5.419.
Stewart PA. Modern quantitative acid–base chemistry. Can J Physiol Pharmacol 1983;61(12):1444–1461. DOI: 10.1139/y83-207.
Van Slyke DD, Hastings AB, Hiller A, Sendroy J Jr. Studies of gas and electrolyte equilibria in blood: XIV. Amounts of alkali bound by serum albumin and globulin. J Biol Chem 1928;79:769–780. DOI: 10.1016/S0021-9258(20)79962-X.
Figge J, Rossing TH, Fencl V. The role of serum proteins in acid–base equilibria. J Lab Clin Med 1991;117(6):453–467. PMID: 2045713.
Fencl V, Rossing TH. Acid–Base disorders in critical care medicine. Annu Rev Med 1989;40:17–29. DOI: 10.1146/annurev.me.40.020189.000313.
Cook L, Macdonald DH. Management of paraproteinaemia. Postgrad Med J 2007;83(978):217–223. DOI: 10.1136/pgmj.2006.054627.
Dubin A, Menises MM, Masevicius FD, Moseinco MC, Kutscherauer DO, Ventrice E, et al. Comparison of three different methods of evaluation of metabolic acid–base disorders. Crit Care Med 2007;35(5):1264–1270. DOI: 10.1097/01.CCM.0000259536.11943.90.
Fencl V, Jabor A, Kazda A, Figge J. Diagnosis of metabolic acid–base disturbances in critically ill patients. Am J Respir Crit Care Med 2000;162(6):2246–2251. DOI: 10.1164/ajrccm.162.6.9904099.
Murray T, Long W, Narins RG. Multiple myeloma and the anion gap. N Engl J Med 1975;292(11):574–575. DOI: 10.1056/NEJM197503132921107.
O'Connor DT, Stone RA. Hyperchloremia and negative anion gap associated with polymyxin B administration. Arch Intern Med 1978;138(3):478–480. PMID: 204265.
Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1(8476):307–310. PMID: 2868172.
McAuliffe JJ, Lind LJ, Leith DE, Fencl V. Hypoproteinemic alkalosis. Am J Med 1986;81(1):86–90. DOI: 10.1016/0002-9343(86)90187-7.
Chaiyakulsil C, Mueanpaopong P, Lertbunrian R, Chutipongtanate S. Connecting two worlds: positive correlation between physicochemical approach with blood gases and pH in pediatric ICU setting. BMC Res Notes 2019;12(1):742. DOI: 10.1186/s13104-019-4770-6.
Wilkes P. Hypoproteinemia, strong-ion difference, and acid–base status in critically ill patients. J Appl Physiol (1985) 1998;84(5):1740–1748. DOI: 10.1152/jappl.1998.84.5.1740.
Kaplan LJ, Kellum JA. Initial pH, base deficit, lactate, anion gap, strong ion difference, and strong ion gap predict outcome from major vascular injury. Crit Care Med 2004;32(5):1120–1124. DOI: 10.1097/01.ccm.0000125517.28517.74.
Dondorp AM, Chau TT, Phu NH, Mai NT, Loc PP, Chuong LV, et al. Unidentified acids of strong prognostic significance in severe malaria. Crit Care Med 2004;32(8):1683–1688. DOI: 10.1097/01.ccm.0000132901.86681.ca.
Cusack RJ, Rhodes A, Lochhead P, Jordan B, Perry S, Ball JA, et al. The strong ion gap does not have prognostic value in critically ill patients in a mixed medical/surgical adult ICU. Intensive Care Med 2002;28(7):864–869. DOI: 10.1007/s00134-002-1318-2.
Carreira F, Anderson RJ. Assessing metabolic acidosis in the intensive care unit: does the method make a difference? Crit Care Med 2004;32(5):1227–1228. DOI: 10.1097/01.ccm.0000125513.26170.d2.