Anion gap corrected for albumin, phosphate and lactate is a good predictor of strong ion gap in critically ill patients: a nested cohort study

Abstract

ObjectiveCorrected anion gap and strong ion gap are commonly used to estimate unmeasured anions. We evaluated the performance of the anion gap corrected for albumin, phosphate and lactate in predicting strong ion gap in a mixed population of critically ill patients. We hypothesized that anion gap corrected for albumin, phosphate and lactate would be a good predictor of strong ion gap, independent of the presence of metabolic acidosis. In addition, we evaluated the impact of strong ion gap at admission on hospital mortality. MethodsWe included 84 critically ill patients. Correlation and agreement between the anion gap corrected for albumin, phosphate and lactate and strong ion gap was evaluated by the Pearson correlation test, linear regression, a Bland-Altman plot and calculating interclass correlation coefficient. Two subgroup analyses were performed: one in patients with base-excess <-2mEq/L (low BE group - lBE) and the other in patients with base-excess >-2mEq/L (high BE group - hBE). A logistic regression was performed to evaluate the association between admission strong ion gap levels and hospital mortality. ResultsThere was a very strong correlation and a good agreement between anion gap corrected for albumin, phosphate and lactate and strong ion gap in the general population (r2=0.94; bias 1.40; limits of agreement -0.75 to 3.57). Correlation was also high in the lBE group (r2=0.94) and in the hBE group (r2=0.92). High levels of strong ion gap were present in 66% of the whole population and 42% of the cases in the hBE group. Strong ion gap was not associated with hospital mortality by logistic regression. ConclusionAnion gap corrected for albumin, phosphate and lactate and strong ion gap have an excellent correlation. Unmeasured anions are frequently elevated in critically ill patients with normal base-excess. However, there was no association between unmeasured anions and hospital mortality.

Acid/base alterations during major abdominal surgery: 6% hydroxyethyl starch infusion versus 5% albumin

“…SIG is more sensitive at detecting unmeasured anions than AG when serum albumin and phosphate concentrations fluctuate, because anionic albumin and phosphate concentrations are included in its calculation [ 19 ]. In patients with hypoalbuminemia, albumincorrected AG, but not A Gobserved , has been reported to be a good estimator of unmeasured anions [ 20 , 21 ]. Nevertheless, A Gcorrected also provides a better approximation of acid-base status than SIG, because it does not count ions such as Mg 2+ , Ca 2+ , lactate − , and Pi − [ 22 ].…”

The Liver in Critical Illness

“…The anion gap corrected for albumin, phosphate, and lactate correlates well with strong ion difference, although this has not been associated with hospital mortality. 37 Respiratory A previous article addressed in detail respiratory complications of cirrhosis including hepatopulmonary syndrome and portopulmonary hypertension. Critically ill patients with liver disease are also at increased risk for pneumonia, pleural effusions, atelectasis, cardiogenic pulmonary edema, and acute respiratory distress syndrome (ARDS).…”

The Effects of Serum Phosphate on 28-day Mortality in Patients Hospitalized in the Intensive Care Unit, Treated with Mechanical Ventilator Therapy and Treated with CRRT for Septic Shock-Induced Acute Kidney Injury

“…Serum fosfat düzensizlikleri septik şokla ilgili metabolik bulgulardır. Serum fosfat düzeyleri yoğun bakım hastalarının mortalite ve morbiditeleriyle ilişkilidir [3] . Septik akut böbrek hasarı (ABH) yoğun bakım ünitesinde (YBÜ) yaygın görülen bir ABH sendromudur ve tüm ABH vakalarının yarıya yakınını oluşturur [4] .…”