Metabolic acidosis and the role of unmeasured anions in critical illness and injury

Association between albumin-corrected anion gap and in-hospital mortality of intensive care patients with trauma: A retrospective study based on MIMIC-Ⅲ and Ⅳ databases

BACKGROUND

To investigate the correlation between albumin-corrected anion gap(ACAG) within the first 24 hours of admission and in-hospital mortality in trauma patients in intensive care unit(ICU).

MATERIALS AND METHODS

We utilized the MIMIC-Ⅲ and MIMIC-Ⅳ databases to examine trauma patients admitted to the ICU. The relationship between ACAG and in-hospital mortality in trauma patients was analyzed using Receiver Operating Characteristic(ROC) curve, Kaplan-Meier (K-M) survival curve, and Cox regression model. Propensity score matching (PSM) and subgroup analysis were conducted to enhance stability and reliability of the findings. Mortality at 30-day and 90-day served as secondary outcomes.

RESULTS

The study enrolled a total of 1038 patients. The AUC for ACAG (0.701, 95%CI: 0.652-0.749) was notably higher than that for anion gap and albumin. The Log-rank test revealed that the optimal cut-off point of ACAG for predicting in-hospital mortality was determined to be 20.375mmol/L. The multivariate Cox regression analysis demonstrated an independent association between high ACAG level and a higher risk of in-hospital mortality (HR = 3.128, 95% CI: 1.615-6.059). After PSM analysis, a matched cohort consisting of 291 subjects was obtained. We found no signifcant interaction in most stratas. Finally, The in-hospital, 30-day, and 90-day survival rates in the high ACAG group exhibited a statistically decrease compared to those in the low ACAG group both pre- and post-matching.

CONCLUSION

The elevated level of ACAG was found to be independently associated with increased in-hospital mortality among trauma patients in the ICU.

Acid-Base Analysis in the Operating Room: A Bedside Stewart Approach

The bedside Stewart approach to acid–base disorders is a simple, pragmatic tool that can assist anesthesiologists in analyzing and managing acid–base changes in the operating room, particularly metabolic acidosis.

Unmeasured Organic Anions as Predictors of Clinical Outcomes in Lactic Acidosis due to Sepsis

Background and Objectives: In lactic acidosis, lactate can only explain 30% of the variance in the anion gap (AG), and the elevated AG not explained by lactate is due to unmeasured organic anions (UOAs). Some studies using less precise surrogates for UOA have suggested that UOA may predict clinical outcomes better than lactate. The aim of this study was to determine whether UOA predicts clinical outcomes better than lactate levels. Design, Setting, Participants, & Measurements: This was a retrospective cohort study of adult ICU patients with sepsis. Baseline AG and albumin measurements were obtained. An albumin-corrected delta AG was calculated. UOAs were estimated using the formula: Delta AG - serum lactate. A multivariate logistic regression model with its respective ROC curve was constructed to explore the relationship between in-hospital mortality, UOA, and lactate. Results: 526 patients were included. In the combined model examining both lactate and UOA, the odds ratio (OR) [95% CI] for predicting ICU length of stay (LOS) was 1.050 [1.029-1.072] and 1.022 [1.009-1.035], respectively; the OR [95% CI] for predicting in-hospital mortality was 1.224 [1.104-1.358] and 0.997 [0.943-1.054], respectively. The ROC curve for in-hospital mortality demonstrated that the Area Under the Curve (AUC) for lactate, UOA, and combined lactate and UOA was 0.7726, 0.7486, and 0.7732, respectively. The AUC for combined lactate and UOA were not statistically significantly higher than the AUC for lactate alone (P .9193). Conclusions: As expected, serum lactate predicted both ICU LOS and in-hospital mortality. UOA did predict ICU LOS, although the reason for this association is not known. UOA did not predict in-hospital mortality based on the OR and the ROC curve's AUC, contrary to some previous studies. However, our study used a more precise quantitative estimate of UOA, including the use of baseline albumin-corrected AG. Prior studies attempting to identify UOA have identified Krebs cycle intermediates including citrate and isocitrate, suggesting that in our study these anions associated with the Krebs cycle contributed to the UOA.

Determinants of Total/ionized Calcium in patients undergoing citrate CVVH: A retrospective observational study

PURPOSE

To identify potential determinants of the Total/ionized Ca ratio (T/iCa), a marker of citrate accumulation.

MATERIALS AND METHODS

Single-center retrospective observational study evaluating citrate dose, citrate target, albumin, phosphate, pH, lactate, and APACHE II score as potential determinants. Linear mixed models (LMM) using citrate dose and citrate target were developed describing associations with T/iCa.

RESULTS

From a dataset of 471 samples in 103 patients, an LMM in 379 complete samples (95 patients) sets revealed that citrate dose, pH, phosphate, albumin and APACHE were interactively related to T/iCa. A rising citrate dose was associated with a higher increase in T/iCa when phosphate was high, and less when phosphate was low. A rising albumin was associated with a higher increase in T/iCa when APACHE was high and phosphate was low and less when APACHE was low and phosphate high. In case of acidosis, a rising lactate was associated with a higher increase in T/iCa. In the LMM using citrate target, citrate target and pH were the main independent predictors of T/iCa with albumin, phosphate and APACHE score as modifiers.

CONCLUSIONS

Besides citrate dose, a high pH and high phosphate, albumin and APACHE are also associated with a rising T/iCa.