Base excess is superior to lactate-levels in prediction of ICU mortality after cardiac surgery

Abstract

IntroductionCardiac surgery with the use of cardiopulmonary bypass is known to induce distinct metabolic changes. Respective changes in acid-base status including increased systemic lactate levels were previously related to clinical outcomes, but data remain controversial. Therefore, we aim to investigate the relevance of lactate and base excess (BE) levels on ICU-mortality in patients admitted to the ICU after cardiac surgery.Materials and methodsPerioperative data of patients treated in a tertiary care academic center admitted to the ICU after on-pump surgery were analyzed in a retrospective fashion. Receiver operation characteristic (ROC) curves were constructed for admission lactate-levels and BE with calculation of optimal cut-off values to predict ICU mortality. Univariate followed by multivariate regression models were constructed to identify potential outcome-relevant indices.ResultsData from 1,058 patients were included in the analysis. Area under the curves for prediction of ICU mortality were 0.79 for lactate levels at ICU admission (sensitivity 61.9%/ specificity 87.5%; optimal cut-off level 3.9mmol/l), and 0.7 for BE (sensitivity 52.4%/ specificity 93.8%, optimal cut-off level -6.7), respectively. Multivariate regression identified BE < -6.7 as the single metabolic predictor of ICU-mortality (HR 4.78, 95%-CI 1.4–16.33, p = 0.01). Explorative subgroup analyses revealed that the combination of lactate ≤3.9mmol/l and BE ≤ -6.7 has stronger impact on mortality than a combination of lactate of >3.9mmol/l and BE > -6.7 (HR 2.56, 95%-CI 0.18–37.17).ConclusionsAt ICU-admission, severely reduced BE appears superior to hyperlactatemia with regard to prediction of ICU-mortality in patients after cardiac surgery.

Prolonged use of noninvasive positive pressure ventilation after extubation among patients in the intensive care unit following cardiac surgery: The predictors and its impact on patient outcome

“…However, patients who required prolonged NIPPV for durations over 72 h were at a significantly increased risk of postoperative complications and morbidity (longer ICU and hospital stays). Our study patients had a longer ICU and hospital stay than those among patients in recent studies 44–46 . Many factors, such as age, renal failure, and underlying disease influence the length of stay 47 .…”

Course of Lactate, pH and Base Excess for Prediction of Mortality in Medical Intensive Care Patients - A Retrospective Cohort Analysis

“…However, base excess and pH were not superior to lactate for prediction of mortality in this unselected cohort of medical ICU patients. This is in contrast to patients after heart surgery at admission to ICU, where base excess was superior to lactate for prediction of mortality 7 and trauma patients, where base excess has been found a strong predictor of mortality 9,14 . In our analyses, lactate was the strongest predictor of ICU mortality, followed by pH: Lactate values showed the highest AUROC in univariate and multivariable ROC analyses and the highest Hazard ratio per standard deviation increase; pH values had the second highest AUROC in multivariable ROC analysis; Kaplan Meier curve stratified by maximum lactate over the first 24 h and minimum pH over the first 24 h showed the clearest separations.…”

“…To count for the ability to buffer a metabolic (lactate) acidosis, parameters of acid-base balance, such as base excess or pH, could represent the body's conditions as more general parameters than lactate. Acid-base parameters have recently been evaluated as parameters for estimation of mortality in different subgroups of patients: In patients after cardiac surgery, base excess at ICU admission was a stronger parameter for prediction of ICU mortality than lactate-levels 7 . Lactate, anion gap and base excess were interchangeable biomarkers of traumatic shock 8 and base excess was a strong predictor of mortality in a large cohort of trauma patients 9 .…”

Association between base excess and mortality in patients with congestive heart failure

“…The BE value on administration is also a greater indicator for predicting outcomes in patients admitted to the ICU 7 . Another study showed that BE can also predict the risk of ICU mortality in patients undergoing cardiac surgery 15 . These findings suggest that BE value is a notable indicator of hypoperfusion and potentially unstable conditions in patients without hypotension at admission.…”