Mortality prediction after cardiac surgery: blood lactate is indispensible.

Blood lactate is accepted as a mortality risk marker in intensive care units (ICUs), especially after cardiac surgery. Unfortunately, most of the commonly used ICU risk stratification scoring systems did not include blood lactate as a variable. We hypothesized that blood lactate alone can predict the risk of mortality after cardiac surgery with an accuracy that is comparable to those of other complex models. We therefore evaluated its accuracy at mortality prediction and compared it with that of other widely used complex scoring models statistically. We prospectively collected data of all consecutive adult patients who underwent cardiac surgery between January 1, 2007, and December 31, 2009. By using χ2 statistics, a blood lactate-based scale (LacScale) with only four cutoff points was constructed in a developmental set of patients (January 1, 2007, and May 31, 2008). LacScale included five categories: 0 (≤ 1.7 mmol/L); 1 (1.8-5.9 mmol/L), 2 (6.0-9.3 mmol/L), 3 (9.4-13.3 mmol/L), and 4 (≥ 13.4 mmol/L). Its accuracy at predicting ICU mortality was evaluated in another independent subset of patients (validation set, June 1, 2008, and December 31, 2009) on both study-population level (calibration analysis, overall correct classification) and individual-patient-risk level (discrimination analysis, ROC statistics). The results were then compared with those obtained from other widely used postoperative models in cardiac surgical ICUs (Sequential Organ Failure Assessment [SOFA] score, Simplified Acute Physiology Score II [SAPS II], and Acute Physiology and Chronic Health Evaluation II [APACHE II] score). ICU mortality was 5.8% in 4,054 patients. LacScale had a reliable calibration in the validation set (2,087 patients). It was highly accurate in predicting ICU mortality with an area under the ROC curve (area under curve [AUC]; discrimination) of 0.88. This AUC was significantly larger than that of all the other models (SOFA 0.83, SAPS II: 0.79 and APACHE II: 0.76) according to DeLong's comparison. Integrating the LacScale in those scores further improved their accuracy by increasing their AUCs (0.88, 0.81, and 0.80, respectively). This improvement was also highly significant. Blood lactate accurately predicts mortality at both individual patient risk and patient cohort levels. Its precision is higher than that of other commonly used "complex" scoring models. The proposed LacScale is a simple and highly reliable model. It can be used (at bedside without electronic calculation) as such or integrated in other models to increase their accuracy.

Badreldin AM ，Doerr F ，Elsobky S ，Brehm BR ，Abul-dahab M ，Lehmann T ，Bayer O ，Wahlers T ，Hekmat K ... -  《-》

Daily-Mean-SOFA, a new derivative to increase accuracy of mortality prediction in cardiac surgical intensive care units.

Sequential organ failure assessment (SOFA) score is widely used in many cardiac surgical intensive care units (ICUs). Its derivatives (mean and maximum values) are known to be more accurate than the original daily values of SOFA itself. However, they were designed for research purposes and could be calculated only after ICU discharge. We aimed to develop a reliable derivative that can be easily calculated daily (Daily-Mean-SOFA) for aiding daily-decision-making and resource allocation. All consecutive adult cardiac surgical patients from our ICU between January 1, 2007 and December 31, 2008 were included. We obtained Initial-SOFA (on day 1), the Original-Daily-SOFA value from the 1st to the 6th postoperative day, Max-SOFA (highest SOFA value during the whole ICU-stay), Mean-SOFA (sum of all daily SOFA values/the length of ICU-stay), and the new "Daily-Mean-SOFA" from day 2 to 6 (sum of SOFA from day 1 until day-n/n). We compared their accuracies at predicting ICU mortality using calibration and discrimination statistics. Total 2801 patients were included. The newly developed "Daily-Mean-SOFA" was significantly more accurate than the corresponding SOFA value of the same day in correctly predicting survival and mortality in the whole study population (OCC: 94.1 to 95.0%) and in accurately identifying the individual patient's risk of mortality (AUC: 0.859 to 0.904). It was better than all other derivatives except the Mean-SOFA which was superior to it (OCC: 96.3%; AUC: 0.913). The Daily-Mean-SOFA is a reliable derivative for daily risk stratification in cardiac ICUs. Due to its accuracy and daily availability, it may be used for risk-directed therapy in cardiac ICUs.

Badreldin A ，Elsobky S ，Lehmann T ，Brehm BB ，Doenst T ，Hekmat K ... -  《-》

Comparison between Sequential Organ Failure Assessment score (SOFA) and Cardiac Surgery Score (CASUS) for mortality prediction after cardiac surgery.

Our purpose was to evaluate and compare the accuracy of the "Sequential Organ Failure Assessment" score (SOFA) and the "Cardiac Surgery Score" (CASUS) for the prediction of mortality after cardiac surgery. Between January 1, 2007 and December 31, 2008 we prospectively included all consecutive adult patients admitted to our intensive care unit (ICU) after cardiac surgery. Both scoring systems were calculated daily from the 1st day in the ICU (day of operation) until the 7th ICU day. We evaluated the ICU mortality prediction of both models using calibration and discrimination statistics. 2801 patients (29.6% females) were included. Mean age was 66.9 ± 10.7 years. Intensive care unit mortality was 5.2%. The calibration of the "Sequential Organ Failure Assessment Score" and "Cardiac Surgery Score" was reliable for all days (p ≥ 0.05). CASUS was more accurate in predicting survival and mortality compared to SOFA for all days, as evidenced by the larger areas under the Receiver Operating Characteristic curves. Both CASUS and SOFA are reliable mortality prediction tools after cardiac surgery. However, CASUS was more accurate in predicting the individual patient's risk of mortality. Thus, use of the CASUS in cardiac surgery intensive care units is recommended.

Badreldin AM ，Doerr F ，Ismail MM ，Heldwein MB ，Lehmann T ，Bayer O ，Doenst T ，Hekmat K ... -  《-》

Implementation of EuroSCORE II as an adjunct to APACHE II model and SOFA score, for refining the prognostic accuracy in cardiac surgical patients.

Tsaousi GG ，Pitsis AA ，Ioannidis GD ，Pourzitaki CK ，Yannacou-Peftoulidou MN ，Vasilakos DG ... -  《-》

High lactate levels are predictors of major complications after cardiac surgery.

Although hyperlactatemia after cardiac surgery is common, the implications of raised levels remain controversial. The aim of this study was to evaluate whether high lactate levels after cardiac surgery are predictors of major complications including mortality. This was a substudy of TRACS (Transfusion Requirements After Cardiac Surgery), which was designed as a prospective, randomized, controlled trial evaluating the effects of a transfusion strategy on morbidity and mortality. Of the 502 patients enrolled, 52 (10%) had at least 1 major complication. Patients with complications were older, had a higher EuroSCORE, lower left ventricular ejection fraction, lower preoperative hemoglobin, a higher prevalence of renal disease, and received more blood transfusions than the group without complications. Lactate levels were higher in the group with complications at the end of surgery (3.6 mmol/L [2.8-5.1] vs 3.3 mmol/L [2.2-4.8]; P = .018), immediately after intensive care unit (ICU) admission (0 hour) (4.4 mmol/L [3.1-8.4] vs 4 mmol/L [2.6-6.4]; P = .048); 6 hours (4 mmol/L [2.7-5.8] vs 2.6 mmol/L [2-3.6], P < .001), and 12 hours after admission (2.3 mmol/L [1.8-3.2] vs 1.7 mmol/L [1.3-2]; P < .001). In a multivariate model, higher age (odds ratio [OR], 1.048, 95% confidence interval [CI], 1.011-1.086; P = .010), left ventricular ejection fraction (LVEF) lower than 40% (OR, 3.03; 95% CI, 1.200-7.510; P = .019 compared with LVEF of 40%-59%; OR, 3.571; 95% CI, 1.503-8.196; P = .004 compared with LVEF higher than 60%), higher EuroSCORE (OR, 1.138; 95% CI; 1.007-1.285; P = .038), red blood cell transfusion (OR, 1.230; 95% CI, 1.086-1.393; P = .001), and lactate levels 6 hours after ICU admission (OR, 3.28, 95% CI; 1.61-6.69; P = .001) are predictors of major complications. Hyperlactatemia 6 hours after ICU admission is an independent risk factor for worse outcomes in adult patients after cardiac surgery.

Hajjar LA ，Almeida JP ，Fukushima JT ，Rhodes A ，Vincent JL ，Osawa EA ，Galas FR ... -  《-》