BackgroundOutcome prediction scoring systems are increasingly used in intensive care medicine, but most were not developed for use in cardiac surgery patients. We compared the performance of four intensive care outcome prediction scoring systems (Acute Physiology and Chronic Health Evaluation II [APACHE II], Simplified Acute Physiology Score II [SAPS II], Sequential Organ Failure Assessment [SOFA], and Cardiac Surgery Score [CASUS]) in patients after open heart surgery.MethodsWe prospectively included all consecutive adult patients who underwent open heart surgery and were admitted to the intensive care unit (ICU) between January 1st 2007 and December 31st 2008. Scores were calculated daily from ICU admission until discharge. The outcome measure was ICU mortality. The performance of the four scores was assessed by calibration and discrimination statistics. Derived variables (Mean- and Max- scores) were also evaluated.ResultsDuring the study period, 2801 patients (29.6% female) were included. Mean age was 66.9 ± 10.7 years and the ICU mortality rate was 5.2%. Calibration tests for SOFA and CASUS were reliable throughout (p-value not < 0.05), but there were significant differences between predicted and observed outcome for SAPS II (days 1, 2, 3 and 5) and APACHE II (days 2 and 3). CASUS, and its mean- and maximum-derivatives, discriminated better between survivors and non-survivors than the other scores throughout the study (area under curve ≥ 0.90). In order of best discrimination, CASUS was followed by SOFA, then SAPS II, and finally APACHE II. SAPS II and APACHE II derivatives had discrimination results that were superior to those of the SOFA derivatives.ConclusionsCASUS and SOFA are reliable ICU mortality risk stratification models for cardiac surgery patients. SAPS II and APACHE II did not perform well in terms of calibration and discrimination statistics.

Most of general ICU scoring systems use extensive data collection and focus on the first day of ICU stay. Despite this fact, general scores do not perform well in the prediction of outcome in cardiac surgical patients. Our new 10-variable risk index performs very well, with calibration and discrimination very high, better than general severity systems, and it is an appropriate tool for daily risk stratification in ICU cardiac surgery patients. Thus, it may serve as an expert system for diagnosing organ failure and predicting mortality in ICU cardiac surgical patients.

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.

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.

The Provox (Atos Medical AB, Hörby, Sweden) voice prosthesis was developed between 1988 and 1990 and has been used at our centre with regular success since 1993. Since 1996, a second generation of Provox (Provox2) has been used, which can be inserted by an anterograde technique. The aim of this study is to compare the survival lifetime of both voice prostheses. The survival time of the two voice prostheses were compared retrospectively in 152 devices placed in 38 patients. A Kaplan-Meier analysis was performed to determine the survival lifetimes and a log rank test was performed to compare the two curves. Clinical factors affecting the lifetime were also analysed with a Kaplan-Meier plot. The median survival lifetime of the Provox and Provox2 were 303 and 144 days respectively. The Kaplan-Meier estimation shows that this difference is statistically significant (p=0.02). It is considered an early failure if it occurs within the first three months. There was a larger number of early failures with the Provox2 than with the Provox (p=0.04). Neither the gender nor the age affected the lifetime of the devices. Radiotherapy seemed to lengthen the lifetime of the first valve. The survival lifetime of the second generation Provox2 valve is shorter than the lifetime of the first generation Provox. This could be due to the difference in elasticity of these valves that could lead to a different level of colonization and invasion of the valves by micro-organisms.